Precordial ST segment depression in patients with inferior myocardial infarction: Clinical implications

Abstract

A prospective assessment of precordial ST segment depression in acute inferior myocardial infarction was made comparing clinical characteristics, and the hospital and post-hospital course. One hundred and ten consecutive patients with inferior infarction and without previous infarction were allocated to three electrocardiographic groups. Group 1 consisted of 35 patients with inferior or inferolateral infarction without precordial ST depression. Group 2 consisted of 59 patients with 1 mm or more precordial ST depression, subdivided into 36 patients with transient ST depression (2t) and 23 patients with ST depression persisting for 48 hours or more after the admission electrocardiogram (2p). Group 3 had 16 patients with definite inferoposterior or inferoposterolateral infarction. Patients in group 2 were older than those in group 1, had higher peak creatine kinase levels, and had atrial fibrillation and atrioventricular block requiring treatment more frequently. These clinical differences were largely contributed by subgroup 2p. Compared with group 1, subgroup 2p contained relatively more women and there were more instances of ventricular fibrillation and left ventricular failure. The hospital stay was longer in this subgroup. Compared with group 3, patients in group 2p were older, had a greater proportion of women, and were more commonly previously hypertensive. Patients in subgroup 2t had higher creatine kinase levels and more frequent atrioventricular block than those in group 1. Differences in hospital mortality and in other clinical features were not significant among the groups. During a mean follow-up of 17 (12 to 32) months left ventricular failure was more common in subgroup 2p compared with groups 1 and 2t and recurrent infarction occurred more often in subgroup 2p compared with group 1. No late deaths occurred in groups 1 and 3, but three (5%) patients in group 2 died. Our data show that persistent precordial ST depression in patients with inferior infarction is a reliable marker of an adverse hospital and post-hospital course.