Implantable Cardioverter-defibrillator Therapy Research Articles

Abstract 17005: Brugada Syndrome: Is There a Difference Between Probands and Relatives?

Introduction: Brugada syndrome (BrS) is an inherited arrhythmic disease that is rarely linked to sudden cardiac death (SCD), often associated with SCN5A mutations. Hypothesis: The main objective of this study was to report the demographic, clinical findings and outcomes of a BrS registry in the Maltese Islands, comparing probands and relatives. Methods: Data was collected prospectively in all BrS patients. BrS was defined as per the latest European Society of Cardiology SCD guidelines published in 2022. Patients were placed in two groups (proband vs relative). Results: 120 individuals were included (2.7 per 10,000 individuals) (56.7% male, mean age 44.0±16.5 years at diagnosis, 7.5% athletes). 54 (45.0%) were probands. 61 (50.8%) reported cardiac symptoms. A relevant family history of SCD was present in 55 (46.6%). Follow up period of 49.8 ± 33.3 months. A spontaneous type 1 brugada pattern was the primary method of diagnosis in probands (71.1%), ajmaline provocation in relatives (71.6%) (p<0.001). Probands reported more symptoms (33.1% vs 17.8%, p<0.0001), documented arrhythmias during holter monitoring (29.0% vs 9.3%, p=0.028), and manifested J /ST elevation during stress testing (14.0% vs 5.3%, p=-0.039). The age at diagnosis was similar for probands and relatives. Similar proportions of atrioventricular block (15.7%), prolonged QRS (10.2%), early repolarisation (12.8%), QRS fragmentation (5.6%), low QRS voltages (5.6%) and pathological TWI (8.3%) were observed in both groups. 18 (20.4%) were identified with a SCN5A mutation (P, LP, VUS as per ACMG criteria). 5 patients (4.2%) had a novel variant. 17 (15.3%) were referred for a VT study. 20 (16.7%) had an ICD implanted, more frequent in probands (34.0% vs 3.1%) (p<0.001). 3 were implanted because of OHCA. 27 (22.5%) were implanted with an ILR, commoner in probands (33.3% vs 16.4%, p=0.047). Two patients (10% of ICD subgroup) had an appropriate ICD therapy. One patient is on quinidine because of refractory shocks. Conclusions: The prevalence of BrS in Malta is comparable to other studies. 20.4% (probands) had a SCN5A mutation. The higher incidence of symptoms, arrhythmias, abnormal response during exercise and ICD implantation in probands (vs relatives) may suggest they are a higher risk group.

Abstract 13631: Desmoplakin Cardiomyopathy in Pediatric Patients - A Distinct, Underrecognized Cohort of Arrhythmogenic Cardiomyopathy

Introduction: Arrhythmogenic cardiomyopathy is a spectrum of diagnoses including the historically recognized arrhythmogenic right ventricular cardiomyopathy. More recent literature describes predominately left ventricular (LV) or biventricular (BiV) involvement. Variants in the desmoplakin ( DSP) gene commonly cause LV and BiV phenotypes, though data in children are sparse. Hypothesis: Pediatric patients (pts) with DSP mutation have predominantly LV or BiV disease and may present with early onset malignant arrhythmia. Methods: We performed a multicenter, retrospective cohort study of pts <21 years with pathogenic or likely pathogenic DSP variants from 6 tertiary referral children’s hospitals. We describe clinical variation in DSP probands (PBs), the first affected family member prompting genetic testing due to clinical history, as compared to genotype-positive family members (FMs) <21 years of age diagnosed by familial cascade screening. Results: We identified 34 pts; 12 (35%) were PBs and 22 (65%) were FMs. Median age at genetic diagnosis was 13.3 and 12.3 years for PBs and FMs, respectively. Four PBs had LV-predominant disease; 6 had BiV disease (table 1). The most common initial diagnosis for PBs was myocarditis and dilated cardiomyopathy. ECG abnormalities were common in PBs (75%) and included left axis deviation, inferolateral T-wave inversion, and low QRS complex amplitude. The LV ejection fraction (EF) on echo was 48% and 65% for PBs and FMs, respectively. Eight PBs underwent MRI and 6 had late gadolinium enhancement involving the LV only, while 2 had BiV involvement. Six PBs underwent ICD implantation and 2 received appropriate ICD therapy (LVEF 25% and 41%). Two PBs had cardiac transplantation. Conclusion: Pediatric DSP -cardiomyopathy has predominantly LV or BiV involvement and may be misdiagnosed as myocarditis or dilated cardiomyopathy. Probands in particular, may present with early malignant ventricular arrhythmias and significant LV dysfunction.

