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 s egment depression among patients,vith an acute inferior myocardial inf arction. Background. Although precordial ST segment depression has bee n associated with a poor prognosis, this correlation has not been adeq uately quantified, partly because of small sample sizes and methodolog ic limitations in previous studies. Methods. We examined the clinical and angiographic outcomes of 16,521 patients with an acute inferior my ocardial infarction who underwent thrombolysis in the Global Utilizati on of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) study. Patients were classified into those without precordial ST segme nt 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 depr ession in leads V-4 to V-6 only (n = 876 [5.3%]) and those with ST seg ment depression in both leads V-1 to V-3 and leads V-4 to V-6 (n = 3,3 73 [20,4%]) on initial electrocardiography. Outcome measures included postinfarction complications (second or third-degree heart block, cong estive heart failure or shock) and 30 day and 1-year mortality. Result s. Patients with precordial ST segment depression had larger infarctio ns, more postinfarction complications and a higher mortality rate than those without precordial ST segment depression (4.7% vs, 3.2% at 30 d ays; 5.0% vs. 3.4% at 1 year; both p < 0.001), regardless of whether S T 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 inc reased by 36% for every 0.5 mV of precordial ST segment depression. Co nclusions. Assessment of the magnitude of precordial ST segment depres sion is useful for acute risk stratification in patients with an infer ior myocardial infarction.