Implantable Defibrillator Research Articles

Real world battery longevity of the subcutaneous implantable cardioverter-defibrillator (S-ICD)

Abstract Background Subcutaneous implantable cardiac defibrillators (S-ICDs) protect against sudden cardiac death and avoid transvenous ICD lead complications. Objective To investigate S-ICD real-world battery longevity estimates and the impact of device parameters and advisory status. Methods Second and third generation S-ICD device longevity labeling is 7.3 years (yr) under normal use (e.g remote monitoring, pre-arrhythmia EGM storage, etc.). De-identified data from S-ICD devices implanted ≥3 months, with recent uploads from the patient devices to the LATITUDE system, were obtained in Nov 2022. For early to mid-life devices (15-100% battery life), longevity estimates were derived from storage time, implant time, and number of high voltage charges (HVC). For late-life devices, longevity estimates were calculated more accurately from battery voltage. Monte Carlo simulations estimated future HVCs. Multivariable maximum likelihood parameter models were used to analyze battery longevity determinants for the overall cohort and for patients who received >1 shock, assuming 1 shock due to conversion testing at implant. Variables were considered clinically significant if univariable difference and multivariable estimate’s magnitude were both ≥0.2 yr. Results are reported in median and interquartile range. Results The 32,678 EMBLEM devices had a 2.5 yr [1.2,4.1] device dwell-time with 8.7 yr [8.3,8.9] longevity estimate. Of these patients, 28,544 (87.3%) received ≥1 shocks and 11,480 (35.1%) received >2 shocks, including shocks delivered during conversion testing. Late life devices (n=3091, 9.5%) had a 5.2 yr [4.6,5.9] dwell time. For devices under the battery depletion advisory (n=13,900), the Monte Carlo model does not account for premature battery depletion (PBD), which is projected to impact 11.5% of advisory devices at 5 yrs. Longevity for PBD is 6.6 yr (Q4 2022 product performance report). While all variables except AF trend, AF episodes/yr, and post shock pacing statistically impact device longevity, only advisory status and number of device charges per yr impacted longevity by ≥0.2 yr (Figure, panel A). Patients who received >1 shock have 8.5 yr [8.0,8.8] longevity estimates, vs 8.8 [8.4,8.9] for patients with 0 or 1 shock. For patients with >1 shock, (Figure, panel B), only advisory status had a ≥0.2 yr impact on longevity in multivariable and univariable analyses. Dwell time, shocks delivered per yr, and system impedance software upgrade impacted longevity by only 0.1 yr in univariable analysis. Conclusion Median EMBLEM S-ICD longevity estimate is 8.7 years, which is longer than device labeling. Longevity is reduced by 0.26 years for each device charge. AF monitoring and post shock pacing did not impact device longevity significantly. Low and high voltage impedance as well as remote monitoring transmission impacted longevity by less than 0.1 years. These data are important to consider during shared decision-making.Device Longevity Predictors

Impact of clinical frailty on the outcome of pacing for bradyarrhythmias in a district general hospital population

Abstract Background and Aims There is good evidence for mortality with increasing age, heart disease, peripheral vascular disease, pulmonary disease and renal disease in implantable cardiac defibrillators. And while multimorbid states and fragility are considered in decision to offer for more complex cardiac electronic device implants1,2 we aimed to characterise how much frailty and co-morbidities impact mortality in patients receiving simple bradyarrhythmia cardiac pacing device implants. Methods Retrospective examination of 700 consecutive novel standard bradyarrhythmia cardiac device implants (DDD, VVI, AAI) at Walsall Manor Hospital between 01/01/2016 to 28/02/2021 was undertaken through the electronic patient record. Patients’ frailty was calculated with Rockwood Frailty Score (RFS) and comorbidities at the time of implant recorded.3 Prospective follow up until 14/02/2023 was conducted, allowing at least a 2 year follow-up for all surviving patients. Results were analysed with Kaplan-Meier survival curves and Hazard Ratios (HR) and Risk Ratios (RR). Results Mean age of implant was 78.4±10.3 with mortality rate of 87/700 (12.4%) at one year and total 282/700 (40.3%). Overall, a RFS of 5 or more was associated with death overall HR 2.05 (95% CI 1.61-2.60) and 3.42 (95% CI 2.23-5.24) within 1 year (Fig. 1). Heart failure (OR 2.38, 95% CI 1.59-3.57), valvular heart disease (OR 3.19, 95% CI 2.08-4.89), atrial fibrillation/flutter (OR 1.44, 95% CI 1.09-1.91), chronic kidney disease (OR 1.89, 95% CI 1.296-1.72), malignancy (OR 1.91, 95% CI 1.08-3.36) were important co-morbidities of death within one year of implant. Ischemic heart disease and cognitive impairment including dementia demonstrated a trend towards worse mortality but did not reach significance (Fig. 2). Conclusion High frailty score as well as comorbidities including heart failure, valvular heart disease, atrial fibrillation, chronic kidney disease and malignancy indicate increased risk of early death after novel implant of bradycardia cardiac pacing device implants. Although advanced age alone is not a barrier to offer pacing, consideration should be given to advanced frailty and multimorbid states which may detract from any perceived benefit bradyarrhythmia correction may offer. These data have impacted our shared decision making during the consent process with our patients and in our multidisciplinary team discussions.Figure 1Figure 2

Intermuscular placement and defibrillation with the extravascular ICD: a single-centre experience

