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Background: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, and sudden cardiac death represents an important mode of death in these patients. Data evaluating the implantable cardioverter defibrillator (ICD) in this patient population remain scarce. Methods: A Nationwide French Registry including all patients with tetralogy of Fallot with an ICD was initiated in 2010 by the French Institute of Health and Medical Research. The primary time to event end point was the time from ICD implantation to first appropriate ICD therapy. Secondary outcomes included ICD-related complications, heart transplantation, and death. Clinical events were centrally adjudicated by a blinded committee. Results: A total of 165 patients (mean age, 42.2±13.3 years, 70.1% males) were included from 40 centers, including 104 (63.0%) in secondary prevention. During a median (interquartile range) follow-up of 6.8 (2.5–11.4) years, 78 (47.3%) patients received at least 1 appropriate ICD therapy. The annual incidence of the primary outcome was 10.5% (7.1% and 12.5% in primary and secondary prevention, respectively; P =0.03). Overall, 71 (43.0%) patients presented with at least 1 ICD complication, including inappropriate shocks in 42 (25.5%) patients and lead dysfunction in 36 (21.8%) patients. Among 61 (37.0%) patients in primary prevention, the annual rate of appropriate ICD therapies was 4.1%, 5.3%, 9.5%, and 13.3% in patients with, respectively, 0, 1, 2, or ≥3 guidelines-recommended risk factors. QRS fragmentation was the only independent predictor of appropriate ICD therapies (hazard ratio, 3.47 [95% CI, 1.19–10.11]), and its integration in a model with current criteria increased the 5-year time-dependent area under the curve from 0.68 to 0.81 ( P =0.006). Patients with congestive heart failure or reduced left ventricular ejection fraction had a higher risk of nonarrhythmic death or heart transplantation (hazard ratio, 11.01 [95% CI, 2.96–40.95]). Conclusions: Patients with tetralogy of Fallot and an ICD experience high rates of appropriate therapies, including those implanted in primary prevention. The considerable long-term burden of ICD-related complications, however, underlines the need for careful candidate selection. A combination of easy-to-use criteria including QRS fragmentation might improve risk stratification. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03837574.

Supplemental Digital Content is available in the text., Background: The subcutaneous (S) implantable cardioverter-defibrillator (ICD) is safe and effective for sudden cardiac death prevention. However, patients in previous S-ICD studies had fewer comorbidities, had less left ventricular dysfunction, and received more inappropriate shocks (IAS) than in typical transvenous ICD trials. The UNTOUCHED trial (Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction) was designed to evaluate the IAS rate in a more typical, contemporary ICD patient population implanted with the S-ICD using standardized programming and enhanced discrimination algorithms. Methods: Primary prevention patients with left ventricular ejection fraction ≤35% and no pacing indications were included. Generation 2 or 3 S-ICD devices were implanted and programmed with rate-based therapy delivery for rates ≥250 beats per minute and morphology discrimination for rates ≥200 and

Background: Atrial arrhythmias are common in patients with implantable cardioverter-defibrillator (ICD). External shocks and internal cardioversion through commanded ICD shock for electrical cardioversion are used for rhythm-control. However, there is a paucity of data on efficacy of external versus internal cardioversion and on the risk of lead and device malfunction. We hypothesized that external cardioversion is noninferior to internal cardioversion for safety, and superior for successful restoration of sinus rhythm. Methods: Consecutive patients with ICD undergoing elective cardioversion for atrial arrhythmias at 13 centers were randomized in 1:1 fashion to either internal or external cardioversion. The primary safety end point was a composite of surrogate events of lead or device malfunction. Conversion of atrial arrhythmia to sinus rhythm was the primary efficacy end point. Myocardial damage was studied by measuring troponin release in both groups. Results: N=230 patients were randomized. Shock efficacy was 93% in the external cardioversion group and 65% in the internal cardioversion group ( P Conclusions: This is the first randomized trial on external vs internal cardioversion in patients with ICDs. External cardioversion was superior for the restoration of sinus rhythm. The unmasking of silent lead malfunction in the internal cardioversion group suggests that an internal shock attempt may be reasonable in selected ICD patients presenting for electrical cardioversion. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03247738.

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Background: Research points to reciprocal influences that patients and partners may have on one another’s recovery in cardiac illness, yet interventions to enhance recovery after an implantable cardioverter defibrillator (ICD) are usually directed only toward the patient. Purpose: To compare 2 social cognitive (SC) intervention conditions (patient only or P-only, and patient + partner or P+P) from the Patient + Partner RCT. Patient physical symptoms and depression were compared with partner caregiver burden over 12 months post initial ICD. Methods: The study included 301 patient-partner dyads (151=P-only; 150=P+P) who participated in 1 of 2 nurse-led SC interventions delivered by telephone in the first 3 months after the patient received an ICD. Patient symptoms were measured with the PCA, depression with the PHQ-9, and partner caregiver burden with the OCBS, at baseline, 3, 6, and 12 months. Parallel process growth modeling and mixed effects models were used to compare intervention outcomes. Results: Patients were on average 64±12 years old, male (74%), white (91%), and most received an ICD for primary prevention (60%). Partners were on average 62±12 years, female (74%), and white (88%). In the first 3 months, decline in patient depression was significantly associated with decline in partner caregiver burden in P+P (β=0.93; pnot in P-only (β= -0.14; p=0.54). Decline in physical symptoms was more strongly associated with decline in partner caregiver burden in P+P (β=0.93, p Conclusion: A SC intervention that included intimate partners (P+P) showed greater reductions in patient physical and depressive symptoms and partner caregiver burden and reflected greater reciprocal influence than the P-only intervention. Dyadic SC interventions can provide added support for patients after an ICD and may improve partner caregiver burden.

