Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up. OBJECTIVES: The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. METHODS: Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. RESULTS: A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. CONCLUSIONS: In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618).

Infection in patients with subcutaneous implantable cardioverter-defibrillator: Results of the S-ICD Post Approval Study.

BACKGROUND: Early subcutaneous implantable cardioverter-defibrillator (S-ICD) studies included atypical cohorts of patients who were younger with fewer comorbidities. Recent S-ICD studies included patient populations with more comorbidities. OBJECTIVES: The goals of this study were to determine the incidence and predictors of S-ICD-related infection over a 3-year follow-up period and to use these results to develop an infection risk score. METHODS: The S-ICD Post Approval Study is a US prospective registry of 1637 patients. Baseline demographic characteristics and outcomes with 3-year postimplantation follow-up were compared between patients with and without device-related infection. A risk score was derived from multivariable proportional hazards analysis of 22 variables. RESULTS: Infection was observed in 55 patients (3.3%), with 69% of infections occurring within 90 days and a vast majority (92.7%) within 1 year of implantation. Late infections more likely involved device erosion; no infections occurred after year 2. The annual mortality rate postinfection was 0.6%/y. No lead extraction complications or bacteremia related to infection were observed. An infection risk score was created with diabetes, age, prior transvenous ICD implant, and ejection fraction as predictors. Patients with a risk score of ≥3 had an 8.8 hazard ratio (95% confidence interval 2.8-16.3) of infection compared with a 0 risk score. CONCLUSION: Infection rates in the S-ICD Post Approval Study were similar to other S-ICD populations and not associated with systemic blood-borne infections. Late infection (>1 year) is uncommon and associated with system erosion. A high-risk infection cohort can be identified that may facilitate preventive measures.

Impact of Degree of Left Ventricular Remodeling on Clinical Outcomes From Cardiac Resynchronization Therapy.

OBJECTIVES: This study tested the hypothesis that the extent of left ventricular (LV) eccentric structural remodeling in heart failure with reduced ejection fraction (HFrEF) is directly associated with clinical event responses to cardiac resynchronization therapy (CRT). BACKGROUND: Whether the severity of LV structural remodeling influences CRT treatment effects is unknown. METHODS: COMPANION (Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure) trial data were analyzed retrospectively. Left ventricular internal dimensions at end diastole indexed by body surface area (LVEDDI) were measured pre-randomization by 2-dimensional echocardiography. LVEDDI values were stratified around the median value of 35 mm/m2, and CRT (including CRT-P [CRT with only pacing capability] and/or CRT-D [CRT with an implantable defibrillator]) treatment effects were assessed and compared by LVEDDI group. Patients assigned to these treatments were compared to those undergoing optimal pharmacologic therapy (OPT) for the outcomes of all-cause mortality (ACM) or ACM and heart-failure hospitalization (ACM/HFH). RESULTS: In the LVEDDI ≥35 mm/m2 group (n = 614), CRT vs. OPT was associated with a lower ACM/HFH hazard ratio (HR) (HR: 0.53; 95% confidence interval [CI]: 0.40 to 0.70; p <0.001), whereas in the LVEDDI <35 mm/m2 group, the CRT vs. OPT ACM/HFH hazard ratio was not statistically significant (HR: 0.80; 95% CI: 0.59 to 1.08; p = 0.15). For ACM alone, in the LVEDDI ≥35 mm/m2 group, the hazard ratio for CRT-P was 0.59 (95% CI: 0.39 to 0.90; p = 0.012) and for CRT-D 0.50 (95% CI: 0.32 to 0.77; p = 0.002). Neither of the CRT groups showed a statistically significant reduction in ACM in the LVEDDI <35 mm/m2 group. CONCLUSIONS: Larger versus smaller LVEDDIs are associated with a reduction in ACM with CRT-P or CRT-D treatment, and with a more effective reduction in ACM/HFH for the combined CRT treatment groups.

Influence of left ventricular lead location on outcomes in the COMPANION study.

