Impact of impaired renal function on kinetics of high-sensitive troponin I (hs-cTnI) following cardiac surgery

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Abstract Background Renal insufficiency might result in increased levels of cardiac troponin due to decreased elimination. Hence, the diagnostic utility of hs-cTnI might be lower in patients with impaired renal function. There is only scarce data on kinetics of high-sensitivity cardiac troponin I (hs-cTnI) following cardiac surgery with regard to renal function. Purpose The aim of this study was to assess the impact of impaired renal function on the kinetics of hs-cTnI following cardiac surgery differentiating between patients with and without postoperative myocardial infarction (PMI) and to analyze the prognostic value of hs-cTnI elevations in patients with impaired renal function. Methods We performed a retrospective analysis of all adult patients (>18 years) who underwent cardiac surgery at our hospital between Jan, 1st 2013 and May, 1st 2019. Serial measurements of high-sensitive cardiac troponin I (hs-cTnI) were assessed from baseline up to 48 hours after surgery. Renal function was assessed based on estimated glomerular filtration rate (GFR) using the Modification of Diet in Renal Disease (MDRD) formula with impaired renal function defined by GFR <60 ml/min. Postoperative myocardial infarction was defined by new vessel occlusion on angiography. Predictors of long-term all-cause mortality were assessed by cox regression analysis. Results A total of 14,465 patients were included (51.4% underwent coronary artery bypass grafting (CABG), 39.4% had valvular procedures and 9.2% thoracic aortic procedures). Levels of hs-cTnI were higher in patients with impaired renal function in the overall collective (figure 1). However, in patients with postoperative myocardial infarction levels of hs-cTnI did not differ with regard to renal function (figure 2). Cox regression analysis showed postoperative elevation of hs-cTnI to be a significant predictor of long-term all-cause mortality over a median follow-up of 3.0 years regardless of baseline kidney function (Hazards ratio 1.67, 95% Confidence interval [1.46–1.91], p<0.001). Conclusion Renal function had an impact on postoperative hs-cTnI kinetics only in patients with an uneventful postoperative course. In patients with postoperative myocardial infarction kinetics of hs-cTnI were not affected by baseline renal function. Moreover, elevated hs-cTnI levels were a significant predictor of all-cause mortality regardless of baseline renal function. Funding Acknowledgement Type of funding sources: None.