[Assessment of the first myocardial infarctions with lead ECG --implications in the study of hospital mortality and its reduction using thrombolytic drugs].
STUDY OBJECTIVE: Correlation between mortality reduction of first Myocardial Infarction (MI) by thrombolytic therapy and MI size evaluated with the classical Electrocardiogram (ECG). DESIGN: A retrospective sequential study. SETTING: Coronary Unit patients. PATIENTS: Sequential sample of 132 patients with first MI obeying all the following criteria: 1) no previous MI; 2) age less than or equal to 70 years; 3) clinical evolution less than 12 hours; 4) no Left Bundle Branch Block in the CCU first ECG; 5) ischemic ST elevation in greater than or equal to 1 initial ECG leads. Patients were divided into Group A, with less than or equal to 3 initial ECG leads with ischemic ST elevation (n = 80), and Group B, with greater than or equal to 4 initial ECG leads with ischemic ST elevation (n = 52). Only 34 patients (25.7%) did thrombolytic therapy with IV Streptokinase (SK); 15 from Group A and 19 from Group B. MEASUREMENTS AND MAIN RESULTS: 17 patients died in MI acute phase (12.8%); 4 in Group A (5%) and 13 in Group B (24.9%). Inhospital mortality was statistically worst in Group B than in Group A (24.9% vs 5% with p less than 0.01). Creatin kinase (CK) maximal values (A = 911.5 UI; B = 1444.6 UI with p less than 0.01) and initial Heart Rate (A = 75.7; B = 86.7 with p less than 0.001) were also statistically greatest in Group B. Inhospital mortality was smaller in patients treated with SK (8.8% vs 14.3%), as in Group B (10.5% vs. 33.3%), both without statistical significance. CONCLUSIONS: Inhospital mortality and thrombolytic therapy benefit were so bigger as MI size evaluated by the number of initial ECG leads with ischemic ST elevation, by initial HR and maximal values of CK. Classical ECG can be useful by identifying patients with first MI that can more benefit with thrombolytic therapy (greater than or equal to 4 leads with ischemic ST elevation).