Introduction: Cardiac troponin I (cTnI) is a highly sensitive and specific marker of myocardial injury in patients who have undergone vascular surgery. Sixty percent of these patients have severe coronary artery diseases and commonly have postoperative myocardial ischaemia . We evaluated the association between a preoperative low positive level of cTnI without unstable angina and postoperative cardiac complications (CC) after vascular surgery.
Method: Fifty-five consecutive patients with or at high risk for coronary artery disease undergoing carotid endarterectomy or abdominal aortic surgery were prospectively studied. The cTnI levels were measured with an Access AccuTnI assay (Beckman Coulter) the day before the surgery, 6 hours after the procedure and on postoperative days 1, 2 and 5. The AccuTnI assay was a new generation test with a functional sensitivity known at 0.02 ng mL−1, upper reference limit 99 percentile = 0.04ngmL−1, myocardial infarction (MI) = 0.5ngmL−1. The level of preoperative cTnI defined two groups of patients: either <0.02 ng mL−1, or between 0.02 and 0.5 ng mL−1. We have compared these two groups for the incidence of increased cTnI level in the first 48 h, and incidence of MI and CC (MI, congestive heart failure and severe arryhthmia). Statistical analysis consisted of ANOVA, and Fisher's exact test when appropriate.
Results: 14 patients (25%) had preoperative cTnI ≥ 0.02 ng mL−1 (0.02 to 0.07) and the cTnI was <0.02 ng mL−1 in 41 patients (75%). An early postoperative increased of cTnI was observed in 8 patients (57%) of the ≥0.02 ng mL−1 cTnI group and only 4 patients (10%) in the other group. The relative risks for MI and CC are presented in Table 1. No other preoperative factor was found to predict postoperative ischaemic complications. All CC during the postoperative period occurs in patients with increased cTnI during the first postoperative 48 h. Only one death occurred in the cTnI positive group.
Discussion: The study shows that even low levels of preoperative cTnI can identify patients at high risk of developing postoperative CC after vascular surgery. Besides, postoperative monitoring of cTnI is useful for detecting precociously severe myocardial ischaemia, which is associated with delayed CC.
1 Landesberg G, Shatz V, Akopnik I, et al. Association of cardiac troponin, CK-MB, and postoperative myocardial ischemia with long-term survival after major vascular surgery. J Am Coll Cardiol