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Risk stratification prior to vascular surgery: does the location of a dipyridamole thallium scintigram defect provide
T T Nguyen1, E A Amsterdam, S Schaefer
1Department of Internal Medicine, University of California Davis Medical Center, USA.
Insights
Myocardial scintigraphy using dipyridamole thallium identifies patients at risk for vascular surgery. Abnormalities in any location, anterior or inferior, indicate increased cardiac complications, not just specific defect locations.
Area of Science:
- Cardiology
- Nuclear Medicine
- Vascular Surgery
Background:
- Dipyridamole thallium myocardial scintigraphy is established for risk assessment before vascular surgery.
- The prognostic value of the specific location of thallium abnormalities remains unclear.
Purpose of the Study:
- To determine if the location of dipyridamole thallium abnormalities predicts cardiac complications after vascular surgery.
- To compare the risk associated with anterior versus inferior/inferolateral perfusion defects.
Main Methods:
- Retrospective review of 435 patients undergoing vascular surgery.
- Analysis of cardiac complications in patients with anterior (n=62) or inferior/inferolateral (n=105) dipyridamole thallium defects.
Main Results:
- Normal scintigraphy had a low complication rate (2%).
- Anterior defects showed 12% complications (no deaths); inferior defects showed 18% complications (4 deaths).
- The incidence of complications was similar between anterior and inferior defects (p=0.65).
Conclusions:
- Inferior/inferolateral dipyridamole thallium abnormalities do not confer a lower risk than anterior abnormalities.
- Any abnormal dipyridamole thallium study signifies elevated perioperative cardiac risk.
- Abnormal findings may necessitate further evaluation and intervention prior to surgery.
Background:
While the value of myocardial scintigraphy using dipyridamole thallium is accepted for risk assessment prior to vascular surgery, it is unknown whether the location of the thallium abnormalities provides prognostic information.
Methods:
Records from 435 consecutive patients scheduled for vascular surgery were reviewed and patients with dipyridamole thallium abnormalities involving the anterior distribution (ANTERIOR n = 62), or inferior or inferolateral distribution (INFERIOR n = 105) were assessed for cardiac complications of surgery (death, myocardial infarction, unstable angina or ischemic congestive heart failure).
Results:
Patients with a normal dipyridamole thallium scintigraphy had few surgical cardiac complications: 2/86 (2%). Patients with an ANTERIOR dipyridamole thallium defect had a 12% incidence of surgical cardiac complications (7/57) without any cardiac deaths, while patients with an INFERIOR dipyridamole thallium defect had a similar incidence of surgical cardiac complications, 18% (18/100; p = 0.65 vs. ANTERIOR) including 4 cardiac deaths.
Conclusions:
Significant inferior or inferolateral dipyridamole thallium scintigraphy abnormalities are not associated with a lower risk of cardiac complications following vascular surgery than anterior abnormalities. Rather, any clearly abnormal dipyridamole thallium study is a marker for increased risk of perioperative events and may warrant further evaluation and treatment.