Introduction: Risk stratification for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) has evolved with notable differences in international practice trends and US vs European guidelines. Hypothesis: Utilization of primary prevention implantable cardioverter defibrillators (ICD) is higher in the US. Methods: We examined rates of primary prevention ICD implantation in 5,063 HCM patients in the international SHaRe registry from 2000 - 2020 (NUS=2,390; Nnon-US=2,673). Using multiple logistic regression we compared probability of ICD implantation for US vs non-US sites adjusting for standard SCD risk factors (Figure 1A). Interaction tests were performed to identify risk factors differentially associated with ICD implantation in US vs non-US sites after 2014 when the European Society of Cardiology (ESC) risk score was introduced. Results: The odds of ICD implantation were 3-fold higher in US sites [ORUS/non-US=3.11 (2.54 -3.81)] (Figure 1A). Odds remained similar after adjustment for ESC risk score [OR =3.17 (2.57 -3.91)]. Implantation rates were higher in the US throughout the study period with a notable drop in rates in both US and non-US sites after 2014 and a reduction in the magnitude of the difference in ICD utilization between US and non-US sites (ORUS/non-US ( 40 mm) was a stronger predictor in non-US sites [ORNon-US=2.9 (2.1-4.0) vs ORUS=1.3 (1-1.6); pinteraction Conclusions: ICD utilization rates vary globally. In this study, primary prevention ICD utilization rates were 3-fold higher in the US despite adjustment for standard SCD risk factors. Further studies are needed to evaluate outcomes of these practice differences.

Background: Implantable cardioverter-defibrillator (ICD) therapy prevents sudden cardiac death in selected patients with heart failure. When a primary prevention ICD arrives at elective replacement interval (ERI), conventional management is to replace the device. However, the effectiveness of ICDs in patients with nonischemic and ischemic cardiomyopathy (NICM and ICM, respectively) whose left ventricular ejection fraction (LVEF) improved to ≥50% before replacement is unclear. Hypothesis: The therapeutic benefit of primary prevention ICD for NICM is attenuated by the recovery of LVEF at the time of ERI. Methods: Consecutive patients presenting for first time primary prevention ICD battery change-out at a single quaternary care center between 1/1/2008 and 6/27/2019 were included. The primary endpoint was the rate of ICD therapy (ICD discharge and anti-tachycardia pacing) according to LVEF recovery at ERI. Results: During the study period 6851 ICDs were placed, of which 310 underwent battery change-out, of whom 100 did not receive therapy from the first ICD, of whom 44 had NICM. The demographics of the NICM cohort are in the table. Following ERI, 0 (0%) with NICM and recovered LVEF had received ICD therapy, whereas 13 (30%) with persistently low LVEF had received therapy (p = 0.07). Furthermore, among patients without recovered LVEF, the NICM group had a lower rate of therapy (4, 12%) than the ICM group (12, 32%) (p=0.04). Conclusion: Rates of ICD therapy provided by primary prevention ICD after first battery change out trended towards a significantly lower rate in NICM patients with LVEF that recovered to ≥50% than those without LVEF recovery. No other patient demographic significantly predicted therapy-free survival but the analysis was limited by sample size. A prospective study with a larger cohort would be necessary to better estimate therapy-free survival.

Introduction: The subcutaneous ICD is an attractive option in ARVC patients as they rarely require pacing, it preserves vascular access, and it avoids the long-term morbidity related to intravascular lead placement. However, the limitations of the S ICD have not been fully demarcated by clinical trials. Case: After her father presented with a cardiac arrest, a 16-year-old female was diagnosed with ARVC on MRI after initially presenting with palpitations. This was corroborated via genetic testing, and an S ICD was placed after she passed pre-implant screening. Initially she did well, but she suffered inappropriate shocks approximately seven months after implant, in the setting of “hugging her boyfriend”. Interrogation revealed apparent noise, which was felt to be most likely due to lead fracture or possibly generator malfunction. At reoperation, first her lead was replaced, but continued noise was demonstrated intra-operatively, and thus her generator was also replaced. However, she was found again to have noise in each vector causing recurrent inappropriate shocks. Further testing ultimately determined that the noise was due to myopotentials, which were present in all vectors and unable to be programmed around. Ultimately, the S ICD was removed and replaced with a transvenous device. Discussion: While the S ICD is an attractive option in ARVC patients, the limitations of the technology must be acknowledged. The far-field nature of the sensing algorithm in the S ICD leads to a risk of myopotential oversensing. If this occurs, sometimes the system cannot be salvaged and the patient must be converted to a transvenous system. Recognizing this at the initial presentation with inappropriate shocks can avoid unsuccessful attempts at S ICD system modification and morbidity from future inappropriate shock events.

Introduction: Current Implantable cardioverter-defibrillator (ICD) needs high CD shock (35J), which is not tolerable under consciousness. Our multi-physics computer-simulation demonstrated extra-low energy defibrillation (0.36J)can be possible if sheet electrodes are arranged upper (base) and lower (apex) side of the heart. Hypothesis: We developed the epicardial ICD net electrodes system (Ep-ICD) made of upper and lower parts with fine conductive fibers. The objective of this study was to test whether Ep-ICD can stop ventricular fibrillation with painless level ( Methods: Ep-ICD was constructed by fine tungsten fibers using computer-assisted knitting machine (Shimaseiki Co., Japan). Middle part was knitted by polyester fibers. Upper and lower electrode nets were connected to RV and SVC coils of DF-1 lead (Medtronic), respectively. Five beagle dogs were used for this experiment. The Ep-ICD net was directly attached to the heart, and electrodes were connected to commercially available ICD system. DC discharges were controlled by telemetry controller. Vf was induced by attaching 9V battery onto the heart surface. Ten seconds after Vf induction, DC was delievered from minimal energy 0.4J (Medtronic Viva XT) or 0.1J (Boston Scientific Perciva). DC energy was gradually increased until defibrillation was accomplished. After 3 minutes of recovery, the ventricular fibrillation induction and defibrillation tests were repeated. Defibrillation threshold (DFT) was defined as 75% of success of defibrillation. To compare current ICD system, commercial ICD lead was inserted in one dog through internal juglar vein, and defibrillation test was conducted. Results: Defibrillation was accomplished by 0.1J~1J, All hearts recovered instantaneously to sinus rhythm. DFT were 0.6J for 4 dogs and 0.8J for one dog. Current ICD system needed 30J for defibrillation. Conclusions: Our preliminary results shows that the Ep-ICD accomplished defibrillation with painless level of DC energy (

