The association between cardiac risk factors and the probability of acute myocardial infarction in the emergency department: analysis from a multicentre prospective observational study in the high sensitivity troponin era

Background and objective Hypertension, hyperlipidaemia, diabetes mellitus, smoking and family history are established risk factors for coronary artery disease. This study sought to determine the diagnostic value these factors have in patients presenting to an emergency department (ED) with suspected acute myocardial infarction (AMI). Design, settings and analysis This secondary analysis of a prospective diagnostic test accuracy study took place across 14 hospitals in England. A total of 1273 patients, presenting with suspected cardiac chest pain, were included for analysis - 179 (14.1%) had an adjudicated diagnosis of AMI. Outcome measure and analysis AMI diagnosis was adjudicated with serial troponin testing conducted on arrival and 3-12 hours later. The presence of any risk factors was documented at the time of initial presentation. Results The post-test probability of AMI in the absence of risk factors (9.7%) shifts to only 23.5% when 4-5 factors are present. Associations of risk factors with AMI diagnosis were found as follows; hypertension [odds ratio (OR) 1.47, confidence interval (CI) 1.07-2.02], hyperlipidaemia (OR 1.57, CI 1.14-2.16), diabetes mellitus (OR 1.51, CI 1.04-2.20), smoking (OR 1.51, CI 1.05-2.17) and family history (OR 0.98, CI 0.71-1.37). The area under the receiver operating characteristic curve was 0.58. Conclusion Traditional cardiac risk factors have limited association with AMI in the ED, but an increasing risk factor burden is associated with increasing prevalence of AMI. These findings suggest that future work to refine existing decision aids used in this patient group may be of value.