Quantitative ECG changes and patency of infarct-related arteries after intravenous streptokinase

Thirty-three patients with acute inferior myocardial infarction (MI), who were treated with intravenous streptokinase, were studied by serial 12-lead ECGs for 48 hours to determine the relationship between early changes in the sum of elevations above the baseline 40 ms after the end of the QRS complex in leads II, III and AFV (SumST), the sum of amplitude of R waves in leads II, III and AVF, the sum of the Q waves in leads II, III and AVF, the sum of ST-segment depression in leads V1-V4 as measured from the baseline to 80 ms after the J point (SumST (V1-V4] and the patency of the infarct-related artery at angiography after MI. Patients with patent arteries had a faster rate of decline in the SumST during the first 2.5 hours; reached the steady state earlier; had a more pronounced decrease in the SumST at 1.25 hours; a larger percentage drop in SumR at 4.5 hours and a more pronounced SumST (V1-V4) early on but resolution times similar to that of patients with closed arteries. Several ECG indices may indicate reperfusion of the infarct-related artery in patients with inferior MI.