A030 False-positive Diagnosis in Suspected Acute Coronary Syndrome - an ANZACS-QI Study

Abstract

Incidence and mortality of acute coronary syndrome (ACS) have declined, in part due to an increase in the rate of percutaneous coronary intervention (PCI). However, many conditions can mimic ACS presentations. With a rise in PCI availability, there is potential for inappropriate and unnecessary procedural risks. We aim to assess the rate of false-positive ACS diagnosis in patients presenting with suspected ACS in NZ. Consecutive patients ≥18y presenting with their first suspected ACS and underwent coronary angiography in 2015-2019 were identified from the ANZACS-QI registry. Two cohorts were compared: 1) suspected STEMI and 2) suspected NSTEACS. Patient demographics, investigations and discharge diagnosis were obtained from the registry. 30,317 patients were identified. Of 6059 (20%) suspected STEMI, 90.6% were correctly diagnosed, 3.4% diagnosed with NSTEACS and 5.9% of non-ACS condition, resulting in a false-positive rate of 9.4%. Of the 24258 (80%) suspected NSTEACS, 80.7% were correctly diagnosed, 19.2% were non-ACS. Patients who are younger, of female gender and of non-European ethnicity were more likely to have a non-ACS diagnosis. Patients with confirmed NSTEACS tend to have more established cardiovascular comorbidities. Rate of stress test/CTCA usage in suspected STEMI is <5%. In suspected NSTEACS, stress test was 8%, CTCA 5.5%. Overall “false-positive” rate of ACS diagnosis is 17%. This is comparable with international figures for STEMI. In contrast, in NSTEACS it is less well studied and despite higher false-positive diagnostic rates, our non-invasive test usage rate is relatively low. Furthermore, the higher rate of non-ACS diagnosis in female, non-Europeans should prompt further exploration.