Frequency of non-st elevation myocardial infarction in patient with normal electrocardiogram

 Submission: 20 August 2025 | Acceptance: 25 September 2025 | Publication: 30 November 2025

¹Anjli, ²Parshad, ³Dr Pardeep Sainani, ⁴Preeti batheja, ⁵Hafiz Syed Wahaj Azim Fatmi, ⁶Dr Ahsan Ali, ⁷Muhammad Nauman Khan

¹Fcps trainee NICVD

²Fcps trainee LUHMHS Jamshoro

³Senior Registar, Nephrology, Bahria University of Medical Sciences, Karachi Campus

⁴Senior Registar, CTS, Bahria University of Medical Sciences, Karachi Campus

⁵Designation Consultant Cardiologist, HOD ICU, The Kidney Centre

⁶Senior Registrar, Cardiology, Bahria University of Medical Sciences, Karachi Campus

⁷Assistant Professor MBBS, FCPS (CRD), NICVD

Vol: 16/02. 321-238

Received: January 25, 2026 Accepted: March 02, 2026 Published: July 06, 2026

 

Abstract

Background: Non-ST elevation myocardial infarction (NSTEMI) may present without definitive electrocardiographic (ECG) abnormalities, posing a diagnostic challenge in emergency settings. Relying solely on ECG findings risks underdiagnosis of myocardial injury, particularly in patients with typical chest pain but normal ECG results.

Objective: To determine the frequency of NSTEMI in patients presenting with typical chest pain and normal electrocardiographic findings, using cardiac troponin I levels as the diagnostic standard.

Methods: This cross-sectional study was conducted at the National Institute of Cardiovascular Diseases (NICVD), Karachi, over a period of six months. A total of 271 patients aged 18–70 years presenting with chest pain and normal ECG were enrolled using consecutive sampling. Patients with prior myocardial infarction, coronary interventions, or chronic kidney disease were excluded. Blood samples were collected to evaluate troponin I levels. NSTEMI was diagnosed if troponin I exceeded >0.05 ng/dL for males and >0.03 ng/dL for females. Data were analyzed using SPSS version 23, with statistical significance set at p ≤ 0.05.

Results: Among the 271 patients, 168 (62%) were male, and the mean age was 47.8 ± 13.1 years. NSTEMI was diagnosed in 65 patients (24%), despite normal ECG findings. Higher NSTEMI frequencies were observed among diabetics (33%), hypertensives (28.4%), and urban residents (25.1%). The majority of patients with elevated troponin levels had no specific ECG changes at presentation.

Conclusion: A significant proportion of patients with chest pain and normal ECGs were diagnosed with NSTEMI, indicating that ECG alone is insufficient for ruling out myocardial infarction. Routine troponin testing is essential to prevent missed diagnoses and enable timely intervention.

Keywords: Acute Coronary Syndrome, Biomarkers, Chest Pain, Electrocardiography, Myocardial Infarction, NSTEMI, Troponin I