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Impact of Target Vessel on the Procedural Techniques and Outcomes of Chronic Total Occlusion Percutaneous Coronary Intervention
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ABSTRACT
BACKGROUND. There is limited information on the impact of the target vessel on the procedural techniques and outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). METHODS. We analyzed the baseline clinical and angiographic characteristics and procedural outcomes of 11,580 CTO PCIs performed between 2012 and 2022 at 44 centers. RESULTS. The most common CTO target vessel was the right coronary artery (RCA) (53.1%) followed by the left anterior descending artery (LAD) (26.0%) and the left circumflex artery (LCX) (19.8%). RCA CTOs were longer and more complex, with a higher Japanese CTO score compared with LAD or LCX CTOs. Technical success was higher among LAD (88.8%) lesions when compared with RCA (85.7%) or LCX (85.8%) lesions (P<.001). The incidence of major adverse cardiovascular events (MACE) was overall 1.9% (n = 220) and was similar among target vessels (P=.916). There was a tendency toward more frequent utilization of the retrograde approach for more proximal occlusions in all 3 target vessels. When compared with all other RCA lesions combined, distal RCA lesions had higher technical success (87.7% vs 85.3%; P=.048). Technical success was similar between various locations of LAD CTOs (P=.704). First/second/third obtuse marginal branch had lower technical success when compared with all other LCX lesion locations (82.7% vs 86.8%; P=.014). There was no association between MACE and CTO location in all 3 target vessels. CONCLUSIONS. LAD CTO PCIs had higher technical and procedural success rates among target vessels. The incidence of MACE was similar among target vessels and among various locations within the target vessel.
INTRODUCTION
Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) can be highly challenging, with success rates varying based on various angiographic characteristics.1-3 The impact of CTO target vessel and target lesion location has received limited study, with circumflex lesions appearing to have lower success rates in prior analyses.4-6 The goal of our study was to examine the impact of CTO target vessel on the procedural techniques and outcomes of CTO PCI in a large multicenter registry.
METHODS
Patient population. We analyzed the impact of target vessel and target lesion location on the procedural techniques and outcomes of 11,580 CTO PCIs performed between 2012 and 2022 at 44 centers. Patients who had a second CTO lesion were excluded from the analysis. Data collection was recorded in a dedicated online database (PROGRESS CTO: Prospective Global Registry for the Study of Chronic Total Occlusion Intervention; Clinicaltrials.gov identifier: NCT02061436). Study data were collected and managed using REDCap (Research Electronic Data Capture) electronic data capture tools hosted at the Minneapolis Heart Institute Foundation.7,8 The study was approved by the institutional review board of each center.
Definitions. Coronary CTOs were defined as coronary lesions with TIMI (Thrombolysis in Myocardial Infarction) grade 0 flow of at least 3 months duration. Estimation of the duration of occlusion was clinical, based on the first onset of angina, prior history of myocardial infarction (MI) in the target vessel territory, or comparison with a prior angiogram. Technical success was defined as successful CTO revascularization with achievement of <30% residual diameter stenosis within the treated segment and restoration of TIMI grade 3 antegrade flow. Procedural success was defined as the achievement of technical success without any in-hospital major adverse cardiac events (MACE). In-hospital MACE included any of the following adverse events prior to hospital discharge: death, MI, recurrent symptoms requiring urgent repeat target-vessel revascularization with PCI or coronary artery bypass graft (CABG) surgery, tamponade requiring either pericardiocentesis or surgery, and stroke. MI was defined using the Third Universal Definition of Myocardial Infarction (type 4a MI).9 The Japanese CTO (J-CTO) score was calculated as described by Morino et al10, the PROGRESS-CTO score as described by Christopoulos et al11,the PROGRESS-CTO MACE score as described by Simsek et al12, and the PROGRESS-CTO perforation score as defined by Kostantinis et al.13
Statistical analysis. Categorical variables were expressed as percentages and were compared using the Pearson’s chi-square test. Continuous variables are presented as mean ± standard deviation or as median (interquartile range [IQR]) unless otherwise specified) and were compared using the student’s t-test for normally distributed variables and the Wilcoxon rank-sum test for nonparametric variables, as appropriate. The variables associated with technical success and MACE were examined using univariable logistic regression; variables that had P<.10 and were deemed clinically/angiographically significant were included in the multivariable analysis. All statistical analyses were performed using JMP, version 16.0 (SAS Institute). A P-value of <.05 was considered to indicate statistical significance.
