Prognostic Significance of Insomnia in Heart Failure

Background: Insomnia is associated with incident heart failure (HF), but the clinical significance and impact of insomnia on HF remain unclear. Methods and Results: Consecutive 1,011 patients admitted for HF were divided into 2 groups according to the presence of insomnia: HF with insomnia (insomnia group, n=519) and HF without insomnia (non-insomnia group, n=492). We compared (1) cardiac event rates including cardiac death and worsening HF; and (2) underlying clinical background including laboratory data, echocardiographic data, and cardiopulmonary exercise test between the 2 groups. On Kaplan-Meier analysis, cardiac event rate was significantly higher in the insomnia group than in the noninsomnia group (39.1 vs. 23.4%, P<0.001). The insomnia group, as compared with the non-insomnia group, had (1) higher plasma renin activity (P=0.042), renin concentration (P=0.007), and aldosterone (P=0.047); (2) lower peak (V) over dotO(2) (14.9 vs. 16.3 ml/kg/min, P=0.002) and higher (V) over dotE/(V) over dotCO(2) slope (36.0 vs. 33.5, P=0.001); and (3) similar B-type natriuretic peptide and left ventricular ejection fraction. Importantly, on multivariate Cox proportional hazard analysis after adjusting for potential confounding factors, insomnia was an independent predictor of cardiac events in HF patients (hazard ratio, 1.899; P<0.001). Conclusions: Insomnia is an independent predictor of cardiac events in HF patients. HF patients with insomnia have activated renin-angiotensin-aldosterone system and lower exercise capacity.