FUNctional eFficacy of Hybrid coronAry REvascularization

Overview

The purpose of the study is to compare iFR-guided hybrid coronary revascularization (HCR) and traditional coronary artery bypass grafting (CABG) in terms of a functional efficacy of revascularization assessed by weighted average of iFRs measured 12 month post-procedure in the qualified coronary arteries (all arteries with at least one significant lesion and diameter \>1.5 mm at baseline). The true significance of coronary artery disease (CAD) is reflected by the pressure gradients in coronary arteries showing the actual drop in myocardial perfusion whereas the degree of anatomical narrowing in fact only indicates a potential for hemodynamical changes that also depend on vessel compliance, distal vascular resistance, and collateral circulation. Then, the true effect of myocardial revascularization as treatment of CAD should be likewise assessed by measuring residual pressure gradients in coronary arteries remaining after revascularization, i.e. as the functional efficacy in analogy to the functional significance of CAD.

New generation of drug eluting stents (DES) have been shown to have better long-term patency rates than the vein grafts utilized in conventional CABG. Then, it may be expected that hybrid coronary revascularization (HCR) combining minimally invasive direct coronary artery bypass (MIDCAB) grafting of left anterior descending (LAD) artery by left internal mammary artery (LIMA) and stenting of non-LAD coronary arteries with the new generation DESs may have superior efficacy and safety compared to conventional CABG in patients with multivessel coronary artery disease (CAD). The true significance of CAD is reflected by the pressure gradients in coronary arteries that show actual changes in coronary blood flow and myocardial perfusion whereas the degree of anatomical narrowing only indicates a potential for the hemodynamical changes that also depend on vessel compliance, distal vascular resistance, and collateral circulation. Then, the true effect of myocardial revascularization as treatment of CAD should be likewise assessed by measuring residual pressure gradients in coronary arteries after revascularization, i.e. as the functional efficacy in analogy to the functional significance of CAD. For multi-vessel disease the summary hemodynamic effectiveness of revascularization may be captured either by continuous variable, e.g. averaged magnitude of the post-procedural pressure gradients in the qualified arteries or by categorical index, e.g. a relative proportion of the arteries with significant post-procedural pressure gradients among the qualified arteries both preferably weighted for their significance in myocardial blood supply. For comprehensive comparison of the revascularization strategies the qualified arteries should include all arteries/branches that had significant disease at baseline and were amenable to treatment with at least one of the revascularization methods, e.g. with at least one stenosis \>70% and diameter \>1.5 mm. The categorical measure of the functional efficacy may also be considered a measure of the functional completeness of revascularization in analogy to the conventional anatomical completeness. This functional completeness in terms of removal of all significant pressure gradients in coronary arteries is expected to be superior to anatomical completeness for assessing the procedural success of the intervention because the successful grafting/stent implantation does not guarantee the permanent removal of the pressure gradients, which may still persist due to development of intimal hyperplasia along the suture line of surgical anastomosis or stent underexpansion/edge dissection. The primary purpose of the study is to assess whether iFR -guided HCR done as the staged procedure with LIMA-LAD MIDCAB at first stage, and percutaneous coronary intervention (PCI) of non-LAD arteries at the second stage, is superior to conventional CABG in terms of the functional efficacy of revascularization assessed by the weighted average of iFRs measured 12 month post-procedure in all coronary arteries with at least one significant stenosis (\>70% for CABG group, iFR ≤ 0.89 for iFR-guided HCR) and diameter ≥1.5 mm at baseline. For proximal lesions in major coronary arteries - LAD, circumflex (Cx), and right coronary artery (RCA) - the simple weights 0.5, 0.25, 0.25 will be used, respectively. For other lesions the Duke jeopardy scores will be used instead. Measurement of functional efficacy at 12 month post-procedure will allow assessment of the final result of the intervention after complete vessel healing, endothelialization of the stents, on stable antithrombotic treatment, etc. Also, this study will assess whether achieving the functional completeness of revascularization described above in addition to the anatomical completeness of the procedure may further improve the treatment outcomes in patients with multivessel CAD. Specifically, the investigators will assess the relationship between the functional completeness of the revascularization and the occurrence of the MACCE over 1, 3, and 5 years following randomization in the patients with anatomically complete procedures. Finally, the hypothesis will be tested that iFR-guided HCR has better overall safety than CABG. Whereas, compared to CABG HCR is associated with less frequent perioperative complications, blood transfusions, shorter ICU and hospital stays, these benefits of less invasive treatment may be overridden by the additional complications of stenting, e.g. acute stent thrombosis, dissection, arterial perforation/rupture and others. With iFR guidance of the HCR these additional complications of PCI are expected to be less frequent and the whole procedure - more safe.