Acute and six-month depression-related abnormalities in the sleep-wake rhythm of cardiac autonomic activity in survivors of acute coronary syndromes

Abstract

Objectives: To characterize the influence of changes in depression symptoms severity six months after an acute coronary syndrome (ACS) on the circadian pattern of cardiac autonomic activity, a known independent predictor of adverse outcomes. Methods: One hundred two patients consecutively admitted to the coronary care unit (CCU) with an ACS were evaluated with a clinical interview (including a psychiatric evaluation for depression), the 21-item Hamilton Depression Scale (HAM-D) for symptom severity and a 24 h recording of heart rate variability (HRV) at admission and six months post-discharge from the CCU. HRV was measured during wake and sleep (23.00 h–07.00 h) with a fast Fourier transform algorithm. We obtained meanRR (mRR), low-frequency HRV (LF) influenced by both sympathetic and parasympathetic activity, high-frequency HRV (HF) determined solely by parasympathetic activity, and LF/HF ratio as a measure of the sympatho-vagal balance onto the heart (LF/HF). Results: Upon admission to the CCU, major depression was present in 44% of subjects. Depression was associated with shorter mRR (higher heart rate), during sleep (p < 0.05). At six months, depression was associated with shorter mRR during wake (p < 0.05) and sleep (p < 0.01), decreased mRR sleep-wake difference (p < 0.05), and lower LF both during wake (p < 0.05) and sleep (p < 0.05). LF and HF changes were related to HAM-D changes 6 months after the index episode. Conclusions: Depression influenced circadian rhythm of autonomic activity, most notably upon 6-month follow up. Changes in depressive symptom severity after a 6-month observation period were related to changes in HRV known to adversely affect coronary prognosis.