Cardiopulmonary effects of chronic amiodarone therapy in the early postoperative course of cardiac surgery patients

ABSTRACT

We compared the early postoperative course of 28 consecutive patients who underwent cardiac surgery while on amiodarone therapy (group 1) with the consecutive 28 patients who underwent similar surgery and were later given amiodarone (group 2). Group 1 patients received a cumulative dose of 373.6 ± 546.2 mg/kg amiodarone over a period of 60.5 ± 107.5 days. Preoperatively, sustained ventricular tachycardia (P < .01) and sudden cardiac death (P < .01) were significantly more common in group 1 than in group 2. Postoperatively, incidences of congestive heart failure, low cardiac index, bradycardia necessitating pacing, ventricular arrhythmias, and myocardial infarction were similar in the two groups. Postoperative respiratory failure was more common in group 1 and led to longer intubation and longer intensive care unit (ICU) stays. Four patients with respiratory failure had significantly lower PaO₂ and higher (A-a) PO₂ values preoperatively compared with the 24 group 1 patients without respiratory failure. Subclinical amiodarone pulmonary toxicity may be the underlying cause of significantly higher incidence of postoperative respiratory failure, leading to longer intubation and ICU periods. Arterial blood gas analysis may help differentiate high-risk patients before cardiac surgery.