Abstract Background Extravascular (EV) implantable cardiac defibrillators (ICD) with substernal lead have recently proved to be a safe and effective alternative to conventional transvenous (TV) and subcutaneous defibrillators (S-ICD), owing to the possibility to deliver antitachycardia and asystole pacing while saving intravascular hardware. The proposed implantation technique for EV-ICDs is a subcutaneous pocket along the mid axillary line, although an intermuscular ICD placement can potentially reduce the risk of pocket complications, device migration and improve patient comfort and aesthetic outcomes. Purpose exploring the safety and feasibility of extravascular ICDs implantation with a substernal coil and an intermuscular generator placement. Methods Seventeen patients with a class I or IIa ICD indication either for primary (14/17) or secondary (3/17) prevention underwent EV-ICD implantation in our centre as part of the EV ICD Pivotal Study from May 2021 to November 2022. Access and tunnelling along the retrosternal space were performed based on current standard recommendations for EV-ICDs implantation. An intermuscular pocket for generator placement was obtained between the latissimus dorsi and the serratus anterior muscles beyond the left mid-axillary line. Results Mean age, BMI, NYHA class and left ventricular ejection fraction (LVEF) were respectively 53±9yrs, 25.3 ±6 kg/m2, 2 ±0.7, and 39±14%. The main aetiology was non ischemic cardiomyopathy (12/17), including 3 arrhythmogenic cardiomyopathy patients and one with hypertrophic cardiomyopathy. The implantation was successful in 16 (6 females) out of 17 patients, with one implant failure due to inadequate sensing (0,5 mV); the median sensing amplitude was 2,3 mV (min = 1,3 mV; max = 5,8 mV), with R1R2 being the final sensing vector chosen for 14/16 and R2-Can for 2/16. Defibrillation Testing (DFT) was performed in all patients: a 15 J shock terminated induced ventricular fibrillation (VF) in 12/16 patients, 20 J terminated VF in 3, a single patient had VF terminated at 30 J. No patient had infection or skin erosion or complained pain/discomfort at the pocket site along an 18±4 months follow-up. Only 1/16 patients had ventricular tachycardia at follow-up, successfully treated by the device. Conclusions Intermuscular placement of the EV ICD may be a feasible and reliable alternative to a subcutaneous one in terms of defibrillation efficacy, enabling patient comfort and aesthetic acceptance in thin-habit or young patients. Additional long-term data and larger patient cohorts are required to confirm its advantage compared to the subcutaneous placement.

Contrasting patterns of symptoms compared to mortality in women and men with Congestive Heart Failure (the G-CHF registry)

Abstract Background There is a paucity of data on the clinical characteristics, management, and outcomes of women compared with men with heart failure, especially in low-and middle-income countries. Purpose In this study from the Global Congestive Heart Failure registry, we examined sex differences in risk factors, clinical characteristics, treatments, and the risk of heart failure hospitalization and mortality by country economic status and by left ventricular ejection fraction (LVEF) category. Methods In the prospective Global-Congestive Heart Failure (G-CHF) study, participants with established heart failure were considered for inclusion from 40 high-, middle-, and low-income countries. We recorded information on the demographic characteristics, medical history, and treatments of participants. We report data on heart failure hospitalization and mortality by sex overall, by country economic status, and by LVEF category. Results From December 2016 to July 2022, 23,000 participants were recruited and followed up. The average age of women in the study was 62 years compared to 64 years in men. Fewer women than men had a LVEF ≤40 (51.7% women vs 66.3% men). By contrast, more women than men had an LVEF≥ 50 (33.2% women vs 18.6% men). Hypertensive heart failure was the most common etiology in women (25.5% women vs 16.8% men), and ischemic heart failure was the most common etiology in men (45.6% men vs 26.6% women). Signs and symptoms of heart failure were more common in women than men: 42.6% of women were NYHA functional class III/IV compared to 37.9% of men. Among participants with a LVEF <35, use of implantable cardiac defibrillator (ICD) was lower in women than men in the overall study (8.7% women vs 17.2% men), and within countries categorized by economic status. However, the use of heart failure medicines and cardiac tests did not differ systematically by sex. Differences by sex were not observed in the adjusted risk of heart failure hospitalization overall (women-to-men adjusted hazard ratio 1.0 (95% CI 0.94 to 1.07)). This pattern was consistent within countries categorized by economic status, geographic region, and by LVEF category. Women had a lower adjusted risk of mortality overall (women-to-men adjusted hazard ratio 0.82 (95% CI 0.77 to 0.87), which was consistently observed within countries categories by economic status, geographic region, and LVEF levels. Conclusions There are differences between women and men in heart failure symptoms, underlying causes, ejection fraction categories, and use of an ICD. However, use heart failure medications, cardiac tests, and hospitalization were similar in women and men; but women had a lower risk of death.

Mathematical software tool that helps clinicians to classify clinicand and spurious alerts in patients with heart failure and cardiac implantable devices

Abstract Introduction Heart failure (HF) is the leading cause of cardiovascular hospitalisation in developed countries. More and more HF patients are receiving cardiac implantable electronic devices (CIED) that collect physiological data that may be used to predict HF decompensations and avoid hospitalisation through early medical interventions. Some CIEDs have a Multiparameter heart failure index (HF-I), which is an algorithm based on the information provided by five sensors (heart sounds, respiration, chest impedance, heart rate and activity level) capable of predicting 34 days before HF decompensation episodes when the reported index is ≥16 (HF-I alert) with a sensitivity of 70%, although with a significant rate of false positive HF diagnosis. Purpose Develop a computational tool to analyse HF-I curve dynamics to find the mathematical variables with the highest predictive accuracy of true clinical events in a tertiary hospital. Methods We developed a computational tool to analyse curves of 71 HF-I alerts in 25 patients with HF who were implanted with an implantable cardiac defibrillator (ICD) or cardiac resynchronisation-defibrillator (CRT-D) between 2017 and 2021, using mathematical software (fig 1). It includes peak, time to peak, area under the curve, increase and decrease slopes, variability and monotony. Alerts (HF-I ≥16) were clinically classified as real HF decompensation (clinical alerts) and false positive HF decompensation (spurious/subclinical alerts). Results Median age of the study group was 68 years, and 60% had non-ischemic cardiomyopathy. Median left ventricle ejection fraction (LVEF) was 29%; 60% had non-ischaemic cardiomyopathy. Patients with clinical alerts had higher raise slopes 7 days after alert onset (p=0.0055), higher HF-I values 3 days after crossing the alert, higher raise variability and less monotonic curves. Additionally, significant differences were observed in alert duration (p=0.004), HF-I maximum value (p< 0.0001), area under the overall alert curve (p< 0.0001), area under the alert curve at 3 / 7 days (p=0.04/0.002 respectively) and time to maximum peak of the alert (p=0,0032). HF-I value at the 7th day from the alert onset was an early and robust predictor of clinical events (P< 0.0001). A value at day 7 from alert onset ≥ 28 had a 95% sensitivity and 100% specificity for detecting clinical events (fig 2). Conclusion a computational mathematical tool can help to classify true positive clinical alerts versus spurious alerts in patients with a multiparameter heart failure index and CIED.Figure 1.Figure 2.

