Correlation of Myocardial Fractional Flow Reserve with Thallium-201 Spect Imaging In Intermediate Severity Coronary

The physiologic assessment of angiographically intermediate-severity stenosis remains problematic. The purpose of this study was to compare measures of fractional flow reserve of the myocardium (FFRmyo) with results of quantitative coronary angiography (QCA) and stress single-photon emission computed tomography (SPECT) thallium- 20ı (201TI) imaging in patients with intermediate severity coronary artery disease (ISCAD). We prospectively evaluated 20 lesions of QCA determined ISCAD [% diameter stenosis (DS) between 30 and 70] in ı5 patients (age 53.3±ı0.2 years, %66.6 male) using a O.Oı4 inch pressure wire during elective coronary angiography. All patients subsequently underwent to SPECT 201 Tl imaging in the following week and blinded results were compared. There was a moderate correlation between %DS and FFRmyo (53.1±13.4 and 0.75±0.09, respectively. R: -0.59, p: 0.006). There were perfusion defects in ı ı (%55) of 20 vascular territories (Group 1) and 9 (%45) territories w ere found as normal (Group 2). While stenosis severity determined by QCA was not different between Group ı and Group 2 (55.9±1 1.5 vs. 49.7±15.5, respectively, p: 0.3); FFRmyo was found to be s ignificantly different between the two groups (83.5±5.3 vs 68.2±5.4 respectively, p:O.OOı ). When the results of both tes ts w ere dichotomised as normal (FFRmyo~ 0.75 and %DS < %50) and abnormal, and SP ECT 20 ı Tl tak en as the golden standart sensitivity, speificity, positive predictive value and negative predictive value of both tests were 0.9ı vs 0.55, 100 VS 0.56, ı00 VS 0.60, 0.90 VS 0.50, respectively. In conclusion: FFRmyo accurately predicts the pres en ce of ischemia on SPECT 20 1 Tl in patients with ISCAD. QCA does not reliably assess the physiologic impact of the same lesions.