Background: Cardiac MIBG imaging provides prognostic information in patients with chronic heart failure (CHF). Recent studies showed that the highest occurrence of severe arrhythmic events (SAE) was seen in CHF patients with an intermediate decrease in MIBG uptake rather than the lowest values. On the other hand, non-sustained ventricular tachycardia (NSVT) has been shown to be associated with SAE in CHF patients. However, there is little information available on long-term prognostic value of intermediate decrease in MIBG up take and NSVT for the prediction of severe ventricular tachyarrhythmias in implantable cardioverter defibrillator (ICD) patients. Methods and Results: We prospectively enrolled 201 consecutive outpatients with ICD (age: 64±14 years, male: 81%, NYHA class:1.7±0.7, LVEF: 49±17%). At entry, all patients underwent cardiac MIBG imaging and 24-hour Holter electrocardiogram monitoring. An intermediate decrease in heart-to-mediastinum ratio on delayed planar image (H/M) was defined as 1.40-1.89. NSVT was defined as consecutive 3 or more beats and more than 100 bpm. During a follow-up period of 4.0±2.5 years, 59 patients had appropriate ICD discharge for severe ventricular tachyarrhythmias. At multivariate Cox regression analysis, intermediate decrease in H/M and NSVT were significantly and independently associated with appropriate ICD discharge after adjustment with age, sex and low left ventricular ejection fraction (≤35%). Appropriate ICD discharge was significantly more frequently observed in patients with both intermediate decrease in H/M and NSVT and with either intermediate decrease in H/M or NSVT than with none of them (47% vs 36% vs 14%, p Conclusions: Combination of cardiac MIBG imaging and NSVT would be more strongly associated with an increased risk for severe ventricular tachyarrhythmias in ICD patients.

Background: Implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT-D) reduce mortality and improve functional status in selected patients with heart failure (HF). However, there are potential procedural risks and psychosocial concerns associated with device implant. This qualitative study aims to explore patients’ and families’ understanding of ICD/CRT-D, heart failure and arrhythmia in the process of decision making regarding device implant. Methods: We conducted 14 focus groups or interviews in Salt Lake City UT and Silver Spring MD. This study included 23 patients, who had either an ICD or CRT-D implant for primary prevention, and 14 family members. Grounded theory analysis was performed to reach a conceptual understanding of patients’ and families’ perceptions and needs. Results: Patients and families largely made decision of ICD/CRT implant based on physicians’ recommendations, e.g. “I really try to do what they tell me to do” (icdpt 1). Patients perceived ICD as lifesaving and CRT being helpful to improve functional status. Many patients described ICD as lifesaving by “restarting a heart if it stops”, while did not understand HF or ventricular arrhythmia. Patients perceived an urgency to consider ICD implant from their physicians, but no such urgency was perceived when they discussed about CRT-D implant. Few participants were concerned with costs, or had knowledge of potential lead malfunction, device removal and associated risks. Many emphasized the importance of information about life expectancies, what HF is, options of different devices, complications and precautions, and what to expect regarding lifestyle changes. Conclusion: Patients and families largely relied on the information provided by physicians and followed physicians’ guidance. They had limited understanding of their prognosis, HF and arrhythmia, and they were motivated to learn. Discussion about devices should include prognosis and healthy life style changes.

Introduction: The subcutaneous (S-) implantable cardioverter defibrillator (ICD) is an alternative to the transvenous (TV-) ICD that is increasingly implanted in younger patients. However, data on the safety and effectiveness of the S-ICD in older patients are lacking. Methods: We compared S-ICD and single chamber TV-ICD implants in Medicare beneficiaries (≥65yrs) using National Cardiovascular Data Registry ICD Registry data from 9/28/2012 through 12/31/2017. We excluded patients with prior pacemaker or ICD, an indication for pacing or resynchronization, and those undergoing implant in an acute setting. Mortality status was determined using the Medicare master summary beneficiary file. Cox regression analyses with overlap weights were used to compare all-cause mortality. Mean cumulative counts of all-cause readmissions were compared among for Fee for Service beneficiaries. Results: A total of 23,717 patients met inclusion criteria [mean age 72.7±5.8 years, 29% female, 69% ischemic heart disease, 33% atrial arrhythmias, 49% NYHA II, 31.7% NYHA III, ejection fraction (EF) 28±9%, 3% dialysis dependent, 20% with prior ventricular tachycardia]. Compared to TV-ICD patients (n=22,264), S-ICD patients (n=1,453, 6% overall) were more often male, black, diabetic, dialysis dependent and were less likely to have atrial or ventricular arrhythmias or ischemic heart disease. There was no difference in age or EF between the 2 groups. In adjusted analyses, during a median follow-up of 2.3 years (IQR: 1.2 - 3.5), there was no difference between the 2 groups in all-cause mortality (HR 1.04, CI 0.91-1.17, Figure A ) or readmissions (based on overlap of confidence intervals, Figure B ). Conclusions: In a large representative cohort of older patients undergoing ICD implant, all-cause mortality and readmission were similar among S-ICD and TV-ICD recipients. These findings support use of the S-ICD for the prevention of sudden cardiac death in appropriately selected older patients.

