Peri-operative myocardial injury in patients undergoing surgery for critical limb ischaemia

Introduction. Although up to a half of patients undergoing abdominal aortic aneurysm (AAA) repair suffer myocardial injury, as indicated by a rise in cardiac troponin I (cTnI), this is infrequently accompanied by a rise in creatine kinase (CK)MB fraction or electrocardiogram (ECG) changes. This study compares for the first time peri-operative cTnI, CK-MB and ECG changes in patients undergoing surgery for critical lower limb ischaemia (CLI). Methods. Twenty-nine patients (20 men, median age 75 [range, 57-95] years) were studied prospectively. cTnI, CKICKMB ratio and ECG were performed pre-operatively and on post-operative days 1, 2 and 3. Results. Eleven (38%) patients had an elevated cTnI > 0.5 ng/ml. Five (17%) patients had an elevated CK-MB fraction > 4% and all of these patients had an elevated cTnI. Eleven (38%) patients had ischaemic changes on ECG including seven of 11 (64%) patients with elevated cTnI and all five patients with elevated CK-MB fraction. There was no relationship between pre-operative cardiac status, antiplatelet use or type of anaesthesia and post-operative cTnI rise. Patients with a cTnI rise were younger (p = 0.01), and were more likely to have presented with gangrene (p = 0.04) and have a longer operation time (p=0.01) than patients who did not demonstrate a cTnI rise. Four patients developed clinically apparent cardiac complications: cardio-pulmonary arrest (n = 1), cardiogenic shock (n = 1), acute CCF (n = 1) and rapid atrial fibrillation (n = 1). Survival at 6 months was 26 of 29 (90%) patients. Conclusion. These data demonstrate that over a third of patients operated for CLI sustain peri-operative myocardial injury, many of which are not clinically apparent. Pre-operative medical optimisation may improve prognosis in this group of patients.