Qualitative angiographic and quantitative myocardial perfusion assessment using fluorescent cardiac imaging during graded coronary artery bypass stenosis.

Intraoperative graft assessment in coronary artery bypass (CAB) grafting is important to avoid early graft failure. This study aimed to evaluate the accuracy of fluorescent cardiac imaging (FCI) for intraoperative qualitative angiographic and quantitative myocardial perfusion assessment during graded CAB stenosis compared to coronary angiography (CA). After CAB grafting to the left anterior descending coronary artery, graded distal bypass stenoses were created in ten pigs by 25, 50, 75, and 100% flow reduction assessed by transit-time flow measurement (TTFM). Visual angiographic assessment was performed by FCI and CA during baseline and graded bypass stenoses. Altered myocardial perfusion was assessed by quantitative intraoperative fluorescence intensity (QIFI) derived from FCI and correlated to TTFM. Patent bypass grafts and graft occlusion were visualized successfully by FCI and CA, while discrimination between various graded bypass stenosis was possible in 73.3%. The degree of CAB stenosis was overestimated in 16.7% and underestimated in 10.0% by FCI compared to CA. Graded CAB stenosis reduced regional myocardial perfusion quantified by decreased QIFI value (p < 0.001). Mean QIFI value was 76.8 (95% CI 67.2-86.3) during baseline, 55.6 (95% CI 45.3-65.9) during 25% flow-reduction, 30.6 (95% CI 22.3-39.0) during 50% flow-reduction, 20.3 (95% CI 15.4-25.3) during 75% flow-reduction, and 0 during CAB occlusion (p < 0.001) with a significant correlation to TTFM (r = 0.955; p < 0.0001). Solely visual assessment of CAB quality using FCI is limited as compared to CA. Additional QIFI assessment identified graded CAB stenosis and occlusion with a significant correlation to TTFM.