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

The significance of anterior ST segment depression in inferioracute myocardial infarction (AMI) remains controversial. Theaim of this study was to relate precordial ST segment depressionto the topography of residual myocardial ischaemia, with myocardialmapping of the asynergic area and coronary anatomy. Twenty-fivepatients with first inferior AMI (15 patients with anteriorST segment depression: group A and 10 patients without anteriorST segment shift: group B), all underwent: (1) electrocardiographicevaluation on admission to the Coronary Care Unit and at 24h intervals thereafter; (2) 2D-echocardiographic study within3 h of CCU admission: (3) dipyridamole echocardiographic test(DET) (doses of dipyridamole up to 0.84 mg.kg^–1 i.v. over10 min) 4 days after AMI; (4) coronary arteriography within14 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 anatomyof the infarct-related vessel. Compared to group B, group Apatients showed a significantly greater maximal ST segment elevationin inferior limb leads (lead III: 3.9±1.9 mm vs 2.2±1.1mm, P<0.05; aVF: 3.5±13 mm vs 1.7±0.8 mm, P<0.001).Group A patients showed greater WMSI (1.35±0.22 vs 117±0.12,P<0.05), with more frequent postero-lateral wall involvement(72% vs 20%, P<0.05). No patient of either group showed asynergyof the anterior, anterolateral or anteroseptal segments. Nodifferences in the distribution of coronary artery disease wereobserved. Left anterior descending coronary artery disease waspresent in only three patients (20%) in group A and in one patientin group B. DET was positive in eight patients (53%) in groupA and in three (30%) in group B (P = statistically not significant).In all patients DET induced new wall motion abnormalities locatedin the territory of the infarct-related artery. None of thepatients developed new wall motion abnormalities remote fromthe infarct zone or adjacent to the infarct zone, but locatedin different vascular regions. In conclusion, anterior ST segmentdepression in inferior A MI appears to indicate a more extensivearea of asynergy, with frequent involvement of the posterolateralwall. The topography of DET-induced residual myocardial ischaemiadoes not support the hypothesis of concomitant anterior ischaemia.