POSTOPERATIVE MYOCARDIAL-ISCHEMIA - ETIOLOGY OF CARDIAC MORBIDITY OR MANIFESTATION OF UNDERLYING DISEASE

Study Objective: To determine the relationship between postoperative S T segment changes and clinically apparent cardiac morbidity in noncard iac surgery patients. Design: Prospective, cohort study. Setting: Gene ral inpatient and intensive care units at a tertiary care hospital. Pa tients: 145 high-risk noncardiac surgery patients. Measurements and Ma in Results: Patients were monitored for ST segment changes using ambul atory electrocardiographic (ECG) recorders from the end of the surgica l period for up to the third postoperative day. Patients were evaluate d for a clinically apparent cardiac event (cardiac death or myocardial infarction) by daily 12-lead ECGs, and CK-MB isoenzymes, as clinicall y indicated. Nine patients sustained a clinically apparent cardiac eve nt, 7 of whom had a cardiac event during the period in which they were monitored by ambulatory ECG. All 7 patients who sustained a cardiac e vent during the monitoring period had at least one episode of myocardi al ischemia, which persisted for a minimum of 30 minutes either prior to or at the same time of the event, with no morbidity occurring in th e group of patients who had only short durations of myocardial ischemi a. Three of the patients with events had continuous ST segment changes , while the other patients had transient ST segment changes. Conclusio ns: These observations suggest that clinically apparent cardiac events are associated with prolonged ST segment changes detected on ambulato ry ECG recorders. The cardiac ischemia leading to prolonged postoperat ive ST segment changes may itself result in cardiac morbidity, or it m ay be a reflection of underlying pathophysiology.