Introduction: Twiddler’s syndrome refers to deliberate or unintentional twisting of pulse generator in device pocket resulting in lead migration, which can present as malfunction of pacemaker or implantable cardioverter-defibrillator (ICD). In the past 50 years, twiddler’s syndrome with transvenous ICD and pacemaker has been well-described and thoroughly studied. However, there are very little data on twiddler’s syndrome with subcutaneous ICD (S-ICD). Case presentation: The patient is a 50-year-old male with a past medical history of hypertrophic cardiomyopathy, cardiac MRI showing left ventricular hypertrophy with a wall thickness of 24 mm, non-sustained ventricular tachycardia and evidence of late gadolinium enhancement scar, who underwent implantation of S-ICD for primary prevention. First follow-up 2 weeks post-implant showed appropriate device function. Two weeks later, remote monitor documented atrial fibrillation and ICD shocks. Surface ECG showed reduced R wave and delivered shock impedance was 7 ohms. Patient reported no symptoms and was clapping hands to music when it occurred. Chest X-Ray revealed S-ICD lead dislodged and retracted with coiling around the generator in the left lateral chest wall (Figure 1). Subsequently patient underwent lead revision and device replacement. To reduce the risk of future dislodgement, during re-implantation, the tip of the ICD lead was secured with 0-Silk. Conclusion: Twiddler’s syndrome is a rare complication after ICD implantation, not only with transvenous-ICDs but also involving S-ICDs. Risk factors include advanced and younger ages, redundant skin, obesity, oversized pocket, and psychiatric disorder. It can be a potentially dangerous and even fatal due to undetected or unsuccessful therapy for ventricular tachyarrythmias. Therefore, it is of paramount importance to diagnose and intervene early to avoid morbidity and mortality in these patients.

Introduction: Catheter ablation of ventricular tachycardia (VT) reduces implantable cardioverter defibrillator (ICD) therapies, improves hospitalization, and improves survival in patients with ischemic cardiomyopathy (ICM). Hypothesis: The goal of this study is to evaluate outcomes of patients with VT ablation by scar location in patients with ICM. Methods: Consecutive retrospective review of patients with ICM who underwent VT ablation at Minneapolis Veterans Affairs Health Care system between July 2008 and September 2019 were assessed for clinical outcomes. Results: Seventy-five patients with ICM underwent VT ablation during the study period. Average age was 67.6 ± 7 years old and 100% Male. Three patients were lost to follow up. Overall mortality was 53.3% and was highest in the inferior wall scar (IWS) group (Figure 1A, Table). Mean survival after ablation was 2.2 years. Most common cause of death was cardiac which included congestive heart failure, myocardial ischemia, and cardiac arrest (VT and pulseless electrical activity) (Figure 1B). On post-ablation echocardiogram, patients with anterior wall scar (AWS) had a lower mean ejection fraction (23%) compared to IWS group (30%) and this was statistically significant (p < 0.03, two-tailed t-test). The average number of ablations for recurrent VT was 1.4 with no significant difference between the groups. Fifty-five percent of patients were on anti-arrhythmics post ablation. Conclusions: VT ablation patients with IWS mediated VT have a trend towards higher mortality compared to those with AWS. This may be due to neuroregulatory pathway of VTs based on cardiac innervation.

Introduction: Ventricular assist devices (VAD) are a primary method of treatment for patients with advanced heart failure. Previous studies have provided some evidence for alterations in ICD lead parameters following VAD implants, but all have had a very small sample size. Hypothesis: VAD implantation causes alterations in ICD lead parameters. Methods: Electronic medical records of a large patient cohort receiving VAD implants at Northwestern Hospital from 2012-2018 were manually reviewed. When available, high-voltage (HV) impedance, right ventricular (RV) lead pacing impedance, pacing threshold, and sensing amplitude were compared both immediately (I) and late (L), at 6-12 months follow-up after VAD implant, to baseline (B) pre-implant values. Results: A total of 271 VAD patient records were reviewed. Long-term, HV impedance changed from 51 ± 16 Ω to 49 ± 15 Ω (N=63, p=0.04), and 29% of patients had a long-term absolute change of at least 10 Ω. RV pacing impedance decreased slightly acutely from 405± 84 to 427 ±78 (N=96, p=.006), but there was no significant change long-term: 443 ± 201 Ω vs 449 ± 94 Ω (N=85, p=0.77). Yet, 19% of patients had a long-term change ≥ 100 Ω. Long-term RV pacing threshold was not significantly changed 1 ± 0.8 V to 1.1 ± 0.7 V (N=47, p=0.5), and all leads were still functional for pacing. RV sensing amplitude decreased acutely from 10.8 ± mV to 8.6 ± 4.3 mV (N=81, p Conclusions: In conclusion, our data suggest that VAD implantation in patients with an ICD may result in immediate and long-term ICD parameter changes. For many patients, these changes may be clinically insignificant, but careful monitoring is warranted. The clinical impact of those changes merits further investigation.

