New Aspects in Percutaneous Coronary Intervention of Chronic Total Occlusions

Coronary Chronic total occlusions (CTOs) are defined as coronary lesions with Thrombolysis in Myocardial Infarction (TIMI) grade 0 flow of at least 3-month duration. Symptomatic patients with CTOs can be managed in three ways, conservatively with medical therapy, with coronary artery bypass grafting (CABG) or with percutaneous coronary intervention (PCI). CTO PCI can be challenging to perform with variable success rates, depending on operator experience and expertise, but with the development of new techniques and equipment the success rates are getting higher and the complication rates lower. In this dissertation, we focused on three aspects of CTO PCI: (a) the impact of prior failure on the outcomes of CTO PCI, (b) balloon uncrossable lesions and (c) the frequency of use and outcomes of intravascular imaging. We examined the prevalence, clinical and angiographic characteristics, management and procedural outcomes of CTO PCIs in a contemporary, large, multicenter CTO PCI registry. Prior CTO PCI failure has been associated with lower procedural success rates and is part of the Japanese Chronic Total Occlusion (J-CTO) score that was developed to predict the likelihood of successful guidewire crossing within 30 minutes. We sought to examine the impact of prior failure on the subsequent outcomes CTO PCI. The main finding of our study is that a prior failed CTO PCI attempt is associated with higher angiographic complexity, longer procedural duration and fluoroscopy time, but not with lower success and higher complication rates of subsequent CTO PCI attempts. Balloon uncrossable lesions are lesions that cannot be crossed with a balloon after successful advancement of the guidewire distal to the lesion. These lesions can be challenging to treat, requiring specialized techniques and equipment. In our study, we found that balloon uncrossable CTOs are common, are associated with high rates of technical failure, and require specialized techniques for successful treatment. Intravascular imaging can facilitate CTO PCI. Use of intravascular ultrasound (IVUS) for stent optimization during CTO PCI has been shown to improve long-term outcomes, yet its impact on crossing has received limited study. In our study, we found that intravascular imaging is frequently performed during CTO PCI both for crossing and for stent selection/ optimization. Despite its use in more complex lesion subsets, intravascular imaging was associated with similar rates of technical and procedural success for CTO PCI