Abstract
Background Although co-occurrence of sleep disorder with heart failure is known, it is not clear whether that condition is a cause or consequence of heart failure. The present study was conducted as a longitudinal examination of the predictive value of sleep parameters on progression of left ventricular diastolic dysfunction. Methods and Results Four-hundred fifty-two subjects were followed for a mean of 34.7 months. An outcome of diastolic dysfunction was defined as increase in early inflow velocity/early diastolic tissue velocity >14. Sleep apnea-hypopnea index, minimal oxygen saturation, sleep duration, and activity index (physical movement during sleep time, a potential parameter of poor sleep quality) were determined using apnomonitor and actigraphy findings, while heart rate variability was measured with a 24-hour active tracer device. Sixty-six of the patients developed diastolic dysfunction during the follow-up period, with a median time of 25 months. Kaplan-Meier analysis results revealed that those with sleep apnea classified as moderate (apnea-hypopnea index 15 to <30, P<0.01 versus none) or severe (apnea-hypopnea index ≥30, P<0.01 versus none), and with a high activity index (Q3 or Q4, P<0.01 versus Q1), but not short sleep duration (P=0.27) had a significantly greater risk for a diastolic dysfunction event. Results of multivariable Cox proportional hazards regression analysis indicated that moderate to severe sleep apnea after a follow-up period of 3 years (hazard ratio [HR], 9.26 [95% CI, 1.89-45.26], P<0.01) and high activity index (HR, 1.85 [95% CI, 1.01-3.39], P=0.04) were significantly and independently associated with future diastolic dysfunction. Moreover, significant association of high activity index with the outcome was not confounded by either minimal oxygen saturation or heart rate variability. Conclusions Sleep apnea and physical movement during sleep, but not sleep duration and autonomic nervous dysfunction, are independent important predictors for progression of left ventricular diastolic dysfunction.