Impact of sodium-glucose cotransporter-2 (SLGT2) inhibitors treatment initiation on the reduction of atrial and ventricular arrhythmias in patients with implanted cardiac devices

Abstract Introduction Sodium-glucose cotransporter-2 (SLGT2) inhibitors have demonstrated benefits on survival and hospital admissions in patients with heart failure and reduced ejection fraction. However, their impact on the burden of ventricular (VA) and atrial arrhythmias (AA) is unknown. Methods Retrospective multicentric study of heart failure patients with implantable cardiac defibrillator device (ICD) from 2015 to 2020 with or without cardiac resynchronization therapy (CRT) receiving SGLT2 inhibitors. Device-registered arrhythmic events were analyzed and compared during one year following SLGT2 inhibitor initiation and during one year before initiation. Relevant VA were defined as the occurrence of any sustained VT (SVT) (>30 seconds), ventricular fibrillation (VF), or appropriate therapy (antytachycardia pacing or shock). All VA included all the relevant VA and the occurrence of non-sustained ventricular tachycardia (NSVT). AA included atrial fibrillation (AF) burden, and episodes of more than 24 hour of AF. Results 147 patients (67 ± 10 years, 82.3% males, LVEF 30.3 ± 11%, CRT 39.3%), were included in the study. 77.6% had complete remote tele-monitoring during the entire follow up and there was no difference in the antiarrhythmic therapy between the two periods. Following SGLT2 inhibitor initiation, there was a significant reduction in the percentage of patients with relevant VA (19.7% pre vs 10.9% post; p=0.019) and all VA (47.6% pre vs 30.6% post; p<0.001) (Figure 1 and 2). There was a reduction in the prevalence of NSVT (40.1% pre vs. 27.2% post; p<0.001), of SVT (17.7% vs 8.8%; p<0.001), of VF (4.1% vs 2%; p=NS) and appropriate therapies (14.3% vs 9.5%; p=NS). Among patients with any VA, there was a significant reduction in the incidence of NSVT (p<0.001), but not in the incidence of SVT or appropriate therapies (p=NS). There was no impact on atrial fibrillation burden or in the number of AF episodes lasting more than 24 hours (p=NS). Conclusions In our study, initiation of a SGLT2 inhibitor in patients with heart failure, was associated with a reduction in the prevalence of relevant VA and any VA, with a significant reduction in the number of NSVT per patient. There was no impact on AF burden or the number of AF episodes lasting more than 24 hours. Prospective studies should be performed to sustain these conclusions.Relevant ventricular arrhythmiasAny ventricular arrhythmia

Lead placement in extravascular ICD recipients: the first step to prevent P-wave oversensing

Abstract Background Extravascular (EV) implantable cardiac defibrillators (ICD) with substernal lead have recently proved to be a safe and effective alternative to conventional transvenous (TV) and subcutaneous defibrillators (S-ICDs) 1, owing to the possibility to deliver antitachycardia and asystole pacing while saving intravascular hardware. However, inappropriate shock delivery occurred in 9.7% of patients, and P-wave oversensing accounted for 42% of inappropriate shocks in the EV ICD Pivotal Study. Purpose to investigate the difference of lead placement in patients with and without P-wave oversensing. Method 17 patients undergoing implantation as part of the EV ICD Pivotal Study received the substernal lead placement based on computer tomography imaging (CT) and following the protocol recommendations. Lead placement beyond the left lateral sternum border was attempted whenever possible, based on CT guidance. P-wave detectability (P detected visually but non sensed by the device) on the sensing vector and P-wave oversensing by the device were investigated at each follow-up. The distance of sensing ring electrodes (R1 and R2) from the mid-spine line (line connecting the spinous processes from cervical to lumbar vertebral processes) was measured in each patient on the posterior-anterior chest radiogram. Results Mean age, BMI, NYHA class and left ventricular ejection fraction (LVEF) were respectively 53±9yrs, 25.3 ±6 kg/m2, 2 ±0.7, and 39±14%. The main aetiology was non-ischemic cardiomyopathy (12/17), including 3 arrhythmogenic cardiomyopathy patients and one with hypertrophic cardiomyopathy. The implantation was successful in 16 (6 females) out of 17 patients without any complication, with one implant failure due to inadequate sensing (0,5 mV) despite several attempts at tunnelling in different locations (rightward and leftward of the sternum). One patient with P-wave detectability had lead dislodgement after 2 weeks, and underwent repositioning to a more leftward location, where P-wave was not detectable. Only one patient had P-wave oversensing at follow-up, and received inappropriate shocks (Figure A); the remaining 15 patients neither had detectable P-wave on the sensing vector nor inappropriate shocks (Figure B). The median sensing amplitude at implantation was 2,7±1.4 mV and 2.6±1.2 mV along a 18±4 months follow-up, with R1-R2 being the final sensing vector chosen for 14/16 and R2-Can for 2/16 patients. The distance of R1 and R2 from the mid-spine line was significantly longer in patients with detectable P-wave compared to those without (37±13mm vs 18 mm and 30±15 vs 16 mm, respectively). Conclusions Placement of the EV ICD lead leftward to the left sternum border is safe, and prevents P-wave detection. The mid-spine line represents an easy landmark to guide lead placement during implantation. R1 distance ≥ 25 mm and R2 distance ≥ 20 mm from the mid-spine line provide a reliable marker of freedom from P-wave oversensing.Figure AFigure B

Cardiac magnetic resonance for prophylactic implantable-cardioVerter defibrillator therapy international registry in patients with ischemic cardiomyopathy

