Defibrillator Therapy Research Articles

Left ventricular global longitudinal strain (LV-GLS) by speckle-tracking echocardiography (STE) predicts appropriate defibrillator therapy in patients with dilated cardiomyopathy (DCM)

Abstract Background Patients with dilatied cardiomyopathy (DCM) have an increased risk for sudden cardiac death (SCD) which may be prevented by an implantable cardioverter-defibrillator (ICD). Current guidelines set the indication to implant an ICD in DCM patients based on a left ventricular ejection fraction (LVEF) of ≤ 35 %. However, this approach has been questioned by recent research in non-ischemic DCM. Left ventricular global longitudinal strain (LV-GLS) as assessed by speckle-tracking-echocardiography (STE), directly measuring myocardial deformation in the longitudinal dimension, is a new method to characterize global LV function. Data is scarce regarding the diagnostic value of LV-GLS in predicting sudden cardiac death (SCD) events. Purpose The aim of this study was to assess whether LV-GLS measurements predict the rate of appropriate ICD therapies in DCM patients better than LVEF. Methods Patients with DCM who underwent primary prophylactic ICD implantation from 2011-2016 at our hospital, who had baseline echocardiographic data adequate for STE analysis, and a follow-up duration of > 6 months were included. ICD interrogation data were retrieved from hospital electronic records. Patients with secondary preventive ICD indication were excluded. Results 115 patients were included (26% females, age: 61.3 ± 12.4 years, LVEF 27.9 ± 5.4%, NYHA functional class 2.7 ± 0.5). During a follow-up time of 35.2 ± 12.3 months 30 patients had at least one appropriate ICD therapy (25 patients had anti-tachycardia pacing (ATP), 8 patients had ICD-shocks). Mean LV-GLS in patients with ICD therapy was significantly worse than in those without ICD therapy (-6.4% vs. -7.8%, p=0.018). Multivariate logistic regression analysis showed that LV-GLS (odds ratio 1.31, 95% confidence interval: 1.07-1.60, p= 0.01) but not LVEF (OR 0.97, p= 0.47) was an independent predictors of appropriate ICD therapy. Using ROC analysis, we found a cut-off value of -9,7% for LV-GLS to best predict ICD therapy over follow-up with a sensitivity of 93.3% sensitivity (c-statistic 0.64). Conclusion Our findings indicate that LV-GLS is a useful marker to risk stratify patients with DCM, outperforming the current standard LVEF. LV-GLS should be implemented in the standard echocardiographic assessment of patients with cardiomyopathy.

How Electrical Storms Recur Over Time in Patients With Implantable Cardioverter Defibrillators ― Subanalysis of the Nippon Storm Study ―

Electrical storms (E-storms), defined as multiple fatal ventricular arrhythmias over a short period, negatively affect the prognosis of patients receiving an implantable cardioverter defibrillator or cardiac resynchronization therapy with a defibrillator (ICD/CRT-D). However, the prognostic impact of recurrent E-storms has not been well elucidated. We analyzed the association between E-storm recurrences and mortality using data from 1,274 participants in the Nippon Storm Study, a prospective observational study conducted at 48 ICD/CRT-D centers in Japan. Differences in E-storm recurrences by patient characteristics were evaluated using the mean cumulative function (MCF), which is the cumulative number of E-storm episodes per patient as a function of time. Patients with multiple E-storms had a 3.39-fold higher mortality risk than those without E-storms (95% confidence interval 1.82-6.28; P<0.01). However, there was no significant difference in mortality risk between patients with a single E-storm and those without E-storms. The MCF curve exhibited a slower ascent in patients who received primary prevention ICD/CRT-D than in those who received secondary prevention ICD/CRT-D. However, when analyzing only patients with E-storms, the MCF curves demonstrated comparable trajectories in both groups. E-storm recurrences may have a negative impact on prognosis. Once patients with primary prevention experience an E-storm episode, they face a similar risk of subsequent recurrent E-storms as patients with secondary prevention.

