Acute coronary syndrome (ACS) is a term that is used to describe sudden and life-threatening conditions that result in reduced blood flow to the heart. This term includes acute myocardial infarction (or heart attacks) and unstable angina.

How common is acute coronary syndrome?

In 2020, there were an estimated 56,700 acute coronary events among people aged 25 and over – equivalent to around 155 events every day. Around 12% of these events (6,900 cases) were fatal (AIHW 2023). The age-standardised rate of acute coronary events fell by more than half (59%) between 2001 and 2020. The decline in rates of acute coronary events has been attributed to a number of factors, including improvements in medical and surgical treatment, and reductions in risk factor levels (AIHW 2023).

Heightened risk of secondary acute coronary syndrome events

People who have been admitted to hospital for ACS are at an increased risk of having another cardiovascular event in the future. Medication use, lifestyle changes such as quitting smoking, and cardiac rehabilitation can reduce the risk of subsequent events. Research from Western Australia reported nearly half of coronary heart disease events (which includes acute coronary syndromes) from 1995 to 2005 occurred in the 6% of the general population (aged 35 to 84) with a history of the disease (Briffa et al. 2011).  

Effective secondary prevention is important to reduce national incidence of ACS events. The need for improvements in the transition from hospital care into the community, and support services for those people with heart disease after discharge, are key actions outlined in the National Strategic Action Plan for Heart Disease and Stroke (Department of Health 2020).  

Medications for secondary prevention

The Australian Clinical Guidelines for the management of Acute Coronary Syndromes (Chew et al. 2016) recommend that people who survive an ACS event be prescribed a multidrug regime, which includes 4 classes of medicines - a statin, beta blocker, angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) and antithrombotic agents. Despite strong evidence that this substantially reduces the risk of future cardiovascular events, not all patients are prescribed these drugs and, among those who are, not all continue to take them over the long-term (Naderi et al. 2012; Packard and Hillman 2016; AIHW 2022). Some people may be unable to, or choose not to, follow the advice of their doctor. For others, the decision to not start or continue these medications may be done in consultation with a medical professional due to adverse side effects, contraindications, a new therapeutic approach, or other clinical reasons. 

What does this project add?

This project provides real-world evidence on the treatment pathways utilised by those who survived an ACS hospitalisation, including interventional procedures and medication use in the year post-hospital discharge. In addition, it examines health outcomes, demographic and clinical characteristics among those who followed different treatment pathways. However, it is important to note that interventional procedures and patterns of medication use are only a component of secondary prevention. Many factors, including some not captured in the analysis, impact both treatment decisions and the risk of experiencing poor health outcomes. For example, poor prognosis due to age-related frailty or multimorbidity may drive the decision to not perform interventional procedures while also contributing to poorer health outcomes (Nedkoff et al. 2023). 

The AIHW published a detailed analysis of the factors that are associated with patterns of medication use by coronary heart disease (CHD) and ACS patients discharged from hospital, in the report: Medication use for secondary prevention after coronary heart disease hospitalisations: patient pathways using linked data (AIHW, 2022). This 2022 report used multivariate logistic regression analysis to investigate the relationships between measures of medication used and factors including demographic and clinical characteristics, and use of community-based health care.

In comparison, this project presents descriptive unadjusted data to explore patient journeys. The cohort used for this project is slightly different and has a longer follow-up period due to the analysis being undertaken in a newer version of the National Integrated Health Services Information (NIHSI) data.