Abstract Background Sudden cardiac death (SCD) in patients with ischemic cardiomyopathy (ICM) remains a leading cause of death. Current guidelines provide a class I recommendation for implantable cardioverter–defibrillator (ICD) implantation in ICM patients with transthoracic echocardiographic (TTE) left ventricular ejection fraction (LVEF) ≤35%. and NYHA functional class II or III. The current paradigm is suboptimal in identifying patients who are likely to benefit. In fact, only a relatively small proportion of ICD recipients for SCD primary prevention receive appropriate device therapy and instead there is a not negligible percentage of patients who experienced SCD event despite not fulfilling criteria for implantation. Purpose The DERIVATE-ICM registry sought to evaluate the additional prognostic value for the indication of ICD implantation using cardiac magnetic resonance (CMR) as compared to standard of care based on TTE in a large cohort of ICM patients. Methods We enrolled 861 ICM patients (86% male, mean age 65±11 years) with chronic heart failure and TTE-LVEF<50%. Major adverse arrhythmic cardiac events (MAACE), defined as the combination of SCD, aborted SCD event, and sustained ventricular tachycardia. were the primary endpoint. Independent predictors were used to calculate a CMR risk score for each patient. Risk levels were defined as low (quantile 1 [Q1]), medium (Q2 and Q3) and high (Q4). Results During a median follow-up of 1054 days, MAACE occurred in 88 (10.2%). Left ventricular end-diastolic volume index (HR:1.007, 95%CI:1.000-1.011, p=0.05), CMR-LVEF (HR:0.972, 95%CI: 0.945-0.999, p=0.045) and late gadolinium enhancement (LGE) mass (HR:1.010, 95%CI: 1.002–1.018, p=0.015) were independent predictors of MAACE. Based on the multivariate analysis, CMR weighted risk score was developed according to the following equation [0.005 * EDV/BSA (mL/m2) – 0.029 * LVEF (%) + 0.010 * LGE ischemic mass (g)]. A multiparametric CMR weighted predictive derived score effectively identifies subjects at high risk for MAACE as compared to TTE-LVEF cut-off of 35% with a Continuous NRI: 31.7% (95%CI: 8.6%-54.8%, p=0.007) (Figure 1, Figure 2). Conclusions In this large multicenter registry, a multi-parametric CMR predictive model provides additional prognostic stratification for MAACE predictions in a large cohort of ICM patients as compared to standard of care. This model identifies a large number of patients with TTE-LVEF<35% at low risk of SCD event and on the other side it identifies a subset of patients who are at high risk of MAACE despite TTE-LVEF≥35% (i.e. the population currently not fulfilling the guideline-based criteria for ICD implantation). Further randomized trials to test a CMR guided strategy for ICD implantation versus standard of care are now needed.Kaplan-Meier curvesEvent rate redistribution

Clinical characteristics of patients with cardiac sarcoidosis who were hospitalized for heart failure

Abstract Background Cardiac sarcoidosis (CS) often leads cardiac dysfunction and exacerbates heart failure. However, there are limited data regarding CS patients who were hospitalized for acute heart failure (AHF). Purpose We aimed to compare the patient characteristics and outcomes between patients with CS who were hospitalized for AHF (CS-AHF) and patients with AHF of other etiology. Methods A total of 4,556 hospitalized patients with CS were identified from the Japanese Diagnosis Procedure Combination database from 2012 to 2020. Among them, we analyzed 254 patients who were hospitalized due to AHF. Patient characteristics, prior medical history, medical therapy for heart failure, intensive care management during hospitalization, in-hospital outcomes and rehospitalization within one year after the index hospitalization were compared with general 4,056 hospitalized AHF patients who were enrolled in the Kyoto Congestive Heart Failure registry. Results Patients with CS-AHF were younger (71 [63-78] vs 80 [72-86]) and more women (69% vs 45%; p < 0.001) than general AHF patients. In addition, CS-AHF were associated with lower prevalence of hypertension, diabetes and dyslipidemia (46% vs 72%, p < 0.001; 28% vs 37%, p = 0.005; and 21% vs 38%, p < 0.001), and lower prescription of angiotensin converting enzyme inhibitors or angiotensin II receptor blocker (28 % vs 46%; p < 0.001) while prescription of beta-blockers were similar between the groups. The length of hospital stay was significantly longer in CS-AHF (23 [14-39] days vs 16 [11-25] days), more patients were treated by intensive respiratory care (32% vs 25%; p = 0.05) and cardiac resynchronization therapy defibrillator (CRTD) implantation (6% vs. 0.5%; p < 0.001) Although in-hospital mortality was similar between the groups, the rate of rehospitalization within one year was higher in CS-AHF (51% vs 39%; p = 0.001). Conclusions Patients with CS-AHF were younger, more women and had lower cardiovascular risk factors than those with AHF in general. CS-AHF were associated with longer hospital stay, higher rate of CRTD implantation and higher rehospitalization rates. More attention might be needed for this distinct group of patients.

Feasibility and Safety Study of Concomitant Left Bundle Branch Area Pacing and Atrioventricular Node Ablation with Same-Day Hospital Dismissal.