The risk of failure of subcutaneous implantable cardioverter defibrillator therapy: from PRAETORIAN score to clinical practice.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative to traditional ICDs. The PRAETORIAN score, based on chest radiographs, has been validated to predict the probability of successful S-ICD defibrillation testing by assessing factors like fat thickness between the coil and sternum and generator placement. This study evaluated the correlation between the PRAETORIAN score and clinical characteristics, as well as implantation variables. We retrospectively analyzed data from 1253 patients who had undergone implantation of an S-ICD across 33 centers. The intermuscular positioning of the pulse generator was adopted in all patients. Post-implantation posterior-anterior and lateral chest radiographs were analyzed to calculate the PRAETORIAN score. 95.7% of patients had a PRAETORIAN score <90, indicative of a low risk of conversion failure. Body mass index (BMI) was the only independent predictor of a score ≥90, and all patients with BMI <25kg/m2 (normal weight or underweight) had a score <90. The intermuscular positioning technique resulted in optimal posterior placement of the device in all patients and significant sub-generator fat in only 3% of cases. A shock impedance value >88Ohm enabled to detect a PRAETORIAN score ≥90 with 98% (95% CI 97%-99%) negative predictive value. In contemporary practice, the PRAETORIAN score can be simplified. By adopting an intermuscular approach, two of the three steps of the score-evaluating the adequate posterior positioning of the generator and measuring the sub-generator fat-become superfluous, and impedance may serve as a reliable surrogate of sub-coil fat thickness. Furthermore, our data suggest that for non-obese patients, a favorable PRAETORIAN score is assured, making the score evaluation potentially unnecessary.

Risk factors for non-benefit of implantable cardioverter defibrillator therapy

Studies have demonstrated overall prognostic benefits of ICD implantation in patients at increased risk of sudden cardiac death. However, results are inconsistent in certain subgroups. This study aims to evaluate the prognostic implications of comorbidities on ICD outcomes and compare trends in patient selection and outcomes over a decade-long inclusion period. This study analysed 422 patients undergoing ICD implantation between 2011 and 2020. The study endpoint “no-benefit” was characterized by death from any cause occurring without prior appropriate ICD therapy. Benefit of ICD implantation was defined as either receiving appropriate ICD therapy before death or surviving until the end of the observation period. During a mean follow-up of 4.2 ± 3.0 years, no-benefit of ICD implantation was observed in 84 patients (20%). Independent risk factors for no-benefit were age ≥ 68 years (HR 4.599, p < 0.001), anemia (HR 2.549, p < 0.001), peripheral artery disease (HR 2.066, p = 0.007), and chronic obstructive pulmonary disease (HR 1.939, p = 0.014). Subgroup analysis by age < 68 years and ≥ 68 years demonstrated that the risk of no-benefit increases with age and comorbidities. When comparing patients with ICD implantation in 2011–2015 with those in 2016–2020, there were no significant differences in one-, two- and three-year-no-benefit rates. Different comorbidities were associated with no-benefit in the early and late implantation groups. Risk factors such as older age and specific comorbidities are associated with a higher likelihood of no-benefit from ICD implantation. A careful patient selection and consideration of individual risk factors besides advanced age is important.

Subcutaneous defibrillator therapy in women

Subcutaneous defibrillator therapy in women

Arrhythmogenic Right Ventricular Cardiomyopathy: The Importance of Biventricular Strain in Risk-Stratification.

Despite arrhythmogenic right ventricular cardiomyopathy (ARVC) being predominantly a right ventricular (RV) disease, concomitant left ventricular (LV) involvement has been recognized. ARVC is diagnosed by the RV-centric 2010 Task Force Criteria(TFC) using routine echocardiography, but previous studies have suggested that strain imaging may be more sensitive to detect RV and LV dysfunction. No data however are available regarding the additional value of combining biventricular strain for risk stratification. This study aims to assess the prognostic value of both LV global longitudinal strain (GLS) and RV free wall strain (FWLS) in patients with ARVC. To accomplish this, 204 patients who met the TFC for the ARVC spectrum were included. Patients (age 41 ± 17 years,55% men) were divided into impaired(n = 33), discordant (RV or LV impaired, n = 70), and normal (n = 101) strain groups based on a value of ≥18% for both ventricles. During a follow-up of 87 [24-136] months, 57 (28%) experienced the composite outcome of all-cause mortality, arrhythmic events, implantable cardioverter defibrillator therapy and heart failure events, and a significant difference in event-free survival was observed (p <0.001) between the 3 groups. In the multivariable analysis, the strain groups remained associated with outcomes (p = 0.014) after adjusting for age, sex, history of syncope and definite ARVC diagnosis. A subanalysis including only definite and borderline diagnosed ARVC confirmed that the strain groups were independently predictive of the endpoint (p = 0.023). In conclusion, biventricular involvement by strain analysis may help risk stratification in ARVC patients, with the worst outcomes of patients with both RV and LV impaired strain.

Smoking and sudden cardiac death in patients with previous coronary artery disease.

