The incidence and outcomes of high-risk acute coronary syndromes in the Western Cape Province of South Africa: a prospective cohort study.

Tygerberg Hospital (TBH) is a tertiary level hospital in the Western Cape of South Africa that serves a large, low to middle income population with centralised advanced cardiac care. Acute coronary syndrome (ACS) remains an important cause of death in the region, despite a high burden of communicable diseases, including people living with human immunodeficiency virus (PLHIV).   Objectives. We sought to describe the incidence of ST elevation myocardial infarction (STEMI) and high-risk non-ST elevation ACS (HR-NSTEACS) in the TBH referral network, describe the in-hospital and 30-day mortality of these patients and identify important high-risk population characteristics.  Methods. The Tygerberg Acute Coronary Syndrome Registry (TRACS) database is an ongoing prospective study that enrols all STEMI and HR-NSTEACS patients in the TBH referral network. All patients older than 18 years presenting with STEMI or HR-NSTEACS were treated in accordance with current European Society of Cardiology (ESC) guidelines and were included prospectively over a 9-month surveillance period. A waiver of consent was granted to include patients who demised prior to giving informed consent. Collected data included a demographic profile, risk factors for cardiovascular disease, in hospital therapy and 30-day mortality.  Results. A total of 586 patients were enrolled, with a male predominance (64.5%) and incidence rates of STEMI and HR-NSTEACS of 14.7/100 000 and 15.6/100 000 respectively.  The mean patient age was 58.1 years and STEMI patients tended to be younger than HR-NSTEACS patients (56yrs vs.58yrs; p=0.01). Cardiovascular risk factors were prevalent overall, but hypertension (79.8%vs.68.3%; p<0.01), and pre-existing coronary artery disease (29%vs.7%; p=0.03) were more prevalent in the HR-NSTEACS group.  HIV was present in 12.6% of patients tested, similar to the background population rate. The overall 30-day all-cause mortality was 6.1% with an in-hospital mortality rate of 3.9%. The 30-day mortality rates were similar for STEMI (6.7%) and HR-NSTEACS (5.7%; p=0.83).  PLHIV did not impact mortality.   Conclusions. The use of a guideline-based approach to treating ACS in a low-middle income countries (LMIC) setting yields mortality rates comparable to high income countries. However, the lower-than-expected incidence rates of both STEMI and NSTEACS in a relatively young population with a high prevalence of traditional cardiovascular risk factors, and relatively high proportion of STEMI, suggests potential under recording of ischemic heart disease (IHD) in the region.  The rate and outcomes of coronary artery disease (CAD) in PLHIV was similar to people without HIV, suggesting that traditional risk factors still drive CAD outcomes in the region.