Left bundle branch area pacing (LBBAP) has rapidly emerged as a promising modality of physiologic pacing and has demonstrated excellent lead stability. In this retrospective study, we evaluate whether this pacing modality can allow concomitant atrioventricular node (AVN) ablation and same-day dismissal. Twenty-four consecutive patients (female 63%, male 37%) with an average age of 78 ± 5 years were admitted for pacemaker (75%)/defibrillator (25%) implantations and concomitant AVN ablation. Device implantation with LBBAP was performed first, followed by concomitant AVN ablation through left axillary vein access to allow for quicker post-procedure ambulation. The patients were discharged on the same day after satisfactory post-ambulation device checks. LBBAP was successful in 22 patients (92% in total, 20 patients had an LBBP and two patients had a likely LBBP), followed by AVN ablation from left axillary vein access (21/24, 88%). All patients had successful post-op chest x-rays, post-ambulation device checks, and were discharged on the same day. After a mean follow up of three months, no major complications occurred, such as LBBA lead dislodgement requiring a lead revision. The LBBA lead pacing parameters immediately after implantation vs. three-month follow up were a capture threshold of 0.8 ± 0.3 V@0.4 ms vs. 0.6 ± 0.3 V@0.4 ms, sensing 9.9 ± 3.9 mV vs. 10.4 ± 4.1 mV, and impedance of 710 ± 216 ohm vs. 544 ± 110 ohm. The QRS duration before and after AVN ablation was 117 ± 32 ms vs. 123 ± 14 ms. Mean LVEF before and three months after the implantation was 44 ± 14% vs. 46 ± 12%. LBBA pacing not only offers physiologic pacing, but also allows for a concomitant AVN ablation approach from the left axillary vein and safe same-day hospital dismissal.

The management of patients with heart failure in Sweden: a survey conducted among physicians in Sweden

Abstract Background Guideline-directed medical therapy (GDMT) improves outcomes in patients with heart failure (HF) with reduced ejection fraction (HFrEF). However, real-world studies highlight underutilization of GDMT. Purpose To describe physicians´ general knowledge and opinions on GDMT use, diagnostic workup, and follow-up care in HF in Sweden. Methods A survey comprising 42 multiple-choice questions about HF and its management was sent by mail to a random sample of 828 physicians including any specialist, general practitioners (GP) and interns in Sweden during 2021 and 2022. Answers were reported as percentages and comparisons were made by specialty (general practitioners vs specialists) by the chi-square test. Results 168 physicians (60% males, median age 43) responded to the survey (response rate: 20%), of whom 41% GPs, 18% cardiologists and 13% internists, 24% specialists in training, and 4% other specialists; 72% of participants report to meet less than 10 HF patients per week. Electrocardiography and a New York Heart Association class evaluation are mostly performed once a year by GPs (46%) and at every outpatient visit by other specialists (40%). Echocardiography is mostly requested if there is clinical deterioration (60%). 85% of the participants reported to never assess patient-reported parameters and outcomes with questionnaires. One-third of participants screen for iron deficiency only if there is anemia, and 45% do it every year. Figure 1 reports the major measured obstacles to implementation of GDMT in HFrEF; there were no significant differences according to specialty or age of participants. Implantable cardioverter defibrillation (ICD) implantation for primary prevention of sudden death is deemed appropriate by most responders regardless of aetiology (69%) and patient age (74%). ICD or cardiac resynchronization therapy is considered by most after the three months from optimization of GDMT (61%). Specialists answered correctly to questions to test knowledge on GDMT more often than GPs. 86% of participants think that GDMT should be implemented as much as possible, but only 7% estimate that full optimization is reached in more than 75% of their patients. The main reasons why patients with HFrEF do not receive optimal HF medical therapy (Figure 2) reflect the concern about side effects as well as possible knowledge deficiencies. To maximize the adherence to guidelines, 27% reported that patients should be regularly evaluated in tertiary care and 50% in nurse-led clinics, although for 29% of respondents such facilities are not present. Conclusion Obstacles to GDMT implementation according to physicians in Sweden are mainly related to potential side effects, lack of knowledge and structural aspects, including the lack of availability of nurse-led clinics. Improving implementation may require novel strategies, such as improved access to cardiology specialists, more generalizable trials, and potentially screening for GDMT indications.Figure 1Figure 2

Scar characterisation to predict arrhythmia and death in ischaemic cardiomyopathy: insights from the REVIVED trial

Abstract Background Ischaemic cardiomyopathy continues to have unacceptably high mortality despite contemporary medical and device therapy (1). Ventricular arrhythmias are a leading cause of both death and morbidity in this population. Current guidelines recommend implantable cardioverter defibrillator (ICD) implantation in patients with a left ventricular ejection fraction (LVEF) below 35% but many who meet criteria never receive a therapy and there is a persistent sudden cardiac death risk in those who do not. Scar characteristics are not currently included in risk stratification algorithms, however both volume and entropy, a measure of myocardial heterogeneity, have been linked to arrhythmic risk. Purpose To assess whether left ventricular scar burden and morphology predicts fatal and non-fatal arrhythmia, independent of LVEF in severe ischaemic cardiomyopathy. Methods REVIVED-BCIS2 was a prospective, randomized controlled trial, which recruited 700 patients from 40 centres across the United Kingdom (1). Trial eligibility required the presence of ≥4 dysfunctional but viable myocardial segments; the majority of patients had viability assessed by cardiac magnetic resonance imaging (CMR). Semi-quantitative CMR scar burden was determined through consensus by two CMR experts in a blinded core laboratory. Scar morphology was further characterised by left ventricular entropy measured using novel dedicated software (TexRAD Ltd., Feedback plc, UK). The primary outcome was the composite of all-cause death and aborted sudden death (in turn, defined as appropriate ICD therapy or resuscitated cardiac arrest). Cox proportional hazard models were used to determine the effect of scar burden and entropy on clinical outcomes, adjusted for baseline LVEF, extent of coronary disease, type of implantable device and randomized treatment. Results Four hundred and ninety one patients underwent viability assessment by CMR and 478 were included in this analysis (Figure 1). Mean age was 69 ± 9; median follow up duration was 3.3 [2.3-4.9] years. By the end of trial follow up, 257/478 had a device in situ (CRT-D 99, ICD 147, CRT-P 11). The primary outcome occurred in 182 patients (38.1%). Each 10% increase in scar volume was associated with a 24% increase in the incidence of the primary outcome (adjusted HR per 10% 1.24, 95% CI: 1.11 to 1.39, p = 0.0002)(Figure 2). LVEF at baseline was not predictive (adjusted HR per 5% increase 0.94, 95% CI 0.86 – 1.02, p = 0.13). The relationship between LV entropy and outcomes will be presented at ESC. Conclusions In patients with severe ischaemic cardiomyopathy, scar volume was predictive of death and potentially fatal arrhythmias. Left ventricular ejection fraction was not a significant predictor in this cohort. Scar characteristics should form an integral part of risk stratification.Consort diagramPrimary outcome by scar burden