Smoking is a known risk for sudden cardiac death (SCD) in the general population. However, its significance in patients with acute coronary syndrome (ACS), a condition that also elevates the risk of SCD, is disputable. A total of 9704 consecutive ACS patients with available smoking data were included in the analysis. Comprehensive patient data were obtained from the Mass Data in Detection and Prevention of Serious Adverse Events in Cardiovascular Disease research database. A composite endpoint of SCD, SCD aborted by successful resuscitation and accurate implantable cardioverter defibrillator therapy to otherwise potentially fatal ventricular fibrillation/ventricular tachycardia was used. Univariate, age- and sex-adjusted, and a multivariate fine-gray competing risk regression with adjustment to traditional risk factors was conducted. Median follow-up time was 6.8 years (IQR, 4.1-10.2), and 454 (4.7%) SCD cases were identified. At the baseline, 23.7% (N = 2444) were active smokers, and 20.8% (N = 2146) were ex-smokers. In the multivariate model, active smokers had an elevated risk of 1.79 (95% CI, 1.41-2.27; P < 0.001) for future SCD. Ex-smokers had no elevated risk for SCD in fine-gray subdistribution hazard. Also, active smokers were notably younger (mean age 58.7 years) than non- or ex-smokers (71.1 years and 68.9 years, respectively, P < 0.001 for both comparisons). Active smokers had a 79% higher risk of SCD when compared with nonsmokers. Smoking cessation should be heavily encouraged after ACS. Also, a person's smoking status should be considered in further studies developing SCD and implantable cardioverter defibrillator-benefit risk scores.

Inappropriate Therapy and Shock Rates Between the Subcutaneous and Transvenous Implantable Cardiac Defibrillator: A Secondary Analysis of the PRAETORIAN Trial.

Inappropriate therapy (IAT) is an undesirable side effect of implantable cardiac defibrillator (ICD) therapy. Early studies with the subcutaneous ICD (S-ICD) showed relatively high inappropriate shock (IAS) rates. The PRAETORIAN trial demonstrated that the S-ICD is noninferior to the transvenous ICD (TV-ICD) with regard to the combined end point of IAS and complications. This secondary analyses evaluates all IAT in the PRAETORIAN trial. This international, multicenter trial randomized 849 patients with an indication for ICD therapy between S-ICD (n=426) and TV-ICD therapy (n=423). ICD programming was mandated by protocol. All analysis were performed in the modified intention-to-treat population. In both groups 42 patients experienced IAT (48-month Kaplan-Meier estimated cumulative incidence, 9.9% and 10.1%, respectively; hazard ratio (HR), 0.99 [95% CI, 0.65-1.52]; P=0.97). There was no significant difference in patients experiencing IAS between both groups (P=0.14). In the S-ICD group, 81 IAT episodes with 124 IAS and 1 inappropriate antitachycardia pacing occurred versus 89 IAT episodes with 130 IAS and 124 inappropriate antitachycardia pacing in the TV-ICD group. IAT episodes were most frequently caused by supraventricular tachycardias in the TV-ICD group (n=83/89) versus cardiac oversensing in the S-ICD group (n=40/81). In the TV-ICD group, a baseline heart rate >80 bpm (HR, 1.99 [95% CI, 1.05-3.76]; P=0.03), a history of atrial fibrillation (HR, 2.66 [95% CI, 1.41-5.02]; P=0.003), and smoking (HR, 2.46 [95% CI, 1.31-4.09]; P=0.005) were independent predictors for IAT. A QRS duration >120 ms was an independent predictor for IAT caused by cardiac oversensing in the S-ICD group (HR, 3.13 [95% CI, 1.34-7.31]; P=0.008). Post-IAS interventions significantly reduced IAS recurrence in both groups (P=0.046). There was no significant difference in IAT and IAS rates between the S-ICD and TV-ICD in a conventional ICD population, but causes and predictors for IAT differed between the devices. After the first IAS, an intervention significantly reduced the recurrence rate of IAS. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Life-Threatening Ventricular Tachyarrhythmia in Isolated Cardiac Sarcoidosis Compared With Cardiac Sarcoidosis With Extracardiac Involvement.

Although isolated cardiac sarcoidosis (CS) is not uncommon, little is known about the risk of life-threatening ventricular tachyarrhythmia. We aimed to evaluate the incidence of ventricular tachyarrhythmia in patients with isolated CS. Ninety-four patients with CS were enrolled. Isolated CS was diagnosed by histological or clinical confirmation in the heart alone. The endpoint was sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia, or implantable cardioverter defibrillator (ICD) therapy for ventricular fibrillation or sustained ventricular tachycardia. Twenty-five patients were diagnosed with isolated CS, and 69 with CS with extracardiac involvement. As the initial cardiac manifestation leading to the CS diagnosis, 10 (40%) patients with isolated CS had ventricular tachyarrhythmia. Over the median follow-up of 48 months after the CS diagnosis, sudden cardiac death occurred in 2 (8%) patients with isolated CS. Ventricular fibrillation or sustained ventricular tachycardia, including ICD therapy, occurred in 15 (60%) patients with isolated CS and 13 (19%) with CS with extracardiac involvement. The rate of ventricular tachyarrhythmia was higher in patients with isolated CS than in those with CS with extracardiac involvement (log-rank, p < 0.01). Cox proportional hazard analysis showed that isolated CS was independently associated with ventricular tachyarrhythmia. Two or more ventricular tachyarrhythmias more frequently occurred in patients with isolated CS (52% vs 13%, p < 0.01). Electric storm more frequently occurred in patients with isolated CS (24% vs 6%, p = 0.01). In conclusion, patients with isolated CS have ventricular tachyarrhythmia at a higher rate, compared with those with CS with extracardiac involvement.

