Quantitative flow ratio of the donor coronary artery supplying a chronic total occlusion territory.

Background: Coronary physiology to guide multi-vessel coronary intervention is associated with better outcome. In the presence of a coronary chronic total occlusion (CTO), hemodynamic evaluation of intermediate lesions in the donor coronary artery supplying a CTO territory still has limitations. We aim to evaluate implementing quantitative flow ratio (QFR) in assessing angiographically intermediate lesions of the main donor coronary artery supplying a CTO territory.

Methods: We recruited 219 patients with a single main donor vessel to a CTO territory from a single-center CTO registry between 2017 and 2020. Angiographically intermediate coronary lesions of the donor vessels were evaluated using offline QFR before and at a median of 6 months after successful percutaneous coronary intervention (PCI) of CTO.

Results: The mean age of the study population was 66.9 ± 11.3 years, and 77.6% were males. Three-vessel disease was documented in 49.8%. The mean QFR value increased significantly in the donor vessels after successful CTO revascularization (0.93 ± 0.062 vs. 0.95 ± 0.046, p < 0.001) and was more prominent in donor vessels with angiographically intermediate stenosis (0.88 ± 0.063 vs. 0.92 ± 0.053, p < 0.001). While the change in QFR was not significant in angiographically normal donor vessel (0.97 ± 0.025 vs. 0.97 ± 0.026, p = 0.814). Fifteen patients had hemodynamically significant stenosis in the donor coronary artery (QFR ≤ 0.80) before CTO-PCI. Among those patients, 40% (n = 6) were turned to be non-significant with QFR > 0.80 after CTO recanalization, and 30% (n = 5) patients remained significant and were treated with PCI.

Conclusion: QFR overestimates the severity of intermediate coronary lesions of a donor vessel supplying a CTO territory like other invasive modalities for physiology assessment.