Abstract 15291: Early Outcomes With Left Cardiac Sympathetic Denervation for Medically Refractory Idiopathic Ventricular Fibrillation

Introduction: Treatment options for patients with recurrent ventricular arrhythmias (VAs) refractory to pharmacotherapy and/or ablation are minimal. Although left cardiac sympathetic denervation (LCSD) is well established in long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT), LCSD’s role in idiopathic ventricular fibrillation (IVF) is less clear. Here, we report our single-center experience regarding the early outcomes of LCSD in patients with IVF. Hypothesis: To determine the efficacy of LCSD on reducing VAs in IVF patients refractory to conventional therapy. Methods: A retrospective analysis of the electronic health record of patients with IVF between January 2000 to April 2023 was performed. Cardiac event rates [defined as arrhythmic syncope/seizure, appropriate implantable cardioverter defibrillator (ICD) therapy, sudden cardiac arrest (SCA), or sudden cardiac death (SCD)] before and after LCSD for each patient were calculated and a Wilcoxon signed rank test was performed. Results: In total, 94 patients (41% female) were classified as IVF. Overall, 15/94 patients (16%) had LCSD due to refractory VAs (60% male; mean age at LCSD 36 ± 20 years) despite beta-blocker treatment (100%) or combined drug therapy (67%). In total, 14 patients (15%) had an electrophysiology study performed before LCSD of which 10 (67%) had VAs ablation. All patients had a structurally normal heart and genetic testing performed in 14/15 patients (93%) confirmed absence of genetic cardiomyopathies and channelopathies. SCA was the sentinel event in 10 of 15 patients (67%); 14 patients (93%) had an ICD in place. The average follow-up time after LCSD was 3 ± 4 years. The VA event rate before LCSD was 4 ± 3 events per year and was reduced to 1 ± 3 per year (p<0.04) after LCSD. Patients had a median of 3.2 less events per year after LCSD (p=0.02) with 7 patients (47%) having no post-LCSD recurrences thus far while 3 (20%) patients were deemed LCSD non-responders with no reduction of event rate. Conclusions: LCSD represents a substrate-independent, anti-fibrillatory treatment option for patients with life-threatening, genetic arrhythmias. While not curative, the early outcomes of LCSD for patients with medically refractory IVF are promising.

Abstract 13760: Systematic Review and Meta-Analysis of Clinical Outcomes in Cardiac Sarcoidosis: A Comprehensive Review

Introduction: Cardiac sarcoidosis (CS), often overlooked due to its myriad and non-specific presentation, is mainly understood through small studies. Hypothesis: What comprehensive evidence exists regarding the cumulative clinical outcomes in CS patients? Methods: A literature search in PubMed and EMBASE was conducted until September 8, 2022. Data from Kaplan-Meier curves were reconstructed using WebPlotDigitizer, with subsequent analysis was conducted via Cox proportional hazards models and non-parametric methods. Results: We reviewed 183 studies with 29,830 CS-diagnosed patients, and CS predominantly affected middle-aged, White, and Black individuals, with data primarily derived from Europe, North America, and Japan. The prevalent arrhythmias were ventricular arrhythmias (25%) and conduction block (low-degree, 21%; high-degree, 15%). Steroids were the primary treatment, with implantable cardioverter-defibrillators (ICD) used in 20% of cases (Image 1) . Survival meta-analysis showed that immunosuppressants significantly lower mortality risk in CS patients (HR: 0.52, 95% CI: 0.38-0.7, p < 0.0001) compared with the general CS population. ICD implanted for primary prevention in CS patients was associated with lower risk of inappropriate ICD therapy compared with ICD for secondary prevention (HR: 0.29, 95% CI: 0.19-0.44, p < 0.0001). Post-transplant survival was superior in CS patients than non-CS patients (HR: 0.58, 95% CI: 0.46-0.72, p < 0.0001) (Image 2) . Conclusions: This study is the first to provide comprehensive outcomes in CS patients. We encourage global research efforts to include underrepresented population in order to better understand CS.

