Association of sustained ventricular arrhythmias with transient myocardial ischemia in patients hospitalized with acute coronary syndrome

Abstract

Background: Myocardial ischemia is a known substrate for the development of malignant ventricular arrhythmias. Purpose: The purpose of this secondary analysis was to determine the occurrence of ventricular arrhythmias at the time of transient myocardial ischemia in patients hospitalized with acute coronary syndrome (ACS). Methods: Patients who presented to the emergency department at the San Francisco Medical Center, University of California, San Francisco, Calif, with chest pain or anginal equivalent were enrolled in a prospective study involving 12-lead electrocardiogram Holter ST-segment monitoring. Transient myocardial ischemia was defined as a change in ST-segment amplitude of 200 lV or greater in 1 lead or more or 100 lV or greater in 2 leads or more, lasting for at least 60 seconds. An associated arrhythmia was defined as sustained ventricular tachycardia (VT) or ventricular fibrillation during or 10 minutes before or after an ST event. Results: One thousand one hundred thirty-six (emergency department) patients evaluated for chest pain/anginal equivalent were monitored for 24 hours. Of these, 270 patients were hospitalized with a diagnosis of ACS (acute myocardial infarction, n = 95; unstable angina, n = 175). Of the 270 patients, 31 (11%) had a total of 44 STevents (number, 1.4F 1.6; range, 1-10; duration, 27 F 15 minutes). Of the 44 ST events, 24 (55%) had an isolated premature ventricular contraction or ventricular couplet; however, none had associated sustained VT/ventricular fibrillation. The figure below shows the longest sustained arrhythmia (9-beat VT) among the 31 patients, and it occurred in the absence of electrocardiogram signs of ischemia. Conclusions:With current medical management, frequency of ischemia is low in patients hospitalized with ACS, and malignant ventricular arrhythmias were not observed in this cohort.