A Detailed Analysis of Perforations During Chronic Total Occlusion Angioplasty

概要

Introduction:
Chronic total occlusion (CTO), which is defined as 100% blockage of the coronary artery for at least 3 months, is a commonly encountered problem which can cause poor blood flow of the myocardium which can lead to quality of life limiting angina (Fefer et al., 2012). CTOs are the most complex and challenging lesion to treat for interventional cardiologists, and the complication rates are higher compared to usual percutaneous coronary intervention (PCI). Among the complications associated with CTO PCI, coronary perforation is the most feared complication as it is associated with mortality. The incidence of perforation is higher during CTO PCI compared with non-CTO PCI (Al-Lamee et al., 2011, Kinnaird et al., 2017), and is reportedly highest among retrograde procedures (Danek et al., 2017).

When the perforation occurs during CTO PCI, operators need to decide whether to treat the perforation with balloon inflation, covered stents or embolization material, or to simply observe. However, the characteristics of perforation during CTO PCI that require treatment compared to those that can be safely observed have not been previously described. Therefore, to address these key clinical gaps of knowledge, we sought to describe the angiographic characteristics, strategy associated with perforation and the management of perforation during CTO PCI.

Methods:
The OPEN-CTO study is a prospective, single-arm registry that enrolled consecutive patients with CTOs who underwent attempted CTO PCI at 12 experienced U.S. sites (Sapontis et al., 2017b). Among 1000 consecutive patients who were enrolled in this study, 89 (8.9%) had core-lab adjudicated angiographic perforations. Clinical perforation was defined as any perforation requiring treatment (Sapontis et al., 2017a). Major adverse events (MAE) were defined as in-hospital death, cardiac tamponade and pericardial effusion. Each perforation was evaluated for maximal area, length, location, shape, presence of staining, speed of filling, speed of drainage and strategy which caused the perforation, by the core-lab.

Results:
Among the 89 perforations, 43 (48.3%) were clinically significant, and 46 (51.7%) were simply observed. MAE occurred in 25 (28.0%) and in-hospital death occurred in 9 (10.1%). Four of the fatal perforation occurred among subjects with history of coronary artery bypass grafting (CABG) and 5 fatal perforations occurred among non-CABG patients.

Compared to non-clinical perforations, clinical perforations were larger in size, more often at a collateral location, high-risk shape, and less likely caused staining or fast filling. Compared to perforations not associated with MAE, perforations associated with MAE were larger in size, more proximal or at collateral location and had a high-risk shape. When the core-lab attributed the approach employed when the perforation occurred, among the 51 patients who had both antegrade and retrograde approaches during the CTO PCI, perforation occurred during antegrade attempt in 31 patients (60.1%). Notably, all 8 perforations that occurred in the epicardial vessels were clinical perforations and among the 8 patients, 4 suffered in-hospital death which represents the most fatal perforation type.

Discussion:
In this first study to describe the detailed angiographic characteristics experienced by patients undergoing CTO PCI, we found that larger size, collateral location, a high-risk shape, less staining, fast filling and fast drainage were associated with clinically-important perforations requiring treatment. High- risk perforations included “cloud-like” and “floating” among the 7 shapes evaluated.

Our study is the first study to determine the strategy that caused perforation based on core-lab review. We found that 6 out of 10 perforations occurred with antegrade approaches among patients who had both strategies attempted. This finding suggests that the reported complication rates from previous studies cannot be attributed solely to the retrograde strategy itself and may be related to the complex anatomy in patients undergoing retrograde or combined strategy compared to antegrade only strategy. Future studies need to take the strategy that caused perforation into account when comparing antegrade and retrograde approaches.
Our finding of higher risk of MAE than expected when perforations occur at the epicardial collaterals are in line with the previous studies (Azzalini et al., 2017). This is most likely related to the increased risk of pericardial effusion/cardiac tamponade given the anatomy, and difficulty controlling the bleeding due to dual blood supply from both antegrade and retrograde arteries. This finding suggests that epicardial collaterals should be reserved as a last resort when planning CTO PCI. In particular, less experienced operators may need to compare the risk of epicardial collaterals when perforations occur with safer antegrade bail-out options such as sub-intimal tracking and re-entry (STAR) technique (Colombo et al., 2005) or subintimal plaque modification (SPM) technique (Hirai et al., 2018) when no other options are available.

These findings should help both current and emerging CTO operators avoid perforations, understand high risk features, and better triage perforation treatment during CTO PCI.

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