DEPRESSION-RELA TED ABNORMALITIES IN CIRCADIAN RHYTHM OF CARDIAC AUTONOMIC ACTIVITY IN SURVIVORS OF ACUTE CORONARY SYNDROMES
We sought to characterize the influence of depression on the circadian pattern of cardiac autonomic activity, a known independent predictor of adverse outcomes six months after an acute coronary syndrome (ACS), in 102 patients. They were studied with a clinical interview, a 21-item Hamilton Depression Scale, and a 24h recording of heart rate variability (HRV) at admission and at six months. HRV was measured during wake and sleep (11PM-7AM) with a fast Fourier transform algorithm. We measured
... thm. We measured meanRR (mRR); low-frequency HRV (LF, LFnu) influenced by both sympathetic and parasympathetic activity; high-frequency HRV (HF, HFnu) determined by parasympathetic activity; and LF/HF ratio indicating the sympathovagal balance (LF/HF). At admission depression had a prevalence of 44%, and was associated with higher mRR, that is higher heart rate, during sleep (p<0.05; Table 2 ). At six months, depression was associated with higher RRm during wake (p<0.05) and sleep (p<0.01), and with mRR sleep-wake diffence (p<0.05; Table 3 ). Patients showed a lower LF both during wake (p<0.05) and sleep (p<0.05; Table 3 ). LF changes during follow-up were correlated with HAM-D changes. We conclude that depression is associated with changes in the circadian rhythmicity of autonomic activity, and such changes are more evident six months after an ACS. Also, changes in depression are correlated with changes in HRV. Circadian HRV changes may mediate the worsening of prognosis associated to clinical depression after an ACS.