Emergency Medicine

Prognosis of Ventricular Fibrillation in Acute Myocardial Infarction

By Michael H. Crawford, MD
Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco

Source: Bougouin W, et al. Incidence of sudden cardiac death after ventricular fibrillation complicating acute myocardial infarction: A 5-year cause-of-death analysis of the FAST-MI 2005 registry. Eur Heart J 2014;35:116-122.

Currently, more evidence is needed to warrant implantable cardioverter-defibrillator (ICD) therapy than simply ventricular fibrillation soon after acute myocardial infarction (MI). In spite of mechanical and pharmacological therapy’s purported efficacy in cases of acute MI, there still exist serious concerns that the risk of sudden cardiac death (SCD) following VF occurrence is significantly higher than traditionally thought. To test the validity of this concern, investigators from the French registry on Acute ST elevation and non-ST elevation Myocardial Infarction (FAST-MI), carried out a 5-year study of 3670 patients beginning in 2005. After enrollment, patients were required to not only meet the international standards for myocardial infarction but also be present within 48 hours of initial symptom onset. Iatrogenic MI cases were excluded from the final study analysis. Incidences of death, including sudden cardiac death, non-sudden cardiac death, non-cardiac death, and deaths related to ventricular fibrillation, were the primary endpoints.

The incidence rate of in-hospital ventricular fibrillation was 3.2%, 79% of which was early VF. Compared to the MI population as a whole, VF patients were younger and more likely to be smokers. Anterior MI location was found to be the only disease characteristic associated with ventricular fibrillation use. Of note, multivariate analysis revealed that VF occurrence was also associated with atrial fibrillation demonstrated on the first ECG. In-hospital mortality was much higher among VF patients than among the population of MI patients. Early VF patients also had a higher mortality rate than late VF patients. Non-VF patients and VF patients also often had differing causes of death: in-hospital death among VF patients was primarily due to arrhythmias (82%); amongst non-VF patients, cardiogenic shock (62%) was the most common cause. At the 5-year mark the survival rate was 74%, which after multivariate analysis was not found to be associated with occurrence of in-hospital VF. Moreover, rates of sudden cardiac death were not higher in the VF group. Nonetheless, the authors concluded that development of ventricular fibrillation during the acute states of myocardial infarction is associated with higher risk of in-hospital mortality.