Association between scar quantification and documented history of ventricular tachycardia in patients with hypertrophic cardiomyopathy

Abstract Background Hypertrophic cardiomyopathy (HCM) is a major risk factor for sudden cardiac death, and it is crucial to accurately identify patients who may benefit from implantable cardioverter defibrillator (ICD) implantation. Therefore, accurate risk stratification remains an unmet clinical need for patients with obstructive (HOCM) and non-obstructive (HNCM) hypertrophic cardiomyopathy. Methods and Aim Consecutive HCM patients were enrolled at a tertiary academic center and underwent cardiac magnetic resonance imaging. We aimed to explore risk factors for a documented history of ventricular tachycardia (VT). Results In total 246 HCM (160 HNCM, 86 HOCM) patients were included in the present analysis. Patients with HOCM and HNCM had similar rates of documented VTs (20.0% vs. 23.2%, p=0.61). However, the HCM-risk-score was significantly lower in HNCM patients (4.56% vs. 3.36%, p=0.003). There was no significant difference in age (53 vs. 57 years, p=0.65), sex (female sex 30% vs. 42%, p=0.14), or echocardiographic parameters, including the maximum outflow tract gradient (59 vs. 67 mmHg, p=0.71), the maximum wall thickness (21 vs. 20 mm, p=0.088), and the left atrial diameter (57 vs. 56 mm, p=0.59), in patients with versus without a history of documented VT. Furthermore, NT-proBNP (1040 vs. 1199 pg/mL, p=0.74) and high sensitivity troponin-T levels (22 vs. 19 ng/L, p=0.38) did not differ between groups. Patients with a history of VT were significantly more likely to have late gadolinium enhancement (LGE, 80% vs 50%, p=0.007) and had a higher percentage of LGE in relation to the left ventricular mass (9.2% vs 3.7%, p=0.001). These findings were consistent in patients with HOCM and HNCM (3.32% vs. 5.72% p=0.085). In an adjusted logistic regression model, the percentage of LGE was independently associated with the presence of VT (Odds ratio 1.27 [95%CI 1.08-1.50]). Conclusion These findings suggest that LGE may be a useful imaging marker for risk assessment in patients with HOCM and HNCM.

Prediction of all-cause mortality using a multisensor implantable defibrillator algorithm for HF monitoring

Abstract Background The HeartLogic algorithm combines multiple implantable defibrillator (ICD) sensor data and has proved to be a sensitive and timely predictor of impending heart failure (HF) decompensation. Purpose We determined if remotely monitored data from this algorithm can be used to identify patients at high risk of mortality. Methods The HeartLogic feature was activated in 568 ICD patients from 26 centers. Results During a median follow-up of 26 months [25th–75th percentile: 16-37], 1200 HeartLogic alerts were recorded in 370 (65%) patients. Overall, the time IN the alert state was 13% of the total observation period (151 out of 1159 years) and 20% of the follow-up period of the 370 patients with alerts. During follow-up, 55 patients died (37 in the group with alerts). Experiencing any alert episode was associated with a substantially increased risk of death [hazard ratio (HR): 2.08, 95% confidence interval (CI): 1.16–3.73, P = 0.039]. Additionally, a time IN alert ≥20% was associated with death (HR: 4.07, 95%CI: 2.19-7.54, p<0.001, Figure), even after multivariate correction for age, atrial fibrillation on implantation, chronic kidney disease, ischemic cardiomyopathy (HR: 3.26, 95%CI:1.87-5.70, p<0.001). The rate of death was 0.25/patient-year (95%CI: 0.17-0.34) with the HeartLogic IN the alert state and 0.02/patient-year (95%CI: 0.01-0.03) OUT of the alert state, with an incidence rate ratio of 13.72 (95%CI: 7.62-25.60, p<0.001). Conclusions The HeartLogic algorithm provides an index that can be used to identify patients at higher risk of all-cause mortality. The index status identifies periods of significantly increased risk of death.

Asthma and the risk of cardiac events among patients with long QT Syndrome after age 40

Abstract Background The effect of asthma on the clinical course of long QT syndrome (LQTS) in the middle and old age population has not been studied. Purpose The present study was designed to investigate the association between asthma comorbidity, β2-agonist treatment and cardiac events among LQTS subjects after age 40 years. Methods The risk of cardiac events (comprising syncope, aborted cardiac arrest, implantable defibrillator shock, or sudden cardiac death) from age 40 through 75 years, by the presence of asthma and time-dependent β2-agonist use was assessed among 1020 LQTS patients from the LQTS Registry. Results Asthma was identified in 162 (16%) study patients and 63% of asthma patients received β2-agonist inhalers. Patients with asthma vs. no asthma had a higher cumulative rate of cardiac events during follow-up (44% vs. 26%, respectively; p<0.001 [Figure: left panel]). Consistently, multivariate analysis demonstrated that asthma was a powerful predictor of cardiac events with an associated 2-fold (HR=1.97, p=0.001) increased risk for cardiac events as compared to patients with no asthma. β2-agonist inhalers use was associated with a similar increased risk for cardiac events (HR =1.90, p=0.035) among all study patients (Figure: right panel]). Subgroup analysis did not show a statistically significant difference in the association of asthma with cardiac events by risk subsets of LQTS patients, including QTc duration, syncope prior to age 40 years, beta-blocker use, sex, and the LQTS genotype (all p-values for risk subset-by-asthma interaction >0.10). Conclusion The presence of asthma and β2-agonist treatment are associated with an increased risk of cardiac events among middle and old age patients with LQTS.

