Purpose: There is a paucity of data regarding the border zone parameters in patients with chronic coronary total occlusion (CTO). We investigated the border zone extent and contractile function and their associations with collateral flow.
Methods: CTO patients (n = 47) and sex- and age-matched volunteers (n = 15) were prospectively enrolled and underwent cardiac MRI examinations to acquire cine and late-gadolinium enhancement (LGE) images. Myocardial peak strain (PS) and the time to PS were determined at the segmental level and global level. Infarct, border zone, adjacent, and remote regions were defined according to the transmural extent of infarction (TEI) by LGE at each segment. Angiographic collateral flow was evaluated using the Rentrop grading system.
Results: CTO patients with well-developed collateral flow had a higher TEI in border zone regions compared to patients with poorly developed collateral flow (p = 0.02). Conversely, CTO patients with poorly developed collaterals showed a higher TEI in infarct regions (p < 0.01). Enhanced border function, characterized by greater PS and earlier time to PS, was noted in well-developed collaterals (all p < 0.05). In the multivariate linear analyses, the level of collateral flow was an independent predictor of the border zone extent (β = 0.40, p = 0.02) and contractile function (radial: β = -0.42, p = 0.02; circumferential: β = 0.39, p = 0.02; and longitudinal: β = 0.47, p < 0.01).
Conclusions: In CTO patients, the presence of well-developed collateral flow was closely linked to a greater extent of LGE and contractile function in border zone regions. Our findings shed light on the cardiac MRI-based pathophysiological underpinning in border zone regions, which could offer complementary and prognostic information in clinical practice.
Keywords: Border zone; Cardiac MRI; Chronic coronary total occlusion; Collateral flow; Myocardial strain.
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