Determinants and outcomes of coronary angiography after non-ST-segment elevation myocardial infarction. A cohort study of the Myocardial Ischaemia National Audit Project (MINAP)

John S Birkhead ¹, Clive F M Weston ^2* and Ruoling Chen ³

¹ National Institute for Clinical Outcomes Research, United Kingdom
² The School of Medicine, Swansea University, United Kingdom
³ University College London, United Kingdom

^* To whom correspondence should be addressed. E-mail: c.f.m.weston{at}swansea.ac.uk.

Accepted 10 March 2009

Abstract

Objective: To investigate determinants of, and outcomes from, coronary angiography and intervention in patients with non-ST-segment elevation myocardial infarction (nSTEMI).

Design: Observational study.

Setting: 44 British hospitals with interventional facilities.

Patients: 13489 admissions with nSTEMI; July 2005 - December 2006.

Main outcome measures: Rate of angiography during index admission; death and readmission to hospital within 180 days.

Results: Significantly lower rates of angiography were observed for females, the elderly, the most deprived and those having cardiac, and most non-cardiac co-morbidities. Performance of angiography, compared with no angiography, was not associated with lower rate of readmission (multiple adjusted hazard ratio (HR) 0.96, 95% CI 0.74-1.24) unless accompanied by coronary intervention (HR 0.73, 95% CI 0.56-0.95). Angiography was associated with reduction in 180-day mortality for survivors of hospitalization (HR 0.59, 95% CI 0.49-0.72); with greater reduction when followed by an intervention (HR 0.34, 95% CI 0.28-0.42). This mortality benefit following intervention was seen in both females (HR 0.42, 95% CI 0.29-0.6) and males (HR 0.31, 95% CI 0.24-0.41), across age groups; <65 years, (HR 0.25, 95% CI 0.14-0.44), 65 – 79 years, (HR 0.29, 95% CI 0.22-0.39) and 80 or more years, (HR 0.52, 95% CI 0.37-0.74). Mortality benefit was not significantly attenuated by the presence of co-morbidities.

Conclusion: Performance of angiography and coronary intervention following nSTEMI was associated with mortality benefit that persisted in the presence of both cardiac and non-cardiac co-morbidities. Mortality benefit was observed across age groups and was similar for both sexes.