Long-term outcome of cardiac resynchronization therapy in the elderly

Abstract

Background: Mean patients' age in cardiac resynchronization therapy (CRT)-intervention trials was 60-70 years with few elderly patients. Long-term outcome of the elderly undergoing CRT has not been fully evaluated. Purpose: To evaluate long-term clinical outcome of elderly patients who underwent CRT. Methods: CUBIC study is a multi-center registry of patients with heart failure (HF) undergoing CRT during 2004-2010 at 11 institutions in Japan. The study subject consist of 967 patients (340 elderly patients: age ≥ 75 years; 627 younger patients: age < 75 years). Results: A mean follow-up period was 1142 days. Compared with the younger, the elderly were more likely to have wide QRS width (158 msec. vs. 152 msec. p=0.007), high BNP values (805 pg/ml vs. 644 pg/ml, p=0.007), high left ventricular (LV) ejection fraction (29% vs. 28%, p=0.01) and small LV end-diastolic dimension (60 mm vs. 63mm, p < 0.0001). No significant difference was found in the prevalence of ischemic etiology (the elderly: 34% vs. the younger: 28%), chronic kidney disease (CKD) (29% vs. 25%), chronic atrial fibrillation or flutter (cAF/AFL) (25% vs. 21%), diabetes mellitus (35% vs. 34%) and severe mitral regurgitation (15% vs. 11%). The crude survival rates were lower in the elderly compared with the younger (at 3 years, the elderly: 76.1% vs. the younger: 79.6%, log rank p=0.03). There were no significant differences in the rates of freedom from hospitalization for heart failure (at 3 years, the elderly: 64.6% vs. the younger: 66.0%, p=0.52), freedom from cardiovascular death (83.7% vs. 84.4%, p=0.32) and freedom from a composite of death and hospitalization for HF (55.0% vs. 58.0%, p=0.12). Responder rate defined as an improvement (≥ 1 score) of NYHA class after 6 months was similar (the elderly: 67.0% vs. the younger: 63.3%, p=0.26). Reverse LV remodeling defined as LV end-systolic volume reduction ≥ 15% assessed by echocardiography after 6 months was more often seen in the elderly than in the younger (66.4% vs. 56.3%, p=0.01). By Cox hazard models, the elderly was not significantly associated with an increased risk of a composite of death and hospitalization for HF (hazard ratio [HR] 1.19, 95% CI 0.98-1.45, p=0.08). Independent predictors of a composite of death and hospitalization for HF in the elderly were CKD (HR 1.60 95% CI 1.15-2.21), cAF/AFL (HR 1.49 95% CI 1.04-2.12), left bundle branch block (HR 0.63 95% CI 0.43-0.92) and use of ACE inhibitors or ARBs (HR 0.68 95% CI 0.49-0.95). Conclusions: The elderly patients had comparably favorable long-term clinical outcomes of CRT to the younger.