Rationale and Design of the Personalized Therapy Study: Evaluating Real-World Performance of Two Automated Defibrillation Therapy Algorithms.

Barriers to maximizing patient benefit with implantable defibrillation devices include limited ability to tailor antitachycardia pacing (ATP) therapy in real-time and identify patients at risk of heart failure (HF) events early on. The Personalized Therapy study aims to evaluate the performance of two algorithms, intrinsic ATPTM (iATP) and TriageHFTM, to address these barriers in routine clinical practice. The Personalized Therapy Study was designed as a prospective, multicenter, post-market registry study expected to enroll approximately 2,200 patients meeting the following criteria: (1) implanted with a study-eligible device regardless of procedure type; (2) Medtronic CareLink® Network enrolled; (3) TriageHF enabled within CareLink and High Risk Alert notifications turned ON; and (4) iATP enabled. The primary study objectives are to demonstrate iATP effectiveness in the fast ventricular tachycardia zone and estimate the positive predictive value of TriageHF high-risk status for worsening HF. Additionally, objectives include characterizing iATP effectiveness in all ventricular detection zones and characterizing TriageHF based clinical actions and related HF-hospitalizations. This study is expected to generate real-world evidence on the performance of the iATP and TriageHF algorithms, which aim to improve clinical practice by tailoring arrhythmia and HF therapies to individual patient disease state.

Abstract 4122247: Impact of serum chloride levels for ventricular arrhythmias in patients with heart failure undergoing cardiac resynchronization therapy

Background: As previous reports of ventricular arrhythmia (VA) as a prognostic marker of mortality in heart failure (HF) patients included those with implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) devices, little is known about the risk factors of VA among patients undergoing cardiac resynchronization therapy (CRT), especially those without previous VA. The prognostic role of electrolyte abnormalities has been highlighted in HF patients. This study evaluated the impact of serum chloride levels for VA and all-cause death in patients with HF who underwent CRT without VA before CRT implantation. Methods: From the retrospective cohort of 397 HF patients (age 63+/-13, male 74%) who undergoing CRT implantation between 2010 and 2020, this study enrolled 175 patients (82% implanted CRT with a defibrillator) without a previous history of VA (sustained ventricular tachycardia (VT) of ventricular fibrillation (VF)). We studied the impact of serum chloride levels before CRT implantation. The primary endpoint was defined as VA, VA with ICD therapy and sudden cardiac death. The secondary endpoint was all-cause mortality. Results: During median follow-up of 35 months, 53 patients (30%) experienced VA. Patients with VA had a tendency toward high LVESV (172ml vs. 150ml, p&lt;0.09) and low left ventricular ejection fraction (26 vs. 29, p&lt;0.09), and significantly reduced rate of angiotensin converting enzyme inhibitors or angiotensin receptor blockers (30% vs. 70%, p&lt;0.05) at the time of CRT implantation. The rate of CRT responders was significantly higher in patients without VA than with VA (59% vs. 40%, p&lt;0.05). The cut-off value of chloride for VA was determined to be 102mEq/l using receiver operating characteristic analysis. The patients with chloride ≤102mEq/l had significantly higher rates of VA (41% vs. 25%, log-rank p&lt;0.05) and mortality (33% vs. 18%, log-rank p&lt;0.05) (Figure). By multivariate cox analysis, the level of chloride had an independent predictive value of VA in patients with CRT (hazard ratio [HR] 1.08 per 1mEq/l decrease, 95% confidence interval [CI] 1.00-1.16, p&lt;0.05) (Table). Conclusions: The chloride level had a predictive value for VA after CRT implantation in HF patients without previous VA. The management of electrolytes, including chloride, might be important for preventing fatal arrhythmia in patients with HF undergoing CRT implantation.

