Background: Routine laboratory testing to rule out myocardial infarction (MI) after carotid endarterectomy (CEA) is common in many centers. Its use in this patient population has not been thoroughly investigated. We hypothesize that routine testing for MI in post-CEA patients is of low yield and not cost-effective.
Methods: A retrospective review of 291 consecutive CEAs from February 2011 to July 2015 was performed. Two patients were excluded: one for postoperative noncardiac death and one for preoperative MI. Patient demographics, medications, medical history, type of anesthesia, and postoperative laboratory results were reviewed. All patients had troponin-I and creatine kinase-MB levels taken postoperatively. A patient was judged to have an MI if troponin-I was greater than or equal to 0.6 ng/mL or CK-MB is >6.3 ng/mL. The incidence of postoperative MI was recorded, and a cost analysis was performed.
Results: The mean age was 70.2 years (range: 42-92). Of all, 59.5% were male, and 92.4% had a history of hypertension. Preoperatively, 57.4% were on beta-blocker therapy, 86.5% on aspirin, and 52.2% on both. Most (80.6%) were on preoperative statin therapy, 26.9% had a prior history of MI (37.2% within 5 years of surgery), and 56.4% of patients had a prior coronary intervention (27.6% percutaneous, 28.7% coronary artery bypass grafting, and 11% both). All patients received general anesthesia. The mean procedure time was 121.5 min (range: 62-258). The mean postoperative length of stay was 2.6 days. Eight patients (2.7%) were judged to have acute MI, one of which was symptomatic. Three of the 8 (38%) had a prior history of MI. In asymptomatic patients, the peak level of troponin-I ranges from 0.52 to 3.64 ng/mL and that of CK-MB from 11.8 to 24 ng/mL. The symptomatic patient had chest pain and bradycardia. The patient had a peak troponin-I level of 1.59 ng/mL, with a CK-MB level of 11.5 ng/mL. All patients were treated medically. The cost per troponin-I and CK-MB is $27.78 and $31.44, respectively, in our institution. We estimate that eliminating routine postoperative troponin-I and CK-MB testing in patients who underwent CEA would have saved an estimated $51,343 over the course of treatment of the studied population.
Conclusions: Routine postoperative cardiac laboratory testing in asymptomatic patients after CEA increases the hospital cost. The low overall rate of postoperative MI suggests that cardiac testing is best reserved for symptomatic patients or those with clinical suspicion for MI.
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