RESULTS
Target vessel
Patient characteristics. During the study period, 11,580 CTO PCIs were performed at 44 study centers. The most common CTO target vessel was the right coronary artery (RCA) (53.1%) followed by the left anterior descending artery (LAD) (26.0%) and the left circumflex artery (LCX) (19.8%) (Figure 1). Left main was the CTO target vessel in 77 cases (0.7%), saphenous vein graft in 37 cases (0.3%), and left internal mammary artery in 11 cases (0.1%). The baseline clinical characteristics by target vessel are presented in Table 1. Male gender, diabetes, prior MI, prior PCI, and prior CABG were more common in LCX patients, while current smoking and chronic lung disease were more common in the RCA group. Mean left ventricular ejection fraction was higher in patients with RCA CTOs compared with patients who had LAD or LCX CTOs (51.4 ± 12.3% vs 49.2 ± 13.6% and 49.1 ± 13.1%, respectively; P<.001).
Angiographic characteristics. RCA CTOs were longer and more complex with a higher J-CTO score and higher PROGRESS-CTO MACE score compared with LAD or LCX CTOs. The angiographic characteristics of the CTO lesions by target vessel are shown in Table 1.
Procedural characteristics. RCA CTO PCIs more frequently required the use of advanced techniques, such as the retrograde approach and antegrade dissection and re-entry (ADR) technique, compared with LAD or LCX CTOs (Figure 2). RCA CTO PCIs required longer procedure time and fluoroscopy time, as well as higher air kerma (AK) radiation dose, compared with LAD or LCX CTO PCIs. However, LAD CTO PCIs required higher contrast volume (Figure 3).
Procedural outcomes. Technical and procedural success rates were higher among LAD CTOs when compared with RCA or LCX CTOs (Figure 4A). After adjusting for multiple clinical and angiographic characteristics, RCA CTOs were associated with lower technical success when compared with LAD CTOs (odd ratio [OR] = 0.81, 95% confidence interval [CI] 0.67-0.97), but there was no association when compared with LCX CTOs (OR = 0.90, 95% CI 0.74-1.09) (Figure 5).
The incidence of periprocedural MACE was 1.9% (n = 220): death (0.4%), acute MI (0.5%), stroke (0.2%), repeat PCI (0.2%), emergency CABG (0.1%), and tamponade requiring pericardiocentesis (0.9%) without differences between target vessels. The incidence of in-hospital complications was similar among target vessels (Figure 4B).
Target lesion location
Right coronary artery. The majority of the RCA CTOs were located within the proximal (41.0%) and mid (43.5%) segment, followed by the distal RCA (12.1%) and right posterior atrioventricular segment (PAV), right posterior descending artery (PDA), and right posterolateral (PL) segments (3.4% combined) (Figure 1). When compared with all other RCA lesions combined, proximal RCA lesions were longer (43.4 ± 27.1 mm vs 30.0 ± 19.1 mm; P<.001), had a higher J-CTO score (2.80 ± 1.18 vs 2.35 ± 1.29; P<.001), and were more likely to have an ambiguous proximal cap (45.6% vs 29.7%; P<.001) (Table 2).
There was more frequent utilization of antegrade wiring (AW) and less frequent utilization of ADR or the retrograde approach for more distal RCA CTOs (Table 2). This was mirrored in the distribution of the final successful crossing strategy (Figure 6A): proximal lesions were crossed using the retrograde approach (38.9%), whereas, more than half (63.1%) of the technical success in distal lesions was achieved using AW.
