New Q waves on the presenting electrocardiogram independently predict increased cardiac mortality following a first ST-elevation myocardial infarction.

AIMS

The prognostic significance of pathological Q waves appearing in the acute phase of myocardial infarction has not been determined. We investigated whether new Q waves on the presenting electrocardiogram of patients with acute ST-segment elevation were independently associated with a worse outcome after a first myocardial infarction.

METHODS AND RESULTS

The presence or absence of new Q waves on the presenting electrocardiogram was assessed in 481 patients who presented within 4 h of symptom onset and were randomized to receive either captopril or placebo within 2 h of streptokinase therapy for myocardial infarction. Ventriculography was performed at 22+/-6 days and mortality status was obtained at a median follow-up of 5.6 years. New Q waves were associated with a lower ejection fraction (51+/-13% vs 61+/-12%, P<0.0001), a larger end-systolic volume index (37 ml vs 28 ml, P<0.001), and increased cardiac mortality at 30 days (7% vs 2%, P=0.01) and at follow-up (17% vs 7%, P=0.002). On multivariate analysis, age (P<0.01), new Q waves at presentation (P<0.01) and a history of angina (P=0.046) were independent predictors of cardiac mortality, whereas randomization to captopril and the time from symptom onset to streptokinase administration were not.

CONCLUSION

New Q waves at presentation are independently associated with a worse outcome after a first myocardial infarction. The presence of new Q waves on the presenting electrocardiogram allows very early identification of patients at risk of increased cardiac mortality.