What is the Optimal Rate of Invasive Coronary Angiography After Acute Coronary Syndrome? - An ANZACS-QI Substudy

Abstract

Background: Wide variability in the use of invasive coronary angiography in acute coronary syndromes (ACS) has been previously documented. Our aim was to investigate whether coronary angiography is being used appropriately after ACS, taking into account relative contraindications of the procedure. Method: Patients presenting with ACS in 2015 to two New Zealand (NZ) District Health Boards (DHBs) – Counties Manukau (CMDHB) and Waitemata (WDHB) - were identified from the NZ Ministry of Health National Dataset using ICD-10-AM codes. Patient data were obtained from the electronic and paper clinical records. Pre-defined relative contraindications to coronary angiography were identified. Results: Of the 3,809 patient admissions coded with ACS, 600 (300 from each DHB) were reviewed. 61 (10%) did not meet diagnostic criteria for ACS on review of clinical data and were excluded. Of the patients reviewed, 55% received coronary angiography, with a higher rate in WDHB than CMDHB (61% and 49%, respectively). The overall rate of angiography was appropriately high in those without a relative contraindication (90.3%) and low in those with one (7.4%). There were fewer patients with relative contraindications in WDHB than CMDHB (36.7% and 48.5%) but the rate of angiography in those without (92.5% and 87.5%) contraindications in the two DHBs was similar. Conclusion: Approximately 60% of patients had no documented relative contraindication suggesting that this may be an appropriate angiography rate in New Zealand practice. Differences between the two DHBs of around 10% appear to be clinically appropriate due to variation in contraindication rates.