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Lifelong Outcomes With CRT in Mild Heart Failure
Study Questions:
What are the lifelong outcomes with cardiac resynchronization therapy (CRT) in mild heart failure (HF)?
Methods:
The study investigators used data from the 5-year follow-up of the REVERSE study to extrapolate survival and HF hospitalizations. They compared patients with CRT-ON versus CRT-OFF and CRT defibrillators (CRT-Ds) versus CRT pacemakers (CRT-Ps). They utilized multivariate regression models to estimate treatment-specific all-cause mortality, disease progression, and HF-related hospitalization rates. They used rank-preserving structural failure time (RPSFT) models to adjust for protocol-mandated crossover in the survival analysis.
Results:
The study cohort was comprised of 610 patients, in whom 84 deaths were observed. Of those, 75% (n = 63) deaths occurred during time periods before treatment-mandated crossover. The mortality was 10% (n = 67 deaths) among CRT-D patients and 11.8% mortality (n = 17) in CRT-P patients. The study investigators found that CRT-ON was predicted to increase survival 22.8% (CRT-ON 52.5% vs. CRT-OFF 29.7%; hazard ratio [HR], 0.45; p = 0.21), leading to expected survival of 9.76 years (CRT-ON) versus 7.5 years (CRT-OFF). They found that CRT-Ds showed a significant improvement in survival compared with CRT-Ps (HR, 0.47; 95% confidence interval [CI], 0.25-0.88; p = 0.02), and were predicted to offer 2.77 additional life-years. New York Heart Association (NYHA) class II patients had 30.6% higher HF hospitalization risk than class I (I vs. II incident rate ratio [IRR], 0.69; 95% CI, 0.57-0.85; p < 0.001), and three times lower compared to class III (III vs. II IRR, 2.98; 95% CI, 2.29-3.87; p < 0.001).
Conclusions:
The study authors concluded that RPSFT modeling estimated that CRT has long-term benefit in mild HF including improved survival and reduced risk of HF hospitalization. Their model predicted that CRT-D prolonged life more than CRT-P. They found a significantly reduced risk of HF hospitalization in NYHA class I/II patients when compared to class III.
Perspective:
Little is known about the long-term impact of CRT in mild HF. This is an important study because it is the first study to predict that CRT prolongs survival by ~2 years (+27%) in mild HF when compared with optimal medical therapy, and that CRT-D devices prolong survival almost 3 years when compared with CRT-P devices (+30%). In addition, CRT reduced the risk of HF hospitalizations. It would be interesting to estimate the long-term cost-effectiveness of CRT in mild HF using the statistical techniques utilized by these investigators.
Keywords: Arrhythmias, Cardiac, Cardiac Resynchronization Therapy, Cardiac Resynchronization Therapy Devices, Defibrillators, Disease Progression, Heart Failure, Pacemaker, Artificial, Risk, Secondary Prevention, Survival Analysis
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