Background: Chronic Obstructive Pulmonary Disease (COPD) is increasingly recognized not only as a respiratory disorder but also as a systemic disease with significant cardiovascular implications. Among emerging biomarkers, Brain Natriuretic Peptide (BNP) has shown promise in detecting subclinical cardiac dysfunction in COPD patients, yet its prognostic value in stable cases remains underexplored.

Objectives: To assess the prognostic utility of plasma BNP levels in stable COPD patients and evaluate their correlation with left ventricular ejection fraction (LVEF), valvular dysfunction, and spirometric parameters.

Methods: This cross-sectional observational study enrolled 120 spirometry-confirmed COPD patients aged 40–70 years from a tertiary care teaching hospital. All patients underwent pulmonary function testing, chest radiography, echocardiography, and plasma BNP estimation. Echocardiographic parameters included LVEF and severity of tricuspid, mitral, and aortic regurgitation. Statistical analyses included unpaired t-tests and Pearson correlations.

Results: The majority of patients were male (87.5%) and smokers (100%), with a mean BMI of 25.8 ± 2.3 kg/m². Reduced LVEF (<55%) was observed in 61.7% of cases. Valvular abnormalities were frequent, with tricuspid regurgitation present in 79% of patients. BNP levels were elevated (>100 pg/mL) in 78% of the cohort, with levels >1000 pg/mL associated with LVEF <50% and moderate-to-severe valvular regurgitation. A strong correlation was observed between reduced FEV₁/FVC ratios and declining LVEF. BNP levels significantly correlated with both echocardiographic findings and spirometric parameters (p < 0.05).

Conclusion: Elevated plasma BNP levels in stable COPD patients are strongly associated with impaired LVEF and valvular dysfunction, especially tricuspid and mitral regurgitation. BNP may serve as a non-invasive biomarker for identifying subclinical cardiac involvement in COPD, guiding risk stratification and management. Integration of BNP into routine evaluation may enhance early detection of cardiovascular complications in COPD populations.