A patient with depression may find it harder to recover his/her heart rate variability after a heart attack, increasing his/her chances of coronary death. Patients who are successfully treated for depression tend to experience improvement in heart rate variability after acute coronary syndromes, compared to depressed patient’s who aren’t (treated for depression), says an article in Archives of General Psychiatry (JAMA/Archives), September issue.
The degree to which your heart rate changes from beat to beat in response to normal impulses is known as your heart rate variability.
The authors wrote “Low heart rate variability predicts death after myocardial infarction (heart attack). It is reduced in depressed compared with non-depressed patients after myocardial infarction and has been proposed to be a mediator of the increased mortality associated with depression.” Patients without depression who have an acute coronary episode experience a fall in heart rate variability – this recovers substantially in the months after an episode (not completely).
Alexander H. Glassman, M.D., of the Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, and team looked at 290 patients with depression three weeks after they had been hospitalized for acute coronary syndrome – their heart rate variability was measured. They were then randomly selected to either receive sertraline, which is an antidepressant, or just a placebo, for a period of 24 weeks. At 16 weeks they all had their heart rate variability measured again. The scientists also rated each patient’s depression (for severity) and their clinical response to treatment.
The researchers had found that previous episodes of depression were clearly linked to lower heart rate variability at the beginning of the study. At 16-weeks into the trial those patients who were still suffering from depression had slower heart rate variability recovery rates than those whose depression was either improving or had gone. In fact, some of the still-depressed patients had poorer heart rate variability readings at 16-weeks.
The writers explained “Both sertraline treatment and symptomatic recovery from depression were associated with increased heart rate variability compared with placebo-treated and non-recovered post – acute coronary syndrome control groups, respectively, but this results primarily from decreased heart rate variability in the comparison groups.”
Why there is a link between heart rate variability, depression and cardiac death is unclear, the researchers said. “What is clear is that depression is associated with biological changes involving increased heart rate, inflammatory response, plasma norepinephrine, platelet reactivity, decreased heart rate variability and now absent post – acute coronary syndrome heart rate variability recovery, all of which is associated with life-threatening consequences. Understanding why these characteristics so strongly associate with depression is crucial to understanding the nature of depression itself. From a clinician’s point of view, patients with depression after myocardial infarction, especially those with prior episodes, should be both carefully watched and aggressively treated, because they are at an elevated cardiac risk and less likely to get better spontaneously,” they concluded.
“Heart Rate Variability in Acute Coronary Syndrome Patients With Major Depression Influence of Sertraline and Mood Improvement”
Alexander H. Glassman, MD; J. Thomas Bigger, MD; Michael Gaffney, PhD; Louis T. Van Zyl, MB, ChB, MMed (Psych)
Arch Gen Psychiatry. 2007;64:1025-1031.
Written by: Christian Nordqvist