Impact of European Society of Cardiology/American College of Cardiology guidelines on diagnostic classification of patients with suspected acute coronary syndromes

Abstract

Background: Assessment of the relative diagnostic accuracy of investigation strategies for patients with suspected acute coronary syndromes (ACS). Methods: A prospective observational study followed two groups of patients over a 3-month period in a UK district general hospital. Group one: all admissions with suspected ACS (n=576); group two: non-cardiac in-patients who were suspected of developing ACS (n=87). Both were investigated by full clinical history, examination and serial electrocardiographs (ECGs). Conventional World Health Organization (WHO) criteria for myocardial damage were compared with diagnosis based on cardiac troponin T (cTnT). Clinical discharge diagnosis based on conventional WHO criteria was compared with the review diagnosis based on measurement of cTnT. Results: Diagnosis based on WHO criteria missed 58 patients (8.7%) admitted with suspected ACS who had high risk unstable angina. Thirty-three patients (5% of all admissions) who were diagnosed as non-Q wave acute myocardial infarction (AMI) were found to have normal troponin values and to have been incorrectly classified as AMI. Conclusions: Diagnostic strategies based on WHO criteria are inaccurate. The measurement of cTnT in all patients with suspected ACS would have increased the number of those with a diagnosis of AMI by 58 (8.7%), while avoiding inaccurate diagnosis in 33 (5%), therefore producing an absolute increase of 25/663 (3.8%) but a relative increase of 58/138 (42%). In patients with a primary diagnosis of suspected ACS, the overall increase in patients with a diagnosis of AMI will be 55 (9.5%), a relative increase of 55/118 (46.6%) but an absolute increase of 36/576 (6-3%).