Predictors of early ventricular fibrillation before reperfusion therapy for acute ST-elevation myocardial infarction

Background: Early VF accounts for the majority of deaths during the acute phase of acute MI. In patients treated with fibrinolytics, in-hospital VF occurs most frequently with inferior MI. Contrariwise, out-of-hospital VF seems to be associated with anterior wall MI and preinfarction angina (preconditioning) may protect against VF.

Aim: To study clinical characteristics of patients with or without VF before or during reperfusion therapy.

Study design and methods: From January 1995 until December 2001, we treated 2826 patients for acute MI and reviewed the clinical records of all patients. Patients who developed early VF were classified according to the first episode of VF: either before or during the angioplasty procedure.

Results: VF developed in 219 (8%) patients. Early VF before reperfusion therapy (n=145, 5%) was independently related to anterior MI (RR 2.3 (95% CI 1.53-3.50), p<0.001), absence of preinfarction angina (RR 2.1 (95% CI 1.38-3.24), p=0.001) and Killip class >1 (RR 3.8 (95% CI 2.34-6.10), p<0.001). The majority of patients with VF during angioplasty (n=74, 3%) had inferior MI (61%).

Conclusion: Early VF before reperfusion therapy is independently associated with anterior MI, absence of preinfarction angina and Killip class >1, whereas the majority of patients with VF during angioplasty have inferior MI.