Abstract 16061: Correlation Between Obesity and Ventricular Tachycardia in Individuals With HFrEF: Analysis From the DERIVATE Cohort

Background: Ventricular arrhythmias (VA) are a significant cause of morbidity and mortality in heart failure. Obesity has been proposed as a potential risk factor for increased VA incidence, but previous studies with limited sample sizes and single-center enrollment have yielded conflicting results. To address this, we utilized data from the international multicenter DERIVATE study, which includes individuals with heart failure with reduced ejection fraction (HFrEF) as well as baseline cardiac MRI (CMR) assessment of myocardial structure and function. We sought to investigate the association between obesity and sustained ventricular tachycardia (VT) occurrence in this patient population. Methods: Study cohort comprised of patients enrolled in the CarDiac MagnEtic Resonance for Primary Prevention Implantable CardioVerter DefibrillAtor ThErapy (DERIVATE) registry who had HFrEF and had simultaneous baseline CMR and echocardiography evaluation. Demographics, comorbidities, and CMR variables were used to evaluate the correlation between obesity and ventricular tachycardia. Obesity was defined as BMI>30 kg/m 2 . A multivariate logistic regression analysis was used to determine the association between clinical, imaging variables and the occurrence of VA. Statistical software SAS 9.4 was used to perform the analysis. Results: Among 2,537 individuals, 505 (19.9%) were obese. Mean age was 60 years and 23.9% were female. Median follow-up was 994 days. Obesity was not associated with VT (OR 0.94, CI 0.60-1.48, P=0.79). The occurrence of VT was associated with the presence of an ischemic cardiomyopathy (OR 1.76, CI 1.37-2.26, p<0.01), and amiodarone use (OR 1.89, CI 1.28-2.80, P<0.01). As expected, left ventricular ejection fraction was inversely associated with VT (OR 0.96, CI 0.94-0.98, P<0.01), while indexed left ventricular end diastolic volume was directly associated with VT (OR 1.01, CI 1.00-1.01, P<0.01). Conclusions: In individuals with HFrEF, there was no association between obesity and the occurrence of sustained VT. The presence of ischemic cardiomyopathy was associated with higher incidence of sustained VT, as well as larger indexed left ventricular end diastolic volume which is an imaging marker of HF chronicity and severity.

Abstract 14398: Predictors of Major Adverse Cardiac Events in Individuals With Left Bundle Branch Block and Cardiac Resynchronization Therapy: Analysis From the Derivate Registry

Background: Cardiac resynchronization therapy (CRT) plays an important role in managing patients with advanced heart failure (HF) with reduced ejection fraction and interventricular conduction block, as it reestablishes synchrony and cardiac function while reducing the risks of HF-related hospitalizations and mortality. Despite the well-described advantages of CRT, approximately 30% to 40% of patients fail to respond to therapy. Therefore, our study aimed to define patient characteristics associated with major adverse cardiac events (MACE) in individuals with left bundle branch block (LBBB) who received CRT. Methods: The study cohort included patients enrolled in the CarDiac MagnEtic Resonance for Primary Prevention Implantable CardioVerter DefibrillAtor ThErapy (DERIVATE) registry who had LBBB and had previously undergone CRT. We defined MACE as a composite outcome including cardiac death, hospitalization for heart failure, or major adverse arhythmic events. Cox regression analysis was used to examine the relationship between MACE and CRT therapy. Kaplan-Meier curves were utilized to explore the association between CRT and cardiac death. Results: Out of 300 individuals, 144 (48%) experienced MACE. The cohort had a mean age of 63.9 ± 10.9, with 29% being male. The median follow-up period was 1285 days. Ischemic cardiomyopathy was identified as an independent predictor of MACE (HR = 3.54; 95% CI [2.31-5.41]; P<0.01) and cardiac death (HR = 24.10; 95% CI [10.71-54.21]; P<0.01) in patients with LBBB and CRT. Amiodarone therapy was associated with a 1.91-fold (95% CI [1.20-3.05]; P=0.01) increased risk of MACE. Notably, multivariate analysis did not reveal a significant association between gender, hypertension, renal function, diabetes mellitus, or NYHA class III/IV and the occurrence of MACE. Conclusion: Our findings suggest that ischemic cardiomyopathy and the use of amiodarone therapy are independent predictors of MACE in patients with LBBB who previously underwent CRT. These findings suggest that patient-level characteristics are important predictors of MACE; however, further research is needed to better understand the interplay between ejection fraction, conduction disease, and patient characteristics post-CRT therapy.

