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%).
