PERIOPERATIVE MYOCARDIAL-ISCHEMIA IN PATIENTS UNDERGOING NONCARDIAC SURGERY .2. INCIDENCE AND SEVERITY DURING THE 1ST WEEK AFTER SURGERY

[摘要] Because of the importance of postoperative myocardial ischemia and because substantial physiologic changes can occur for prolonged periods postoperatively, the incidence, severity and temporal course of myocardial ischemia were studied in 100 high risk patients during the 1st week after major noncardiac surgery. Electrocardiographic (ECG) changes consistent with ischemia were continuously monitored using ambulatory solid state ECG in the 100 patients with or at risk for coronary artery disease. ischemic episodes were defined as reversible ST segment depression greater-than-or-equal-to 1 mm or elevation greater-than-or-equal-to 2 mm above the baseline value, with the baseline adjusted for respiratory and positional variation and temporal drift. All ischemic episodes were confirmed by three independent blinded investigators using hard-copy recordings. Total ECG monitoring time was 10,445 h. Twenty-seven patients (27%) developed 437 episodes of ischemia during the 1st week after surgery. The total duration of ischemia was 18,658 min, or 1.8 min of ischemia/h monitored. Ischemia was most severe during the early (days 0 to 3) versus late (days 4 to 7) postoperative period: 284 versus 153 episodes; 2.2 versus 1.2 min of ischemia/h. The greatest severity occurred on postoperative day 3: 109 episodes, 3.4 min of ischemia/h monitored, 1.5 mm mean ST change and 130 min mean duration. However, in 8% of patients, severe episodes also occurred late: postoperative day 6 = 44 episodes, 1.7 min of ischemia/h monitored, 1.3 mm mean ST change (59% greater-than-or-equal-to 2 mm) and 92 min mean duration. Most ischemic episodes (57%) were associated with tachycardia. Eighty-four percent of episodes were silent, unaccompanied by symptoms of angina, pulmonary congestion or syncope. All five severe adverse cardiac outcomes (unstable angina, myocardial infarction or cardiac death) were preceded by postoperative ischemia occurring greater-than-or-equal-to 1 day before the outcome. It is concluded that in at-risk patients undergoing noncardiac surgery: 1) postoperative ECG ST changes consistent with myocardial ischemia are most common during the 1st 3 days after surgery, with changes persisting for greater-than-or-equal-to 1 week; 2) postoperative ischemia is clinically silent throughout the entire period and therefore difficult to detect; 3) postoperative ischemia may be related to the persistently elevated heart rate during the 1st week after surgery; and 4) an association between both early and late postoperative ischemia and severe cardiac outcomes is suggested.

[发布日期] 1991-03-15