EPIDURAL MORPHINE REDUCES THE RISK OF POSTOPERATIVE MYOCARDIAL-ISCHEMIA IN PATIENTS WITH CARDIAC RISK-FACTORS

Perioperative myocardial ischaemia is a predictor of postoperative car diac morbidity (PCM). Epidural anaesthesia and adequate perioperative analgesia have been shown to improve myocardial oxygen dynamics due to interruption of pain and sympathetic pathways. The aim of the present study was to compare the incidence of ischaemia after either general anaesthesia followed by parenteral analgesia with morphine or combined epidural/general anaesthesia followed by analgesia with epidural morp hine. In a prospective observer-blinded analysis of the occurrence of ischaemia, 55 patients (epidural = 29/parenteral = 26) scheduled for e lective surgery with defined risks for ischaemic cardiac disease were entered and followed for 24 hr after surgery with two-lead continuous Holter monitoring Groups were similar with respect to age, weight, mod ified Goldman (Detsky) risk classification and the use of cardiac medi cations. Fewer patients receiving the epidural anaesthesia/analgesia h ad ischaemic episodes (172 vs 50.0%, P = 0.01), and tachyarrhythmias ( 20.7 vs 50.0%, P < 0. 05). Epidural patients had a four-fold reduction of the relative risk for either event (P < 0.001). All ischaemic even ts were asymptomatic and unrecognized (silent). All major morbid event s (n = 5) (MI congestive heart failure and death) occurred in patients who had perioperative episodes of ischaemia. There wee three distinct peaks in onset of ischaemia, at 1-4 hr, 9-12 hr and 22-24 hr postoper atively One third of postoperative ischaemic events occurred within th e first four hours after operation and lasted from 1 to 31 min. Forty- two percent of ischaemic episodes were associated with a heart rate > 100 bpm, or an increase of 20% over the baseline heart rate We conclud e that epidural anaesthesia/analgesia reduces but does not eliminate t he risk of myocardial ischaemia and tachyarrhythmia. We were unable to determine any associated reduction in the risk of PCM.