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

Abstract

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. (C) 2000 The European Society of Cardiology.