Dipyridamole echocardiography evaluation of acute inferior myocardial infarction with concomitant anterior ST segment depression.

The significance of anterior ST segment depression in inferior acute myocardial infarction (AMI) remains controversial. The aim of this study was to relate precordial ST segment depression to the topography of residual myocardial ischaemia, with myocardial mapping of the asynergic area and coronary anatomy. Twenty-five patients with first inferior AMI (15 patients with anterior ST segment depression: group A and 10 patients without anterior ST segment shift: group B), all underwent: (1) electrocardiographic evaluation on admission to the Coronary Care Unit and at 24 h intervals thereafter; (2) 2D-echocardiographic study within 3 h of CCU admission: (3) dipyridamole echocardiographic test (DET) (doses of dipyridamole up to 0.84 mg.kg i.v. over 10 min) 4 days after AMI; (4) coronary arteriography within 14 days from AMI. To assess regional left ventricular wall motion, a 16 segment model was used and a wall motion score index (WMSI) was derived. The results of DET were correlated to the anatomy of the infarct-related vessel. Compared to group B, group A patients showed a significantly greater maximal ST segment elevation in inferior limb leads (lead III: 3.9±1.9 mm vs 2.2±1.1 mm, <0.05; aVF: 3.5±13 mm vs 1.7±0.8 mm, <0.001). Group A patients showed greater WMSI (1.35±0.22 vs 117±0.12, <0.05), with more frequent postero-lateral wall involvement (72% vs 20%, <0.05). No patient of either group showed asynergy of the anterior, anterolateral or anteroseptal segments. No differences in the distribution of coronary artery disease were observed. Left anterior descending coronary artery disease was present in only three patients (20%) in group A and in one patient in group B. DET was positive in eight patients (53%) in group A and in three (30%) in group B ( = statistically not significant). In all patients DET induced new wall motion abnormalities located in the territory of the infarct-related artery. None of the patients developed new wall motion abnormalities remote from the infarct zone or adjacent to the infarct zone, but located in different vascular regions. In conclusion, anterior ST segment depression in inferior A MI appears to indicate a more extensive area of asynergy, with frequent involvement of the posterolateral wall. The topography of DET-induced residual myocardial ischaemia does not support the hypothesis of concomitant anterior ischaemia. [ABSTRACT FROM PUBLISHER]