The Safety of Tricyclic Antidepressants in Cardiac Patients

IN 1977, we first reported the antiarrhythmic effect of imipramine hydrochloride.¹Prior to that time, physicians generally believed that the tricyclic antidepressants (TCAs) caused arrhythmia. That belief stemmed from the propensity of overdoses of these drugs to provoke arrhythmias.²However, it subsequently became apparent, both from our studies³⁻⁶and the work of others,⁷that at plasma concentrations therapeutic for depression,⁸TCAs suppress arrhythmias, and their cardiac effects closely resemble those of class I antiarrhythmic drugs.⁹,¹⁰Until recently, it was our belief that depressed patients with preexisting arrhythmias would benefit from the antiarrhythmic effect of TCAs.¹¹,¹²Unfortunately, recent studies indicate that this opinion may need to be revised. Ventricular premature depolarizations (VPDs) are a well-documented risk factor for sudden death after myocardial infarction (MI)¹³,¹⁴and the assumption had been that drugs that suppress VPDs would reduce this associated mortality.