Distal Radial Access in Chronic Total Occlusion Percutaneous Coronary Intervention: Insights From the PROGRESS-CTO Registry

Background. The outcomes of distal radial access (dRA) in chronic total occlusion percutaneous coronary intervention (CTO-PCI) have received limited study. Methods. We compared the clinical, angiographic, and procedural characteristics of 120 CTO-PCIs performed via dRA access with 2625 CTO-PCIs performed via proximal radial access (pRA) in a large, multicenter registry. Results. The dRA group had lower mean PROGRESS-CTO score than the pRA group (1.0 ± 1 vs 1.2 ± 1, respectively; P=.05), while J-CTO score (2.4 ± 1.2 vs 2.3 ± 1.3; P=.43) and PROGRESS-CTO Complications score (2.8 ± 1.8 vs 2.6 ± 1.9; P=.16) were similar in the dRA vs pRA groups, respectively. Technical success was similar in the 2 groups (90% dRA vs 86% pRA; P=.14). Concomitant use of femoral access did not alter procedural success. The incidence of major periprocedural adverse cardiac events was similar in the 2 groups (0.8% dRA vs 2.4% pRA; P=.26), whereas the incidence of tamponade requiring pericardiocentesis was lower with dRA (0% dRA vs 4.69% pRA; P<.001), as was air kerma radiation dose (median, 1.7 Gy; interquartile range [IQR], 0.97-2.63 Gy in the dRA group vs median, 2.27 Gy; IQR, 1.2-3.9 Gy in the pRA group; P<.001). Conclusions. Use of dRA in CTO-PCI is associated with similar procedural success and risk of complications as compared with pRA.

Key words: coronary occlusion, percutaneous coronary intervention, radial artery

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) requires use of dual arterial access in most cases.¹ Although bifemoral access was initially preferred, use of radial access has increased over time and is currently used in approximately two-thirds of CTO-PCI cases performed at experienced centers² with good outcomes.^2-6 The use of distal radial access (dRA) in CTO-PCI has received limited investigation⁷ and was the focus of the present study.

Patient population. We analyzed the clinical, angiographic, and procedural characteristics of 2745 CTO-PCIs performed using at least 1 radial access site in 2690 patients consecutively enrolled in the PROGRESS CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention; NCT02061436) registry between May 2012 and August 2019 at 25 United States, 1 Greek, 1 Russian, 1 Lebanese, and 1 Canadian center. The REDCap database was used for data collection and management.^8,9 The study was approved by the institutional review board of each center.

Definitions. Coronary CTO was defined as a coronary lesion with Thrombolysis in Myocardial Infarction (TIMI) flow grade 0 of at least 3-month duration. Estimation of the duration of occlusion was clinical, on the basis of the first onset of angina, history of myocardial infarction (MI) in the target-vessel territory, or comparison with a prior angiogram. Calcification was assessed by angiography as mild (spots), moderate (involving ≤50% of the reference lesion diameter), or severe (involving >50% of the reference lesion diameter). Moderate proximal vessel tortuosity was defined as the presence of at least 2 bends >70° or 1 bend >90° and severe tortuosity as 2 bends >90° or 1 bend >120° in the CTO vessel. Blunt or no stump was defined as lack of tapering or lack of a funnel shape at the proximal cap. Interventional collateral vessels were defined as collateral vessels considered amenable to crossing by a guidewire and a microcatheter by the operator. Adequate distal landing zone was defined as a distal vessel segment with a diameter of >2.0 mm and without diffuse disease. A procedure was defined as retrograde if an attempt was made to cross the lesion through a collateral vessel or bypass graft supplying the target vessel distal to the lesion; if not, the procedure was classified as antegrade only. Antegrade dissection or re-entry was defined as antegrade PCI during which a guidewire was intentionally introduced into the subintimal space proximal to the lesion, or re-entry into the distal true lumen was attempted following intentional or inadvertent subintimal guidewire crossing.

A procedure was classified as dRA if at least 1 access site was at the left or right distal radial artery. Fully transwrist approach refers to procedures where only pRA or dRA was obtained, without use of any femoral access sites. Vascular access complications included small (<5 cm) or large (≥5 cm) hematomas, arteriovenous fistulas, pseudoaneurysms, and acute arterial closures.

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 achievement of technical success with no in-hospital major adverse cardiovascular event (MACE).

In-hospital MACE was the composite of all-cause death, myocardial infarction, recurrent angina requiring urgent repeat target-vessel or target-lesion revascularization (with PCI or coronary artery bypass graft [CABG] surgery), stroke or tamponade requiring pericardiocentesis, or surgery. Follow-up MACE was the composite of all-cause death, myocardial infarction, repeat target-vessel or target-lesion revascularization with PCI or CABG, or stroke. Myocardial infarction was defined according to the third universal definition.¹⁰ The J-CTO (Multicenter CTO Registry in Japan) score was calculated as described by Morino et al,¹¹ the PROGRESS CTO score as described by Christopoulos et al,¹² and the PROGRESS CTO Complications score as described by Danek et al.¹³ The glomerular filtration rate (GFR) was estimated using the Cockroft-Gault method.¹⁴

Statistical analysis. Categorical variables are expressed as percentages and were compared using the Pearson’s chi-square test or Fisher’s exact test. Continuous variables are presented as mean ± standard deviation or median (interquartile range [IQR]) unless otherwise specified and compared using the Student’s t-test for normally distributed variables and the Wilcoxon rank-sum test or the Kruskal-Wallis test for non-parametric variables. The incidence of MACE during follow-up was calculated using the Kaplan-Meier method and compared using the log-rank test. A 2-sided P-value <.05 was considered to indicate statistical significance. All statistical analyses were performed with JMP, version 15.0 (SAS Institute).

