Abstract 21024: Anemia is not a Substrate for Ventricular Dysrrhythmias in Heart Failure and its Partial Amelioration by Cardiac Resynchronization Therapy Implies that It Partly Arises from the Syndrome Itself
Background: Anemia is a powerful predictor of death in heart failure (HF) but little is known about its origins and the mechanisms via which it escalates the risk of mortality. Prior analyses have suggested that anemic HF patients (pts) die more from gradual pump failure than sudden death and that low hemoglobins (Hb) might, in part, be driven by HF via hemodilution, cytokine activation and renal dysfunction.
Hypothesis: We reasoned that if anemia does not predispose to sudden death in HF then it should not enhance the risk of life threatening arrhythmias. Additionally, if it arises partly from HF itself, then interventions that improve the HF syndrome but have no direct hematological effects (e.g cardiac resynchronization therapy [CRT]) should augment Hb.
Methods: We analyzed stored electrograms to determine the relation between Hb levels and the incidence of ventricular tachycardia (VT) and fibrillation (VF) in pts implanted with an ICD alone (n=62, mean [±SD] age 66±11y, LVEF 28±7%, 22% NYHA 3/4) or CRT-ICD (n=116, age 66±13y, LVEF 25±8%, 65% NYHA 3/4) for primary prophylaxis. Temporal trends in Hb were available in a representative subset.
Results: Over a median (±IQR) follow-up of 24±11 and 24±10 months (P=0.7), 24 ICD (all VT) and 41 CRT-ICD (40 VT, 1 VF) pts had an event. Only higher, and not lower, Hb levels predicted an increased risk of arrhythmias in ICD (HR 1.27, 95% CI 1–1.6, P=0.04) but not CRT-ICD (P=0.6) pts. A Hb=14.4 g/dL was optimally predictive (AUC 0.66, P=0.03) in ICD pts and conferred a 2.8-fold amplified risk of VT (Figure A). Over time, Hb levels mildly declined in ICD pts (△Hb -0.04±2.1 g/dL, P=0.9) and increased in CRT-ICD subjects (△Hb 0.66±1.2 g/dL, P=0.002, Figure B) in parallel with improvements in LVEF and LV dimensions (all P<0.05).
Conclusions: Anemia is not a risk factor for lethal arrhythmias in HF and could be consequent to the syndrome itself as it is amenable to CRT. Anemia management might therefore need to differ between CRT eligible and ineligible pts.
- © 2010 by American Heart Association, Inc.