Clinical and Angiographic Profile of STEMIEquivalent Electrocardiographic Patterns in Acute Coronary Syndrome: A Prospective Observational Study

Introduction: Prompt diagnosis of acute coronary occlusion plays an important role in lowering deaths in patients suffering from Acute Coronary Syndrome (ACS). Although ST-Elevation Myocardial Infarction (STEMI) forms the basis of reperfusion therapy, there are many high-risk non ST-segment elevation electrocardiographic presentations of ACS known as STEMI equivalents, which represent acute coronary occlusion but are frequently under-recognised. Aim: To determine the incidence of STEMI-equivalent presentations among ACS patients, describe their clinical and angiographic characteristics, and compare in-hospital outcomes based on reperfusion strategy. Materials and Methods: The present prospective observational study was conducted in the Emergency Department of a tertiary care teaching hospital, Datta Meghe Institute of Higher Education and Research, in Wardha, Maharashtra, India, over 24 months from August 2022 to August 2024, involving 120 patients diagnosed with ACS. Baseline demographics, including age, gender, Body Mass Index (BMI), and cardiovascular risk factors such as hypertension, diabetes mellitus, and thyroid disorders, were recorded. The clinical presentation, Electrocardiogram (ECG) findings, biochemical parameters, echo parameters, angiographic findings, reperfusion strategy, and clinical outcome were also recorded. Subjects were divided into a classical STEMI group and STEMI-equivalent groups, and comparisons were made among them and among groups based on reperfusion strategy. Continuous variables are represented as mean±Standard Deviation (SD) and were analysed using unpaired Student’s t-test, while categorical variables were represented as frequency (%) and analysed using Chi-square or Fisher’s exact test. A p-value of <0.05 was accepted as significant. Results: Among 51 STEMI-equivalent patients, males constituted 33 (64.7%). The most common patterns were left bundle branch block (20, 39.2%) and Wellens’ syndrome (19, 37.3%). Among STEMI-equivalent patients, the prevalence of multivessel coronary artery disease was 47.1% (24/51), compared with 30.4% (21/69) in classical STEMI patients. Similarly, reduced left ventricular ejection fraction (<50%) occurred in 54.9% (28/51) of STEMI-equivalent patients, compared with 43.5% (30/69) in classical STEMI patients. In-hospital mortality was highest in the de winter pattern (3/6, 50%) and aVR ST elevation (1/3, 33.3%); however, these estimates were based on small subgroup sizes. Survival was significantly higher in patients undergoing primary Percutaneous Coronary Intervention (PCI) than in those receiving thrombolysis (94% vs 78.1%, p=0.042). Conclusion: A significant proportion of ACS has STEMIequivalent patterns and is associated with poor outcomes. Prompt diagnosis and early primary PCI dramatically improve survival.