Absence of Q waves after thrombolysis predicts more rapid improvement of regional left ventricular dysfunction.

Although the natural history of regional left ventricular (LV) dysfunction after Q-wave and non-Q-wave myocardial infarction (MI) was well defined in the prethrombolytic era, the functional and structural implications of the absence of Q waves after thrombolysis are less clear. Echocardiography was performed within 48 hours of admission (entry) in 86 patients treated with thrombolysis for their first MI. The extent of abnormal wall motion (AWM; square centimeters) and LV endocardial surface area index (ESA; square centimeters per square meters) were quantified by using a previously validated echocardiographic endocardial surface-mapping technique. Electrocardiography (ECG) performed at 48 hours after thrombolysis was used to classify patients into groups with (Q; n=70) and without (non-Q; n=16) Q waves. All patients in the Q group had regional LV dysfunction on initial echocardiogram compared with 69 percent of those in the non-Q group (p<0.001). When the patients in the non-Q group without AWM were excluded from analysis, there was no significant difference in the extent of AWM between the Q and non-Q groups. Among those patients with AWM on entry, follow-up echocardiography at 6 to 12 weeks demonstrated a significant reduction in extent of AWM for both the Q and non-Q groups. However, the fractional change in AWM was significantly greater in the non-Q than in the Q group (-0.74 +/- 0.28 vs -0.29 +/- 0.44; p<0.02), with a trend toward less AWM at follow-up in the non-Q than in the Q group. The mean ESAi was not significantly different between the two groups at entry or at follow-up. In conclusion, failure to develop Q waves after thrombolysis predicts a lower likelihood of developing regional LV dysfunction and, when such dysfunction is present, predicts a greater degree of recovery.