Depression symptoms predict heart rate recovery after treadmill stress testing

Abstract

Altered autonomic nervous system (ANS) functioning may help to explain the relationship between depression and cardiac mortality. Heart rate (HR) recovery after the cessation of a treadmill stress test assesses ANS functioning and predicts mortality. This study examined the relationship between depression symptoms and HR recovery among patients entering phase II cardiac rehabilitation. Two hundred sixty patients were assessed at the time of their enrollment in cardiac rehabilitation. Patients completed a ramped-protocol treadmill stress test, providing an assessment of exercise capacity and HR recovery at 2 minutes post exercise. Depression symptoms were measured using the Beck Depression Inventory. Other medical information was obtained by chart review. Patients with higher Beck Depression Inventory scores exhibited slower HR recovery after exercise. This remained true after controlling for age, sex, and beta-blocker usage. Controlling for exercise capacity rendered the relationship between depression score and HR recovery non significant, suggesting that exercise capacity may partly account for this relationship. These findings confirm that depression is characterized by dysregulation of the ANS and implicate impaired exercise capacity as a potential mechanism.