Association Between the Lead I Electrocardiographic Sign and Chronic Obstructive Pulmonary Disease: A Case Control Study

Background Chronic Obstructive Pulmonary Disease (COPD) affects millions worldwide, yet early diagnosis remains challenging due to limited availability of pulmonary function testing. The Lead I sign on electrocardiogram has been anecdotally observed in COPD patients. Objective To determine the association between the presence of Lead I sign on ECG and COPD diagnosis in patients aged 30–70 years. Methods This retrospective case-control study included 201 patients (96 with positive Lead I sign, 105 with negative Lead I sign). Lead I sign was defined as ≥ 2 criteria: isoelectric P wave, QRS amplitude < 1.5 mm, and T wave amplitude < 0.5 mm in lead I. COPD diagnosis was confirmed through pulmonary function testing and clinical documentation. Results Among patients with positive Lead I sign, 80 (83.3%) had COPD, while only 12 (11.4%) with negative Lead I sign had COPD (p < 0.001). The Lead I sign demonstrated sensitivity 87.0%, specificity 85.3%, positive predictive value 83.3%, and negative predictive value 88.6%. Conclusion The Lead I sign shows a strong association with COPD diagnosis with excellent diagnostic performance, suggesting potential utility as an accessible screening tool.