Abstract 18880: Ventricular Arrhythmia Prevalence and Burden in Patients With Third Generation Continuous Flow Left Ventricular Assist Devices

Background: Ventricular arrhythmias (VAs) are common in patients with left ventricular assist devices (LVADs). Little is known about the impact of third-generation LVADs (Heartmate 3, HM3) on VAs prevalence and burden. Aims : To characterize the impact of HM3 LVAD implantation on VAs prevalence and burden in patients with advanced heart failure (HF) and implantable cardioverter-defibrillators (ICDs). Methods: We included consecutive patients with advanced HF and ICDs who received HM3 devices at our center between 2016 and 2022. The study outcomes were the prevalence of sustained VAs, defined as >30s VA episode detected by the ICD monitor zone or appropriately treated (ATP or shock), sustained VA burden (total number of episodes), and VA storm (≥3 appropriate ICD interventions in 24/h period). Data was collected over the 1 year before and after HM3 implantation. Results: A total of 321 patients were included (28% female, mean age 60±12 years, mean INTERMACS score 3±0.95). At 1 year follow-up after HM3 implantation, 27 patients died. A total of 128 patients (43%) had at least one sustained VA episode in the year before the HM3 implantation compared to 51 patients (17%) in the year following the HM3 (p<0.001 for comparison). The sustained VA burden decreased from a mean of 3.8 events per person-year (PPY) to a mean of 0.8 events PPY (p=0.005). Similarly, appropriate ICD therapy occurred in 123 patients (38%) before implantation and 46 patients (14%) after implantation (p<0.001). The burden of appropriate therapy was also reduced (from a mean of 2.57 events PPY to a mean 1.32 events PPY; p=0.03). The prevalence of VA storm was reduced from 19% to 8% (p<0.001). Conclusions: In patients with advanced HF and ICDs undergoing HM3 implantation, the prevalence of sustained VAs, VAs burden, appropriate ICD interventions, and VA storm were all significantly reduced in the year following HM3 implantation.

Abstract 15009: Extra-Low Energy Defibrillation With Epicardial Implantable Cardioverter Defibrillator Networks With Electrically Conductive Fibers in Disease Models

Introduction: We previously reported that extra-low energy (<0.6J) defibrillation is possible with the epicardial ICD net lead system (Ep-ICD) in normal canine hearts. Hypothesis: The aim of this study was to test whether the Ep-ICD can terminate ventricular fibrillation (Vf) with the same energy in two disease models (heart failure and long QT syndrome (LQT)). Methods: 1. Ep-ICD was constructed by fine tungsten fibers at the top and bottom of the cardiac mesh (Figure 1), connected to the RV and SVC coils of the DF-1 lead, respectively. 2. Heart failure was induced by rapid right ventricular pacing (170 bpm, 8 weeks). 3. Vf was induced by placing a 9V battery on the surface of the heart. DC shock was delivered with a minimum energy of 0.4J (Medtronic Viva XT). 4. Defibrillation threshold (DFT) was defined as 75% of defibrillation success. 5. LQT was simulated by reducing the conductance (Gk) of the IKS current by (x 1.0(CTL) or 0.8(LQT)) by computer simulation. Results: 1. DFT(J) of Ep-ICD in the canine HF model: 0.8, 1.2, 1.2. 3, Minimum DF energy(J): 0.6, 0.6, 0.8, 2. Maximum DF energy(J): 1.2, 1.6, 5, 52. Immediate return to sinus rhythm (SR) was achieved in most cases after DC delivery. In a small number of cases, brief periods of VT occurred, with rapid return to SR. No tachycardic arrhythmias occurred after return to SR. 3. The DFT was 0.39 for LQT and 0.52 for CTL. Conclusions: 1. DFT of Ep-ICD increased from 0.6 J in normal canine heart to 1.2 J in canine HF model, but still much lower energy used in current ICD system (36 J). 2. The Ep-ICD lead system is the least traumatic and still within the acceptable range while conscious. 3. DFT of LQT with Ep-ICD is 25% lower than normal heart. 4. Ultra-low energy DC can avoid conduction abnormalities or malignant arrhythmias after shock. Hearts return to SR immediately. 5. Ep-ICD can deliver the DC shock before loss of consciousness, improving quality of life and safety of ICD therapy.

Abstract 13917: Predictors of Ventricular Arrhythmias in Patients With Left Ventricular Ejection Fraction Improvement to >35% Following Cardiac Resynchronization Therapy

