Risk factors, hospital management and outcomes after acute myocardial infarction in South Asian Canadians and matched control subjects

Abstract

Background: Coronary artery disease affects a significantly larger proportion of Canadians of South Asian origin than Canadians of other ethnic origins. We compared differences in presentation, risk factors and management of myocardial infarction (MI) between South Asian Canadians and matched control subjects.

Methods: We reviewed the charts of 553 South Asian patients and 553 non-South Asian matched control subjects presenting with acute MI (International Classification of Diseases code 410) to 2 hospitals in Canada from January 1994 to April 1999. We identified South Asian subjects by their surnames and first names, and by using self-reported ethnicity and country of birth when available. Patients of Southeast Asian and Middle Eastern origin were excluded. The remaining patients were classified as non-South Asian. Subjects were matched by age within 5 years, sex, discharge date within 6 months and hospital of admission. Presentation characteristics, risk factors and major complications were compared between the 2 groups.

Results: The median time from symptom onset to presentation with acute MI was significantly longer among the South Asian subjects than among the control subjects (3.92 v. 3.08 hours) (p = 0.04). The South Asians were more likely than the control subjects to have diabetes mellitus (43.4% v. 28.2%) (p < 0.001) despite having a significantly lower mean body mass index (25.7 v. 28.0) (p = 0.05) but were less likely to have hyperlipidemia (36.2% v. 42.7%, p = 0.05), to smoke (29.3% v. 67.8%) (p < 0.001) or to have pre-existing vascular disease (49.4% v. 55.0%, p = 0.04). Treatment of acute MI was similar between the South Asian and matched control groups. Also similar were the in-hospital outcomes, including mortality (9.6% and 7.8%, p = 0.27).

Interpretation: There are clear differences in the risk factor profile between Canadians of South Asian origin and those of non-South Asian origin who have acute MI. Despite the higher incidence of cardiovascular disease in the South Asian population, our results indicate that the in-hospital case-fatality rate for MI is the same for South Asian and non-South Asian Canadians.