Evaluation of Cardiac Biomarkers in Serum and Saliva of Heart Failure Patients: A Two-Center Multicenter Study

<ns3:p>Background Salivary biomarkers are being explored as non-invasive tools for Heart failure (HF) monitoring. This study examined salivary N-terminal pro–B-type natriuretic peptide (NT-proBNP) and high sensitive cardiac troponin I (hs-cTnI) alongside serum levels to distinguish heart failure patients from healthy controls and to assess diagnostic potential and cross-matrix concordance. Method This two-center, prospective case-control study (Nov 2024–Apr 2025) enrolled heart failure patients and healthy controls, diagnosed per European Society of Cardiology criteria and confirmed by labs and echocardiography. Serum and saliva N-terminal pro–B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (hs-cTnI) were measured by sandwich ELISA. Samples: 100 serum and 47 saliva from patients; 100 serum and 91 saliva from controls. Biomarkers were limited by serum volume (43 patients; 45 controls); saliva was measured in 47 patients and 45 controls. This limitation reduced the sample size for cardiac biomarker analyses relative to the total collected samples. Results HF patients showed higher serum NT-proBNP (309 [220–399] ng/L) and salivary NT-proBNP (24 [21–29] ng/L) versus controls (77 [63–106] ng/L; 18 [15–22] ng/L; P &lt; 0.001). Serum hs-cTnI rose non-significantly (90 [69–101] vs 66 [35–115] pg/mL; P = 0.080); salivary hs-cTnI was higher (22 [13–24] vs 4 [3–8] pg/mL; P &lt; 0.001). Salivary NT-proBNP correlated with serum NT-proBNP (r = 0.540; P &lt; 0.001). Salivary creatinine (r = 0.606; P &lt; 0.001) and uric acid (r = −0.178; P = 0.037) associated with serum levels. ROC: serum NT-proBNP AUC 0.97; salivary NT-proBNP 0.77; serum hs-cTnI 0.60; salivary hs-cTnI 0.88. Conclusion Serum NT-proBNP remains the strongest HF diagnostic biomarker. Salivary NT-proBNP and hs-cTnI show diagnostic potential and moderate concordance with serum, suggesting saliva as a complementary non-invasive HF monitor. Limited sample availability and need for standardization limit generalizability.</ns3:p>