Device specific quality of life in subcutaneous versus transvenous implantable cardioverter defibrillator implantations: results from the ATLAS multi-centre randomized controlled trial

Abstract Background Newer innovative subcutaneous implantable cardioverter defibrillators (S-ICDs) offer an alternative to transverse ICDs (TV-ICDs), placing leads outside of the heart thereby potentially reducing lead-related complications. The ATLAS trial, a multi-centre randomized controlled trial, showed a significant reduction in perioperative complications in TV-ICD versus S-ICD patients. The following results report device-related quality-of-life (QoL) measured in the trial. QoL measures are recognized as key patient-reported outcome measures (PROMs). Purpose To compare TV-ICD and S-ICD post implantation device-related QoL in the ATLAS trial. Methods Sample included all randomized ATLAS trial patients. The Florida Patient Acceptance Survey (FPAS) was completed at 1- and 6-months post implantation. The FPAS includes a total score and 4 subscale scores; 1) return to function, 2) device-related distress, 3) positive appraisal, and 4) body image concerns. Scores are scaled from 0-100, with total scores below 63 suggesting poor device acceptance. The primary analysis was based on complete cases and used analysis of covariance (ANCOVA) with 6-month scores as the dependent variable, group as the independent variable, and 1-month FPAS scores as the covariate. Change in FPAS total score over time within each group was explored using paired t-tests. Results There were 252 TV-ICD and 251 S-ICD patients enrolled in the main ATLAS trial, and of these, in the present analysis, 404 patients (197 TV-ICD; 207 S-ICD) had complete FPAS data. Sample mean age (SD) was 49.31 (11.54) years, males (74.3%) and Caucasian (83.7%). There were no substantive differences in patient characteristics between groups. The primary analyses found no differences between TV-ICD and S-ICD groups for FPAS total score (Mean Difference=-0.75; 95% CI, -3.15, 1.66; p=0.510) or FPAS subscale scores. Mean FPAS total scores increased from 74.43 (15.35) to 78.25 (15.88) and 73.73 (16.09) to 77.05 (16.13) between 1-month and 6-months in the TV-ICD and S-ICD groups respectively. The increase from 1-month to 6-months was statistically significant in both groups (p< 0.001). These findings suggest that regardless of ICD type, there is device acceptance in both groups from implantation and over time. Conclusion Analysis of the FPAS measure, a device-specific QoL measure, found both TV-ICD and S-ICD patients reported good acceptance of their devices, with no significant differences between groups for up to 6 months post implantation. These findings provide an important piece to the TV-ICD versus S-ICD line of inquiry in ICD patient populations particularly for this newer S-ICD innovation and can be included in decision making between health professionals and patients.

Immediate, early and late ventricular fibrillation complicating acute myocardial infarction: insights from a real life registry

Abstract Background Conflicting data exist on the prognosis of ventricular fibrillation (VF) based on its timing in relation to coronary occlusion in acute myocardial infarction (AMI). Purpose To describe the patient profile and prognostic impact of VF during AMI according to its time of occurrence. Methods Data from three nationwide French cohorts carried out 5 years apart from 2005 to 2015 were analysed (FAST-MI program). All consecutive patients with AMI (STEMI and Non-STEMI) over a 1-month period were enrolled and followed 5 years. The present analysis focused on patients who presented with VF according to its time of occurrence defined as: immediate (out-of-hospital cardiac arrest), early (<48h at admission) and late (≥48h after admission). Results Out of 13 125 patients admitted for AMI (66±14 years, 71% men, 52% ST-elevation myocardial infarction-STEMI), 406 (3.1%) presented with VF including 205 immediate (50.5%), 147 early (36.2%) and 54 late (13.3%) VF episodes. Immediate and early VF were most frequent during STEMI (respectively 2.3% and 1.8% vs. 0.8% and 0.4% in non-STEMI, p<0.001), while late VF incidence was as frequent in ST-elevation and non-STEMI (0.5% vs 0.4%, p value). The proportion of immediate, early and late VF in AMI were similar in 2005, 2010 and 2015. Patients with immediate (61.6±13.2 yo) or early (62.4±14.2 yo) VF were younger than those with no VF (66.1±14.1 yo, p<0.001) while patients with late VF patients were the oldest (70.5±13.6 yo). LVEF was lower in patients with early (48±10%) or late (48±13%), compared with patients without VF (52±11%) or those with immediate VF (51±12%) (p<0.001). In-hospital mortality was particularly high in patients who developed immediate (24.9%) and late (37.0%) VF, intermediate in early VF patients (10.9%) and lowest in non-VF patients (3.0%) (p<0.001). Among patients alived at hospital discharge, and compared with patients with no VF (4.2%), the six-month mortality was considerably increased in the late VF subgroup (17.6%, adjusted HR: 6.04 [2.69-13.58], P<0.001), moderately increased in immediate VF (5.2%, HR:2.15 [1.06-4.34, P=0.03) ) and did not differ in early VF (1.5%, HR: 0.52 [0.13-2.11 P=0.36). At five years, mortality was also significantly higher in patients with late VF (38.2%, adjusted HR 1.72 [1.01-2.91]), with no significant difference between immediate, early, and non VF patients (14.2%, 11.5% and 19.3% respectively). Conclusions Patients with immediate, early and late VF during AMI do present with significantly different profiles. Still, only late VF (≥48h after admission) was associated with poorer outcome after the index hospitalisation, especially within the initial 6 months. By contrast with current guidelines based on relatively old data from the 2000s in secondary prevention in ischemic or non-ischemic settings, the extent to which patients with late VF would benefit from rapid cardioverter defibrillator implantation is questionable.3 months survival after VF in AMI5 year survival after VF in AMI

Abstract 15856: Genetics, Pathologic Characteristics, and Burden of Lethal Hypertrophic Cardiomyopathy Among Countywide Sudden Deaths

