CCTA reveals correlation between distal collaterals, myocardial infarction

Coronary CT angiography (CCTA) has revealed the presence of well-developed distal collaterals in patients with chronic total occlusion and the extent of downstream myocardial infarction, according to a study published online Feb. 19 by Radiology.

“Collaterals usually develop in the setting of [chronic total occlusion] to balance the myocardial blood supply in the territory of the occluded segment, and the beneficial effect of well-developed collateral vessels on both the salvageable myocardium and the occurrence of future major cardiac ischemic events has been demonstrated clearly,” wrote the study’s lead author, Jiayin Zhang, MD, of the Shanghai Jiao Tong University Affiliated Sixth People’s Hospital in China, and colleagues.

Zhang et al aimed to assess the correlation between the filling pattern of distal coronary vessels in patients with chronic total occlusion observed at CCTA and the extent of downstream myocardial infarction.

Their study included 97 patients with 106 chronic total occlusions. A four-point scale was utilized to semiquantitatively classify distal filling of the epicardial segment (a score of a three indicated well-developed distal collaterals). Cardiac MRI was used to semiquantitatively verify downstream myocardial infarction transmurality and wall motion abnormality.

Results revealed three lesions with a score of zero, 21 with a score of one, 35 with a score of two, and 47 with a score of three. The non-myocardial infarction subgroup was associated with higher collateral grading at CCTA, while the transmural myocardial infarction subgroup was associated with lower grading. The well-developed collateral group was correlated with a lower summed transmurality score and a lower summed regional wall motion abnormality score.

“In patients with coronary total occlusions, coronary CT angiography can be used to accurately grade distal coronary vessel opacification as a marker of collateral filling,” concluded the study’s authors.