Abstract 4137113: The Effectiveness of Cardiac Resynchronization Therapy in Patients with Cardiac Sarcoidosis: A Retrospective Analysis

Background: Cardiac sarcoidosis (CS) manifests in a wide range of clinical presentations, including conduction system abnormalities, ventricular arrhythmias, and systolic heart failure. Although cardiac resynchronization therapy (CRT) has shown efficacy in treating select nonischemic cardiomyopathy patients, its specific impact on CS patients remains less explored. This study aimed to evaluate the outcomes of CRT therapy in CS patients, focusing on implantable cardioverter defibrillator (ICD) therapies, heart failure (HF) hospitalizations and mortality. Methods: We retrospectively reviewed all patients with a clinical or histological diagnosis of CS who underwent device implantation (ICD or Permanent Pacemaker (PPM)) with or without CRT therapy at Johns Hopkins Hospital between 2004 and 2024. Baseline characteristics and echocardiographic parameters were assessed. Heart failure hospitalizations, the frequency of ATP (Anti-Tachycardia Pacing) or ICD shocks, and all-cause mortality were also evaluated as the outcomes. Results: The study included 212 patients (40.1% female, average age 52.8 ± 11.1 years). Eighty-five patients underwent CRT implantation (82 CRT-D and 3 CRT-P), whereas the rest received either an ICD or a PPM without CRT therapy. Most CRT devices (58.82%) were upgrades from an initial PPM or ICD. Over a follow-up of 6.15 ± 4.43 years, 27 (12.74%) patients were hospitalized for heart failure (HF), 86 (40.56%) experienced ATP or ICD shocks, and 17 (8.02%) died. The composite outcome was observed in 103 patients (48.5%), with no significant differences between CRT and non-CRT groups ( P = .51). Survival analysis indicated significantly reduced freedom from HF hospitalizations in the CRT group compared to non-CRT group ( P = .01). However, ATP/ICD shocks did not have a significant difference. CRT recipients showed an improvement in left ventricular ejection fraction (LVEF) from 35.3 ± 12.6% to 38.9 ± 13.6% at 6 months ( P = .01). Non-recipients showed no significant change in LVEF ( P = .43). Conclusions: Over an average six-year follow-up period, CRT upgrade does not appear to affect ATP/ICD shock and mortality in CS patients, although it is associated with significantly higher rates of heart failure (HF) hospitalizations compared to CS patients with an ICD or PPM alone. These findings underscore the complex response of CS patients to CRT, highlighting the need for further research to optimize treatment strategies within this subgroup.

Quality of Life in Subcutaneous or Transvenous Implantable Cardioverter-Defibrillator Patients: A Secondary Analysis of the PRAETORIAN Trial.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to overcome the risk of lead-related complications associated with the transvenous implantable cardioverter-defibrillator (TV-ICD). In contrast to the TV-ICD, the S-ICD is a completely extrathoracic device. Subsequently, complications differ between these 2 implantable cardioverter-defibrillators, which might impact patient perceptions of the therapies. This prespecified secondary analysis of the PRAETORIAN trial evaluates differences in quality of life. The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) randomized patients with an implantable cardioverter-defibrillator indication, without the need for pacing to S-ICD or TV-ICD therapy. Two questionnaires were collected at baseline, discharge, 12 months, and 30 months. The Duke Activity Status Index measures cardiac-specific physical functioning, and the 36-Item Short Form Health Survey measures physical and mental well-being, with the subscales bodily pain and mental health being of interest in this analysis. Mann-Whitney U tests were used to compare study arms, and a mixed model was used to describe the questionnaire outcomes over time. Patients were randomized to S-ICD (n=426) and TV-ICD (n=423). In the S-ICD group, 20% were women versus 19% in the TV-ICD group. The median age was 63 (interquartile range, 54-69) years in the S-ICD group versus 64 (interquartile range, 56-69) years in the TV-ICD group. There were no significant differences in the Duke Activity Status Index and 36-Item Short Form Health Survey subscales for bodily pain and mental health between the groups at any time point. Patients with a shock in the last 90 days had significantly lower scores for social functioning (P=0.008) and role limitations due to emotional problems (P=0.001) than patients without a shock, but this effect did not differ between treatment arms. In a large randomized cohort of patients with an S-ICD or TV-ICD, no difference in overall quality of life was observed. However, implantable cardioverter-defibrillator shocks resulted in a reduction in quality of life, regardless of the device type or appropriateness. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Desmoplakin Cardiomyopathy in Pediatric Patients: A Distinct, Underrecognized Cohort of Arrhythmogenic Cardiomyopathy.

