[Evaluation of the risk of arrhythmia after infarction]

Abstract

Evaluation of the risk of arrhythmias after myocardial infarction involves identification of those patients at a high risk of arrhythmic events, i.e. those who fall victim to ventricular tachycardia or sudden death. Such identification is an essential first stage before any treatment can be proposed. It has been clearly shown that the existence of premature ventricular contractions following infarction is an indicator of poor prognosis. In addition to evaluation of premature ventricular contractions, a Holter record can identify sinus variability, a parameter which the prognostic importance is currently being increasingly emphasized. Electrocardiography with averaging and high amplification has now been shown to be of value in the evaluation of arrhythmic risk after infarction. The negative predictive value of this investigation is very high, of the order of 90 percent. In addition to Holter and electrocardiography with averaging, two other non-invasive investigations can be used to determine arrhythmic risks after infarction. Stress testing can seek the presence of premature ventricular contractions related to exercise, while isotope ventriculography measures the value of ejection fraction which, in itself, has a high predictive value in terms of arrhythmic events. Mortality after infarction is proportional to the lowering of ejection fraction and among deaths approximately half are probably due to arrhythmias. Programmed ventricular pacing also has a role to play in evaluation of arrhythmic risk after infarction, but should not be routine. It may be indicated in those patients showing all of the signs of risk, i.e. repetitious forms by Holter, late potentials and low ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)