Introduction: Implantable cardioverter defibrillator (ICD) implantation in patients with cardiac amyloidosis is controversial, with no clear guidelines for clinical decision-making.. The role of ICD implantation in hereditary Transthyretin Amyloid Cardiomyopathy (hATTR-CM) is unclear. We sought to establish the burden of ventricular arrhythmias and the outcomes of ICD implantation in a single center cohort of hATTR-CM patients. Methods: A total of 69 patients with a confirmed diagnosis of hATTR-CM from genetic testing, and technetium pyrophosphate (PYP) scanning, or endomyocardial biopsy underwent retrospective chart review for demographic, clinical, and arrhythmia data. Results: Seventy-four percent of the cohort was male, with a mean age at diagnosis of 68 (SD=18 years). Sixty-five patients (94.2%) patients were African-American; all of whom carried the Valine 122 Isoleucine mutation. Most had systolic heart failure (New York Heart Association Staging II [18, 26%] and III [40, 58.8%]); 37 (54%) patients had an LVEF ≤ 35%. Thirty-six (52.2%) patients had documented episodes of non-sustained ventricular tachycardia (NSVT), three (4.3%) with ventricular tachycardia (VT), and one (1.5%) with ventricular fibrillation (VF). A total of 15 (21.7%) patients had ICDs placed for prevention of sudden cardiac death in the setting of low LVEF (EF Conclusions: In a cohort of patients with hATTR-CM, we observed a high incidence of NSVT, yet only 41% of patients with severe systolic heart failure had ICDs implanted. A high rate of successful defibrillation and no inappropriate ICD shocks were noted, suggesting that ICDs should be strongly considered, and may be underutilized, in patients with systolic heart failure and/or arrhythmias in the setting of hATTR-CM.

Introduction: We assessed the hypothesis that markers of LV wall stress, such as LV sphericity index (SI), may predict appropriate therapy for ventricular arrhythmias (VA) in patients with primary prevention defibrillators, independent of LV ejection fraction. Methods: We performed a retrospective analysis of consecutive patients with new ICD or CRT-D placement for primary prevention at a single hospital from 01/01/2015 to 06/30/2018. TTE images were used for calculating LV SI, which was defined as the ratio of bi-plane LV end-diastolic volume to the volume of a hypothetical sphere with a diameter of LV end-diastolic length in apical 4-chamber view. Device interrogations were reviewed for appropriate therapy for VA and inappropriate therapy for non-VAs. Kaplan-Meier curves stratified by LV SI tertile were constructed, and Cox proportional hazards models were used to evaluate time to appropriate and inappropriate therapy, and all-cause mortality. Results: A total of 282 patients (ICD 154, CRT-D 128) were included. Baseline characteristics are described in the Table. We found a trend towards increased appropriate therapy as LV SI increased in the ICD but not the CRT-D group, but this was non-significant in both (ICD log-rank 0.63, p-value 0.73; CRT-D log-rank 0.07, p-value 0.96). There was no correlation between LV SI and time to all-cause mortality in the ICD (log-rank 0.53, p-value 0.76) or the CRT-D patients (log-rank 0.51, p-value 0.77). LV SI correlated significantly with time to inappropriate therapy in the ICD (log-rank 8.6, p-value 0.01), but not the CRT-D patients (log-rank 2.4, p-value 0.3). Conclusions: LV SI demonstrated a non-significant trend towards increased appropriate device therapy in the ICD but not the CRT-D group. LV SI predicted inappropriate therapy in the ICD but not the CRT-D group. Study power was limited by lower than expected event rates, possibly due to changes in device programming and improvements in heart failure therapies over time.

Introduction: Cardiac amyloidosis is associated with high risk for sudden cardiac death. However, the potential benefit of implantable cardioverter defibrillator (ICD) implantation in CA is unknown due to limited available data regarding outcomes following ICD implantation in this patient population. We sought to perform a meta-analysis of trials that evaluated the outcomes of ICD implantation in CA. Methods: We performed a systematic literature review in PubMed, SCOPUS, and Cochrane to identify all studies that evaluated ICD therapy in CA until May 2020. Outcomes analyzed were all-cause mortality and appropriate ICD therapy rates. A random effects model was used to calculate percentages and 95% confidence intervals (CI) of outcomes. Results: Of the screened articles, 5 observational studies were included for analysis. A total of 151 patients were analyzed. Mean age of population was 61.6 +/- 0.7 years and 79.2% were male. The all-cause mortality rate was 33% (95% CI:16 to 51%) and the incidence of appropriate ICD therapy was 23% (95% CI:16 to 30%) over a mean follow up period of 16 months (Figure). In trials that evaluated ICD therapy in non-ischemic cardiomyopathy such as DANISH, DEFINITE and SCD-HeFT trials mortality rates in the ICD arm were 21.6 % over 67.6 months, 9.4% over 29 months and 16.7% over 45.5 months, respectively. The incidence of appropriate therapy in DANISH, DEFINITE and SCD-HeFT trials were 28.9%, 19.8 % and 21% respectively. Conclusions: CA patients with ICD have equivalent appropriate therapy with disproportionately higher mortality over a shorter follow up compared to randomized trials of primary prevention ICD placement in NICMP. The benefit of ICD placement for mortality reduction in CA remains unclear and further large-scale studies are required to address this issue.

Background: The risk of sudden cardiac death (SCD) in patients with heart failure after coronary artery bypass graft surgery (CABG) has not been examined in a contemporary clinical trial of surgical revascularization. This analysis describes the incidence, timing, and clinical predictors of SCD after CABG. Methods: Patients enrolled in the STICH trial (Surgical Treatment of Ischemic Heart Failure) who underwent CABG with or without surgical ventricular reconstruction were included. We excluded patients with prior implantable cardioverter-defibrillator and those randomized only to medical therapy. The primary outcome was SCD as adjudicated by a blinded committee. A Cox model was used to examine and identify predictors of SCD. The Fine and Gray method was used to estimate the incidence of SCD accounting for the competing risk of other deaths. Results: Over a median follow-up of 46 months, 113 of 1411 patients who received CABG without (n = 934) or with (n = 477) surgical ventricular reconstruction had SCD; 311 died of other causes. The mean left ventricular ejection fraction at enrollment was 28±9%. The 5-year cumulative incidence of SCD was 8.5%. Patients who had SCD and those who did not die were younger and had fewer comorbid conditions than did those who died of causes other than SCD. In the first 30 days after CABG, SCD (n=5) accounted for 7% of all deaths. The numerically greatest monthly rate of SCD was in the 31- to 90-day time period. In a multivariable analysis including baseline demographics, risk factors, coronary anatomy, and left ventricular function, end-systolic volume index and B-type natriuretic peptide were most strongly associated with SCD. Conclusions: The monthly risk of SCD shortly after CABG among patients with a low left ventricular ejection fraction is highest between the first and third months, suggesting that risk stratification for SCD should occur early in the postoperative period, particularly in patients with increased preoperative end-systolic volume index or B-type natriuretic peptide. Clinical Trial Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT0002359.

