Electrocardiographic ST-T wave patterns, extent of coronary artery disease, and left ventricular performance following non-Q-wave myocardial infarction.

Subendocardial, nontransmural, or non-Q-wave myocardial infarction (NQM) carries a serious prognosis. Many previous studies of NQMI include only patients without new Q waves at the time of infarction. Since the site of transmural MI (by Q waves) has implications concerning extent of coronary disease (CAD) and left ventricular (LV) dysfunction, we wondered what the extent of CAD and LV dysfunction is among acute MI patients who have neither new nor old Q waves. Furthermore, we sought to determine whether ST-T wave patterns or resting LV ejection fraction (EF), alone or combined, could separate NQMI patients with significant CAD from those with normal or nearly normal coronaries. Therefore, we retrospectively examined angiographic and electrocardiographic data in 55 symptomatic patients with NQMI. ST-T wave patterns on admission were classified as either ischemic (transient ST elevation, persistent horizontal ST depression, or persistent deep T wave inversion) or nonspecific. Eleven patients (20%) had normal or nearly normal coronaries (N); ten patients (18%) had one, seven patients (13%) had two, and 19 patients (34%) had three vessel CAD; eight patients (15%) had left main (LM) disease. Six of the 11 N patients had ergonovine tests and all six were negative. Segmental LV wall motion abnormalities (WMA) were commonly observed; however, diffuse LVWMA were present only among patients with three vessel and LM disease. EF was below 0.50 in 48% of patients with three vessel or LM disease. Although ischemic ST-T wave patterns were more common (P less than 0.05) among patients with significant CAD than among N patients, neither the ST-T wave pattern nor EF, alone or in combination, allowed confident separation of N patients from significant CAD patients. We conclude 1) A large proportion of NQMI patients have LM disease, three vessel disease, or normal or nearly normal coronaries. 2) Despite the absence of Q waves, LV dysfunction is common and the degree of LV impairment is worse among patients with more extensive CAD. 3) NQMI patients who may have normal or nearly normal coronaries cannot be reliably separated from NQMI patients with significant CAD on the basis of ST-T wave patterns or resting LVEF. 4) Coronary angiography appears warranted to assess the extent of CAD in symptomatic NQMI patients.

High-dose, brief intravenous streptokinase early in acute myocardial infarction.

An acute thrombus at the proximal border of a high-grade atherosclerotic obstruction is the usual cause of myocardial infarction. Although intracoronary thrombolysis is potentially an exciting new therapy for reducing the extent of myocardial infarction by lysing coronary clot, a number of major difficulties limit its widespread application. It is a complex procedure requiring intracoronary visualization and infusion within a few hours of onset of symptoms. Since intravenous streptokinase could be widely applied if effective, we and others have wondered whether high-dose, brief-duration intravenous streptokinase infusion given early in myocardial infarction would lyse coronary clots without bleeding. To date we have treated 13 patients within 6 hours of onset of symptoms and with ECG and angiographic evidence of typical myocardial infarction caused by coronary clot. Clot lysis and angiographically proved coronary reperfusion were achieved in 6 patients within 1 hour of starting a systemic intravenous infusion of 850,000 IU of streptokinase. Schroeder et al., in Berlin, West Germany, achieved angiographically proved coronary reperfusion in 11 of 21 patients with acute myocardial infarction following a 30-minute intravenous streptokinase infusion of 500,000 IU. Neuhaus et al., in Göttinen, West Germany, achieved angiographically proved coronary reperfusion in 24 of 39 similar patients within 48 minutes by intravenous infusion of 1,700,000 IU of streptokinase. In these three studies, no serious bleeding occured; left ventricular function was improved in patients who achieved coronary reperfusion. We conclude that rapid intracoronary clot lysis and coronary reperfusion can be achieved early in myocardial infarction by brief-duration systemic intravenous infusion of high-dose streptokinase without a high incidence of serious bleeding.