Coronary competitive reverse flow: Imaging findings at CT angiography and correlation with invasive coronary angiography.

OBJECTIVE: To study the imaging features of coronary competitive reverse flow and incidence of a "reverse attenuation gradient" in coronary CT angiography (CTA) with correlation to invasive coronary angiography (ICA).

METHODS: Patients who had undergone coronary CTA and ICA within 2 weeks were retrospectively identified in our database and reviewed. All cases with ICA-confirmed competitive reverse flow or chronic total occlusions (CTOs) were included for further analysis. The "reverse attenuation gradient sign" was defined as a reverse intraluminal opacification gradient of vessels which showed higher opacification in more distal compared with proximal segments. ICA findings were recorded and served as the reference to identify the clinical implications of this sign.

RESULTS: In total, 134 patients (mean age, 68.1 ± 11.3 years; range, 38-90 years; 104 men) were included in our study. ICA revealed 11 cases of coronary competitive reverse flow and 123 cases of CTO. A reverse attenuation gradient sign was present in 9 of 11 patients (82%) with coronary competitive reverse flow and 72 of 123 (59%) chronically occluded coronary arteries. Myocardial bridges, distal collateral filling, as well as direct visualization of collateral connection were all more frequent in cases with coronary competitive reverse flow group compared with cases with a CTO.

CONCLUSIONS: The reverse attenuation gradient sign distal to an upstream coronary severe stenosis indicates the presence of competitive collateral flow. Coronary CTA is able to correctly detect coronary competitive collateral flow and differentiate it from CTOs.