Background Acute coronary syndrome (ACS) is a major cause of emergency department visits and is associated with significant morbidity and mortality. Early diagnosis is crucial for timely intervention, but conventional diagnostic methods often have limitations. High-sensitivity troponin (hs-Tn) has emerged as a valuable biomarker for detecting myocardial injury, allowing for faster and more accurate diagnosis of ACS.This study aimed to evaluate the utility of hs-Tn in the early diagnosis of ACS among patients presenting to the emergency department with chest pain. The study assessed the effectiveness of initial and serial hs-Tn measurements in differentiating ACS from non-ACS conditions. Methods This prospective observational study was conducted at Jinnah Medical College, Peshawar, from January 2023 to January 2024. A total of 93 patients with suspected ACS were enrolled and classified into two groups: ACS (47 patients) and non-ACS (46 patients). Clinical history, electrocardiogram (ECG) findings, and hs-Tn levels were recorded at presentation and after serial measurement within 1 to 3 hours. ‘Statistical analysis was performed to compare hs-Tn levels between the two groups and assess their diagnostic value’. Results ‘Hs-Tn levels were significantly higher in ACS patients compared to non-ACS cases at both presentation (85.6 ± 34.2 ng/L vs. 12.8 ± 6.4 ng/L, p<0.001) and after serial measurement (120.4 ± 45.7 ng/L vs. 14.6 ± 7.1 ng/L, p<0.001)’. The delta change in hs-Tn was also significantly greater in ACS patients (p<0.001), confirming its role in improving diagnostic accuracy. ECG abnormalities were more common in ACS cases (p=0.003), but hs-Tn remained the strongest predictor of ACS. Patients with higher hs-Tn levels had a greater need for hospitalization, coronary interventions, and a higher incidence of major adverse cardiac events (p=0.015). Conclusion Hs-Tn is a highly effective biomarker for the early detection of ACS in emergency department patients presenting with chest pain. Serial hs-Tn measurements further enhance diagnostic accuracy by detecting dynamic changes in troponin levels. Integrating hs-Tn testing with clinical and ECG findings can improve early diagnosis, facilitate timely treatment, and reduce the risk of complications.