Background: Annual incidence of sudden cardiac death (SCD) is reported at 1% in cohorts with known hypertrophic cardiomyopathy (HCM), but these estimates presume arrhythmic cause and miss occult cases dying before diagnosis. Hypothesis: Prospective surveillance and postmortem investigation of community sudden deaths will uncover the true burden of presumed SCD (pSCD) and arrhythmic death (SAD) attributable to HCM. Objectives: Determine characteristics and precise contribution of HCM to population pSCD and SAD. Methods: POST SCD (POstmortem SysTematic Investigation of Sudden Cardiac Death) is a prospective cohort study using autopsy, clinical records, and toxicology to adjudicate arrhythmic (potentially rescuable with implantable defibrillator) or non-arrhythmic (e.g., tamponade, overdose) causes among pSCDs 0-90 years in San Francisco County. We included all incident cases from 2/1/11-3/1/14 (n=525) and approximately every 3rd day from 3/1/14-9/1/22 (n=497). We identified HCM victims via 3 parallel approaches: 1) pathology criteria; 2) echocardiogram (TTE) review; 3) genetic analysis. Results: Of 1022 pSCDs in the 11-year study period, we identified 13 cases with HCM, yielding a 2% contribution to arrhythmic death burden: 10 met pathology criteria; 2 via review of 203 TTEs (missed on initial report); 1 with pathogenic ALPK3 mutation. Only 2 of 13 (15%) pSCDs with HCM had premortem diagnosis. A greater proportion of pSCDs with HCM had autopsy-confirmed arrhythmic cause than pSCDs without HCM (11/13 [85%] vs. 547/1009 [54%], p=0.03). HCM contribution to pSCD burden decreased with age (p=0.003), highest among victims <35 years, accounting for 7.1% (6/84) of pSCDs and 9.4% (3/32) of SADs. Genetic testing of 317 consented pSCDs (5/12 meeting pathologic or TTE HCM criteria) yielded pathogenic mutations in 40% (2/5), and identified 1 additional case without clinical phenotype. Conclusions: In this 11-year countywide postmortem study, HCM meeting pathologic, clinical, or genetic criteria was associated with autopsy-confirmed arrhythmic cause of sudden death, accounting for 2% of SADs, highest in cases <35 years. As 85% of cases were undiagnosed before pSCD, the true burden of HCM-related sudden death may be substantially underestimated.

Abstract 16401: Optimizing ChatGPT to Detect VT Recurrence From Complex Medical Notes

Introduction: Large language models (LLMs), such as ChatGPT, have remarkable ability to interpret natural language using text questions (prompts) applied to gigabytes of data in the world wide web. However, the performance of ChatGPT is less impressive when addressing nuanced questions from finite repositories of lengthy, unstructured clinical notes (Fig A). Hypothesis: The performance of ChatGPT to identify sustained ventricular tachycardia (VT) or fibrillation after ablation from free-text medical notes is improved by optimizing the question and adding in-context sample notes with correct responses (‘prompt engineering’). Methods: We curated a dataset of N = 125 patients with implantable defibrillators (32.0% female, LVEF 48.9±13.9%, 61.7±14.0 years), split into development (N = 75) and testing (N = 50) sets of 307 and 337 notes, with 256.8±95.1 and 289.8±103 words, respectively. Notes were deidentified. Gold standard labels for recurrent VT (Yes, No, Unknown) were provided by experts. We applied GPT-3.5 to the test set (N=337 notes), using 1 of 3 prompts (“Does the patient have sustained VT or VF after ablation” or 2 others), systematically adding 1-5 “training” examples, and repeating experiments 10 times (51,561 inquiries). Results: At baseline, GPT achieved an F1 score of 38.6%±19.4% (mean across 3 prompts; Fig B). Increasing the number of examples progressively improved mean accuracy and reduced variance. The optimal result was the illustrated prompt plus 5 in-context examples, with an F1 score of 84.6%±6.4% (p<0.05). Conclusions: ChatGPT can accurately identify VT recurrence from small numbers of complex medical notes with optimal prompt engineering. Future studies should define optimal context for different medical questions and domains. These findings pave the way for automated analysis of large medical repositories to broadly improve decision making.

Abstract 18812: Premortem Risk Assessment Among Countywide Sudden Deaths

Introduction: Heart failure (HF) and left ventricular ejection fraction (EF) assessment have been hallmarks of sudden cardiac death (SCD) risk stratification for over 20 years. However, their sensitivity, specificity, and positive predictive value (PPV) for true arrhythmic death in the general population are unknown because nearly all SCD studies presume arhythmic causes. Aims: To define sensitivity, specificity, and PPV of current SCD risk stratification criteria for the autopsy-confirmed arrhythmic cause among countywide sudden deaths. Methods: POST SCD (POstmortem SysTematic Investigation of Sudden Cardiac Death) is a prospective cohort study using autopsy, clinical records, and toxicology to adjudicate arrhythmic (SAD; potentially rescuable with implantable defibrillator) or non-arrhythmic (non-SAD; e.g., tamponade, overdose) causes among presumed SCDs (pSCDs) in San Francisco County. We analyzed sensitivity, specificity, and PPV for syncope, EF≤35%, diagnosed HF, or the presence of any of 3 factors to discriminate SADs among pSCDs. Results: Between February 2011 and September 2022, 845 of 904 (93%) pSCDs 18-90 years had complete medical records available, of which 491 (58%) were SADs. Seventy-three pSCDs had history of syncope, with similar prevalence in SADs and non-SADs (p=0.4), while prevalence of HF was higher in SADs vs. non-SADs (88/491[18%] vs. 39/354 [11%], p=0.003). EF assessment was performed in 206 pSCDs (24%, 133 SADs, 73 non-SADs); prevalence of EF ≤ 35% was similar between SADs and non-SADs (p=0.112). A greater proportion of SADs had ≥1 factor than non-SADs (122/491[25%] vs. 65/354 [18%], p=0.015). Sensitivity of syncope, EF≤35%, HF, ≥1 factor for SAD was 9, 26, 17, 25%, specificity was 92, 82, 90, 82%, and PPV was 60, 73, 69, 65%, respectively. Conversely, 369 of 491 (75%) SADs had no risk factors before sudden death. Defibrillators were implanted in 4/491 (0.8%) SADs. Conclusions: In this 11-year countywide postmortem study, conventional risk factors had low sensitivity and PPV but high specificity for autopsy-confirmed arrhythmic cause of sudden death. Three-fourths of SADs had no risk factors before sudden death, highlighting the need for improved risk prediction in the general population.