Chest pain is a common presenting complaint to the emergency department (ED), representing around 10% of ED visits [1]. With an extensive differential diagnosis, identification of life-threatening causes such as acute coronary syndrome (ACS) may be challenging and poses significant pressure on resources in the emergency and medical departments. Therefore, scoring systems were developed to assist in the risk stratification of patients with chest pain and suspected ACS in the ED, facilitating safe discharges and effective use of inpatient resources. One of the most utilized scores is the HEART (History, Electrocardiogram [ECG], Age, Risk factors and Troponin) score, which is recommended by the 2021 American Heart Association (AHA) guidelines [2]. The HEART score risk stratifies patients aged >21 years with acute chest pain and no ST elevation on ECG into low, moderate and high-risk groups. Patients with low risk may be safe for ED discharge without additional cardiac evaluation or inpatient admission [[3], [4], [5]].

However, the HEART score is not foolproof, and around 1.0–2.5% of low-risk patients proceed to develop acute myocardial infarction (MI), require revascularization or die within 4 to 6 weeks of the ED evaluation [[4], [5], [6], [7]]. Factors traditionally associated with increased risk of ACS not considered in the HEART score may further identify patients at risk of ACS within the low HEART score subgroup. For example, males are 2–3 times more likely to experience acute MI than females, even after adjusting for comorbidities and age [8]. The risk of cardiovascular diseases may also be higher in South Asian and Black individuals than in Caucasians [9], suggesting possible ethnic or geographical variations. While only a small proportion of ACS is missed in patients with low-risk HEART scores, the clinical consequences may be grave, thus it is important to identify characteristics that predict ACS in low risk groups.

In this study, we aim to characterize the risk factors for major adverse cardiovascular events (MACE) in patients with low HEART score. This may assist clinicians in detecting cases that require further cardiac monitoring and investigation, and reduce the risk of missed cardiac events in the ED.