Stenosis Length and Severity on Coronary Angiography does not Always Correlate with Sestamibi Perfusion Defect Severity
AIMS: To determine if there is a relationship between sestamibi defect severity and coronary stenosis severity and length as demonstrated on angiography.
METHODS: 75 consecutive abnormal Tc-99m sestamibi scans (exercise n=22, dipyridamole n=53) followed, within three months, by coronary angiography were retrospectively analysed. The perfusion images and coronary angiography were compared in each case. The degree of luminal coronary artery stenosis was reported as mild (<50%), moderate (50-70%), or severe (>70%).
Cardiac Catheterisation
Mild Moderate Severe Total
Tc-99m Sestamibi Mild 31 5 9 45
Myocardial
Perfusion Moderate 3 23 1 27 Imaging Severe 1 1 10 12
Total 35 29 20 84
RESULTS: A total of 84 defects were reported on perfusion imaging. On comparison with angiogram, perfusion defect severity correlated with stenosis severity for mild (31/35) and moderate (23/29) stenoses. In contrast, of the 20 angiographic severe stenoses, 9 showed only mild sestamibi defects. On reviewing the angiogram images of the discrepant cases, 7 of 9 defects showed long (> 10 mm) segments of diffuse luminal stenosis, in contrast to the tight localized stenoses in 9/10 defects correctly reported as severe on perfusion imaging.
CONCLUSIONS: There was good concordance between severity of perfusion defects in the mild and moderate severity stenoses. Correlation of perfusion defect severity in severe stenoses was not as good. The inverse relationship between stenoses length and severity of perfusion defect was surprising and needs further investigation.