Evolution of electrocardiographic and echocardiographic abnormalities during the 4 years following first acute myocardial infarction

Therapies aimed at salvaging jeopardized myocardium in patients with acute myocardial infarction (MI) are now routine. The success of these therapies must often be estimated by non-invasive tests, such as an 12-lead electrocardiogram (ECG) or two dimensional echocardiography. To monitor QRS changes and left ventricular (LV) function over time in patients who have received therapies aimed at myocardial salvage, it is important to know the 'spontaneous' evolution of these estimates. Consecutive MI survivors admitted in the pre-thrombolytic era with their first MI were re-studied at 4 years. Patients were excluded if they had experienced reinfarction, coronary revascularization or bundle branch block in the acute or follow-up period. A standard ECG and a two-dimensional echocardiogram were obtained prior to discharge and at follow-up. The quantitative ECG analysis was performed according to the Selvester QRS scoring method. During the two-dimensional echocardiogram each of the 20 segments of the LV were assessed to provide a wall motion score. Eighty patients with a median age of 64 years (range 40-79) were included in the study. Thirty-two had anterior 48 inferior MI. A significant decrement in median QRS score estimated AMI size occurred between pre-discharge and follow-up ECGs in the entire group (18.3% vs 10.5%; P<0.00001). This difference occurred both in anterior (21.6% vs 10.5%; P<0.00001) and inferior-posterior (16.5% vs 10.5%; P<0.00001) MI locations. In the anterior MI group there was a trend towards a greater total decrease of QRS points than in the inferior-posterior MI group (42% vs 27%; P=0.10). Within the anterior MI group, more QRS points awarded in the anteroseptal leads (V₁-V₃) remained at follow-up than in the anterosuperior and apical leads (I, aVL and V₄-V₆), (80% vs 49%; P=0.03). Within the inferior-posterior MI group there were no significant differences in QRS point resolution between lead groups. The comparison between pre-discharge and follow-up two-dimensional echocardiograms demonstrated a significant decrease in wall motion score in the population as a whole (median 9.4 vs 7.6; P=0.01). The same trend was found for both anterior (median 16.4 vs 14.8, P=0.057) and inferior-posterior MI (7.5 vs 5.5, P=0.11). There was a significant correlation between the resolution of QRS score and the improvement in wall motion score (P=0.04). In MI patients not treated with reperfusion therapies therapies, without re-infarction or revascularization during 4 years follow-up, a significant and parallel improvement in ECG and two-dimensional echocardiographic indices of MI size occurs. These results can provide control data for evaluating long-term benefits of thrombolytic therapy.