A cross-sectional observational study enrolling 223 patients with 3-vessel coronary artery disease, has shown that compared to conventional invasive coronary angiography, a noninvasive physiology assessment using fractional flow reserve CT scanning (FFRCT or multi-slice CT scanning) changed heart team’s treatment decision-making and procedural planning in 1/5th of the patients.
The SYNTAX III REVOLUTION Trial was a randomized, multi-center study which randomized two heart teams to make a treatment decision between percutaneous coronary interventions (PCI) and coronary artery bypass grafting (CABG) using either coronary computed tomography angiography (CTA) or conventional invasive angiography while blinded to the other imaging modality. The study included patients with complex coronary artery disease, defined as, left main (isolated, or associated with 1, 2 or 3 vessel disease) or de novo 3-vessel coronary artery disease (DS ≥50%), who were able to receive cardiac CT with a multi-slice CT scanner. Coronary CTA was performed with the GE Revolution CT scanner that has a nominal spatial resolution of 230 microns along the X–Y planes, a rotational speed of 0.28 s, and a Z-plane coverage of 16 cm enabling to image the heart in one heartbeat. Patients with concomitant atrial fibrillation, cardiac valve disease and prior history of PCI or CABG were excluded from the study. The primary outcome was the inter-rater agreement (assessed by Cohen’s Kappa Kappa; a value of 0.82) on revascularization strategy of two heart teams by employing the use of either an “Angio-first” algorithm or a “CT First” algorithm 1 to 2 weeks after patient enrollment. The addition of FFRCT changed the treatment decision in 7% of the patients and modified selection of vessels for revascularization in 12%. With conventional angiography as a reference, FFRCT assessment resulted in reclassification of 14% of patients from intermediate and high to low SYNTAX score tertile.
The American and European guidelines recommend a heart team based approach for the decision-making process regarding the revascularization strategy and recommend the evaluation of the anatomical complexity using the SYNTAX score. Patients with SYNTAX scores >34 have been found to do much better with bypass surgery than those with lower SYNTAX scores. The SYNTAX scores can be divided into three tertiles. Higher scores signify complex conditions and indicate greatest risks to patients undergoing PCI. Calculation of the SYNTAX score takes into account complex lesions including bifurcations, chronic total occlusions, thrombus, calcification, and small diffuse disease with a total of 11 measures of lesion complexity. The score ranges from 0 to greater than 60 in very complex coronary anatomy.
Previously validated SYNTAX II score utilizes SYNTAX I score and then combines it with clinical prognostic variables such as age, creatinine clearance, gender, left main vessel involvement, left ventricular ejection fraction, chronic obstructive pulmonary disease (COPD) and peripheral vascular disease (PVD) in order to guide selection between PCI and CABG for patients with multivessel coronary disease. The results of the SYNTAX III Trial suggest the potential feasibility of a treatment decision-making and planning that stems from a non-invasive imaging modality and clinical information.