The occurrence of myocardial injury after carotid endarterectomy

Editor, Recent reports have revealed that myocardial injury after noncardiac surgery is a common complication associated with higher postoperative morbidity and mortality.1–4 Such injury typically develops in patients without overt clinical ischaemic symptoms; hence, in the absence of routine postoperative cardiac troponin measurement it is frequently missed in clinical practise.1–3 Little is known on the prevalence of myocardial injury in patients undergoing carotid endarterectomy. Therefore, we performed a small retrospective cohort study of 72 consecutive patients who underwent carotid endarterectomy between January 2015 and July 2017 in the Vascular Surgery Department of St. John Grande Hospital in Kraków. The study received approval by The Bioethics Committee of The Regional Chambers of Physicians in Kraków (Chairperson Dr Mariusz Janikowski) on 27 December 2016. Screening for myocardial injury was performed routinely after the procedure. Blood was collected at least once within the first 3 postoperative days to measure troponin level. Myocardial injury was defined as a troponin level elevation over the 99th percentile upper reference limit for troponin I and T (i.e. high-sensitivity troponin T ≥14 ng l−1, ultra-sensitivity troponin I Vidas (Biomerieux) ≥19 ng l−1 and troponin I Vidas ≥0.01 μg l−1) based on the definition presented in the Fourth Universal Definition of Myocardial Infarction.5 Patients’ baseline characteristics, as well as postoperative outcomes (up to the 30th day after surgery), were collected from the medical records or by phone contact with the patient or her/his next of kin. Three patients (out of 72; 4.2%) who suffered from a peri-operative stroke were excluded from the troponin analysis due to immediate transfer to the Stroke Unit and lack of troponins measurements. Detailed patients’ baseline characteristics are shown in Table 1.Table 1: Baseline characteristics of patients with and without myocardial injury after carotid endarterectomy [all data are numbers (%); otherwise indicated]The most common cardiovascular complication after endarterectomy was myocardial injury (17/69 patients; 24.6%), followed by stroke (5/72; 6.9%) and acute heart failure (1/72; 1.4%). All-cause mortality within 30 days was 1.4% (1/72). Myocardial infarction diagnosed according to the Universal Definition occurred in one patient (1.4%).5 In contrast to our study, Grobben et al.6 observed a lower prevalence of postoperative troponin elevation (15%) after carotid endarterectomy during the first 3 postoperative days. The subanalysis of the VISION study including patients undergoing vascular surgeries revealed that 30-day all-cause mortality was notably higher in patients who suffered from myocardial injury in comparison with those that did not (12.5 vs. 1.5%).2 Thus, we propose, concordant with existing guidelines, that high-sensitivity troponins should be measured in patients undergoing carotid endarterectomy during the peri-operative period.7 Significantly, we observed high rates of troponin elevation among patients undergoing general anaesthesia. Therefore, in further studies the relationship between the type of anaesthesia and myocardial injury should be investigated. The study has major limitations. First, the study is small and multivariate analyses could not be performed to identify relevant associations. Second, the study may have a risk of bias related to limited available variables. Third, the study had no pre-operative troponin value measurement, and therefore patients with chronic troponin elevation could not be identified. Finally, in the majority of patients, troponin levels were measured only once, hence we may not have identified all postoperative troponin elevations. Acknowledgements relating to this article Assistance with the letter: none. Financial support and sponsorship: none. Conflicts of interest: none.