Magazine article Clinical Psychiatry News

Heart Rate Variability Tied to Post-MI Mortality

Magazine article Clinical Psychiatry News

Heart Rate Variability Tied to Post-MI Mortality

Article excerpt

SAN JUAN, P.R. -- Low heart rate variability is significantly associated with an increased risk of death in depressed versus nondepressed patients after an acute myocardial infarction, Robert M. Carney, Ph.D., said at the annual meeting of the American College of Psychiatrists.

Depression is common among patients with a recent, acute myocardial infarction (MI)--incidence of major depression ranges from 15% to 23% in the literature. Other researchers found that low 24-hour heart rate variability is a strong predictor of cardiac mortality in patients with a recent MI (Ann. Noninvasive Electrocardiol. 2005;10:88-101). Heart rate variability was as robust a predictor as ventricular dysfunction or the size of the infarction in this review article.

The aim of the current study was to determine whether 24-hour heart rate variability is lower in depressed patients, and if so, whether this finding explains why depression reduces cardiovascular mortality after an MI, said Dr. Carney, professor of psychiatry and director of the behavioral medicine center at Washington University, St. Louis.

He and his associates assessed 305 depressed patients (135 with major depression and 170 with minor depression) with 24-hour ambulatory ECG readings 1-3 weeks post MI. Another group of 366 nondepressed, post-MI patients was included for comparison.

The investigators measured frequency domain heart rate variability using very-low-frequency (VLF) power spectral analysis. "VLF reflects parasympathetic modulation and is one of the best predictors of post-MI mortality," Dr. Carney said.

Dr. Carney and his associates found a difference in log of VLF power (LnVLF) measurements: 6.32 in the depressed group, compared with 6.59 in the nondepressed patients.

"This was statistically significant, but is it clinically significant?" Dr. Carney asked.

In the study, 16% of depressed patients and 7% of nondepressed controls had a VLF below 180 squared milliseconds. …

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