Validation of the J-Channel Score for Retrograde Channel Crossing in the PROGRESS-CTO Registry

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J INVASIVE CARDIOL 2024. doi:10.25270/jic/24.00006. Epub February 26, 2024.

Successful collateral channel (CC) crossing is essential for the success of retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI). Based on the Japanese CTO PCI expert registry, the J-Channel score was developed to predict CC crossing. We examined the performance of the J-Channel score in patients who underwent retrograde CTO-PCI at 31 centers between 2013-2023 as part of the Prospective Global Registry for the Study of CTO Intervention (PROGRESS-CTO). While we observed an association between successful CC crossing and the J-Channel score, its predictive efficacy was modest for both wire and microcatheter crossing.

Successful collateral channel (CC) crossing is essential for the success of retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI).^1,2 Based on the Japanese CTO PCI expert registry, the J-Channel score was developed to predict CC crossing success using 4 variables: vessel size, continuous bends, reverse bend, and corkscrew morphology.³ The performance of the J-Channel score has received limited study.

We examined the performance of the J-Channel score in 1689 CCs and 1061 patients who underwent retrograde CTO-PCI at 31 centers between 2013 and 2023 as part of the Prospective Global Registry for the Study of CTO Intervention (PROGRESS-CTO). The J-Channel was calculated according to CC location (septal or non-septal) for all patients, and patient characteristics and outcomes were summarized. Patients were divided in 3 groups (easy: 0; intermediate: 1-2; difficult: ≥ 3) based on their scores. Univariable logistic regression was used to investigate the association between successful crossing and J-Channel score. The discriminative capacity of the score was assessed using the area under the curve (AUC) of the receiver-operating characteristic (ROC) curve. The goodness-of-fit was computed by Hosmer-Lemeshow test and calibration plots. Interrater variability was calculated with Fleiss’s Kappa test with 3 observer groups (2 independent interventional cardiologists and the J-Channel scores reported in the registry). Thirty CCs were randomly sampled for this analysis. All statistical analyses were performed using R Statistical Software, version 4.2.2 (R Foundation for Statistical Computing).

Mean age was 62.7 ± 10.2 years, and most patients were men (81.1%). The most common target vessel was the right coronary artery (80.2%), followed by the left anterior descending coronary artery (15.6%) and left circumflex coronary artery (4.2%). Mean J-CTO score and PROGRESS-CTO scores were 2.92 ± 1.06 and 1.07 ± 0.82, respectively. The most common CC type was septal (81%), followed by non-septal CC (epicardial CC [17.4%], bypass graft CC [1.5%]). Technical success was achieved in 836 patients (78.8%). Successful guidewire crossing rate was higher for septal CC compared with non-septal CC (51.7% vs 42.7%; P = .043). Microcatheter successful crossing rates were similar (45% vs 37.1%; P =.075). Coronary perforations were more common in non-septal CC (9.7% vs 19.2%; P < .001).

The J-Channel score (adjusted for septal and non-septal scores, accordingly) was negatively associated with the likelihood of successful wire crossing (odds ratio [OR]: 0.62 per 1 score unit increase; 95% CI, 0.57-0.67; P < .001) and successful microcatheter crossing (OR:0.62 per 1 score unit increase; 95% CI, 0.56-0.67; P < .001). When compared with the derivation population, the PROGRESS-CTO patients had lower CC wire crossing success for easy difficulty grade based on both septal and non-septal J-Channel scores, and higher CC wire crossing success rates for intermediate and difficult grades (Figure, A and B). The AUC of the J-Channel score was 0.653 (95% CI, 0.628-0.678) for successful wire crossing (Figure, C), and 0.654 (95% CI, 0.629-0.680) for successful microcatheter crossing (Figure, D). The model showed satisfactory goodness-of-fit (Hosmer-Lemeshow P = .59, P = .52; respectively) (Figure, E and F). Interrater reliability resulted in a moderate level of agreement between 3 observer groups for septal J-Channel score (Kappa = 0.415; 95% CI, -0.278-1.108; P < .001) and non-septal J-Channel score (Kappa = 0.432; 95% CI, -0.372-1.236; P < .005).

Suitable CC selection is challenging for recognition as interventional collaterals and a critical factor in determining the strategy type, complexity, and procedural success.^1,4 Calculation of the J-Channel score in septal CC is different from non-septal CC: different points are assigned for small CC size, continuous bends  (only used for septal CC score calculation) and corkscrew collateral morphology (only used for non-septal CCs). For both septal CC and non-septal CCs, the most important factor was vessel size, as quantified by Werner et al.⁵

The original article highlighted the predictive capability of the J-Channel score for wire crossing.³ However, both our study and the study by Chang et al demonstrated that the J-Channel score moderately predicts wire crossing in 2 separate independent study cohorts.⁶ Moreover, despite its moderate capacity, we conducted an external validation of the J-Channel score concerning microcatheter CC crossing.

Our study has limitations. First, there was no core laboratory assessment of angiograms and event adjudication of the complications. Second, procedures were performed by experienced and dedicated CTO-PCI operators, which potentially limits the generalizability to centers with less experience in CTO-PCI.

While we observed an association between successful CC crossing and the J-Channel score, its predictive efficacy was modest for both wire and microcatheter crossing. 

From the ¹Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott Northwestern Hospital, Minneapolis, Minnesota, USA; ²Cleveland Clinic, Cleveland, Ohio, USA; ³Henry Ford Cardiovascular Division, Detroit, Michigan, USA; ⁴Biruni University Medical School, Istanbul, Turkey.

Acknowledgments: The authors are grateful for the philanthropic support of our generous anonymous donors (2), and the philanthropic support of Drs. Mary Ann and Donald A Sens; Mr. Raymond Ames and Ms. Barbara Thorndike; Frank J. and Eleanor A. Maslowski Charitable Trust; Joseph F. and Mary M Fleischhacker Family Foundation; Mrs. Diane and Dr. Cline Hickok; Mrs. Marilyn and Mr. William Ryerse; Mr. Greg and Mrs. Rhoda Olsen; 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 (CCAD) helped support this research project.

Disclosures:  Dr. Khatri receives personal honoraria for proctoring and speaking from Abbott Vascular, Medtronic, Terumo, Shockwave, and Boston Scientific. Dr. Alaswad receives consulting/speaker honoraria from Boston Scientific, Abbott Vascular, Teleflex, and CSI. Dr. Sandoval receives consulting/speaker honoraria from Abbott Diagnostics, Roche Diagnostics, Zoll, and Philips; is an associate editor for JACC Advances; and holds patent 20210401347. Dr. Burke receives consulting and received speaker honoraria from Abbott Vascular and Boston Scientific. 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, and Teleflex; research support from Boston Scientific, GE Healthcare; is the owner of Hippocrates LLC; and is a shareholder of 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: Emmanouil S. Brilakis, MD, PhD, Minneapolis Heart Institute, 920 E 28th Street #300, Minneapolis, MN 55407, USA. Email: esbrilakis@gmail.com.