Prognostic significance of precordial ST segment depression during inferior myocardial infarction in the thrombolytic era: Results in 16,521 patients

Objectives. We examined the prognostic significance of precordial ST segment depression among patients,vith an acute inferior myocardial infarction. Background. Although precordial ST segment depression has been associated with a poor prognosis, this correlation has not been adequately quantified, partly because of small sample sizes and methodologic limitations in previous studies. Methods. We examined the clinical and angiographic outcomes of 16,521 patients with an acute inferior myocardial infarction who underwent thrombolysis in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) study. Patients were classified into those without precordial ST segment depression (n = 6,422 [38.9%]), those with ST segment depression in leads V-1 to V-3 only (n = 5,850 [35.4%]), those with ST segment depression in leads V-4 to V-6 only (n = 876 [5.3%]) and those with ST segment depression in both leads V-1 to V-3 and leads V-4 to V-6 (n = 3,373 [20,4%]) on initial electrocardiography. Outcome measures included postinfarction complications (second or third-degree heart block, congestive heart failure or shock) and 30 day and 1-year mortality. Results. Patients with precordial ST segment depression had larger infarctions, more postinfarction complications and a higher mortality rate than those without precordial ST segment depression (4.7% vs, 3.2% at 30 days; 5.0% vs. 3.4% at 1 year; both p < 0.001), regardless of whether ST segment depression was noted in leads V-1 to V-6 or in leads V-4 to V-6. The magnitude of precordial ST segment depression (sum of leads V-1 to V-6) added significant independent prognostic information after adjustment for clinical risk factors; the risk of 30-day mortality increased by 36% for every 0.5 mV of precordial ST segment depression. Conclusions. Assessment of the magnitude of precordial ST segment depression is useful for acute risk stratification in patients with an inferior myocardial infarction.