Physiological impact of CTO recanalization assessed by coronary pressure measurement: A case report

In this case report, physiological changes of myocardial perfusion in the collateral recipient right coronary artery (RCA) and the collateral donor left anterior descending artery (LAD) with an intermediate lesion were assessed using intracoronary pressure measurement, before and after revascularization of chronic total occlusion (CTO). A 44-year-old male was referred for a catheter examination due to silent myocardial ischemia. An invasive coronary angiogram revealed diffuse narrowing of the RCA with focal occlusive segments in addition to intermediate stenosis in the LAD. A well developed collateral channel from the LAD to the RCA was also confirmed. Fractional flow reserve (FFRmyo) of the LAD before opening the RCA was 0.81. After successful revascularization of the RCA, FFRmyo of the LAD and the RCA were measured with and without an RCA balloon occlusion. Because collateral fractional flow reserve (FFRcoll) of the RCA could be regarded as FFRmyo before revascularization, FFRmyo of the RCA increased from 0.67 to 0.90, meaning a 23% increase of maximum flow by intervention. Interestingly, improvement of FFRmyo of the LAD from 0.81 to 0.93 was also observed, which means a 12% increase of maximum flow. Coronary steal in the LAD was reconfirmed by dramatic worsening of FFRmyo from 0.93 to 0.77 by an RCA balloon occlusion. This phenomenon may be explained by an immediate recruitment of collateral channels. This case clearly demonstrated that CTO opening improves perfusion in not only myocardium supplied by the CTO vessel, but also in that which is supplied by a contralateral collateral donor artery.