Arrhythmogenic potential of silent myocardial ischemia after myocardial infarction

Abstract

In a series of 300 patients who had suffered a transmural infarction and were undergoing coronary angiography because of ischemia in the surviving myocardium, 17 demonstrated an exercise response indicative of myocardial ischemia, in the absence of any signs or symptoms of angina pectoris. The presence of ischemia in the region of the myocardium under scrutiny was proven by:

• 1. ST-segment depression during bicycle ergometry of at least 2 mm, in leads without any QRS or ST-T changes at rest

• 2. > 75% stenosis of vessels supplying the area under investigation, in addition to the vessel supplying the region of infarction

• 3. a reversible Thallium perfusion defect on exercise.

We compared those 17 patients with silent myocardial ischemia with 21 patients having typical angina pectoris on exertion. All patients underwent 24 h Holter monitoring, treadmill testing at target heart rate (previously determined as inducing signs of myocardial ischemia) swimming and callisthenic programs with telemetric ECG recordings. We concluded that there is no close relationship between myocardial ischemia and the occurrence of complex ventricular arrhythmias. In silent ischemia, complex ventricular arrhythmias do not occur at a higher rate than in patients with angina pectoris.