The impact of chronic total occlusion percutaneous coronary intervention on the coronary physiology of the donor epicardial vessel: a case series

Background In chronic total occlusion (CTO), donor vessels supplying collateral flow to the occluded artery may exhibit altered physiological indices, potentially influencing revascularization decisions. This case series evaluates the impact of successful CTO percutaneous coronary intervention (PCI) on instantaneous wave-free ratio (iFR) measurements in donor vessels with moderate stenosis.Methods We present a single-center case series (December 2020–September 2024) involving five patients with right coronary artery (RCA) CTO and a moderately diseased mid-left anterior descending artery (LAD) functioning as a collateral donor. All patients underwent ischemia testing and successful RCA CTO PCI. LAD iFR was measured before and after RCA revascularization.Results Pre-PCI LAD iFR values ranged from 0.73 to 0.89, at or below the ischemic threshold. Post–RCA-PCI iFR improved in all cases (range: 0.87–0.96): in case 1, from 0.82 to 0.93; in case 2, from 0.82 to 0.89; in case 3, from 0.87 to 0.96; in case 4, from 0.73 to 0.87; and in case 5, from 0.89 to 0.96. In all cases, intervention on the LAD was deferred post-PCI, with no adverse clinical events during follow-up.Conclusion Successful RCA CTO PCI leads to immediate improvement in donor vessel iFR, suggesting that collateral demand may exaggerate ischemia. Staged physiologic assessment may improve decision-making in patients with moderate lesions in donor vessels.