DSP cardiomyopathy is a distinct subset of arrhythmogenic cardiomyopathy, reported primarily in adults, that has predominantly left ventricular involvement and features of myocarditis. Clinical characteristics, risk stratification, and management of pediatric patients with DSP variants are not well known. We sought to identify phenotypic features and prognosis of pediatric patients with DSP pathogenic or likely pathogenic variants. Multicenter, retrospective study of patients <21 years of age with DSP variants from 6 tertiary pediatric hospitals. Thirty-four patients, including 10 probands with clinical disease and 24 genotype-positive phenotype-negative patients, were included in the study. The majority of probands were initially diagnosed with myocarditis (50%) and had biventricular (60%) or left ventricular predominant (40%) disease. Chest pain was the most common symptom at presentation (30%), and all had troponin elevation. Probands with homozygous or compound heterozygous DSP variants were likely to present at an early age (<13 years) with symptoms of heart failure, severe biventricular involvement, and dermatologic abnormalities. Low-voltage QRS was the most prominent ECG abnormality. Of those who underwent implantable cardioverter defibrillator implantation, 50% received appropriate implantable cardioverter defibrillator therapy and were found to have significant biventricular involvement in addition to severe left ventricular dysfunction with an ejection fraction <35%. DSP cardiomyopathy in children and adolescents has varied phenotypic manifestations based on age and genotype and often can be diagnosed as myocarditis. Severe left ventricular dysfunction and biventricular involvement may be associated with a higher likelihood of malignant ventricular tachyarrhythmia.

Similar incidence of ICD-shocks in diabetic compared to non-diabetic patients receiving implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D)

Abstract Background and aims Recent studies have suggested that diabetes patients with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) may experience a reduced incidence of appropriate ICD-shocks and an increased mortality rate. This study aims to assess whether there is parity in ATP-treatment and ICD-shocks between patients with and without type 2 diabetes mellitus (T2DM), and to analyze associated mortality rates. Methods Using the Danish pacemaker and ICD registry we included patients who received a first-time ICD or CRT-D implantation with a primary or secondary prophylactic indication, between January 1st 2000 to December 31st 2018. Outcomes were analyzed individually for each outcome. Cause specific Cox was used for i) appropriate ATP therapy or ICD-shock, ii) inappropriate ATP therapy or ICD-shock, and a standard Cox regression model was used for iii) all-cause mortality, iv) mortality rate following an ATP-therapy or ICD-shock. Cumulative incidence curves, generated using the Aalen Johansen estimator, were utilized to compare the incidence rates for ATP therapy and ICD-shock while accounting for competing risk of death, while Kaplan-Meier methodology was utilized for survival curves. Analyses were conducted in the total population and in subgroups divided on indication and device type. Results Out of 14 747 patients who received an ICD or CRT-D, 4377 (30%) had T2DM, 4593 (31%) patients received first-time appropriate ATP therapy or ICD-shock, and 1244 (8,4%) experienced first-time inappropriate treatments, 5 112 (35%) experienced death during the follow-up time (mean 3.9 years (SD 2.7)). T2DM patients were more likely to be male (85% vs 80%), slightly older (66 vs 65 years) and burdened with more comorbidities. No significant differences were seen between T2DM and non-T2DM patients for appropriate ATP therapy (HR 0.96[0.88:1.04] p=0.31), appropriate ICD-shock (HR 0.95[0.86:1.05] p=0.32), inappropriate ATP therapy (HR 0.92 [0.77;1.09] p=0.32) and inappropriate ICD-shock (HR 0.96 [0.78;1.18] p=0.71). In the subgroup analyses, no difference was seen in the primary prophylactic subgroups (Figure 1.), only significant difference was observed in the secondary prophylactic ICD group who received less ATP-therapy at 5-year follow-up (HR0.83[0.70;0.99] p=0.04), and in the secondary prophylactic CRT-D group, were T2DM patients seemed to experience more appropriate ICD-shock treatments (HR 2.07[1.23;3.48] p=0.006). Further, we found a higher mortality rate in T2DM with primary prophylactic ICD (HR 1.46[1.31;1.62] p&amp;lt;0.001) and secondary prophylactic ICD (HR 1.30[1.13;1.51] p&amp;lt;0.001), (Figure 2.) this mortality rate remained largely unchanged post appropriate ATP or ICD-shock in the ICD subgroups. Conclusions Despite similar incidence of ATP-therapy and ICD-shocks, T2DM patients with ICD-device experienced a significantly higher post-treatment mortality and all-cause mortality rate.

