Background Randomized clinical trials have shown conflicting data on the benefit of implantable cardioverter defibrillator (ICD) for primary prevention of sudden cardiac death in patients with more advanced heart failure (HF) symptoms. Using the Israeli ICD Registry data, we sought to examine the effect of HF functional class on the outcome of patients who receive device therapy in a real-world setting. Methods The association between HF functional class (categorized as baseline New York Heart Association [NYHA] functional class I and II in [61%] vs class III and IV in [39%]) and clinical outcomes was assessed among 913 patients who received an ICD (n = 514) or a cardiac resynchronization therapy with a defibrillator (CRT-D; n = 399) device and were prospectively followed in the Israeli ICD Registry between July 2011 and June 2013. Results The risk associated with advanced HF functional class was significantly different in ICD and CRT-D recipients. In the former group, patients with NYHA classes III and IV experienced >3-fold increased risk of HF or death (hazard ratio [HR] = 3.28; P < 0.001), whereas among CRT-D recipients the risk was similar between patients with NYHA III/IV and those with less advanced HF symptoms (HR = 0.97 [95% confidence interval (CI) 0.54-1.78]; P = 0.42; P value for NYHA functional class by device type interaction = 0.002). The risk for ventricular arrhythmia (VA) was significantly lower among patients with more advanced NYHA functional class, regardless of device type (overall HR = 0.52; 95% CI 0.33-0.91; P = 0.04). Conclusion Our findings suggest that patients with less advanced HF symptoms experience a greater risk for VA and the development of HF is attenuated in CRT-D recipients with more advanced NYHA functional class.
- Cardiac resynchronization
- Heart failure