Relationship between contrast-induced nephropathy and blood methemoglobin levels in acute coronary syndrome patients

Introduction: Contrast-induced nephropathy (CIN) is an iatrogenic complication occurring in patients exposed to contrast agents. Objectives: We aimed to investigate the relationship between blood methemoglobin (MHb) levels and the development of CIN in patients undergoing coronary angiography (CAG), with or without primary coronary intervention for acute coronary syndrome (ACS). Patients and Methods: In this retrospective study, 119 patients diagnosed with ACS who underwent coronary angiography were included. MHb levels were measured in patients before and at during the first 1 to 3 hours after the procedure. CIN was defined as an increase in serum creatinine levels by ≥0.3 mg/dL (26.5 µmol/L) from baseline within 48 hours after contrast exposure or an increase of 1.5-1.9 times the baseline value within 7 days. Results: The relationship between CIN-positive and CIN-negative patients and patients with MHb ≤%1 and MHb >% 1 was similar (P=0.4). Multivariate logistic regression analysis showed that an MHb value greater than 1 did not independently predict the development of CIN. Significant differences were observed between these two groups in terms of pre-CAG creatinine levels (P=0.02), Mehran risk score (<0.001), hemoglobin levels (P=0.03), the presence of hypotension (P=0.03), blood pH value (P=0.03), left ventricular ejection fraction (LVEF) (<0.001), the presence of diabetes mellitus (P=0.014), age (P=0.001), and smoking history (P=0.02). Conclusion: Our study demonstrates that traditional risk factors contribute to nephropathy. However, the increased blood MHb levels do not appear to contribute to the development of CIN in ACS patients.