Anemia and the Risk of Life-threatening Ventricular Tachyarrhythmias from the Israeli Implantable Cardioverter Defibrillator Registry

Abstract

Anemia was shown to be associated with increased risk for adverse events in patients with heart failure (HF). However, there are limited data on the association between anemia and the risk for ventricular arrhythmias (VAs) in patients with an implantable cardioverter defibrillator (ICD). The present study population comprised 2,352 patients who were enrolled and prospectively followed up in the Israeli ICD Registry. The risk for a first appropriate ICD shock for VA was assessed by the presence of anemia, categorized at the lower tertile of hemoglobin distribution (≤12 g/dL [n = 753]). Patients who had anemia displayed higher risk clinical characteristics including older age, more advanced HF symptoms, and atrial fibrillation (p <0.01 for all). Kaplan-Meier survival analysis showed that at 2.5 years of follow-up the rate of appropriate shocks was significantly higher in patients with low (11%) versus high (6%) hemoglobin (log-rank p <0.005). Multivariate analysis showed that anemia was independently associated with a significant 56% increased risk for first appropriate ICD shock (p <0.026). When hemoglobin was assessed as a continuous measure, each 1 g/dL reduction in hemoglobin was independently associated with a significant 8% increased risk for first appropriate shock (p <0.03). Anemia was also associated with increased risk for all-cause mortality (hazard ratio [HR] 1.78, 95% confidence interval [CI] 1.4 to 2.27], p <0.001), HF hospitalizations or death (HR 1.78, 95% CI 1.48 to 1.13, p <0.001), but not with inappropriate ICD shocks (HR 1.24, 95% CI 0.70 to 2.21, p = 0.47). In conclusion, our findings suggest that the presence of anemia in patients with ICD is associated with increased risk for VA during long-term follow-up.