Developing a risk score to predict mortality in the first year after implantable cardioverter defibrillator implantation: Data from the Israeli ICD Registry.

INTRODUCTION: Life expectancy of less than 1 year is usually a contraindication for implantable cardioverter defibrillator (ICD) implantation. The aim was to identify patients at risk of death during the first year after implantation. METHODS AND RESULTS: Data were derived from a prospective Israeli ICD Registry. Two groups of patients were compared, those who died and those who were alive 1 year after ICD implantation. Factors associated with 1-year mortality were identified on a derivation cohort. A risk score was established and validated. A total of 2617 patients have completed 1 year of follow-up after ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation. Age greater than 75 years (hazard ratio [HR], 2.7; 95% confidence interval [95% CI], 1.6 to 4.4), atrial fibrillation (AF; HR, 1.9; 95% CI, 1.12 to 3.17), chronic lung disease (HR, 2.0; 95% CI, 1.1 to 3.76), anemia (HR, 2.3; 95% CI, 1.3 to 3.93) and chronic renal failure (CRF; HR, 3.4; 95% CI, 1.74 to 6.6) were independent risk factors for 1-year mortality. We propose a simple AAACC ("triple A double C") score for prediction of 1-year mortality after ICD implantation: Age greater than 75 years (3 points(pts)), anemia (2 pts), AF (1 pt), CRF (3 pts) and chronic lung disease (1 pt). Mortality risk increased with rising number of points (from 1% with 0 pts to 12.5% with >4 pts). The risk score was evaluated with receiver operating characteristic curve and the area under the curve of the validation curve is 0.71 (95% CI, 0.66 to 0.76). CONCLUSIONS: Age greater than 75, AF, chronic lung disease, anemia, and CRF were independent risk factors for 1-year mortality. AAACC risk score identifies patients at high risk of death during 1 year after ICD implantation.

Clinical Outcomes in Patients with Severe Renal Dysfunction Including Dialysis Following Defibrillator Implantation.

BACKGROUND: Renal dysfunction is associated with increased mortality in heart failure (HF) patients. However, there are limited data regarding clinical and arrhythmic outcomes associated with implantable cardioverter defibrillator (ICD) therapy in this population. METHODS: We evaluated outcomes associated with the severity of renal dysfunction with or without dialysis among 2,289 patients who were enrolled and prospectively followed up in the Israeli ICD Registry. The primary endpoint of the study was all-cause mortality. Secondary endpoints included cardiac mortality, HF hospitalization, non-cardiac hospitalization, and appropriate and inappropriate ICD therapy. RESULTS: Severe renal dysfunction patients (estimated glomerular filtration rate<30 ml/min/1.73 m2; n=144 patients; 6%) were older, with higher comorbidities prevalence, and more likely to suffer from advanced HF. Among severe renal dysfunction patients, those on dialysis had a lower prevalence of wide QRS and complete left bundle branch morphology, resulting in lower cardiac resynchronization therapy defibrillator (CRTD) implantation rates. Dialysis was associated with an overall increased risk for all-cause mortality (hazard ratio (HR) 3.22; 95% CI 1.69-6.13; p<0.01) and for noncardiac hospitalizations (HR 2.80; p<0.001) compared to all other study patients. However, within the subgroup of patients with severe renal dysfunction, the presence of dialysis was not an independent risk factor for all-cause mortality (HR 0.99; p=0.97) as compared to non-dialysis. The rate of appropriate ICD therapy for ventricular tachyarrhythmias increased with declining renal function, with the highest rate observed among those undergoing dialysis. CONCLUSIONS: The present findings suggest that dialysis does not significantly modify the adverse outcomes associated with severe renal dysfunction following ICD/CRTD implantation.

Renal dysfunction and clinical outcomes of patients undergoing ICD and CRTD implantation: data from the Israeli ICD registry.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce mortality in patients with heart failure (HF) and left ventricular dysfunction. However, their efficacy in patients with chronic kidney disease (CKD) is controversial. OBJECTIVE: We examined the association between renal dysfunction and clinical outcomes in patients undergoing ICD and CRT defibrillator (CRTD) implantation. METHODS: Data were collected from the Israeli ICD registry. Estimated glomerular filtration rate (eGFR) at implantation was assessed using the modification of diet in renal disease formula. Primary outcome was all-cause mortality. Secondary outcomes included the composite endpoints of death or HF and death or ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]); any hospitalizations; first appropriate and inappropriate ICD therapy. RESULTS: During the study period (July 2010-November 2012), 2,811 patients were implanted with ICD or CRTD. One-year follow-up data were available for 730 ICD patients and 453 CRTD patients. Patients with eGFR < 30 mL/minute/1.73 m(2) (n = 54, 4.6%) were older, had a higher prevalence of diabetes, hypertension, or ischemic heart disease. eGFR <30 mL/minute/1.73 m(2) was associated with increased mortality risk in ICD (HR 5.4; 95% CI 1.5-19.2), but not in CRTD patients (HR 0.9; 95% CI 0.1-7.5). Renal dysfunction was associated with the composite endpoints of death or HF and death or VT/VF in ICD, but not in CRTD patients. Mean eGFR during follow-up decreased by 8.0 ± 4.3 mL/minute/1.73 m(2) in ICD patients (P = 0.06) and by 1.8 ± 1.3 mL/minute/1.73 m(2) in patients with CRTD (P = 0.2). CONCLUSION: Based on this retrospective analysis, CKD is associated with adverse prognosis after ICD implantation, but not after CRTD implantation. GFR decreased in patients with ICD, but not in CRTD patients.

Role of defibrillation threshold testing during implantable cardioverter-defibrillator placement: data from the Israeli ICD Registry.

BACKGROUND: Defibrillation threshold (DFT) testing during placement of an implantable cardioverter-defibrillator (ICD) has been considered mandatory. Accumulating data suggest a more limited role for DFT. OBJECTIVE: The purpose of this study was to compare the outcome of ICD recipients who underwent DFT testing compared with those who did not. METHODS: In this prospective cohort analysis of patients who received an ICD between July 2010 and March 2013, we compared patients who underwent DFT testing and those who did not. Primary end-points were death and malignant ventricular arrhythmias. Secondary end-points included the composite end-points and inappropriate ICD discharges. RESULTS: Of the 3596 patients in the registry, 614 patients (17%) underwent DFT testing during ICD placement vs 2982 (83%) who did not. Variables associated with ICD testing were implantation for secondary prevention (relative risk [RR] 1.87), prior ventricular arrhythmias (RR 1.81), use of antiarrhythmic medication (RR 1.59), and sinus rhythm (RR 2.05). Factors predisposing against testing were cardiac resynchronization therapy defibrillator implantation (RR 0.56) and concomitant diuretic use (RR 0.71). ICD testing was not associated with 1-year mortality (5.3% vs 5.1%, P = .74), delivery of appropriate shocks (8.6% vs 5.6%, P = .16), combined outcomes of ventricular arrhythmias and death (12.9% vs 11.3%, P = .45), or inappropriate ICD discharges (3.9% vs 2.1%, P = .2) compared to no DFT testing. CONCLUSION: No significant differences in the incidence of mortality, malignant ventricular arrhythmias, or inappropriate ICD discharges were observed between patients who underwent DFT testing compared to those who did not. Our results may support avoiding DFT testing during ICD placement, but this requires confirmation by additional prospective studies.