Prognostic significance of precordial ST segment depression on admission electrocardiogram in patients with inferior wall myocardial infarction

Objectives. This study assessed retrospectively the correlation between the pattern of precordial ST segment depression on the admission electrocardiogram (ECG) and hospital mortality in patients with an inferior myocardial infarction treated with intravenous thrombolytic therapy. Background. Previous studies have shown that in acute inferior myocardial infarction, ST segment depression in the precordial leads is associated with increased hospital mortality. However, the significance of the different patterns of precordial ST segment depression has been evaluated in only two previous studies. Methods. The study included 1,321 patients (1,020 men) who enrolled in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) thai in israel and received intravenous thrombolytic therapy. Patients with an ST segment elevation ≤0.1 mV in at least two of the inferior leads were included. Patients were classified into four groups on the basis of their admission ECG: group I = patients with no precordial ST segment depression (n = 346); group II = those for whom the sum of ST segment depression in leads V₁ to V₃ was greater than that in leads V₄ to V₆ (n = 700); group III = those for whom the sum of ST depression in leads V₁ to V₃ was equal to that in leads V₄ to V₆ (n = 162); group IV = those with maximal ST depression in leads V₄ to V₆ (n = 113). Results. The overall hospital mortality rate was 3.6% (48 patients): for groups I, II, III and IV it was 2.9%, 2.8%, 4.3% and 9.7%, respectively. Multivariable logistic regression analysis confirmed that hospital mortality was independently associated with the pattern of precordial ST segment depression. The odd ratios in group IV relative to group I was 2.78 (95% confidence interval 1.26 to 6.13, p = 0.007). Conclusions. The risk of mortality is higher in patients with an inferior myocardial infarction and maximal ST segment depression in precordial leads V₄ to V₆ versus precordial leads V₁ to V₃ on the admission ECG.