• The CT-derived endpoints: Study lesion %DS predicting FFR<0.75; %AS predicting FFR<0.75; MLD predicting FFR<0.75; Study lesion MLA predicting FFR<0.75; IVUS-derived endpoints: Study lesion MLD predicting FFR<0.75; MLA predicting FFR<0.75 [ Time Frame: Upon completion of tests ] [ Designated as safety issue: No ]
  

Invasive X-ray coronary angiography remains the "reference standard" for the evaluation of coronary artery stenoses. Recently, coronary artery computed tomography angiography (CorCTA) has been introduced as a non-invasive method for the evaluation of coronary artery stenoses and has been shown to be highly accurate in stenosis detection when compared to invasive X-ray angiography. While invasive X-ray angiography and CorCTA evaluate morphological features of coronary arterial plaques, fractional flow reserve is an invasive measure of the hemodynamic significance of a stenosis obtained in the catheterization laboratory by measuring changes in intracoronary arterial pressure before and after maximal vasodilation induced by intracoronary adenosine. An FFR value less than 0.75 has been shown to predict ischemia in vascular beds distal to the stenosis by radionuclide perfusion modalities and has been shown to be associated with worse outcomes. Therefore, FFR is considered to be an invasive hemodynamic "reference standard" for the evaluation of the hemodynamic significance of coronary arterial stenoses. While intravascular ultrasound (IVUS) can provide additional morphological information in intermediate stenoses, it can not provide further functional information and cannot be used in more significant stenoses as the IVUS probe cannot be advanced through stenotic lesions.

We are currently conducting investigation in the validation of CorCTA against FFR in intermediate coronary artery stenoses (40-70%) (see below under "Preliminary Data"). However, CorCTA has not been validated against invasive hemodynamic measurements of fractional flow reserve in patients with stenoses >70% by invasive X-ray angiography. We hypothesize that CorCTA-derived measurements are accurate in the diagnosis of hemodynamically significant coronary artery stenoses, using FFR as the reference standard in patients with coronary artery stenoses>70%.