Introduction: Patients undergoing cardiac resynchronization therapy with a defibrillator (CRT-D) show significant improvement in LVEF. We designed this study to identify predictors of ventricular arrhythmic (VA) events among patient with LVEF improvement > 35% after one year of treatment with CRT-D. Hypothesis: We hypothesized that LVEF improvement > 35% is associated with a decreased risk of VA events. Methods: Patients randomized to CRT-defibrillator from the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) trial with LVEF > 35% at 12 months were included in this analysis (N=651). Predictors of an appropriate ICD therapy for VA subsequent to one year were evaluated by cox regression model. Cumulative probability of first event was analyzed by Kaplan Meier Method with time for follow-up beginning at 1 year after device implantation. Results: The average follow-up was 2.04 ± 0.83 years. We identified 3 independent predictors of VA among patients treated with CRT-D subsequent to LVEF improvement to > 35%: (1) baseline non-LBBB morphology (HR=1.93; 95% CI,1.23-3.04; p= 0.004); (2) the occurrence of VA during first year post CRT-D implant (HR=4.91 [95% CI, 2.99-8.07]; p<0.001); and (3) lower range improvement in LVEF (36-40% vs. >40%; HR =1.97 [95% CI 1.21-3.20]; p= 0.006). When compared with patients with 0 risk factors, having one and 2 or more risk factors had significantly higher risk of VTA (2-year rate of VT/VF = 4%, 11% and 32% respectively; HRs = 2.9 [p=0.002]and 7.9 [p=<0.001], respectively [Figure]). Conclusions: We identify a sub-group of patients who remain at high risk of VTA despite improvement in LVEF > 35% with CRT-D. Having a baseline non-LBBB morphology, experiencing VA during the first year post CRT-D, and lower-range LVEF improvement are associated with high risk of future arrhythmias, with a cumulative effect.

Interference of Atrial Fibrillation with Implantable Cardioverter Defibrillator Therapy in Patients with Heart Failure and Reduced Ejection Fraction

Interference of Atrial Fibrillation with Implantable Cardioverter Defibrillator Therapy in Patients with Heart Failure and Reduced Ejection Fraction

Ventricular arrhythmia burden in ICD patients during the second wave of the COVID-19 pandemic

AimCOVID-19 has been associated with cardiovascular complications including ventricular arrhythmias (VA) and an increased number of out-of-hospital cardiac arrests. Nevertheless, several authors described a decrease of VA burden in patients with an implantable defibrillator (ICD) during the first wave of the COVID-19 pandemic. The objective of this study was to determine if these observations could be transferred to later periods of the pandemic as well.MethodsWe retrospectively analyzed a total of 1674 patients with an ICD presenting in our outpatient clinic during the second wave of the COVID-19 pandemic and during a control period for the occurrence of VA requiring ICD interventions.ResultsSeven hundred ninety-five patients with an ICD had a device interrogation in our ambulatory clinic during the second wave of the COVID-19 pandemic compared to eight hundred seventy-nine patients in the control period. There was significant higher amount of adequate ICD therapies in the course of the COVID-19 period. Thirty-six patients (4.5%) received in total eighty-five appropriate ICD interventions during COVID-19, whereas only sixteen patients (1.8%) had sustained VA in the control period (p = 0.01).ConclusionIn contrast to the first wave of COVID-19, which was characterized by a decrease or least stable number of ICD therapies in several centers, we found a significant increase of VA in ICD patients during the second wave of COVID-19. Possible explanations for this observation include higher infectious rates, potential cardiac side effects of the vaccination as well as personal behavioral changes, or reduced utilization of medical services.

Machine learning-derived cycle length variability metrics predict spontaneously terminating ventricular tachycardia in implantable cardioverter defibrillator recipients.

Implantable cardioverter defibrillator (ICD) therapies have been associated with increased mortality and should be minimized when safe to do so. We hypothesized that machine learning-derived ventricular tachycardia (VT) cycle length (CL) variability metrics could be used to discriminate between sustained and spontaneously terminating VT. In this single-centre retrospective study, we analysed data from 69 VT episodes stored on ICDs from 27 patients (36 spontaneously terminating VT, 33 sustained VT). Several VT CL parameters including heart rate variability metrics were calculated. Additionally, a first order auto-regression model was fitted using the first 10 CLs. Using features derived from the first 10 CLs, a random forest classifier was used to predict VT termination. Sustained VT episodes had more stable CLs. Using data from the first 10 CLs only, there was greater CL variability in the spontaneously terminating episodes (mean of standard deviation of first 10 CLs: 20.1 ± 8.9 vs. 11.5 ± 7.8 ms, P < 0.0001). The auto-regression coefficient was significantly greater in spontaneously terminating episodes (mean auto-regression coefficient 0.39 ± 0.32 vs. 0.14 ± 0.39, P < 0.005). A random forest classifier with six features yielded an accuracy of 0.77 (95% confidence interval 0.67 to 0.87) for prediction of VT termination. Ventricular tachycardia CL variability and instability are associated with spontaneously terminating VT and can be used to predict spontaneous VT termination. Given the harmful effects of unnecessary ICD shocks, this machine learning model could be incorporated into ICD algorithms to defer therapies for episodes of VT that are likely to self-terminate.