Microbial specturm and antibiotic sensitivity of pocket swabs in ICD patients undergoing device replacement or lead revision surgery- findings from a ICD registry observational study

Abstract Introduction Infection is a serious complication of implantable cardioverter defibrillator (ICD) therapy, necessitating effective preventive measures during implantation or revision surgery. The intraoperative use of antibacterial envelopes containing rifampicin and minocycline has shown promising results in reducing infection, yet, it is expensive and not cost-effective. Gentamicin sponges might be an alternative to the antibacterial envelope, however its efficacy on targeting the specific microbial spectrum found in device infection must be further investigated. Aim of the study was to identify the bacterial species obtained from pocket swabs of ICD patients undergoing revision surgery, and assess their sensitivity to gentamicin, rifampicin and minocycline. Methods A total of 459 intraoperative pocket swabs were collected from consecutive ICD patients who underwent elective device replacement, system upgrade or lead revision between 2017 and 6/2023. The baseline characteristics were similar in both groups (Table 1). Results Out of the 459 swabs analysed: 416 (90.6%) were negative for microbial growth. The remaining 43 swabs (9.4%) were tested positive for microbial growth (Table 2). Coagulase-negative- staphylococci (CoNS) were the most commonly isolated bacteria, accounting for 56% of cases. Bacteria with available antibiograms exhibited a sensitivity of 92% to gentamicin, 96% to rifampicin and 96% to Minocycline (Table 2). Conclusion The antibiotic sensitivity of the bacteria obtained from the pocket swabs to gentamycin, rifampicin and minocycline was similar. Thus, gentamicin sponges might be an alternative to the antibacterial envelope in patients with ICD undergoing generator replacement or revision surgery.

Targeting ventricular tachycardia originating from the anterolateral papillary muscle with stereotactic body radioablation therapy

Abstract Background Ventricular Tachycardia (VT) is prevalent in the setting of non-ischaemic cardiomyopathy (NICM), a heterogeneous group of conditions characterized by myocardial dysfunction in the absence of coronary artery disease. Challenges of catheter ablation to treat VT in NICM patients are well known, and recurrence rates can be as high as 58%. Stereotactic body radioablation therapy (SBRT) involves precise delivery of radiation to arrhythmogenic substrates, and represents a novel treatment to reduce recurrent implantable cardioverter defibrillator (ICD) therapies in patients with refractory VT. Though SBRT has shown preliminary effectiveness in reducing VT episodes, its effectiveness in NICM patients has not been widely evaluated. Purpose To evaluate SBRT effectiveness in NICM patients with scars at the basal anterolateral papillary muscle at a tertiary care center between November-December 2022. Methods Eligible patients had their VT substrate mapped using a single-use ECGI vest and a 4D-CT simulation scan. In addition, MRI scans were used to aid anatomical identification of the anterolateral papillary muscle which could not be seen on the non-contrast diagnostic CTs. SBRT was delivered in a single fraction of 25 Gy under image guidance. Effectiveness of the treatment was evaluated as changes in frequencies of total antitachycardia pacing (ATP) and ICD shock episodes from 6 months pre-, and within to 3, 6, and 12 months follow up post SBRT. Results Participants were 3 males with NICM, aged 56, 60, and 73 with previous dual chamber ICD implantation, 2 of whom had a history of VT ablation/ VT storm and paroxysmal atrial fibrillation. All participants had basal lateral scar, and were receiving beta blockers, mexiletine, and amiodarone with refractory VT before SBRT treatment. Prior to SBRT, ICD device interrogation showed a total of 119 (77, 7, and 35 in patients 1-3 respectively) ATPs, and 27 (10, 1, and 16 in patients 1-3 respectively) ICD shocks delivered. At 12 month follow-up, none of the participants experienced any episodes of ATP or ICD shock. Ejection fraction remained consistent pre-post SBRT. Conclusion SBRT showed remarkable success in reducing ATP and ICD shock episodes, facilitating uncomplicated 1 year follow-up in 3 male patients with NICM and VT from the anterolateral papillary muscle.

The correlation between cardiac magnetic resonance imaging and echocardiography in patients with severe ischaemic cardiomyopathy

