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Abstract

Background: Cardiac biomarkers such as Troponin I, CK-MB, and NT-proBNP play a pivotal role in diagnosing and prognosticating acute coronary syndrome (ACS). However, their interpretation can be significantly influenced by underlying renal dysfunction, particularly in patients with acute kidney injury (AKI) or chronic kidney disease (CKD). The varying kinetics and clearance of these biomarkers in renal impairment pose a diagnostic challenge.
Aim: To compare the trends of cardiac biomarkers—Troponin I, CK-MB, and NT-proBNP—in patients with ACS having either AKI or CKD, and to evaluate the predictive factors influencing NT-proBNP levels.
Material and Methods: This prospective, comparative observational study was conducted in the Departments of Nephrology and Cardiology at a tertiary care teaching hospital. Sixty adult patients with ACS were enrolled and categorized into two groups: Group A (AKI, n=30) and Group B (CKD, n=30), based on KDIGO 2012 criteria and MDRD-based eGFR. Demographics, comorbidities, renal parameters, and serial cardiac biomarkers (at 0, 6, 12, and 24 hours) were recorded. Left ventricular function was assessed using echocardiography. Statistical analysis included t-tests, chi-square tests, repeated measures ANOVA, and multiple linear regression.
Results: Baseline demographics and comorbidities were comparable between the AKI and CKD groups. Serum creatinine and eGFR showed significant intergroup differences (p = 0.048 and p = 0.026, respectively). Troponin I and CK-MB levels followed a similar trend in both groups, peaking at 12 hours and declining by 24 hours, with no significant differences at any point. However, NT-proBNP levels were significantly higher in the CKD group at all time points (p < 0.001). Multivariate regression revealed CKD status, age, serum creatinine, Killip class ≥ II, and lower LVEF as significant predictors of NT-proBNP levels, with an adjusted R² of 0.65.
Conclusion: Troponin I and CK-MB exhibit comparable patterns in both AKI and CKD patients with ACS. In contrast, NT-proBNP levels are significantly elevated in CKD due to chronic volume overload and impaired clearance. CKD status was the strongest predictor of NT-proBNP elevation. Hence, cardiac biomarker interpretation in ACS must consider renal function for accurate risk stratification and management.