The Prognostic Significance of Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio for Long-Term Survival in Patients With Severe Left Ventricular Dysfunction and Implantable Cardioverter Defibrillator.

A total of 180 compensated heart failure patients with LVEF<35% (ischemic or nonischemic) and implantable cardioverter-defibrillator (ICD) therapy for primary prevention who applied to the cardiology outpatient clinic of Zonguldak Bülent Ecevit Üniversitesi Hospital, Zonguldak,Türkiye, between March 2018 and June 2019 were consecutively included. The patients were followed for one year after the application. In the multivariate logistic regression analysis model, only NLR (OR: 1.328; 95%CI: 1.129-1.563; p <0.01) was found independently associated with the risk of one-year cardiovascular mortality. Based on the NLR, levels were 2.69 ng/ml, and the area under the curve was found to be 0.795 (95%CI: 0.729-0.862) in the evaluation made with the receiver operating characteristic curve. High NLR ratio levels independently predicted one-year cardiac mortality in patients with LVEF<35% and ICD for secondary protection. Large-scale randomized studies are needed to fully demonstrate the relationship between NLR levels and cardiovascular mortality in patients with severe left ventricular dysfunction and ICD.

Electrocardiographic characteristics associated with late gadolinium enhancement and prognostic value in patients with dilated cardiomyopathy.

Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging has emerged as an important tool for assessment of patients with dilated cardiomyopathy (DCM). Electrocardiography (ECG) is an accessible, reproducible, low-cost diagnostic and prognostic tool. This study aimed to investigate the ECG characteristics associated with LGE, as well as to assess the prognostic significance of ECG in patients with DCM. Consecutive patients diagnosed with DCM by CMR [left ventricular ejection fraction (LVEF) < 50%] between 2011 and 2020 were included. Multivariable analysis was conducted to evaluate ECG predictors associated with LGE. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of ECG in combination of clinical data and LVEF for LGE. Two composite outcomes were also assessed among patients with and without ECG predictors: (1) sudden cardiac death (SCD), sustained ventricular arrhythmia, or appropriate implantable cardioverter-defibrillator (ICD) therapy, and (2) all-cause death or hospitalization for heart failure. A total of 422 patients, with a mean age of 59.5 ± 16.3 years (58.3% male), were included. LGE was present in 169 (40%) of the patients. Multivariable analysis identified lateral inverted T-waves, intraventricular conduction delay, low voltage, and fragmented QRS as independent predictors of LGE. ROC analysis showed a significant increase in the area under the curve (AUC) when ECG predictors of the four aforementioned characteristics were added to the clinical-LVEF model (AUC 0.66, 95% CI 0.59-0.71 vs. 0.72, 95% CI 0.67-0.78, p = 0.003). During a median follow-up of 2.7 years (IQR 0.8, 5.2), 16 events of SCD, sustained ventricular arrhythmia, or appropriate ICD therapy, and 70 events of all-cause death or hospitalization for heart failure occurred. ECG predictors were independently associated with SCD, sustained ventricular arrhythmia, or appropriate ICD therapy (HR 4.84, 95% CI 1.34-17.40, p = 0.01). However, ECG predictors were not associated with all-cause death or hospitalization for heart failure (HR 1.22, 95% CI 0.76-1.96, p = 0.39). In patients with DCM, lateral inverted T-waves, intraventricular conduction delay, low voltage, and fragmented QRS were independently associated with LGE. Additionally, these ECG predictors had prognostic value for predicting SCD, sustained ventricular arrhythmia, or appropriate ICD therapy, assisting clinicians in stratifying SCD risk and identifying primary prevention ICD implantation candidates.

One-year outcomes after stereotactic body radiotherapy for refractory ventricular tachycardia

BackgroundCardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refractory ventricular tachycardia (VT). ObjectiveThe purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation. MethodsAfter maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophysiological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes. ResultsFifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function. ConclusionFor a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year.

