Background: Myocardial perfusion assessed by a pharmacological scintigraphic test is a time-honored method to assess the functional significance of a coronary stenosis. There is no study that has compared coronary flow reserve assessed by adenosine/base contrast-enhanced transthoracic echo Doppler in harmonic mode with myocardial perfusion by adenosine/base 99mTc-sestamibi SPECT. The aim of this study was to compare the absolute coronary flow reserve measured in the left anterior descending coronary artery using a new noninvasive method (transthoracic harmonic Doppler) with adenosine/base 99mTc-sestamibi SPECT.
Methods: Twenty-two patients scheduled for coronary angiography underwent evaluation of basal and hyperemic flow in the left anterior descending coronary artery using transthoracic harmonic Doppler. Simultaneously (during the same adenosine infusion) the patients were injected with 99mTc-sestamibi (10 mCi). Baseline scintigraphic study was obtained 4 hours later (99mTc-sestamibi, 30 mCi).
Results: Angiography showed in the left anterior descending coronary artery no or not significant stenosis (< 40% lumen narrowing) in 14 patients (Group I) and a severe stenosis (> 75%) in the remaining 8 patients (Group II). Coronary flow reserve dichotomized as normal (> or = 2.0) or abnormal (< 2.0) gave concordant results with SPECT. Overall, in fact, 18 studies (81%) were in agreement (k = 0.48, p = 0.02). In addition, coronary flow reserve proved to be a useful complementary tool to SPECT in patients with severe multivessel disease (and global hypoperfusion; 2 cases) and left bundle branch block (1 case).
Conclusions: Coronary flow reserve assessed by transthoracic harmonic Doppler gives concordant results with SPECT perfusion scintigraphy. The diagnostic potential of SPECT may be increased by the noninvasive assessment of coronary flow reserve in the left anterior descending coronary artery.