Factors associated with post-operative myocardial ischaemia in elderly patients undergoing major non-cardiac surgery

Forty patients (> 65 years) undergoing hip arthroplasty or peripheral vascular surgery both associated with high risk for post-operative myocardial ischaemia were randomized to receive either spinal or general anaesthesia. Ambulatory ECG recording (Holter) until the third post-operative morning, a daily 12-lead ECG and serum creatine kinase and troponine concentraItions were obtained. The number of ischaemic episodes, total duration of ischaemia and ischaemic minutes per hour were noted for each patient peri-operatively. Sixteen of the patients (40%) had post-operative myocardial ischaemia. An intra-operative increase in the plasma concentration of norepinephrine but not epinephrine was detected in the patients who later developed post-operative myocardial ischaemia. The increase in plasma norepinIephrine concentrations correlated with the decrease in core temperature. The type of anaesthesia had no effect on the incidence of myocardial ischaemia during or after surgery. Our results suggests that intra-operatively decreased core temperature and the increase in plasma concentration of norepinephrine probably caused peripheral vasoconstriction leading to latent cardiac dysfunction. These events should be avoided in the patients at risk of post-operative cardiac ischaemia.