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Prognosis

Age, Killip class, anterior infarction, and cardiac arrest predicted mortality in symptomatic ventricular tachycardia or fibrillation after myocardial infarction

ACP J Club. 1991 Jan-Feb;114:25. doi:10.7326/ACPJC-1991-114-1-025


Source Citation

Willems AR, Tijssen JG, van Capelle FJ et al. on behalf of the Dutch Ventricular Tachycardia Study Group of the Interuniversity Cardiology Institute of the Netherlands. Determinants of prognosis in symptomatic ventricular tachycardia or ventricular fibrillation late after myocardial infarction. J Am Coll Cardiol. 1990Sep;16:521-30.


Abstract

Objective

To assess prognosis in patients with symptomatic ventricular tachycardia or fibrillation late after acute myocardial infarction.

Design

Inception cohort assembled at the time of documented sustained ventricular tachycardia or fibrillation occurring ≥ 48 hours after the onset of myocardial infarction.

Setting

13 cardiology departments in the Netherlands.

Patients

The study sample comprised 473 patients. Patients were excluded because of violations of the admission protocol; retrospective registration; no evidence of infarction; or ventricular tachyarrhythmia attributed to pump failure, ischemia, imbalance of serum electrolytes, or proarrhythmic effects of an antiarrhythmic drug. The final study group was composed of 390 patients. Patients were given standard antiarrhythmic treatment; no patients were lost to follow-up.

Assessment of prognostic factors

Data were collected at regular intervals. Symptomatic recurrent arrhythmic events and causes of death were documented.

Main outcome measures

Total mortality and recurrence of an arrhythmic event.

Main results

The mean follow-up was 1.9 years. The cumulative mortality rates at 1 and 2 years were 22% and 34%. 49% experienced at least 1 recurrent arrhythmic event. 4 characteristics were identified as significant predictors of total mortality in patients who developed arrhythmia < 6 weeks after myocardial infarction: age > 70 years (risk ratio, 4.5 95% CI 2.6 to 7.7 P < 0.001), Killip class III or IV in the first 6 weeks after myocardial infarction (risk ratio 3.5 CI 1.5 to 4.4 P = 0.003), anterior infarction (risk ratio, 2.2 CI 1.2 to 3.9 P = 0.02), and cardiac arrest during the index arrhythmia (risk ratio 1.7 CI 1.0 to 2.8 P = 0.003). 1 variable was identified as a significant predictor of total mortality in patients who developed arrhythmia > 6 weeks after myocardial infarction: cardiac arrest (risk ratio 1.7 CI 1.1 to 2.9 P = 0.05).

Conclusions

Patients with symptomatic ventricular tachycardia or fibrillation late after myocardial infarction who were given standard antiarrhythmic treatment had a high mortality rate. Predictors of total mortality were age > 70 years, Killip class III or IV, anterior infarction, and cardiac arrest.

Sources of funding: The Dutch Heart Foundation and Knoll Pharmaceuticals.

Address for article reprint: Dr. A.R. Willems, Department of Experimental Cardiology, M053, Academic Medical Center, Meibergdreef 9,1105 AZ Amsterdam, the Netherlands.


Commentary

The study by Willems and colleagues is of natural history, and such studies reflect their time. The study was done in the Netherlands, conceived in the early 1980s, with patient enrollment occurring between 1984 and 1987. Patient management decisions at that time included vigorous use of antiarrhythmic drugs, preferably class I antiarrhythmic agents (including procainamide, quinidine, disopyramide, flecanide, and propafenone). We now have evidence that treatment with the class I antiarrhythmic drugs flecanide and encainide for ventricular premature beats and ventricular tachycardia after myocardial infarction is associated with increased mortality (1). It is unfortunate that Willems and colleagues did not include a control group in the study because the lingering question is whether the treatment was worse than the disease. Another crucial issue for this study is its exclusion criterion, ventricular tachycardia attributed to severe left ventricular failure or myocardial infarction. The criteria for elimination of patients with pump failure or ischemia are unclear in a population with ischemic heart disease, especially when 1 of the important prognostic factors was found to be heart failure (Killip class III and IV).

Despite its limitations, the study found that the predictors of survival are similar to those in patients after myocardial infarction, namely, age, the presence of left ventricular failure, anterior wall myocardial infarction, multiple previous myocardial infarctions, and cardiac arrests.

Simon Rabkin, MD
University of British ColumbiaVancouver, British Columbia, Canada


Reference

1. The Cardiac Arrhythmia Suppression Trial (CAST) Investigators. Preliminary report: effect of encainide and flecainide on mortality in a randomized trial of arrhythmia suppression after myocardial infarction. N Engl J Med. 1989;321:406-12.