Vasodilator stress induces infrequent wall thickening abnormalities compared to perfusion defects in mild-to-moderate coronary artery disease: implications for the choice of imaging modality with vasodilator stress.
BACKGROUND
Experimental evidence suggests that although vasodilator stress agents consistently induce regional flow disparity between stenosed and normal coronary vascular beds, the occurrence of functional myocardial ischemia is infrequent, especially in mild-to-moderate coronary artery stenosis. Thus, it is hypothesized that dipyridamole infusion, even at high doses, will result in a disproportionately higher frequency of perfusion defects compared to regional wall thickening abnormalities.


METHODS
We performed simultaneous high-dose (0.84 mg/kg) dipyridamole stress echocardiography (Echo) and Tc-99m sestamibi SPECT (MIBI, methoxyisobutyl isonitrile) in 46 patients with coronary artery diameter stenosis >50% and < o =90% in one or two epicardial coronary arteries, and no previous myocardial infarction.


RESULTS
Of a total of 828 segments, MIBI showed 97 reversible defects while Echo showed only 23 reversible wall thickening abnormalities. Of the 97 segments with reversible MIBI defects, only 13 (13%) showed simultaneous reversible wall thickening abnormalities during dipyridamole infusion. There were 24 patients with MIBI defects, of whom 10 (41%) showed a corresponding wall thickening abnormality. The sensitivity of MIBI and Echo for the detection of coronary artery disease was 52% and 21%, respectively (P = 0.001).


CONCLUSIONS
This suggests that vasodilator stress is not optimally suited for use with techniques that use regional wall thickening abnormality as a marker of ischemia for the diagnosis of coronary artery disease.
Soman
Prem
P
Department of Cardiovascular Medicine, Northwick Park and St Mark's Hospitals and Institute of Medical Research, Harrow, Middlesex, UK.
Lahiri
Avijit
A
Senior
Roxy
R
D000368:Aged; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology; D004176:Dipyridamole / Q000008:administration & dosage / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D025401:Echocardiography, Stress; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D017256:Technetium Tc 99m Sestamibi / Q000008:administration & dosage; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000009:adverse effects
D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi