ISOLATED MID-ANTERIOR MYOCARDIAL-INFARCTION - A SPECIAL ELECTROCARDIOGRAPHIC SUB-TYPE OF ACUTE MYOCARDIAL-INFARCTION CONSISTING OF ST-ELEVATION IN NON-CONSECUTIVE LEADS AND 2 DIFFERENT MORPHOLOGIC TYPES OF ST-DEPRESSION

We describe eight patients with a distinct electrocardiographic patter n of anterior wall myocardial infarction characterized by three main f eatures: (1) a pattern of 'transmural ischemia' (ST-elevation with pos itive T-wave) in nonconsecutive leads: aVL and V-2, and two different types of ST-depression; (2) a pattern of 'true reciprocal changes' (ST -depression and negative T-wave) in III and aVF; (3) a pattern of 'sub -endocardial ischemia' (ST-depression with positive T-wave) in V-4-5, while ST in V-3 was either isoelectric or depressed, We characterize t he electrocardiographic features and correlate them with the echocardi ographic, radionuclide, and angiographic data. All patients admitted t o the coronary care unit from January 1990 to April 1992 with evolving acute myocardial infarction were evaluated prospectively. Patients wh ose admission electrocardiogram met the description above were include d. The electrocardiographic evolution, echocardiographic, Technetium M IBI tomography, and coronary angiography are described. Of 471 patient s with acute anterior wall myocardial infarction, admitted to the coro nary care unit during the study period, eight patients met the inclusi on criteria (1.7% of acute anterior wall myocardial infarction). Echoc ardiographic studies revealed mid-anterior hypokinesis in two patients , anterior and apical hypokinesis in one, and no wall motion abnormali ty in four patients. Technetium MIBI tomography, done in five patients , was consistent with mid-anterior or mid-anterolateral infarction wit hout involvement of the septum or apex. Coronary angiography, performe d in seven patients, demonstrated significant obstruction of the first diagonal branch in all of the patients. In four patients, the diagona l occlusion was the only significant coronary lesion in the left coron ary artery. Conclusion. Most of the anterior myocardial infarctions al so involve the septal and apical regions. Anterior wall myocardial inf arctions limited to the mid-anterior or mid-anterolateral wall, withou t apical or septal wall involvement are relatively rare. This study de scribes a special electrocardiographic form of anterior wall acute myo cardial infarction. This distinct electrocardiographic pattern represe nts true mid-anterior wall myocardial infarction, caused by occlusion of a first diagonal branch of the left anterior descending coronary ar tery. The septal and apical regions are not involved because the blood supply via the left anterior descending artery is not interrupted.