Perioperative Creatine Phosphokinase (CPK) and Troponin I Trends After Elective Hip Surgery

Abstract

Perioperative myocardial infarction (MI) is an important risk factor for cardiac morbidity and mortality after hip surgery. On the basis of the limitations of creatine kinase cardiac muscle isoenzyme (CK-MB) in the perioperative setting, and the high specificity of troponin I, we hypothesized that troponin I would be effective at detecting perioperative MI more frequently than CK-MB would be, after hip surgery. A prospective study of the serum levels of creatine phosphokinase (CPK), its isoenzyme CK-MB, and troponin I, in 90 patients with risk factors for coronary artery disease, undergoing hip surgery is reported. We measured these cardiac markers in the postoperative period for 5 days, after hemiarthroplasty, total hip arthroplasty, and hip intramedullary nailing. We found increased levels of creatine phosphokinase and CK-MB, after all the types of operation, with maximum levels reached on the first postoperative day and the levels were more pronounced after total hip arthroplasty. False-elevated CK-MB index >6% without MI was evidenced in 43.3% of patients. Troponin I levels were elevated >3.1 ng/mL only in the patients who suffered MI postoperatively. All the patients who suffered MI had both CK-MB index and troponin I levels elevated. Also, we found high correlation between maximum CK-MB levels and size of implants, which means that reaming and its heating effect may be responsible for false-elevated CK-MB levels, except direct muscle damage caused by surgical incision. CK-MB index and troponin I have the same sensitivity, but troponin I is more specific than CK-MB index in detecting MI after hip surgery.