Introduction: The prognosis of vasospastic angina (VSA) treated with optimal medication therapy is generally good. However, the patients resuscitated from sudden cardiac arrest (SCA) caused by lethal ventricular arrhythmias are at high risk of recurrent cardiovascular events. Moreover, little is known about the efficacy of implantable cardioverter defibrillator (ICD) therapy in this population The aim of this study is to evaluate the incidence of lethal arrhythmic events in VSA patients with secondary prophylaxis for SCA. Methods: Data from patients who received an ICD as a secondary prophylaxis in our institution between January 2012 and November 2018 were retrospectively analyzed. A total of 123 patients were enrolled in this study and divided into 16 patients with VSA (VSA group) and 107 patients without VSA (non-VSA group). VSA was diagnosed by acetylcholine provocation test or coronary angiography alone on arrival. Results: Current smoker was more prevalent and cardiac function was better in the VSA group. Diabetes mellitus was more prevalent in the non-VSA group. Although VSA patients were treated with calcium-channel blockers, with or without nitrates, 3 patients (18.8%) experienced appropriate ICD therapies due to lethal arrhythmias during a follow-up of 3.2 years. There were no significant differences in the proportion of appropriate and inappropriate therapy between 2 groups. (Table) Conclusions: Recurrent lethal arrhythmic events were common in patients with VSA after SCA. In addition to optimal medical therapy, ICD therapy should be aggressively considered in patients with VSA and a history of lethal arrhythmia.

Advances in the field of defibrillation have brought to practice different types of devices that include the transvenous implantable cardioverter-defibrillator (ICD) with or without cardiac resynchronization therapy, the subcutaneous ICD (S-ICD), and the wearable cardioverter-defibrillator. To ensure optimal use of these devices and to achieve best patient outcomes, clinicians need to understand how these devices work, learn the characteristics of patients who qualify them for one type of device versus another, and recognize the remaining gaps in knowledge surrounding these devices. The transvenous ICD has been shown in several randomized clinical trials to improve the survival of patients resuscitated from near-fatal ventricular fibrillation and those with sustained ventricular tachycardia with syncope or systolic heart failure as a result of ischemic or nonischemic cardiomyopathy despite receiving guideline-directed medical therapy. Important gaps in knowledge regarding the transvenous ICD involve the role of the ICD in patient subgroups not included, or not well represented, in clinical trials and the need to refine the selection criteria for the ICD in patients who are indicated for it. S-ICDs were recently introduced into the clinical arena as another option for many patients who have an approved indication for a transvenous ICD. The main advantage of the S-ICD is a lower risk of infection and lead-related complications; however, the S-ICD does not offer bradycardia or antitachycardia pacing. The S-ICD may be ideal for patients with limited vascular access, high infection risk, or some congenital heart diseases. However, more data are needed regarding the efficacy and effectiveness of the S-ICD in comparison to transvenous ICDs, the extent of defibrillation testing required, and the use of the S-ICD with other novel technologies, including leadless pacemakers. Cardiac resynchronization therapy-defibrillators are indicated in patients with a left ventricular ejection fraction ≤35%, QRS width ≥130 ms, and New York Heart Association class II, III, or ambulatory IV symptoms despite treatment with guideline-directed medical therapy. Multiple randomized controlled trials have shown that the cardiac resynchronization therapy-defibrillator improves survival, quality of life, and several echocardiographic measures. One main challenge related to cardiac resynchronization therapy-defibrillators is the 30% nonresponse rate. Many initiatives are underway to address this challenge including improved cardiac resynchronization therapy and imaging technologies and enhanced selection of patients and device programming.

Background— Older recipients of implantable cardioverter-defibrillators (ICDs) are at increased risk for short-term mortality in comparison with younger patients. Although hospice use is common among decedents aged >65, its use among older ICD recipients is unknown. Methods and Results— Medicare patients aged >65 matched to data in the National Cardiovascular Data Registry – ICD Registry from January 1, 2006 to March 31, 2010 were eligible for analysis (N=194 969). The proportion of ICD recipients enrolled in hospice, cumulative incidence of hospice admission, and factors associated with time to hospice enrollment were evaluated. Five years after device implantation, 50.9% of patients were either deceased or in hospice. Among decedents, 36.8% received hospice services. The cumulative incidence of hospice enrollment, accounting for the competing risk of death, was 4.7% (95% confidence interval [CI], 4.6%–4.8%) within 1 year and 21.3% (95% CI, 20.7%–21.8%) at 5 years. Factors most strongly associated with shorter time to hospice enrollment were older age (adjusted hazard ratio, 1.77; 95% CI, 1.73–1.81), class IV heart failure (versus class I; adjusted hazard ratio, 1.79; 95% CI, 1.66–1.94); ejection fraction Conclusions— More than one-third of older patients dying with ICDs receive hospice care. Five years after implantation, half of older ICD recipients are either dead or in hospice. Hospice providers should be prepared for ICD patients, whose clinical trajectories and broader palliative care needs require greater focus.

