[Stratification of arrhythmia risk and therapeutic options in survivors of acute myocardial infarction]. / Estratificación del riesgo arrítmico y opciones terapéuticas en los supervivientes a infarto agudo de miocardio.

ABSTRACT

A significant improvement in late survival of post-myocardial infarction patients has been observed during the last few years, even before the beginning of the thrombolytic era. However, about half of the fatality rate in these patients is related to arrhythmic sudden death. So, a discussion of the value of different diagnostic and therapeutic tools available for reducing arrhythmic risk seems pertinent. Several features are considered risk markers for sudden arrhythmic death symptomatic ventricular arrhythmias, left ventricular disfunction, myocardial ischemia, frequent or complex premature ventricular contractions, late ventricular potentials in high-resolution ECG and autonomous nervous system disturbances. It seems reasonable to state that the risk markers whose value was established before the thrombolytic era maintain most of their clinical applicability to the present, but none of them has specificity enough as a sudden death predictor to warrant a general systematic strategy to trace such risk arrhythmic factors. Prophylactic administration of Type I antiarrhythmic drugs to patients with frequent or complex premature ventricular contractions can no longer be justified. There is probably a place for betablockers, mainly in patients with mild to moderate depression in left ventricular function. The final results of several trials currently in progress should contribute to establish the potential role of low dose amiodarone. There is not enough evidence to determine which post-myocardial infarction patients will be candidates for an Implantable Cardioverter Defibrillator Device. Patients with risk factors for sudden death, in particular those who have a severe impairment of left ventricular function and/or severe ischemia in the stress test, would be able to take advantage of a revascularization procedure when the culprit vessel remains occluded. In the intermediate risk patients (20-40% of the total population), tests attempting to more precisely evaluate the arrhythmic risk would be warranted, always in an individualized, sequential schedule. In some cases, like the high-resolution ECG or the heart rate variability indices, more clinical investigation is necessary to adequately establish their value in routine clinical practice.