Depression increased the risk of all-cause mortality after acute MI compared to no depression (HR 2.8; 95% CI 1.4-5.4; P<.003), an effect partially mediated by low heart rate variability.
Cohort (n=678)
Does low heart rate variability mediate the effect of depression on all-cause mortality in patients with recent acute myocardial infarction?
Low heart rate variability partially mediates the increased mortality risk associated with depression following an acute myocardial infarction.
Hazard Ratio: 2.8 (95% CI 1.4–5.4)
p-value: p=<.003
BACKGROUND: Depression is associated with an increased risk for mortality after acute myocardial infarction (MI). The purpose of this study was to determine whether low heart rate variability (HRV) mediates the effect of depression on mortality. METHODS: Twenty-four-hour ambulatory electrocardiograms were obtained from 311 depressed patients with a recent acute MI who were enrolled in the Enhancing Recovery in Coronary Heart Disease (ENRICHD) clinical trial and from 367 nondepressed patients who met the ENRICHD medical inclusion criteria. Standard HRV indexes were extracted from the recordings. RESULTS: The log of very low-frequency (LnVLF) power, an index of HRV derived from power spectral analysis of the electrocardiogram signal (0.0033-0.04 Hz in milliseconds squared), was lower in the depressed than in the nondepressed patients (P<.001). There were 47 deaths (6.1%) during a 30-month follow-up. After adjusting for potential confounders, the depressed patients remained at higher risk for all-cause mortality compared with the nondepressed patients (hazard ratio, 2.8; 95% confidence interval CI, 1.4-5.4; P<.003). When LnVLF power was entered into the model, the hazard ratio for depression dropped to 2.1 (95% CI, 1.1-4.2; P = .03). The proportion of the risk for depression attributable to LnVLF power was 0.27 (95% CI, 0.23-0.31; P<.001). CONCLUSIONS: Low HRV partially mediates the effect of depression on survival after acute MI. This finding helps to clarify the physiological mechanisms underlying depression's role as a risk factor for mortality in patients with coronary heart disease. It also raises the possibility that treatments that improve both depression and HRV might also improve survival in these patients.
Carney et al. (Mon,) conducted a cohort in Recent acute myocardial infarction and depression (n=678). Depression vs. No depression was evaluated on All-cause mortality (HR 2.8, 95% CI 1.4-5.4, p=<.003). Depression increased the risk of all-cause mortality after acute MI compared to no depression (HR 2.8; 95% CI 1.4-5.4; P<.003), an effect partially mediated by low heart rate variability.