Aims: The incidence of non-ST-segment elevation myocardial infarction (NSTEMI) is increasing. With the limited intensive care facilities, knowledge of the total risk and predictors of acute life-threatening arrhythmias is of major interest to guide the decision on the intensity of care at the time of admission.
Methods and results: We continuously monitored 588 consecutive patients with NSTEMI admitted to the coronary care unit of a primary and tertiary care centre for malignant ventricular arrhythmias requiring defibrillation. Ninety-seven per cent of the patients underwent coronary angiography during the index hospital admission. Total rate of malignant ventricular arrhythmias and mortality was 2.6% (n=15) and 3.6% (n=21), respectively. More than two-thirds of arrhythmias occurred within the first 12 h after onset of symptoms. In a bootstrapped multivariable regression analysis, the only factor associated with the occurrence of malignant ventricular arrhythmia was higher white blood cell count on admission. Popular risk assessment tools such as Thrombolysis in Myocardial Infarction, Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy, and Predicting Risk of Death in Cardiac disease Tool were predictive of mortality but not of early arrhythmia.
Conclusion: Patients with NSTEMI treated aggressively with early revascularization are at low risk for developing life-threatening arrhythmias. The occurrence of such events remains difficult to predict. The role of baseline inflammatory status as a determinant merits further investigations.