Q wave and non-Q wave myocardial infarction: a multivariate analysis of survival experience and clinical outcome after first diagnosis at a tertiary care hospital.

Introduction: Myocardial infarction (MI) is a well-recognized clinical entity with a worldwide distribution. In the United States alone, 1.5 million cases of MI occur per year. This study compares the in-hospital mortality, 1 year mortality and time to death following a first Q-wave or non Q-wave myocardial infarction (MI).

Methods: One thousand five hundred and ninety-six patients were admitted at the Aga Khan University Hospital with a diagnosis of MI over a period of four years of whom 420 patients met our inclusion criteria. Data was collected from the patients' medical records and on telephone using a pretested questionnaire. Logistic regression and Cox proportional hazard models were used to analyze the data.

Results: The mean age +/- sd of the patients was 59 +/- 10 years. Of the total patients, 151(36%) and 269(64%) suffered non-Q wave and Q-wave MI respectively. A higher in hospital mortality was observed in patients with Q-wave MI (n = 64, 23.8%) than those with non-Q wave MI [n = 16 (10.6%); adjusted OR = 2.76, 95% CI: 1.5-5.01]. Similarly, patients having Q-wave MI experienced increased 1 year mortality (n = 77, 28.6%) compared to patients suffering non-Q wave MI [n = 26 (17.2%); adjusted OR = 2.04, 95% CI: 1.21-3.43].

Conclusion: Patients with Q-wave MI had a worse prognosis compared with patients with non-Q-wave MI and therefore warrant a closer follow up. Further prospective studies are needed to evaluate the efficacy of early aggressive interventions in modifying the natural history of this disease.