Background— Candidates for cardiac resynchronization therapy (CRT) receive either a biventricular pacemaker or a biventricular pacemaker with an implantable cardioverter-defibrillator (CRT-D). Optimal device selection remains challenging because the benefit of implantable cardioverter-defibrillator therapy may not be uniform, particularly in patients at competing risk of nonsudden death. Methods and Results— In this serial cross-sectional study using the National Inpatient Sample database, we identified 311 086 admissions associated with CRT implant between 2006 to 2012. CRT-D was the most common device type (86.1%), including in patients ≥75 years of age with ≥5 Elixhauser comorbidities (75.5%). Multivariate predictors of CRT-D implant included demographic, clinical, and geographic factors: prior ventricular arrhythmia (rate ratio [RR], 1.14; 95% CI, 1.13–1.14), ischemic heart disease (RR, 1.11; 95% CI, 1.10–1.11), male sex (RR, 1.10; 95% CI, 1.09–1.10), black race (RR, 1.06; 95% CI: 1.04–1.07), and Northeast geographic region (RR, 1.06; 95% CI, 1.04–1.09). There was significant interhospital variation in the use of CRT-D (10–90 percentile range, 72.9%–98.0% CRT-D). Conclusions— The majority of patients in this contemporary US cohort underwent implantation of CRT-D. Predictors of CRT-D implant included demographic, clinical, and geographic factors. In patient subgroups predicted to have an attenuated benefit from implantable cardioverter-defibrillator therapy (older adults with multiple comorbidities), CRT-D remained the dominant device type. An improved understanding of the determinants of device selection may aid in decision making and ultimately better align patient risk with device benefit at the time of CRT implantation.

Supplemental Digital Content is available in the text., Background: Current guidelines only recommend the use of an implantable cardioverter defibrillator in patients with dilated cardiomyopathy for the primary prevention of sudden cardiac death (SCD) in those with a left ventricular ejection fraction (LVEF) 35%. Patients with an LVEF >35% also have low competing risks of death from nonsudden causes. Therefore, those at high risk of SCD may gain longevity from successful implantable cardioverter defibrillator therapy. We investigated whether late gadolinium enhancement (LGE) cardiovascular magnetic resonance identified patients with dilated cardiomyopathy without severe LV systolic dysfunction at high risk of SCD. Methods: We prospectively investigated the association between midwall LGE and the prespecified primary composite outcome of SCD or aborted SCD among consecutive referrals with dilated cardiomyopathy and an LVEF ≥40% to our center between January 2000 and December 2011 who did not have a preexisting indication for implantable cardioverter defibrillator implantation. Results: Of 399 patients (145 women, median age 50 years, median LVEF 50%, 25.3% with LGE) followed for a median of 4.6 years, 18 of 101 (17.8%) patients with LGE reached the prespecified end point, compared with 7 of 298 (2.3%) without (hazard ratio [HR], 9.2; 95% confidence interval [CI], 3.9–21.8; P5% compared with those without LGE were 10.6 (95% CI, 3.9–29.4), 4.9 (95% CI, 1.3–18.9), and 11.8 (95% CI, 4.3–32.3), respectively. Conclusions: Midwall LGE identifies a group of patients with dilated cardiomyopathy and an LVEF ≥40% at increased risk of SCD and low risk of nonsudden death who may benefit from implantable cardioverter defibrillator implantation. Clinical Trial Registration: URL: http://clinicaltrials.gov. Unique identifier: NCT00930735.

Background:Although large randomized clinical trials have found that primary prevention use of an implantable cardioverter-defibrillator (ICD) improves survival in patients with cardiomyopathy and heart failure symptoms, patients who receive ICDs in practice are often older and have more comorbidities than patients who were enrolled in the clinical trials. In addition, there is a debate among clinicians on the usefulness of electrophysiological study for risk stratification of asymptomatic patients with Brugada syndrome.Aim:Our analysis has 2 objectives. First, to evaluate whether ventricular arrhythmias (VAs) induced with programmed electrostimulation in asymptomatic patients with Brugada syndrome identify a higher risk group that may require additional testing or therapies. Second, to evaluate whether implantation of an ICD is associated with a clinical benefit in older patients and patients with comorbidities who would otherwise benefit on the basis of left ventricular ejection fraction and heart failure symptoms.Methods:Traditional statistical approaches were used to address 1) whether programmed ventricular stimulation identifies a higher-risk group in asymptomatic patients with Brugada syndrome and 2) whether ICD implantation for primary prevention is associated with improved outcomes in older patients (>75 years of age) and patients with significant comorbidities who would otherwise meet criteria for ICD implantation on the basis of symptoms or left ventricular function.Results:Evidence from 6 studies of 1138 asymptomatic patients were identified. Brugada syndrome with inducible VA on electrophysiological study was identified in 390 (34.3%) patients. To minimize patient overlap, the primary analysis used 5 of the 6 studies and found an odds ratio of 2.3 (95% CI: 0.63–8.66;P=0.2) for major arrhythmic events (sustained VAs, sudden cardiac death, or appropriate ICD therapy) in asymptomatic patients with Brugada syndrome and inducible VA on electrophysiological study versus those without inducible VA. Ten studies were reviewed that evaluated ICD use in older patients and 4 studies that evaluated unique patient populations were identified. In our analysis, ICD implantation was associated with improved survival (overall hazard ratio: 0.75; 95% confidence interval: 0.67–0.83;PPPP