Abstract Background Left ventricular ejection fraction is the single metric that guides therapeutic decision-making, risk stratification and prognosis in patients with severely impaired systolic function. Although cardiac magnetic resonance imaging (CMR) is the current reference standard for quantification of ventricular volume and function, echocardiography is used more often as it is more widely available and less expensive.(1) Aims To evaluate the correlation between CMR and echocardiography in quantifying left ventricular (LV) volume and function and to determine whether these measurements are associated with clinical outcomes in patients with severe ischemic cardiomyopathy (ICM). Methods Participants recruited to the REVIVED-BCIS2 trial who had undergone baseline CMR or echocardiography were included in this analysis. All scans were analyzed in blinded core laboratories as previously reported.(2,3) All volumes were indexed to body surface area. Spearman correlation, Bland Altman analysis and coverage probability methods were performed to assess the correlation between the two modalities. A Cox proportional hazards model was used to assess the association between imaging metrics and the primary outcome, a composite of all-cause death and aborted sudden death. A sensitivity analysis was conducted a priori, restricted to patients undergoing both scans within 60 days of each other. Results A total of 373 participants with paired imaging data were included: mean age 69±9 years, 87% male, BMI 28±5. A moderate correlation was detected for volume measurements between the modalities (end diastolic volume index (EDVI) r=0.66 end systolic volume index (ESVI) r=0.68), with a weaker correlation for LV ejection fraction (EF) (r=0.41). Bland-Altman plots showed moderate agreement in LVEF measurements (Table 1). The sensitivity analysis included 199 patients, and showed similar results (EDVI r=0.72, ESVI r=0.73 LVEF r=0.43, all p&amp;lt;0.000). Only 7.5% of the paired LVEF measurements were within 5% of each other. 30% of participants were misclassified by echocardiography as having an LVEF&amp;gt;35%. (Figure 1) CMR ESVI was associated with the occurrence of the primary outcome (HR 1.05 per 10ml increment, 95% CI 1.00-1.10) however echo ESVI (HR 1.05 per 10ml increment 95% CI 0.99 – 1.10) and all other imaging metrics were not. Conclusion Left ventricular volumes and ejection fraction on CMR and echocardiography were only modestly correlated in this population with severe ICM. When using the binary EF threshold of 35% that is commonly used to select patients of implantable defibrillator therapy, almost a third of patients at risk would have been missed by echocardiography alone. The additional insights provided by CMR, including scar burden, further support preferential use of this modality in the assessment such patients.

Incidence and Predictors of Appropriate Implantable Cardioverter Defibrillator Therapy in Japanese Ischemic Heart Disease Patients

Although the efficacy of an implantable cardioverter defibrillator (ICD) in preventing sudden cardiac death is well established, the incidence and predictors of appropriate ICD therapy in Japanese ischemic heart disease (IHD) patients remain unclear. We retrospectively studied Japanese 141 IHD patients undergoing transvenous ICD or cardiac resynchronization therapy with a defibrillator (CRT-D) implantation for primary or secondary prevention at Hirosaki University Hospital. Over a mean (±SD) follow-up period of 5.5±2.8 years, the incidence of appropriate ICD therapy was similar in the primary and secondary prevention groups, although it was relatively more frequent in the first 2 years in the secondary prevention group. Four patients died due to sustained ventricular tachycardia (VT) or ventricular fibrillation (VF), mainly due to post-shock pulseless electrical activity. Once patients had received their first appropriate ICD therapy, 49.2% received second appropriate ICD therapy within 6 months. Cox proportional hazard analysis revealed that sustained VT as an index life-threatening ventricular tachyarrhythmia before ICD/CRT-D implantation was an independent predictor of appropriate ICD therapy, but VF was not. The incidence of appropriate ICD therapy was comparable in primary and secondary prevention among Japanese IHD patients. We need to recognize the high-risk period for second appropriate ICD therapy after the first therapy and sustained VT as index life-threatening ventricular tachyarrhythmia as a risk factor for appropriate ICD therapy.

Sudden cardiac death after myocardial infarction: individual participant data from pooled cohorts.

Risk stratification of sudden cardiac death after myocardial infarction and prevention by defibrillator rely on left ventricular ejection fraction (LVEF). Improved risk stratification across the whole LVEF range is required for decision-making on defibrillator implantation. The analysis pooled 20 data sets with 140 204 post-myocardial infarction patients containing information on demographics, medical history, clinical characteristics, biomarkers, electrocardiography, echocardiography, and cardiac magnetic resonance imaging. Separate analyses were performed in patients (i) carrying a primary prevention cardioverter-defibrillator with LVEF ≤ 35% [implantable cardioverter-defibrillator (ICD) patients], (ii) without cardioverter-defibrillator with LVEF ≤ 35% (non-ICD patients ≤ 35%), and (iii) without cardioverter-defibrillator with LVEF > 35% (non-ICD patients >35%). Primary outcome was sudden cardiac death or, in defibrillator carriers, appropriate defibrillator therapy. Using a competing risk framework and systematic internal-external cross-validation, a model using LVEF only, a multivariable flexible parametric survival model, and a multivariable random forest survival model were developed and externally validated. Predictive performance was assessed by random effect meta-analysis. There were 1326 primary outcomes in 7543 ICD patients, 1193 in 25 058 non-ICD patients ≤35%, and 1567 in 107 603 non-ICD patients >35% during mean follow-up of 30.0, 46.5, and 57.6 months, respectively. In these three subgroups, LVEF poorly predicted sudden cardiac death (c-statistics between 0.50 and 0.56). Considering additional parameters did not improve calibration and discrimination, and model generalizability was poor. More accurate risk stratification for sudden cardiac death and identification of low-risk individuals with severely reduced LVEF or of high-risk individuals with preserved LVEF was not feasible, neither using LVEF nor using other predictors.