Ischemic and viable myocardium in patients with Non-Q-Wave or Q-Wave myocardial infarction and left ventricular dysfunction: A clinical study using positron emission tomography, echocardiography, and electrocardiography

OBJECTIVES: We investigated whether patients with non-Q-wave myocardial infarction (NQMI) have more ischemic viable myocardium (IVM) than patients with Q-wave myocardial infarction (QMI). BACKGROUND: Non-Q-wave myocardial infarction is associated with higher incidences of cardiac events than QMI, suggesting more myocardium at risk in NQMI. METHODS: To identify myocardial ischemia, hibernation, and scar, the resting and stress ⁸²rubidium perfusion and F-18 fluorodeoxyglucose metabolic positron emission tomographic imaging (PET) was performed in 64 consecutive patients with NQMI (n = 21) or QMI (n = 43). Echocardiography was performed for assessment of left ventricular function and wall motion index (WMI). The relationships between PET, echocardiographic, and electrocardiographic findings were analyzed. RESULTS: There were no significant differences in left ventricular ejection fraction (LVEF) between NQMI and QMI groups (28 ± 10% vs. 25 ± 11%, p > 0.05). Ischemic and viable myocardium was more common in NQMI than in QMI (91% vs. 61%, p < 0.05). The total amount of IVM was significantly higher in NQMI than in QMI (6.5 ± 5.2 vs. 2.9 ± 2.8 segments, p < 0.001). Neither the number of Q waves, residual ST-segment depression of ≥0.5 mm or elevation of ≥1 mm, nor LVEF and WMI were significant predictors for IVM. Wall motion index correlated with scar segments (r = 0.54, p < 0.001) and LVEF (r = -0.67, p < 0.001). CONCLUSIONS: Ischemic and viable myocardium is common in patients with NQMI and left ventricular dysfunction, suggesting that aggressive approaches should be taken to salvage the myocardium at risk in such patients.