Baseline clinical and angiographic characteristics. Distal radial access was used in 120 of the 2745 cases (4% of all radial cases in the PROGRESS-CTO registry), with utilization increasing over time (Figure 1). Patients in the dRA group had higher body mass index (32.3 ± 6.6 kg/m² vs 30.6 ± 6.2 kg/m²; P<.01), higher prevalence of diabetes mellitus (51.3% vs 38.5%; P<.01) and dyslipidemia (95.8% vs 82.8%; P<.001), and lower prevalence of prior cerebrovascular disease (4.3% vs 10.6%; P=.02) vs the pRA group (Table 1).

The CTO lesion characteristics are shown in Table 2. The PROGRESS-CTO score was lower in the dRA group vs the pRA group (1.04 ± 1 vs 1.22 ± 1, respectively; P=.05), while the J-CTO and PROGRESS-CTO Complications scores were similar in the 2 groups.

Technical characteristics. Most dRA cases (81%) were performed in the left radial with simultaneous proximal right radial access (Figure 2). The dRA sheath size was 5 Fr, 6 Fr, or 7 Fr in 2%, 59%, and 39%, respectively, which was smaller than pRA sheaths.

The procedural techniques and outcomes are presented in Table 3. Antegrade wire escalation (AWE) was more frequently the final successful crossing strategy with dRA vs pRA (61% vs 53%, respectively; P=.04). Overall technical success was similar in the 2 groups (90.8% for dRA vs 86.4% for pRA; P=.14).

In cases in which a fully transwrist approach was used (n = 1355), pRA cases had lower J-CTO score (2 ± 1.3 vs 2.4 ± 1.2; P<.01), similar PROGRESS-CTO score (1.2 ± 1 vs 1 ± 1; P=.21), and similar technical success rates (88.3% vs 90.3%; P=.52) compared with dRA cases.

Procedural, in-hospital, and long-term outcomes. Procedural outcomes are shown in Table 4. Procedural success was higher in the dRA group than in the pRA group (91% vs 84%, respectively; P=.05), while in-hospital MACE (2.4% vs 0.83%; P=.26), vascular access complications (1.25% vs 0%; P=.09), and access-site bleeding (0.83% vs 0.66%; P=.82) were similar. The incidence of perforation was lower in the dRA group (0% vs 4.8%; P<.001). Air kerma radiation dose was lower in the dRA group (1.7 Gy [IQR, 1-2.6 Gy] vs 2.3 Gy [IQR, 1.2-3.9 Gy]; P<.001). The 12-month incidence of MACE was also similar between the 2 groups (5.8% dRA vs 8.7% pRA; P_{log rank}=.58).

When a fully transwrist approach was used (n = 1336), procedural success rates (90.2% vs 85.8%; P=.19) were similar between dRA and pRA cases, as was the incidence of in-hospital MACE (0.97% vs 2%; P=.41), vascular access complications (0% vs 0.97%; P=.16), and bleeding (0% vs 0.4%; P=.37).

The main findings of our study were that use of dRA access in CTO-PCI has been increasing over time and was associated with similar success and complication rates compared with pRA.

The main advantages of dRA compared with pRA are improved patient and operator comfort, lower risk for compartment syndrome, and maintenance of antegrade flow via the superficial palmar arch that prevents proximal radial artery occlusion in case of distal radial artery occlusion. On the other hand, the dRA can sometimes be small, making access challenging or impossible.^15,16 Although multicenter data are limited, both right and left dRA approaches appear to be feasible with minimal bleeding complications in both stable and acute coronary syndrome patients in single-center studies.^15,17,18

Two CTO-PCI case series published in 2017 and 2019 demonstrated that dRA access using a 7 Fr, low-profile sheath can be performed with high technical success rates and low vascular access complication and major bleeding rates.^7,19 In the PROGRESS-CTO registry, dRA access was first utilized in 2018 with increasing use over time (5% of all radial cases in 2018 and 13% of all radial cases in 2019) with good success and complication rates.

One of the potential disadvantages of the radial as compared with femoral access is increased operator radiation dose. In our study, however, air kerma radiation dose was lower with dRA,  which is reassuring.

Study limitations. First, this is an observational study, prone to selection bias. Second, all procedures were performed by experienced operators and centers, limiting extrapolation to less-experienced centers. Third, we did not collect information on radial artery spasm. Fourth, no follow-up ultrasound was done to assess radial artery patency. Fifth, the initial plan for arterial access and crossover rates are not known.

The use of dRA in CTO-PCI has been increasing and is associated with favorable outcomes.

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. 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.