Different trials have shown that fractional flow reserve (FFR) could successfully guide revascularization in patients undergoing percutaneous coronary intervention (PCI).

It is conceivable that a similar revascularization guidance could be useful also for surgical revascularization i.e. coronary by-pass graft (CABG). Experience learns that grafts placed on vessels with hemodynamically non-significant stenosis often occlude due to competitive antegrade flow.

Resting full-cycle Flow Ratio (RFR) is a measurement performed to evaluate the hemodynamic severity of coronary stenosis. Differently from FFR which is a measurement performed in maximal hyperemia, the RFR is a measurement that is performed in rest and therefore may predict better than FFR the baseline equilibriums that could lead to graft failure, while it has similar capacity to identify hemodynamically significant stenosis as FFR. It is unknown whether RFR guided CABG revascularization is superior as compared to angiography alone.

Inclusion Criteria:

• All patients between 18 or older undergoing CABG
• Patients willing and capable to provide written informed consent

Exclusion Criteria:

• Previous CABG
• Concomitant severe valvular disease intervention
• Remaining (expected) coronary stenosis of > 50% diameter stenosis distally to graft anastomosis
• Left ventricular ejection fraction <30%
• Known transmural myocardial infarction
• Documented microvascular disease
• RFR/FFR measurement judged impossible
• Life expectancy <2 years
• Participation in other investigational clinical trials

This has not been decided yet.

All patients will undergo RFR and FFR measurement before CABG. RFR and FFR values will be blinded to the patients in both arms. In the control arm (angiography guided CABG) the RFR values will be blinded to the cardiothoracic surgeon.