Key result
Well-developed collaterals were associated with a lower proportion of segments with transmural scar in the CTO territory compared to poorly-developed collaterals (17% vs 25%, p=0.010).
Why the study?
Viability and functional assessments are recommended for CTO indication and intervention, prompting evaluation of myocardial viability and LV function by CMR and their relationship with collaterals.
What is the relationship between coronary collaterals, myocardial viability, and left ventricular function assessed by CMR in patients with chronic coronary total occlusion?
Observational (n=194)
No
What is the relationship between coronary collaterals, myocardial viability, and left ventricular function assessed by CMR in patients with chronic coronary total occlusion?
Absolute Event Rate: 17% vs 25%
p-value: p=0.010
In patients with CTO, well-developed collaterals do not correlate with overall myocardial scar prevalence or LVEF, but are associated with a reduced number of non-viable segments.
Poorly developed collaterals associate with more transmural scar in CTO territories; leaves open whether collateral grading refines CMR viability assessment pre-revascularization.
Objective: Viability and functional assessments are recommended for indication and intervention for chronic coronary total occlusion (CTO). We aimed to evaluate myocardial viability and left ventricular (LV) functional status by using cardiovascular magnetic resonance (CMR) and to investigate the relationship between them and collaterals in patients with CTO. Materials and Methods: We enrolled 194 patients with one CTO artery as detected by coronary angiography. Patients were scheduled for CMR within 1 week after coronary angiography. Results: A total of 128 CTO territories (66%) showed scar based on late gadolinium enhancement (LGE) imaging. There were 1,112 segments in CTO territory, while only 198 segments (18%) subtended by the CTO artery showed transmural scar (i.e., >50% extent on LGE). Patients with viable myocardium had higher LV ejection fraction (LVEF) (56.7 ± 13.5% vs. 48.3 ± 15.4%, p < 0.001) than those with transmural scar. Angiographically, well-developed collaterals were found in 164 patients (85%). There was no significant correlation between collaterals and the presence of myocardial scar ( p = 0.680) or between collaterals and LVEF ( p = 0.191). Nevertheless, more segments with transmural scar were observed in patients with poorly-developed collaterals than in those with well-developed collaterals (25 vs. 17%, p = 0.010). Conclusion: Myocardial infarction detected by CMR is widespread among patients with CTO, yet only a bit of transmural myocardial scar was observed within CTO territory. Limited number of segments with transmural scar is associated with preserved LV function. Well-developed collaterals are not related to the prevalence of myocardial scar or systolic functioning, but could be related to reduce number of non-viable segments subtended by the CTO artery.
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Yang et al. (2021) conducted an observational in Chronic coronary total occlusion (n=194). Well-developed collaterals vs. Poorly-developed collaterals was evaluated on Proportion of segments with transmural scar (>50% LGE) in CTO territory (p=0.010). Well-developed collaterals were associated with a lower proportion of segments with transmural scar in the CTO territory compared to poorly-developed collaterals (17% vs 25%, p=0.010).
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