(P111) PREDICTING LONG-TERM SURVIVAL AFTER DE NOVO CARDIOVERTER DEFIBRILLATOR IMPLANTATION FOR PRIMARY PREVENTION

Background: Current guidelines recommend use of implantable cardioverter-defibrillators (ICDs) for the primary prevention of arrhythmia and sudden cardiac death in patients with reduced ejection fraction cardiomyopathy. While the mortality benefit of ICD insertion has been established in landmark randomized controlled trials, little is known about the long-term outcomes of patients with ICDs in clinical practice. We aimed to develop a risk prediction model for 10-year survival after ICD implantation for primary prevention.

METHODS AND RESULTS: In a multicenter, population-based registry of all ICD patients across 18 centers in Ontario, Canada, we retrospectively examined 10-year survival in patients receiving ICD implant for primary prevention from February 2007 to March 2011. 5097 patients were randomly split 2:1 into derivation and internal validation cohorts. In the derivation cohort, mean age was 65.3 years (standard deviation [SD] 11.0), 664 patients were female (19.5%) and 2344 patients (69.0%) had ischemic cardiomyopathy for primary disease indication. 10-year survival was 45.7% (95% confidence interval [CI] 44.0% to 47.4%) (Figure 1). The final prediction model using Cox proportional hazards modelling included age, sex, ischemic vs. non-ischemic cardiomyopathy, urgency of procedure, New York Heart Association classification, left ventricular ejection fraction, comorbidities (diabetes, hypertension, stroke, smoking, peripheral vascular disease, chronic obstructive lung disease and dialysis), medications (loop diuretic, oral anticoagulation, digoxin, aspirin, clopidogrel), and biomarkers at time of ICD assessment (sodium, hemoglobin, renal function, QRS on electrocardiogram). This model had good discrimination in derivation (0.80; 95% CI 0.78, 0.81) and validation samples (0.79, 95% CI 0.77, 0.81). The model slightly underpredicted risk but was otherwise well-calibrated. Current smoking, loop diuretic use, dialysis, and hypernatremia > 140mmol/L were strongly associated with increased death, where female sex, nonischemic cardiomyopathy and aspirin use was associated with improved survival (Table 1). Sensitivity analyses showed that the addition of device type, provider factors (implantation site, implanter volume, physician main specialty), sex-related interaction terms, and frailty scores did not significantly improve the prediction model.

Conclusion: A combination of demographic and patient factors determined at baseline device evaluation enabled the prediction of 10-year survival in patients undergoing ICD for primary prevention in the clinical practice. Our findings may help identify and monitor individuals at risk of long-term mortality and may be useful in targeting future prevention strategies to enhance longevity in this high-risk population.