Inferior myocardial infarction and right coronary artery occlusive disease. A correlative study.

The present study represents an attempt to correlate the electrocardiogram and coronary arteriogram in patients with an inferior transmural infarct - or total occlusion of the right coronary artery. The influence of the collateral circulation on these findings was also evaluated. Fifty patients with a total occlusion of the right coronary artery had characteristic electrocardiographic changes of an inferior infarct in 44 per cent, very suspicious changes in 32 per cent, and no changes suggesting an inferior infarct in 24 per cent. However, in this latter group who had no evidence of an inferior infarct, we were able to recognize a small number who showed an anterior wall infarct. Collateral circulation was more frequently present and more extensive in those patients whose electrocardiograms did not show changes typical of inferior transmural infarction. This suggested that collateral circulation might minimize some of the electrocardiographic abnormalities which would normally result from occlusive disease of the right coronary artery. Another 50 patients, selected because of definite electrocardiographic evidence of typical inferior transmural infarction, were evaluated by coronary arteriography. Severe obstructive disease of the right coronary artery was present in 86 per cent of the group. In the remaining 7 patients (14 per cent) minimal or no disease was found. Infarction of the inferior wall may have resulted from occlusive disease of the anterior descending artery or have been the result of a right coronary artery occlusion with subsequent recanalization. We conclude from our study that a careful analysis of electrocardiographic abnormalities in theinferior leads will, with certain limitations, permit us to estimate the likelihood of a severe lesion in the right coronary artery, and, in the face of definite electrocardiographic evidence of an inferior infarct, to predict the diseased artery.