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.