Comparison of the effects of cardiac resynchronization therapy in patients with class II versus class III and IV heart failure (from the InSync/InSync ICD Italian Registry)

Abstract

Cardiac resynchronization therapy (CRT) is recommended for patients with New York Heart Association (NYHA) class III or IV heart failure and wide QRS complexes. The aim of this study was to compare the effects of CRT in patients in NYHA class II with those in NYHA class III or IV. Nine hundred fifty-two patients (188 in NYHA class II) consecutively implanted with biventricular devices and enrolled in a national observational registry were studied. Clinical outcomes were estimated after 12 months of CRT, and long-term survival was assessed. At a median follow-up of 16 months, significantly fewer major cardiovascular events were reported in patients in NYHA class II compared with NYHA class III or IV (rate 13 vs 23 per 100 patient-years of follow-up, p<0.001). The percentage of patients who improved in NYHA class status after 12 months of CRT was lower in those in class II than in those in class III or IV (34% vs 69%, p<0.001), whereas the absolute increase in the ejection fraction was similar (8+/-9% vs 9+/-11%, p=NS), as well as the reductions in end-diastolic diameter (-3+/-8 vs -3+/-8 mm, p=NS) and end-systolic diameter (-4+/-10 vs -6+/-10 mm, p=NS). The NYHA class II group experienced lower all-cause mortality (log-rank test p=0.018). In the 2 groups, patients with major cardiovascular events during follow-up exhibited less or no reverse remodeling compared with those with better long-term clinical outcomes. In conclusion, the results of this study indicate that CRT induced similar improvements in ventricular function in the 2 groups, whereas the improvement in functional status was significantly lower for patients in NYHA class II than for those in class III or IV. A positive effect of CRT on cardiac dimensions was associated with a long-term beneficial effect on disease progression in patients in NYHA class II.