When compared with all other RCA lesions combined, distal lesions had higher technical success (87.7% vs 85.3%; P=.048). The incidence of MACE was 1.9% and was similar between various RCA CTO locations (P=.508), but the incidence of perforation was higher among proximal lesions when compared with all other lesions combined (5.6% vs 4.4%; P=.033).
Left anterior descending artery. The majority of the LAD CTOs were located within the proximal (37.4%) and mid (55.2%) LAD segment and 4.5% of the lesions were located in the 1st or 2nd diagonal (Figure 1). When compared with all other LAD lesions combined, proximal LAD lesions were longer (27.8±15.6 mm vs 23.9±15.1 mm; P<.001) and more commonly moderately to severely calcified (48.1% vs 41.1%; P<.001), but were more likely to have suitable collaterals (58.7% vs 44.7%; P<.001) (Table 3).
AW was the most common successful crossing strategy among various LAD segments (Figure 6B). There was a trend for more frequent utilization of the retrograde approach (24.5%) in proximal lesions; the retrograde approach was the final successful crossing strategy in 14.2% of proximal LAD CTO cases.
Technical success was similar between various locations of LAD CTOs (P=.704). The incidence of MACE was 2.0% and was similar between various locations of LAD CTOs (P=.101). However, the incidence of perforation was higher among proximal LAD lesions when compared with all other LAD CTOs combined (5.2% vs 3.3%; P=.009).
Left circumflex artery. The most frequent location of LCX CTOs was the proximal LCX (34.7%), followed by the mid LCX (29.6%) and the first/second/third obtuse marginal (24.6%); 4% of the LCX lesions were located in the ramus (Figure 1). When compared with all other LCX lesions combined, proximal LCX lesions were more complex, with a higher J-CTO score (2.62 ± 1.23 vs 2.19 ± 1.32; P<.001), and were more commonly moderately to severely calcified (53.2% vs 35.5%; P<.001), and tortuous (53.8% vs 39.4%; P<.001) (Table 4).
There was a tendency toward more frequent utilization of the retrograde approach within more proximal LCX segments (Table 4). CTO lesions in the ramus were successfully crossed with AW in 78.3% of the cases. The distribution of the final successful crossing strategy among various locations of LCX CTOs are shown in Figure 6C.
When compared with all other LCX lesions combined, first/second/third obtuse marginal branch had lower technical (82.7% vs 86.8%; P=.014) and procedural (81.2% vs 85.5%; P=.016) success rates. The incidence of MACE was 2.0% and was similar between various locations of LCX CTOs (P=.797).
DISCUSSION
The main findings of our study are that: 1) the RCA was the most common vessel for CTO intervention; 2) RCA CTOs were more complex with a higher J-CTO score; 3) the retrograde approach and ADR were used more frequently in RCA lesions; 4) the RCA group required longer procedure and fluoroscopy times, as well as a higher AK radiation dose; 5) technical and procedural success rates were higher among LAD lesions; 6) the incidence of MACE was 1.9% and was similar among target vessels, and also among various locations within the target vessel; 7) the retrograde approach was used more frequently within more proximal segments of all 3 target vessels; 8) among RCA CTOs, distal RCA lesions had higher technical success; 9) lesion location within the LAD is not significantly associated with outcomes; and 10) the first/second/third obtuse marginal branch had lower technical when compared with all other LCX lesions combined.
