Comparative Analysis of Ischemic Changes in Electrocardiography and Coronary Artery Angiography as Gold Standard

Abstract

Background: Ischemic heart disease (IHD) is a leading cause of death worldwide. Coronary angiography (CAG) is the gold standard for diagnosing coronary artery disease, but it is invasive and costly. The electrocardiogram (ECG) is cheap, safe and widely available, yet its diagnostic performance varies across populations. This study evaluated the diagnostic accuracy of ST-T ischemic changes on ECG against CAG and examined vessel-level and sex-specific performance. Methods: This cross-sectional study included 169 adult patients with chest pain who showed ST-T ischemic changes on ECG and underwent CAG within 1 to 3 days at North West General Hospital and Research Centre, Peshawar, Pakistan. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) and diagnostic accuracy were calculated with CAG as the reference standard, overall and for the left anterior descending (LAD), right coronary (RCA), and left circumflex (LCX) arteries. Performance was compared between men and women. Results: The cohort comprised 104 men (61.5%) and 65 women (38.5%) aged 30 to 85 years. Hypertension (72.7%) and diabetes mellitus (40.8%) were the most frequent risk factors. ECG was positive in 75.1% and CAG in 85.2% of patients, with no significant difference by sex or age. Compared with CAG, ECG achieved a sensitivity of 83.3%, specificity of 72.0%, PPV of 94.5%, NPV of 42.8% and accuracy of 81.7%. Vessel-level accuracy was 82.0% for the RCA, 79.1% for the LAD and 76.8% for the LCX. Specificity was higher in men than in women for the RCA (90.9% vs 80.0%, P = 0.010) and LCX (83.3% vs 72.7%, P = 0.036); other metrics did not differ significantly. Conclusion: ST-T ischemic changes on ECG have good sensitivity and a high positive predictive value but only moderate specificity and a low negative predictive value for coronary artery disease. ECG is a useful first-line, non-invasive indicator, but a negative tracing cannot exclude coronary disease, and CAG remains necessary for definitive anatomical assessment.