Response to exercise in patients taking psychotropic drugs. Arrhythmias and the QT interval (QT wave peak).

Psychotropic drugs may prolong the QT interval, potentially predisposing to ventricular arrhythmias and/or sudden death. Exercise prescribed as therapy for depression may also prolong the QT interval and augment arrhythmia risk. To determine QT-interval (QT wave peak, or QTPK) response to exercise in patients receiving psychotropic drugs, treadmill exercise testing was performed on 20 mentally competent psychiatric inpatients clinically free of heart disease. Twenty-four-hour ambulatory ECGs were performed within one day of exercise testing to detect arrhythmias during routine daily activities. Exercise test results for psychiatric patients were compared with those of normal subjects receiving no medication. Separate regression lines relating heart rate of QTPK interval, calculated for each group, showed no significant difference. No serious arrhythmias occurred during routine daily activities or exercise. Patients without heart disease taking psychotropic drugs have appropriate QTPK-interval shortening with exercise.