Abstract
Background
Acute coronary syndrome (ACS) is a common manifestation of cardiovascular disease. Inconsistent trends have been reported in the management and outcomes of the three main categories of ACS (ST-elevation myocardial infarction [STEMI], non ST-elevation myocardial infarction [NSTEMI] and unstable angina [UA]). The aims of this study were to evaluate recent trends in the incidence, invasive management and case fatality of these ACS subtypes in New Zealand.
Methods
All ACS hospitalisations between 2006–2016 were identified from routinely collected national data, and categorised into STEMI, NSTEMI, UA, and unspecified myocardial infarction (MI). For each ACS subtype, annual hospitalisation and coronary procedure rates, 28-day and 1-year fatality rates were calculated and trends tested using Poisson regression adjusted for age and sex.
Results
There were 188,264 ACS admissions, of which 16.0% were STEMI, 54.5% NSTEMI, 25.7% UA and 3.8% MI unspecified. During this period, the incidence of all ACS subtypes fell, STEMI by 3.4%/y, NSTEMI by 5.9%/year and UA by 8.5%/year. There was also a rise in the proportion of ACS patients receiving angiography and revascularisation. Rates of percutaneous coronary intervention rose for STEMI, NSTEMI and UA, but rates of coronary artery bypass grafting increased only for NSTEMI and UA. Case fatality at 28 days and 1 year was higher for STEMI than NSTEMI, and lowest for UA. Over the period there was a relative 1.6%/y decline in one-year case fatality for NSTEMI (p<0.001), but no significant change for STEMI and UA.
Conclusions
The observed declines in the incidence of all ACS subtypes is reassuring, as is the increase in the rate of revascularisation among these patients. The finding that case fatality declined in NSTEMI patients but not in STEMI and UA patients, despite an increase in invasive management in all groups, require further investigation.