Diagnostic biomarkers for heart failure-related pleural effusion

Pleural effusion is common in clinical practice and has more than 60 causes, with heart failure (HF) being a common cause. The discrimination between HF and non-HF-related pleural effusions is challenging because most available diagnostic tools (e.g., imaging, echocardiography) are subjective. Some patients may even need to try diuretics to confirm the diagnosis. Serum and pleural fluid biomarkers, along with clinical scoring systems, which offer the advantages of objectivity, low cost, and minimal invasiveness, can aid in diagnosis. Many biomarkers have been identified previously, and their diagnostic value for HF-related pleural effusion has been evaluated. This review aimed to summarize research progress on biomarkers (e.g., natriuretic peptides, ischemia-modified albumin, CC class chemokine ligand 22, apolipoprotein E, soluble urokinase plasminogen activator receptor) and scoring systems in diagnosing HF-related pleural effusion. We found that serum and effusion natriuretic peptides (B-type natriuretic peptide, N-terminal pro-B-type natriuretic peptide, and midregional pro-Atrial natriuretic peptide) had high diagnostic accuracy for HF-related pleural effusion, and this accuracy has been validated by multiple studies. Ischemia-modified albumin, CC class chemokine ligand 22, apolipoprotein E, and soluble urokinase plasminogen activator receptor were emerging biomarkers, and their diagnostic accuracy needs to be validated by future studies. The Porcel's score and the BANCA score were the most promising diagnostic scores for HF-related pleural effusion. Taken together, natriuretic peptides, Porcel's score, and the BANCA score should be advocated for diagnosing HF-related pleural effusion.