Prevalence and predictors of myocardial ischemia by preoperative myocardial perfusion single photon emission computed tomography in patients undergoing noncardiac surgery.

BACKGROUND

The prevalence and predictors of myocardial ischemia before noncardiac surgery are unknown. In addition the predictive value of myocardial perfusion single-photon emission computed tomography (SPECT) before noncardiac in individual patients is uncertain.

OBJECTIVE

Evaluate the prevalence and predictors of myocardial ischemia before noncardiac surgery, and determine the postoperative cardiac outcome based on results of myocardial perfusion SPECT.

DESIGN

Retrospective.

SETTING

Single tertiary care center.

PATIENTS AND

METHODS

We reviewed the records of adult patients diagnosed with myocardial ischemia by myocardial perfusion SPECT who were undergoing noncardiac surgery. Myocardial perfusion SPECT had been performed within 4 weeks prior to noncardiac surgery requiring general anesthesia.

MAIN OUTCOME MEASURES: Prevalence of abnormal myocardial perfusion SPECT results on preoperative evaluation; abnormal myocardial perfusion SPECT results as a predictor for postoperative cardiac events such as cardiac death, nonfatal myocardial infarction, and unstable angina.

RESULTS

Of 131 patients who underwent noncardiac surgery from February 2015 to April 2016, 84 (64%) patients were female and the mean (SD) age was 64.1 (13.6) years. The prevalence of abnormal myocardial perfusion SPECT was 18% (24 of 131). Normal myocardial perfusion SPECT was highly predictive (up to 100%), but a positive myocardial perfusion SPECT had low positive predictive value (4%). Variables associated with an abnormal myocardial perfusion SPECT included ischemic heart disease, congestive heart failure, ASA score of 3 or more, limited exercise capacity (less than 4 METs), male sex, hypercholesterolemia, hypertension, smoking, and abnormal ECG. In a multivariable analysis, history of ischemic heart disease and history of smoking were significant predictors of abnormal myocardial perfusion SPECT (P=.001, and .029, respectively).

CONCLUSIONS

Because of the low positive predictive value of myocardial perfusion SPECT, utilization of the technique in the workup of cardiac patients undergoing noncardiac surgery has been inappropriate. Myocardial perfusion SPECT should be restricted to only clearly defined appropriate use criteria.

LIMITATIONS: Relatively small number of patients and retrospective design.