Relation of periodic leg movements during sleep and mortality in patients with systolic heart failure

Abstract

Periodic leg movements during sleep (PLMs) are a disorder characterized by regularly recurring movements of the legs during sleep. Although PLMs are common in patients with heart failure (HF), their clinical significance is unknown. The aim of this study was to determine whether, in patients with HF, PLMs are associated with increased mortality risk. In a prospective cohort study, 218 consecutive patients with systolic HF newly referred to an HF clinic from 1997 to 2004 who underwent overnight polysomnography, regardless of symptoms or signs of sleep disorders, were enrolled. The frequency of PLMs per hour of sleep was quantified as the PLM index (PLMI). Patients were classified as either normal (PLMI <5) or abnormal (PLMI ≥5). Eighty-one of the patients (37%) had PLMIs ≥5. During a mean follow-up period of 32.9 months, complete follow-up data were obtained in 95%. Patients with PLMIs ≥5 were older and had lower left ventricular ejection fractions and higher New York Heart Association classes than patients with PLMIs <5. The mortality rate was significantly higher in patients with PLMIs ≥5 than those with PMLIs <5 (10.4 vs 3.4 deaths/100 patient-years, p = 0.002). After adjusting for significant confounding factors, the presence of PLMI ≥5 remained a significant independent risk for death (hazard ratio 2.42, 95% confidence interval 1.16 to 5.02, p = 0.018). In conclusion, in patients with systolic HF, the presence of PLMI ≥5 is associated with an increased mortality risk, but these findings do not establish a cause-effect relation.