Background— Despite its salutary effects on health, aerobic exercise is often avoided after receipt of an implantable cardioverter defibrillator (ICD) because of fears that exercise may provoke acute arrhythmias. We prospectively evaluated the effects of a home aerobic exercise training and maintenance program (EX) on aerobic performance, ICD shocks, and hospitalizations exclusively in ICD recipients. Methods and Results— A total of 160 patients (124 men and 36 women) were randomly assigned who had an ICD for primary (43%) or secondary (57%) prevention to EX or usual care (UC). The primary outcome was peak oxygen consumption, measured with cardiopulmonary exercise testing at baseline and 8 and 24 weeks. EX consisted of 8 weeks of home walking for 1 h/d, 5 d/wk at 60% to 80% of heart rate reserve, followed by 16 weeks of maintenance home walking for 150 min/wk. Adherence to EX was determined from exercise logs, ambulatory heart rate recordings of exercise, and weekly telephone contacts. Patients assigned to UC received no exercise directives and were monitored by monthly telephone contact. Adverse events were identified by ICD interrogations, patient reports, and medical charts. ICD recipients averaged 55±12 years and mean ejection fraction of 40.6±15.7; all were taking β-blocker medications. EX significantly increased peak oxygen consumption (EX, 26.7±7.0 mL/kg per minute; UC, 23.9±6.6 mL/kg per minute; P =0.002) at 8 weeks, which persisted during maintenance exercise at 24 weeks (EX, 26.9±7.7 mL/kg per minute; UC, 23.4±6.0 mL/kg per minute; P Conclusions— Prescribed home exercise is safe and significantly improves cardiovascular performance in ICD recipients without causing shocks or hospitalizations. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00522340.

We read with great interest the meta-analysis by Golwala et al1 that aimed to assess the benefits of an implantable cardioverter-defibrillator (ICD) for the primary prevention of mortality in patients with nonischemic cardiomyopathy. Their primary analysis demonstrated a 23% risk reduction in all-cause mortality in favor of ICD (hazard ratio, 0.77; 95% confidence interval, 0.64–0.91). They performed a subgroup analysis of the 2 trials that, according to the authors, compared ICD plus cardiac resynchronization therapy (CRT-D) plus optimal medical therapy with CRT-pacemaker …

The debate about the benefit of implantable cardioverter-defibrillator (ICD) for patients with heart failure in the setting of nonischemic cardiomyopathy (NICMP) has been reignited after the 2016 publication of the DANISH trial (Danish Study to Assess the Efficacy of ICDs in Patients With Non-Ischemic Systolic Heart Failure on Mortality).1 Golwala et al2 sought to update the meta-analysis of randomized controlled trials evaluating the utility of ICDs in patients with NICMP. We congratulate the authors for their …

We thank Nery et al for their insightful letter to our article.1 We alluded to the age and survival interaction with implantable cardioverter-defibrillator (ICD) use in patients with nonischemic cardiomyopathy (NICM) noted in the DANISH trial (Defibrillator Implantation in Patients With Nonischemic Systolic Heart Failure) in our article.1 We agree that similar trends have been observed in other trials.2 However, only 4 of 6 trials included in our meta-analysis (DEFINITE [Defibrillator in Nonischemic Cardiomyopathy Treatment Evaluation], COMPANION [Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure], SCD-HeFT [Sudden Cardiac Death in Heart Failure Trial], and DANISH)1 reported age-stratified outcomes. Two of the 4 trials, SCD-HeFT3 and COMPANION,4 reported outcomes for both ischemic and nonischemic patients, making age-stratified analysis in patients with NICM difficult in the absence of individual patient–level data. Nonetheless, we do agree that this should be recognized as one of the key limitations of the currently available data we have from the randomized controlled trials. In addition, all treatment decisions for ICD placement should be personalized and involve …

Sex-specific differences in the epidemiology, pathophysiology, clinical presentation, clinical treatment, and clinical outcomes of atrial fibrillation (AF), sustained ventricular arrhythmias, and sudden cardiac death are recognized. Sex hormones cause differences in cardiac electrophysiological parameters between men and women that may affect the risk for arrhythmias. The incidence and prevalence of AF is lower in women than in men. However, because women live longer and AF prevalence increases with age, the absolute number of women with AF exceeds that of men. Women with AF are more symptomatic, present with more atypical symptoms, and report worse quality of life in comparison with men. Female sex is an independent risk factor for death or stroke attributable to AF. Oral anticoagulation therapy for stroke prevention has similar efficacy for men and women, but older women treated with warfarin have a higher residual risk of stroke in comparison with men. Women with AF are less likely to receive rhythm control antiarrhythmic drug therapy, electric cardioversion, or catheter ablation in comparison with men. The incidence and prevalence of sustained ventricular arrhythmias and sudden cardiac death are lower in women than in men. Women receiving implantable cardioverter defibrillators for primary prevention of sudden cardiac death are less likely to experience sustained ventricular arrhythmias in comparison with men. In contrast, women receiving a cardiac resynchronization therapy implantable cardioverter defibrillator for the treatment of heart failure are more likely to benefit than men. Women are less likely to be referred for implantable cardioverter defibrillator therapy despite current guideline recommendations. Women are more likely to experience a significant complication related to implantable cardioverter defibrillator implantation in comparison with men. Whether sex differences in treatment decisions reflect patient preferences or treatment biases requires further study.

We appreciate Drs Dhruva and Redberg’s thoughtful letter regarding our finding that counseled women were as likely as men to proceed with primary prevention implantable cardioverter-defibrillator (ICD) placement (adjusted odds ratio, 1.13; 95% confidence interval, 0.99–1.29).1 Women were indeed underrepresented in the landmark clinical trials establishing the efficacy of primary prevention ICDs. Post hoc meta-analyses of the randomized data as well as observational studies have reached divergent conclusions regarding the survival benefit of primary prevention ICDs among women compared with men, yet no significant heterogeneity in ICD benefit by sex has been demonstrated to date.2,3 Definitive randomized data likely are not forthcoming given the ethical and cost considerations surrounding a primary prevention ICD trial among women. In this setting, professional societies and especially guideline writing committees have deliberated the body of evidence and determined …