INTRODUCTION: There are no randomized controlled trial data that evaluate mortality and hospitalization rates in cardiac resynchronization therapy (CRT) recipients based on left ventricular (LV) lead location. We analyzed the event-driven outcomes of mortality and hospitalization as well as functional outcomes including Functional Class, Quality-of-Life, and 6-minute walk distance in 1,520 patients enrolled in the COMPANION study of CRT versus optimal medical therapy. METHODS AND RESULTS: Over a mean follow-up after implantation of 16.2 months, patients randomized to CRT, regardless of lead location, experienced benefit compared with optimized pharmacologic therapy (OPT), with respect to all-cause mortality or heart failure hospitalization. All but a posterior location showed benefit with respect to the all-cause mortality or all-cause hospitalization outcome. Mortality benefit in CRT-D patients was indifferent to LV lead position. All functional outcomes including 6-minute walk distance, Quality-of-Life (QOL) and Functional Class improved with CRT, regardless of LV lead location. CONCLUSION: LV lead location was not a major determinant of multiple measures of response to CRT therapy in the COMPANION Trial. While acute data indicate that a left lateral LV lead location results in the most favorable hemodynamic response, these chronic data suggest that positioning an LV lead in an anterior rather than a lateral or posterior LV location has similar benefit.

Cardiac resynchronization therapy reduces the risk of hospitalizations in patients with advanced heart failure: results from the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure (COMPANION) trial.

BACKGROUND: In the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure (COMPANION) trial, 1520 patients with advanced heart failure were assigned in a 1:2:2 ratio to optimal pharmacological therapy or optimal pharmacological therapy plus cardiac resynchronization therapy (CRT-P) or CRT with defibrillator (CRT-D). Use of CRT-P and CRT-D was associated with a significant reduction in combined risk of death or all-cause hospitalizations. Because mortality also was significantly reduced (optimal pharmacological therapy versus CRT-D only), an assessment of the true reduction in hospitalization rates must consider the competing risk of death and varying follow-up times. METHODS AND RESULTS: To overcome the challenges of comparing treatment groups, we used a nonparametric test of right-censored recurrent events that accounts for multiple hospital admissions, differential follow-up time between treatment groups, and death as a competing risk. An end-point committee adjudicated and classified all hospitalizations. Compared with optimal pharmacological therapy, CRT-P and CRT-D were associated with a 21% and 25% reduction in all-cause, 34% and 37% reduction in cardiac, and 44% and 41% reduction in heart failure hospital admissions per patient-year of follow-up, respectively. Similar reductions were seen in hospitalization days per patient-year. The reduction in hospitalization rate for heart failure in the CRT groups appeared within days of randomization and remained sustained. Noncardiac hospitalization rates were not different between groups. CONCLUSIONS: Use of CRT with or without a defibrillator in advanced heart failure patients was associated with marked reductions in all-cause, cardiac, and heart failure hospitalization rates in an analysis that accounted for the competing risk of mortality and unequal follow-up time.

Influence of diabetes on cardiac resynchronization therapy with or without defibrillator in patients with advanced heart failure.

OBJECTIVES: We performed a post hoc analysis to determine the influence of cardiac resynchronization therapy with a defibrillator (CRT-D) or without a defibrillator (CRT-P) on outcomes among diabetic patients with advanced heart failure (HF). BACKGROUND: In patients with systolic HF, diabetes is an independent predictor of morbidity and mortality. No data are available on its impact on CRT-D or CRT-P in advanced HF. METHODS: The database of the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure trial was examined to determine the influence of CRT (CRT-D and CRT-P) on outcomes among diabetic patients. All-cause mortality or hospitalization, all-cause mortality or cardiovascular hospitalization, all-cause mortality or HF hospitalization, and all-cause mortality were analyzed among diabetic patients (n = 622). A Cox proportional hazard model, adjusting for age, gender, New York Heart Association, ischemic status, body mass index, left ventricular ejection fraction, heart rate, QRS, left or right bundle branch block, blood pressure, comorbidities (renal failure, carotid artery disease, peripheral vascular disease, hypertension, coronary artery bypass grafting, and atrial fibrillation), medications, and device (with or without defibrillator), was used to estimate hazard ratios (HRs) and significance. RESULTS: The overall outcome of diabetic patients was similar to that of nondiabetic patients in the optimal pharmacologic therapy arm. With CRT, diabetic patients experienced a substantial reduction in all-cause mortality or all-cause hospitalization (HR = 0.77, 95% confidence interval [CI] 62-0.97), all-cause mortality or cardiovascular hospitalization (HR = 0.67, 95% CI 0.53-0.85), all-cause mortality or HF hospitalization (HR = 0.52, 95% CI 0.40-0.69), and all-cause mortality (HR = 0.67, 95% CI 0.45-0.99) compared with optimal pharmacologic therapy. Procedure-related complications and length of stay were identical in diabetic and nondiabetic patients. CONCLUSION: In diabetic patients with advanced HF, there is a substantial benefit from device therapy with significant improvement in all end points.