In our study, the RCA was the most common vessel for CTO intervention. Previous studies reported similar findings.14-16 In the OPEN-CTO (Outcomes, Patient Health Status, and Efficiency in Chronic Total Occlusion Hybrid Procedures) registry, 61.5% of all CTOs were RCA CTOs, followed by the LAD (20.7%), and the LCX (17.0%).17
Hasegawa et al5 described the differences in the clinical and angiographic characteristics of CTO lesions in the 3 major coronary arteries. Similar to our study, they reported that RCA lesions were longer and more complex with severe angulation and calcification but had better collateral circulation compared with LAD or LCX (Table 1). Therefore, operators more frequently used more advanced CTO PCI techniques for RCA CTOs, such as the retrograde approach or ADR.1,3 Similarly, in our study, the retrograde approach and ADR were used more frequently among RCA lesions (Figure 2).
In our study, procedural success was higher in the LAD (87.7%) when compared with the RCA (84.4%) or LCX (84.4%) (P<.001). Hasegawa et al5 reported a 71.8% procedural success rate in the RCA, 74.8% in the LAD, and 79% in the LCX. The differences in these results compared with our study might be related to population-based differences regarding baseline or angiographic characteristics, or may reflect differences in practice patterns. The higher anatomic complexity of the RCA CTOs can explain the lower technical success rates when compared with LAD CTOs, as well as lower overall procedural efficiency (Figures 3 and 4). Previous studies have described potential explanations of the lower success rates in LCX CTO PCIs, such as significant tortuosity that might hinder attempts to advance guidewires and microcatheters to the lesion and lack of “interventional collaterals” that limits use of the retrograde approach.6,10 Similarly, in our study, LCX CTOs were more frequently tortuous (44.4%) compared with RCA (31.1%) or LAD lesions (14.5%) (P<.001), and were less likely to have “interventional collaterals” (32.8%) (70.3% for RCA and 49.8% for LAD; P<.001).
In 2023, Megaly et al18 evaluated the outcomes of 237 LAD CTO PCIs from a high-volume center and reported a high technical success rate of 97.4%, with no difference between proximal and non-proximal LAD disease. Similarly, technical success was high (88.8%) among LAD CTOs, and lesion location within the LAD was not significantly associated with outcomes in our study.
Although a failed antegrade attempt is the most important indication for use of the retrograde approach, other anatomical subsets, such as ostial lesion location or an ambiguous proximal cap may require the use of the retrograde approach, even as an initial crossing strategy in some cases.6,19-22 In our study, lesion location was identified in the ostium in 13.9% of RCA CTOs, 5.8% of LAD CTOs, and 8.9% of LCX CTOs. This can potentially explain our finding that the retrograde approach was used more frequently within more proximal segments of all 3 target vessels.
In our study, the incidence of MACE was overall 1.9% and was similar among target vessels, and among various locations within the target vessel. Mitomo et al4 evaluated the impact of target vessel on cardiac mortality after successful CTO PCI and reported that long-term cardiac mortality was significantly lower after successful RCA or LAD CTO PCI, but no such association was observed after LCX CTO PCI.
Our study has limitations. First, the PROGRESS-CTO registry is an observational retrospective study without long-term follow-up for all patients. Second, there was no core laboratory assessment of the study angiograms or clinical event adjudication. Third, the procedures were performed at dedicated, high-volume CTO centers by skilled and experienced operators, limiting the generalizability of our findings to centers with limited CTO PCI experience.
CONCLUSIONS
RCA CTOs were the most common subset of CTO lesions treated. They were identified as being more complex and required more frequent use of the retrograde approach and ADR, especially for more proximal lesions. LAD CTO PCIs had higher technical and procedural success rates among target vessels. The incidence of MACE was similar among target vessels and among various locations within the target vessel.
Funding Statement
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, and 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.
Acknowledgments
Study data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools hosted at the Minneapolis Heart Institute Foundation (MHIF), Minneapolis, Minnesota.7,8 REDCap is a secure, web-based application designed to support data capture for research studies, providing: 1) an intuitive interface for validated data entry; 2) audit trails for tracking data manipulation and export procedures; 3) automated export procedures for seamless data downloads to common statistical packages; and 4) procedures for importing data from external sources.
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