ORLANDO, FLA. — Cardiac autonomic nervous system function is not abnormal in older patients who have major depression, Koen G. van der Kooij, M.D., said at Wonca 2004, the conference of the World Organization of Family Doctors.
This observation dashes the hope that indicators of autonomic nervous system (ANS) function readily available on the ECG—including heart rate variability, the QT interval, and QT dispersion—might have utility in primary care practices as a means of identifying within the population of patients with major depression the subset at increased risk for cardiovascular events, said Dr. van der Kooij of VU University Medical Center, Amsterdam.
Major depression has been shown in multiple studies to increase the risk of cardiovascular morbidity and mortality. The underlying mechanism is unclear. There has been speculation that loss of normal control by the ANS is involved; however, this hypothesis wasn't borne out in Dr. van der Kooij's study of 132 patients older than 55 years who were newly diagnosed with major depression and 134 nondepressed controls.
Of the patients with depression, 34% had known CVD, as did 26% of controls. All study participants underwent a 5-minute supine ECG to assess cardiac ANS parameters.
The QT interval, heart rate variability, and QT dispersion did not differ significantly between depressed patients and controls.