Arterial baroreflex dysfunction in major depressive disorder

Patients treated for major depressive disorder are at increased risk for sudden cardiac death. Impaired arterial baroreflex function has been associated with ventricular arrhythmias. Our hypothesis was that arterial baroreflex dysfunction prevails in major depressive disorder and that electroconvulsive therapy in conjunction to medical therapy would improve both depressive symptoms and baroreflex function. Thirty-three patients with major depressive disorder who were treated in hospital were studied before and after electroconvulsive treatment. Eighteen patients underwent follow-up investigations 6 months after discharge. ECG and beat-to-beat blood pressures were recorded continuously. Arterial baroreflex sensitivity (BRS) and effectiveness index were calculated. Twenty healthy subjects were examined for comparison. Heart rate and systolic blood pressures were elevated (P < 0.01 for all) in depressive patients before treatment when compared with healthy subjects, whereas arterial BRS and baroreflex effectiveness were reduced (10 +/- A 7 vs. 15 +/- A 5 ms/mmHg and 0.35 +/- A 0.20 vs. 0.48 +/- A 0.14, P < 0.01 for both). Whereas depressive symptoms decreased after treatment (P < 0.05), blood pressures, heart rate, arterial BRS, and effectiveness remained unchanged. At follow-up, 6 months after discharge all variables were unchanged when compared with values obtained at discharge. Both the sensitivity and the number of times the arterial baroreflex is being active are reduced in major depressive disorder and this baroreflex dysfunction may prevail long-term when depressive symptoms have improved.