The Prevalence and Characteristics of Arrhythmic Mitral Valve Prolapse in Patients With Unexplained Cardiac Arrest

BackgroundThere is growing evidence that mitral valve prolapse (MVP) is associated with otherwise unexplained cardiac arrest (UCA). However, reports are hindered by the absence of a systematic ascertainment of alternative diagnoses. ObjectivesThis study reports the prevalence and characteristics of MVP in a large cohort of patients with UCA. MethodsPatients were enrolled following an UCA, defined as cardiac arrest with no coronary artery disease, preserved left ventricular ejection fraction, and no apparent explanation on electrocardiogram. A comprehensive evaluation was performed, and patients were diagnosed with idiopathic ventricular fibrillation (IVF) if no cause was found. Echocardiography reports were reviewed for MVP. Patients with MVP were divided into 2 groups: those with IVF (AMVP) and those with an alternative diagnosis (nonarrhythmic MVP). Patient characteristics were then compared. The long-term outcomes of AMVP were reported. ResultsAmong 571 with an initially UCA, 34 patients had MVP (6%). The prevalence of definite MVP was significantly higher in patients with IVF than those with an alternative diagnosis (24 of 366 [6.6%] vs 5 of 205 [2.4%]; P = 0.03). Bileaflet prolapse was significantly associated with AMVP (18 of 23 [78%] vs 1 of 8 [12.5%]; P = 0.001; OR: 25.2). The proportion of patients with AMVP who received appropriate implantable cardioverter-defibrillator therapies over a median follow-up of 42 months was 21.1% (4 of 19). ConclusionsMVP is associated with otherwise UCA (IVF), with a prevalence of 6.6%. Bileaflet prolapse appears to be a feature of AMVP, although future studies need to ascertain its independent association. A significant proportion of patients with AMVP received appropriate implantable cardioverter-defibrillator therapies during follow-up.

Stereotactic Cardiac Ablative Radiotherapy (SCAR) for Refractory Ventricular Tachycardia: Western Australia Experience

Ventricular tachycardia is a potentially life-threatening cardiac condition that is associated with significant morbidity and mortality. Despite advances in medical therapies, implantable cardioverter-defibrillator (ICD) and catheter ablative therapy (CAT), some patients continue to suffer recurrent VT. SCAR is a highly accurate, non-invasive, and novel ablative therapeutic option that has shown promising results in the treatment of refractory VT patients associated with structural heart disease. Early case series and subsequent prospective clinical trials have demonstrated SCAR to be well-tolerated with acceptable safety profiles and consistently decreased VT episodes in VT patients, who failed all conventional antiarrhythmic medications and CAT. The aim of the current study is to report the efficacy and safety/tolerability of SCAR in ICD-dependent patients with refractory VT in Western Australia, Australia. Seven patients with recurrent refractory VT, deemed high risk or non-suitable for CAT, were referred to GenesisCare at Fiona Stanley Hospital, Western Australia for SCAR between July 2020 and November 2022. Target volume definition and delineation involved interdisciplinary teams by combining all available clinical, electrophysiological mapping and diagnostic/planning cardiac imaging data to generate radiotherapy plans. Patients were treated whilst awake, with a single dose of 25 Gy using VMAT technique on the Synergy Linac with stereotactic X-ray tool capability. Efficacy was assessed by counting the number of episodes of VT and ICD shocks after SCAR. Safety and tolerability were evaluated by treatment related toxicities during follow up. Of the seven patients referred for SCAR, only five received SCAR as two patients died from their refractory VT before their radiotherapy. For the patients receiving SCAR with at least 6 months follow-up, overall reduction in VT episodes and ICD shocks was 95% and 85%, respectively. No significant treatment-related toxicities were documented during follow-up. Two patients had died. Neither of their deaths were directly attributed to their radiotherapy. One patient died after requesting to cease her antiarrhythmic medications and to have her ICD switched off 2 days after SCAR (against medical advice). The other patient died 431 days after SCAR from aspiration pneumonia after fracturing her cervical spine following a fall at home and was unrelated to her VT. Our data reflects international experience in terms of treatment efficacy and safety profiles of SCAR for patients with refractory VT. SCAR is increasingly recognized as an alternative cardiac ablative option for ICD-dependent VT patients who failed all conventional antiarrhythmic treatments. Nonetheless, careful patient selection and longer-term follow-up are required to ensure the optimal treatment outcomes can be achieved in these patients.

