Impact of Coronary Collaterals on the Outcomes of Chronic Total Occlusion Percutaneous Coronary Intervention

The retrograde approach is an essential tool for achieving higher success rates in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) of complex lesions.¹ To achieve lesion crossing with the retrograde technique, equipment must be advanced through a collateral channel into the distal true lumen of the vessel.² The presence of interventional collaterals, which are collateral vessels deemed crossable by the operator, is a significant factor in determining whether the retrograde strategy should be used according to the global CTO crossing algorithm.³ This study aims to evaluate the impact that the presence of interventional collaterals has on the outcomes of CTO PCI.

We examined the clinical and angiographic characteristics and procedural outcomes of 11 205 patients who underwent 11 444 CTO PCIs at 45 US and non-US centers between 2012 and 2023. Interventional collaterals were defined as collaterals deemed crossable by a guidewire and a microcatheter by the operator as assessed before an attempt to cross them is made. Categorical variables are expressed as percentages and compared using the Pearson’s chi-square test. Continuous variables are presented as mean ± standard deviation and compared using the independent samples t-test. Univariable logistic regression was performed to identify variables that might be associated with technical success and major adverse cardiovascular events (MACE); variables that had P<.10 and were deemed clinically/angiographically significant were included in the multivariable analysis in addition to clinically relevant variables chosen a priori and deemed to influence the outcomes of interest. All statistical analyses were performed using R Statistical Software, version 4.2.2 (R Foundation for Statistical Computing). A P value of <.05 was considered statistically significant.

Interventional collaterals were present in 6553 (57%) CTO PCI cases. Patients without interventional collaterals were more likely to be men (82.1% vs 80.3%; P=.021) and less likely to present with stable angina compared with patients with interventional collaterals (63.2% vs 69.4%; P<.001). Compared with lesions with interventional collaterals, lesions without interventional collaterals were less complex, with shorter length (2.79 ± 0.52 vs 2.96 ± 0.50; P<.001) and higher prevalence of proximal cap ambiguity (30.2% vs 38.7%; P<.001), blunt/no stump (48.2% vs 55.1%; P<.001), and moderate to severe calcification (42.1% vs 45.6%; P<.001). They also had higher PROGRESS-CTO scores (1.84 ± 0.93 vs. 0.81 ± 0.84; P<.001) and were more commonly located in the left circumflex (29.5% vs 11.1%; P<.001) and left anterior descending (30.8% vs 23.1%; P<.001) arteries.

In 126 (2.6%) cases, retrograde was the successful crossing strategy, despite the absence of interventional collaterals. Cases with interventional collaterals were more likely to require a longer procedure (122 vs. 100 min; P<.001) and fluoroscopy (48 vs. 36 min; P<.001) time.

The presence of interventional collaterals was associated with higher technical (88.4% vs 84.1%; P<.001) and procedural (86.8% vs 83.2%; P<.001) success, but also slightly more MACE (2.3% vs 1.5%; P=.004) (Figure 1A). Perforations were also more common in the presence of interventional collaterals (5.4% vs 3.9%; P<.001). After adjusting for potential confounders, the presence of interventional collaterals was associated with higher technical success (odds ratio [OR]: 1.69; 95% CI: 1.47-1.94) (Figure 1B) and no difference in MACE (OR: 1.32; 95% CI: 0.97-1.80; P=.077).

In 2003, Werner et al introduced a collateral grading system designed specifically for CTO cases. This system, known as the Werner collateral connection grade, was found to be a highly significant.⁴ The Werner collateral connection grade of a lesion was shown to be one of the most significant predictors of success when using the retrograde crossing strategy (Werner collateral connection [CC] 1 [OR: 4.87; 95% CI: 2.90-8.19; P<.001] or CC2 [OR: 5.33; 95% CI: 3.02-9.42; P<.001]).⁵ A meta-analysis of 12 studies with a total of 3369 patients found that patients with robust collaterals had a higher likelihood of successful PCI (OR: 4.04, 95% CI: 1.10-14.85), with no difference in acute myocardial infarction and mortality risk, compared with patients with poor collaterals.⁶

The limitations of the study include its retrospective design, the absence of core laboratory assessment of angiograms, and a lack of clinical event evaluation. The CTO PCIs in the PROGRESS-CTO registry were carried out at specialized, high-volume CTO centers with experienced operators, which may limit the applicability of the results to centers with less experience in CTO PCI.

In conclusion, patients with interventional collaterals have more complex lesions and require longer procedures, but they also have higher rates of technical success.

Acknowledgments: The authors are grateful for the philanthropic support of our generous anonymous donors, and the philanthropic support of Drs. Mary Ann and Donald A Sens; Mrs. Diane and Dr. Cline Hickok; Mrs. Wilma and Mr. Dale Johnson; Mrs. Charlotte and Mr. Jerry Golinvaux Family Fund; the Roehl Family Foundation; the Joseph Durda Foundation. The generous gifts of these donors to the Minneapolis Heart Institute Foundation’s Science Center for Coronary Artery Disease helped support this research project.

Affiliations and Disclosures

From ¹the Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott Northwestern Hospital, Minneapolis, MN, USA; ²University Hospitals, Case Western Reserve University, Cleveland, OH, USA

Disclosures: Dr Poommipanit is a consultant for Asahi Intecc, and Abbott Vascular. Dr. Brilakis receives consulting/speaker honoraria from Abbott Vascular, American Heart Association (associate editor Circulation), Amgen, Asahi Intecc, Biotronik, Boston Scientific, Cardiovascular Innovations Foundation (Board of Directors), CSI, Elsevier, GE Healthcare, IMDS, Medicure, Medtronic, Siemens, Teleflex, and Terumo; research support from Boston Scientific, GE Healthcare; is the owner of Hippocrates LLC; and is a shareholder in MHI Ventures, Cleerly Health, and Stallion Medical. The remaining authors report no financial relationships or conflicts of interest regarding the content herein.

Address for correspondence: Paul Poommipanit, MD, UH Parma Medical Center, 6525 Powers Blvd #301, Parma, OH 44129, USA. Email: ppoommipanitmd@gmail.com

References

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