Predicting early mortality in ICD recipients

Multiple trials have shown that implantable cardioverter defibrillators (ICDs) prolong survival in secondary and primary prevention populations. However, in spite of the efficacy of these devices in terminating life-threatening arrhythmias, total mortality remains high.

A team of US workers have evaluated 1703 patients (mean age 67+12 years, 82% male) with conventional ICD indications, who were enrolled and followed between 2001 and 2004 at 128 US centres. Patients were followed for up to a year, and vital status was obtained for 1655 patients (97% median follow-up: 377 days). There were 183 deaths within 1 year of ICD implantation(1-year mortality rate: 16%). Predictors of mortality included a history of atrial fibrillation (AF, P<0.0001), diabetes (P= 0.0001), failure to use cholesterol-lowering medications (P=0.001), use of digitalis and derivates (P<0.0001), use of diuretics (P<0.0001), low body mass index (BMI, P<0.0001), increasing age (P<0.0001), low left ventricular ejection fraction (P<0.0001), low activity hours (P<0.0001), elevated resting heart rate (P=0.014), low mean arterial pressure (MAP, P=0.007), and poor functional status (New York Heart Association class, P<0.0001). In multivariate modeling, AF (P< 0.001), diabetes (P=0.004), BMI (P=0.001), MAP (P=0.040), and functional class (P=0.006) predicted mortality.

In this broad population undergoing ICD implantation for routine clinical indications, mortality is “relatively high” at 16% in the first year after the procedure” the authors conclude. Poor functional status, low MAP, diabetes, low BMI, and AF were strongly associated with death within a year.

Reference

Predictors of early mortality in implantable cardioverter-defibrillator recipients. Stein KM, Mittal S, Gilliam FR. Europace 2009;11:734-740.