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Dipyridamole thallium imaging may not be a reliable screening test for coronary artery disease in patients undergoing
1Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195.
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Dipyridamole SPECT thallium imaging (DST) offers limited benefit for routine cardiac risk stratification in patients undergoing vascular surgery. The test showed low predictive accuracy, failing to identify several patients who experienced perioperative coronary events.
Area of Science:
- Cardiology
- Vascular Surgery
- Diagnostic Imaging
Background:
- Cardiac risk stratification is crucial for patients undergoing peripheral vascular surgery.
- Dipyridamole thallium imaging (DST) has been proposed as a noninvasive tool for this purpose.
Purpose of the Study:
- To evaluate the clinical benefit of dipyridamole SPECT thallium imaging (DST) in the routine preoperative assessment of patients undergoing vascular surgery.
- To determine the diagnostic accuracy of DST for predicting perioperative coronary events.
Main Methods:
- Prospective study of 86 patients undergoing vascular surgery.
- Assessment of preoperative clinical risk factors.
- Performance of dipyridamole SPECT thallium imaging (DST).
- Correlation of imaging results with perioperative coronary events.
Main Results:
- Fifty-nine percent of patients were clinically high-risk; 26% had perfusion defects on DST.
- Ten patients (11.6%) experienced perioperative coronary events.
- DST identified only 3 of the 10 patients who had events, demonstrating low sensitivity.
- The test's predictive accuracy was lower in a mixed-risk population compared to previous studies.
Conclusions:
- Dipyridamole SPECT thallium imaging (DST) is not an ideal routine noninvasive technique for cardiac risk stratification in vascular surgery patients.
- The test's utility may be limited in lower-risk populations, reducing its predictive value for coronary events.
Abstract:
Dipyridamole thallium imaging has been proposed for cardiac risk stratification in patients undergoing peripheral vascular surgery. The purpose of this study was to define the benefit of this investigation in routine preoperative evaluation of these patients. The outcome of 86 patients undergoing vascular surgery procedures was examined in light of preoperative clinical assessment and dipyridamole SPECT thallium imaging (DST). Fifty-one patients (59%) were considered at high risk on clinical grounds, and 22 patients (26%) had perfusion defects. Ten patients suffered a perioperative coronary event, including unstable angina, myocardial infarction, or cardiac death. Seven of the patients with such events were among the 51 clinically high-risk subjects (14%). Three perioperative events occurred in the group of 19 patients with positive DST images who underwent surgery (16%), but the DST test failed to identify 7 patients who suffered coronary events. The frequency of abnormal thallium imaging was similar to the prevalence of angiographically significant coronary disease reported previously at this center, but considerably less than the rate of abnormal thallium imaging in past studies of vascular surgery patients. The application of the test to a low to moderate risk population is probably responsible for its lower predictive accuracy for coronary events. DST is not an ideal routine noninvasive technique for risk stratification in patients undergoing vascular surgery.