Influence of myocardial infarct on ventricular arrhythmias during the exercise test. Study in patients with stable angina of effort.

The incidence of ventricular arrhythmias observed during exercise (EVA) was correlated with the presence of previous myocardial infarction (IM) and angiographic severity of coronary artery disease (CAD) in 162 patients (pts.) with stable angina on effort, who had a positive stress test and greater than 70% stenosis of a major coronary artery. Our study population was divided in two groups: the first was composed of 95 pts. with previous MI, the second of 67 pts. without previous MI. Pts. of both groups were subdivided according to severity of CAD and to presence and degree of abnormal segmental wall motion (ASWM). In the MI group only 11.5% of pts. had single vessel disease, and 86.3% had ASWM. In pts. without MI 28.6% had single vessel disease; ASWM was found in 59.7% (p less than 0.001 vs MI pts.). Pts. with MI showed a higher incidence of EVA than pts. without MI (60% vs 32.8%, p less than 0.001). In both groups EVA were more frequent among pts. with double, triple vessel and main left CAD, than in pts with single vessel disease, but the difference was not significant. In general, EVA were found to correlate better with the number of areas with ASWM: in both groups significant differences of EVA frequency were found when pts. with normal left ventricular function were compared to those with more severe ASWM, while no difference was found between pts with and without MI who had the same degree of CAD. The most severe EVA (Tilkian's classification), were found in pts with a previous MI and a high ASWM score. In conclusion, our results show that a previous MI affects the development of EVA in pts. with stable effort angina. However EVA seem to be better correlated with the severity of LV impairment than with the extent of CAD.