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Determination of cardiac risk by dipyridamole-thallium imaging before peripheral vascular surgery
Insights
Dipyridamole-thallium imaging effectively identifies cardiac risk in patients with peripheral vascular disease. Patients without thallium redistribution had few ischemic events, unlike those with redistribution, who benefited from revascularization.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Vascular Surgery
Background:
- Patients with severe peripheral vascular disease often have undiagnosed coronary artery disease.
- Assessing cardiac risk preoperatively is crucial for surgical outcomes.
Purpose of the Study:
- To evaluate dipyridamole-thallium imaging for assessing coronary artery disease severity in patients with peripheral vascular disease.
- To determine if this imaging modality can predict postoperative cardiac ischemic events.
Main Methods:
- Fifty-four stable patients with suspected coronary artery disease and severe peripheral vascular disease underwent preoperative dipyridamole-thallium imaging.
- Outcomes were compared between patients with and without thallium redistribution.
Main Results:
- Eight of 16 patients (50%) with thallium redistribution experienced postoperative cardiac ischemic events.
- None of the 32 patients without thallium redistribution had such events (P < 0.0001).
- Patients with redistribution identified via imaging often had severe multivessel coronary artery disease.
Conclusions:
- Dipyridamole-thallium imaging is a superior, safer, and less expensive tool than clinical assessment for determining cardiac risk in this population.
- Patients without thallium redistribution are low risk for events and can proceed to vascular surgery.
- Patients with thallium redistribution benefit from preoperative coronary angiography and revascularization to mitigate risks.
Abstract:
To evaluate the severity of coronary artery disease in patients with severe peripheral vascular disease requiring operation, we performed preoperative dipyridamole-thallium imaging in 54 stable patients with suspected coronary artery disease. Of the 54 patients, 48 had peripheral vascular surgery as scheduled without coronary angiography, of whom 8 (17 per cent) had postoperative cardiac ischemic events. The occurrence of these eight cardiac events could not have been predicted preoperatively by any clinical factors but did correlate with the presence of thallium redistribution. Eight of 16 patients with thallium redistribution had cardiac events, whereas there were no such events in 32 patients whose thallium scan either was normal or showed only persistent defects (P less than 0.0001). Six other patients also had thallium redistribution but underwent coronary angiography before vascular surgery. All had severe multivessel coronary artery disease, and four underwent coronary bypass surgery followed by uncomplicated peripheral vascular surgery. These data suggest that patients without thallium redistribution are at a low risk for postoperative ischemic events and may proceed to have vascular surgery. Patients with redistribution have a high incidence of postoperative ischemic events and should be considered for preoperative coronary angiography and myocardial revascularization in an effort to avoid postoperative myocardial ischemia and to improve survival. Dipyridamole-thallium imaging is superior to clinical assessment and is safer and less expensive than coronary angiography for the determination of cardiac risk.