Risk stratification and prognosis of patients treated with amiodarone for malignant ventricular tachyarrhythmias after myocardial infarction

Summary Seventy-seven consecutive patients (mean age 62 years) with episodes of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) after acute myocardial infarction (AMI) were evaluated to assess the long-term efficacy of first-line amiodarone treatment and to identify clinical and laboratory factors associated with a high risk of death or arrhythmia recurrence. The presenting arrhythmia was VT in 41 cases (53%) and VF in 36 (47%). VT or VF occurred between the 4th and 90th day after AMI in 45 cases (58%) and later (more than 90 days) in the remaining 32 (42%). The mean number of arrhythmic episodes was 4.2. Forty patients (52%) were in New York Heart Association (NYHA) class I or II, and 37 (48%) were in class III or IV. Mean left ventricular ejection fraction was 32%; ventricular aneurysm was present in 41 subjects. Most patients had multivessel coronary artery disease. Amiodarone was administered as a first-choice drug in all patients, in combination with other antiarrhythmic drugs in 14. By ventricular stimulation after loading doses of amiodarone, sustained VT was inducible in 46 (62%) and noninducible in 28 (38%). During a mean follow-up of 28 months the incidence of cardiac mortality at 1, 3, and 5 years was 21%, 37%, and 47%; of sudden death was 7%, 19%, and 23%; of nonfatal VT recurrence was 13%, 13%, and 24%, respectively. The overall incidence of amiodarone side effects was 35%. Factors independently associated with mortality for all causes and cardiac mortality included NYHA class III or IV (p<0,01), ejection fraction -35% (p<0,01), and age -65 years (p=0,03). History of cardiac arrest was a weak predictor only by univariate analysis (p=0.05). No single variable was consistently related to an increased risk of sudden death and nonfatal VT recurrence, not even inducibility of sustained VT during electropharmacologic studies (18% of incidence in responders and 30% in nonresponders, p = ns). In this study, amiodarone treatment of patients with life-threatening ventricular tachyarrhythmias after myocardial infarction confirmed its beneficial, but not uniform, efficacy. Severe left ventricular dysfunction, age, and, less significantly, history of cardiac arrest, were independent predictors of death. Identification of patients at high risk of arrhythmia recurrence and sudden death remains undefined during amiodarone treatment.