Q wave and non-Q wave myocardial infarction after thrombolysis

Objectives. We studied the clinical outcome of Q wave and non-Q wave infarction after thrombolytic therapy. Background. Controversy exists over the clinical significance of Q waves after thrombolysis. Methods. We studied postthrombolytic angiographic results and short- and long-term clinical outcome in 150 patients with acute myocardial infarction classified as Q wave and non-Q wave on the 24-h and discharge electrocardiograms (ECGs). The results from the two groups were then compared. Results. Eighty percent of patients had Q wave and 20% non-Q wave infarction on the 24-h ECG. The latter patients had lower peak creatine kinase (CK) levels (p < 0.001), but the two groups did not differ significantly otherwise. In 18 patients with Q wave infarction on the 24-h ECG, pathologic Q waves disappeared. However, in seven patients with non-Q wave infarction on the 24-h ECG, pathologic Q waves appeared throughout the hospital period. Q wave regression was associated with lower peak CK levels (p < 0.001) and an improvement in left ventricular ejection fraction (p < 0.01). Thus, only 72% of patients had Q wave and 28% non-Q wave infarction on the discharge ECG. Patients with non-Q wave infarction on the discharge ECG had higher patency of the infarct-related artery (p < 0.04), lower mean peak CK levels (p < 0.0001), higher ejection fraction (p = 0.001) and lower incidence of heart failure (p = 0.06) than patients with Q wave infarction on the discharge ECG. Although the 2-year incidence of reinfarction and revascularization was higher in patients with non-Q wave infarction on the discharge ECG (p < 0.05), 2-year mortality was lower (p = 0.08). Conclusions. Although the early postthrombolytic distinction between Q wave and non-Q wave infarction conveys no significant information, during the hospital period, non-Q wave infarction is associated with smaller infarct area, improved left ventricular function and lower mortality.