Prevalence of Collateral Typology in Coronary Chronic Total Occlusion and its Impact on Percutaneous Intervention Performance

•The presence of collateral channels is a distinctive characteristic of CTO lesions•Each CTO subset, defined by collateral anatomy, had specific angiographic features•CTO-PCI with ipsilateral collaterals was largely possible through a single access•Procedural success rate was uniformly high irrespective of CTO subset•Phenotyping CTO as hereby described might guide specific procedural considerations The presence of collateral channels providing distal blood supply is a distinctive characteristic of chronic total occlusion (CTO) lesions. However, data about the distinct baseline and procedural characteristics of each collateral subset are scarce. Accordingly, we sought to explore the procedural aspects specific for each collateral typology (ipsilateral collaterals [IC], contralateral collaterals [CC] or mixed) in CTO-percutaneous coronary intervention (PCI). A retrospective analysis of our CTO-PCI registry was performed to investigate the prevalence, procedural characteristics, and outcomes specific for each CTO-PCI subset, defined according to the inter-arterial connection anatomy. A total of 209 cases were included. Forty-five (22%) and 92 (44%) patients displayed solely IC or CC, respectively, whereas in 72 (34%) both IC and CC were present [mixed]. The procedural success rate was high (91.1%) and comparable among the different groups, despite greater lesion complexity in the CC group. The most frequent target vessel was the left circumflex in the IC group (51% of cases) and the right coronary artery in the CC (63%) and mixed (57%) groups. Among the IC cases, 42% showed a poor collateral connection function (2% and 10% for the CC and mixed group, respectively), and 46% showed a suboptimal collateral recipient artery filling (21% and 20% for the CC and mixed group, respectively). Most of IC cases were performed using a single access (96%). In conclusions, the success and complication rates were comparable among the collateral typology groups, irrespective of the differences in the baseline and procedural characteristics. Phenotyping CTO as hereby proposed might be helpful for targeted procedural considerations.