Anemia and the Risk of Life-Threatening Ventricular Tachyarrhythmias: Prospective Real World Data from the Israeli ICD Registry

Background: Anemia is a known risk factor for adverse events and mortality in heart failure (HF) patients. However, there are limited data regarding the relationship between hemoglobin levels and the risk for life-threatening ventricular arrhythmic (VA) events in this population. We hypothesized that reduced hemoglobin levels may predispose VA risk in HF patients implanted with an ICD for the primary prevention of sudden cardiac death.

Methods: We evaluated the association between low hemoglobin levels and the risk for a first appropriate ICD shock among 2112 HF patients who were enrolled and prospectively followed-up in the Israeli ICD Registry. Hemoglobin levels were dichotomized at the lower tertile (<12 g/dL)

Results: Patients with low hemoglobin (n=708) displayed a high frequency of baseline clinical risk factors as compared with those with higher hemoglobin levels (n=1404), including an older age, more advanced renal dysfunction, and more advanced NYHA Class (all p < 0.01). Kaplan-Meier survival analysis showed that at two year of follow-up the rate of appropriate ICD shocks was significantly higher among patients with lower- as compared with those with higher- hemoglobin levels (4% vs. 8%, respectively; log-rank p=0.003 [Figure]). Consistent with these findings, multivariate analysis, after adjustment for multiple comorbidities, showed that low hemoglobin was independently associated with a significant increase in the risk for the occurrence a first appropriate ICD shock (HR=1.56; p=0.02). Anemia was also associated with increased risk for mortality and heart failure events, but not with the occurrence of inappropriate ICD shocks.

Conclusions: Our findings suggest that anemia is independently associated with increased VA risk in HF patients who receive an ICD for the primary prevention of sudden cardiac death. Further prospective studies are required to determine whether hemoglobin correction will reduce arrhythmic risk in this population.