ICD outcome in pediatric arrhythmogenic cardiomyopathy

BackgroundArrhythmogenic cardiomyopathy (ACM) is a very rare condition among pediatric patients. Sudden cardiac death (SCD) is the main complication and often requires ICD implantation.Aim of the study is the evaluation of the outcomes of ICD implanted ACM pediatric patients in terms of safety, efficacy and complications. MethodsAll pediatric patients (<18 y.o.) diagnosed with ACM and who were implanted with ICD since 2009 in Our Institution were collected. Implantation was decided according to current recommendations/ guidelines, and outcome was recorded during follow-up. ResultsNineteen consecutive ACM patients were implanted with ICD. Subcutaneous ICDs (S-ICD) were implanted in 15 patients (79%) while transvenous ICDs (TV-ICD) in 4 patients (21%). Mean age at implantation was 14.3 ± 2.1 y.o. ICDs were implanted for secondary prevention in 4 (21%) patients, and for primary prevention in 15 (79%). During the follow-up (5.59 ± 3.4 years), appropriate ICD interventions were delivered in 4 (21%) patients for sustained VTs, [2 implanted in primary prevention (13%) and 2 in secondary prevention (50%)]. No defibrillation failures occurred. Inappropriate shocks occurred in 2 cases (10.5%). Device-related complications requiring device revision occurred in 3 (16%): lead dislodgement, surgical skin erosion and sensing defect. ConclusionsIn a pediatric ACM cohort, appropriate ICD therapies occurred in a minority of primary prevention patients and frequently in secondary prevention patients. The rate of inappropriate shocks and device-related complications were even more rare and mostly wound related. Therefore, ICD therapy in pediatric ACM is effective and safe.

Association between nighttime heart rate and cardiovascular mortality in patients with implantable cardioverter-defibrillator: A cohort study

Although studies have shown that an increased resting heart rate measured randomly at a single point of the day has been associated with adverse cardiovascular outcomes, the utility of continuous monitoring of nighttime heart rate (NTHR) has remained largely uninvestigated. This study aimed to explore the association between NTHR and cardiovascular mortality. The Study of Home Monitoring System Safety and Efficacy in Cardiac Implantable Electronic Device-implanted Patients, which is a prospective cohort study, enrolled patients with implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator between 2010 and 2015. Baseline NTHR was measured during the programmed sleep period from 30 to 60 days after implantation. The primary outcome was cardiovascular mortality, fitted by a restricted cubic spline function. A total of 534 implantable cardioverter-defibrillator recipients with sinus rhythm during the detection window were included in the study. The mean baseline NTHR was 59.6 ± 8.0 beats/min. During the follow-up period of 60.4 ± 21.8 months, 88 (16.5%) patients experienced cardiovascular mortality. After considering potential confounders, a linear association was observed. Each 1 beat/min increase in NTHR was associated with a 7.8%, 10.1%, and 5.7% increase in the risk of cardiovascular mortality in the total population, patients with heart failure, and patients without heart failure, respectively. Continuous monitoring of NTHR may identify patients at high risk of cardiovascular mortality in a timely manner, with the potential for "preemptive" action. No. ChiCTR-ONRC-13003695.

Fatal Arrhythmic Risks in Cardiac Sarcoidosis With Mildly Impaired Cardiac Function

BackgroundThe prognosis and later fatal arrhythmia in cardiac sarcoidosis (CS) with relatively preserved cardiac function were unclear. ObjectivesThis study aimed to evaluate the prognosis and arrhythmic events in patients with CS and mildly impaired cardiac function. MethodsData were collected from a nationwide Japanese cohort survey conducted in 57 hospitals (n = 420); 322 patients with CS with left ventricular ejection fraction (LVEF) >35% were investigated. ResultsVentricular tachycardia (VT) manifestation was present in 50 patients (16%) and absent in 272 (84%), of whom 36 (72%) and 46 (17%), respectively, had an implantable cardioverter-defibrillator (ICD). Over a median of 5 years, 23 all-cause deaths and 31 appropriate ICD discharges were observed. In Kaplan-Meier analysis, all-cause death did not differ between patients with and without VT manifestation (P = 0.660), although appropriate ICD therapy was significantly less used in patients without VT manifestation than in those with VT manifestation (P < 0.001). Of the 272 patients without VT manifestation, 18 had ventricular arrhythmic events (VAEs), including 3 sudden cardiac deaths and 15 appropriate ICD discharges. In multivariate analysis, concomitant nonsustained ventricular tachycardia (NSVT) with atrioventricular block (AVB), lower LVEF, abnormal gallium-67 scintigraphy or 18F-fluorodeoxyglucose positron emission tomography of the heart (Ga/PET), and concomitant NSVT with abnormal Ga/PET at CS diagnosis were independent predictors of VAEs (P = 0.008, P = 0.021, P = 0.049, and P = 0.024, respectively). ConclusionsIf concomitant NSVT with AVB, concomitant NSVT with abnormal Ga/PET, or abnormal Ga/PET is observed in patients with CS and mildly impaired cardiac function (LVEF >35%), ICD should be considered as primary prevention.