Positivity threshold value for cardiac troponin lc in the diagnosis of perioperative myocardial infarction after on-pump cardiac surgery in adult patients

Abstract

Introduction: This prospective study was conducted at the Laboratoy of Biochemistry of the HMIMV, Rabat, over a period of 1 year. It aimed to analyse the kinetics of troponin lc (cTnl) after on-pump cardiac surgery in order to establish threshold values for the diagnosis of perioperative myocardial infarction. Methods: The study included 58 patients who had undergone on-pump valvular surgery or on-pump coronary artery bypass surgery. These patients were separated into 3 groups according to their clinical and electrical evolution as well as their laboratory tests (cTnI) during the immediate post-operative period. We batched and followed the kinetics of cTnl using immuno-enzymatic technique, CTNI Flex® reagent, before and after on-pump cardiac surgery, at H0, H3, H6, H12, H21, H24 and H72 using automatic SIEMENS Dimension Xpand Plus. Results: The results were higher than in cardiology, even among the group of patients without postoperative cardiac complications, with an average cTnl rate of approximately 2.5 times higher than the threshold value in cardiology. The kinetics of release differed significantly among the 3 groups (p‹ 0.05).Conclusion: The threshold value that we propose to confirm the diagnosis of perioperative myocardial infarction is 13ng/ml obtained between H12 and H24. We recommend to collect 1-2 samples at H12 and then between H20 and H24.