Learning curve of distal radial access for coronary procedures: prospective, multicenter, observational study (IDEAL-BOX)

Q: What are the key findings of this study?

Inexperienced operators performing distal radial access improved procedural success from 83.0% in the first 50 cases to 99.0% in cases 151-200, matching experienced operators after 50 cases.

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Patients scheduled for elective or urgent coronary angiography and percutaneous coronary intervention via distal radial access (n=800). Intervention: Distal radial access performed by inexperienced operators (no prior DRA experience) vs. Distal radial access performed by experienced operators (≥ 1,000 prior DRA procedures). Primary outcome: Successful coronary procedures without access-site crossover across four sequential 50-case quartiles (and overall rate) (p=<0.001 for trend in inexperienced operators (0.714 for overall between-group difference)).

Q: What does this research mean for the field?

Interventional operators inexperienced in distal radial access achieve procedural success rates comparable to experienced operators after approximately 50 cases. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

To evaluate the procedural outcomes and learning curve of distal radial access for coronary procedures between inexperienced and experienced operators.

Namkyun Kim; Oh‐Hyun Lee; Youngjoon Kwon; Seok-Jae Heo; Ji Woong Roh; Eui Im; Deok‐Kyu Cho; Yongcheol Kim

doi:10.1038/s41598-026-79379-0

November 11, 2026Scientific ReportsOpen Access

Learning curve of distal radial access for coronary procedures: prospective, multicenter, observational study (IDEAL-BOX)

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Key result

Distal radial access success improves ~16 points with experience, matching expert operator rates.

P<0.001 for trend in inexperienced operators (0.714 for overall between-group difference)
n=800

Why the study?

Although distal radial access is increasingly used for coronary procedures, prospective data characterizing its operator learning curve remain limited.

Does operator experience with distal radial access (inexperienced vs. experienced operators) affect the learning curve and trend in rates of successful coronary procedures without access-site crossover in patients undergoing coronary angiography or percutaneous coronary intervention?

Key Points

To evaluate the procedural outcomes and learning curve of distal radial access for coronary procedures between inexperienced and experienced operators.
Prospective, multicenter, observational study (IDEAL-BOX) conducted at two academic centers in South Korea enrolling 800 patients (400 per operator group) scheduled for elective or urgent coronary angiography or percutaneous coronary intervention.
Procedures were performed by four operators (two inexperienced with no prior distal radial access experience and two experienced with ≥ 1,000 prior procedures), each performing 200 consecutive cases.
Primary endpoint was the trend across four sequential 50-case blocks (Q1 to Q4) in rates of successful coronary procedures without access-site crossover.
Inexperienced operators demonstrated a significant improvement in success without access-site crossover across quartiles (83.0% in Q1 to 99.0% in Q4, P for trend < 0.001), while experienced operators maintained consistent success (95.0% in Q1 to 93.0% in Q4, P for trend > 0.999).
Procedural success was significantly lower for inexperienced operators compared to experienced operators during Q1 (83.0% vs. 95.0%, P = 0.010), but showed no significant difference in subsequent blocks (Q2–Q4).
No significant difference was observed in overall procedural success without crossover between inexperienced and experienced operators (observed: 92.5% [370/400] vs. 94.5% [378/400]; model-estimated: 94.9% vs. 95.5%, P = 0.714).

Study Design

Type

Observational (n=800)

Multicenter

Yes

Structured PICO

Does operator experience with distal radial access (inexperienced vs. experienced operators) affect the learning curve and trend in rates of successful coronary procedures without access-site crossover in patients undergoing coronary angiography or percutaneous coronary intervention?

P

Population

800 adults (median age 65.0 years, 29.1% female) scheduled for elective or urgent coronary angiography or percutaneous coronary intervention with a palpable distal radial artery pulse, followed for 1 month for access-site complications.

E

Exposure

Distal radial access (DRA) at the anatomical snuffbox or dorsum of the hand performed by two inexperienced operators (no prior DRA experience, extensive conventional transradial access experience; n=400 cases). Patients received intra-arterial unfractionated heparin (3,000 IU) after sheath insertion, and those undergoing PCI received aspirin and a P2Y12 inhibitor before the procedure.

C

Comparator

Distal radial access (DRA) performed by two experienced operators (≥1,000 prior DRA procedures, with ≥50% of PCIs via DRA; n=400 cases), receiving the same procedural anticoagulation and antiplatelet strategy.

O

Outcome

Trend in the rates of successful coronary procedures (completion of CAG and PCI via the initial DRA site) without access-site crossover across four sequential 50-case quartiles (Q1: cases 1–50, Q2: 51–100, Q3: 101–150, and Q4: 151–200).surrogate

Main Result

Absolute Event Rate: 92.5% vs 94.5%

p-value: p=<0.001 for trend in inexperienced operators (0.714 for overall between-group difference)

Inexperienced operators with prior conventional transradial experience can overcome the learning curve for distal radial access after approximately 50 cases, achieving procedural success rates comparable to experienced operators.

Limitations

Prospective observational design with potential selection bias as access site was chosen at the operators' discretion and data for patients undergoing alternative access were not collected.
Anatomical factors affecting puncture (e.g., distal radial artery diameter, pulse quality, hand dominance, tortuosity, prior radial access) were not collected.
Small number of operators (only four operators, including two inexperienced operators, at two centers), limiting generalizability and the reliability of mixed-effects models.
Study was conducted exclusively in South Korean centers, and findings may not apply to operators without prior conventional transradial access experience.
Radial artery occlusion was assessed by clinical palpation rather than routine Doppler ultrasonography, potentially underestimating asymptomatic occlusion.
Ultrasound-guided puncture was performed in only 5.0% of cases, precluding evaluation of routine ultrasound guidance during the learning phase.

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Implication

Rapid proficiency gain in distal radial access for novices; hypothesis-generating for training curricula but should not yet change practice.

Abstract

While distal radial access (DRA) is increasingly used for coronary procedures, prospective data on its learning curve remain limited. We evaluated procedural outcomes in experienced and inexperienced operators. This prospective, multicenter, observational study enrolled 800 patients in whom DRA was attempted by four operators (two inexperienced and two experienced), each performing 200 cases. The primary endpoint was the trend in rates of successful coronary procedures without access-site crossover across four sequential 50-case blocks. Inexperienced operators showed a significant improvement across the case quartiles (83.0% in Q1 to 99.0% in Q4, P for trend < 0.001), whereas experienced operators maintained consistently high success rates (95.0% in Q1 to 93.0% in Q4, P for trend > 0.999). Although inexperienced operators showed a significantly lower success rate during Q1 compared to experienced operators (83.0% vs. 95.0%, P = 0.010), this inter-group difference was not significant in subsequent quartiles (Q2–Q4). No significant difference was observed in the overall procedural success rate without access-site crossover (observed, 92.5% [370/400] vs. 94.5% [378/400]; model-estimated, 94.9% vs. 95.5%, P = 0.714). The procedural success rate of inexperienced operators was lowest in the first 50 cases and did not differ significantly from that of experienced operators after 50 cases.

Discussion

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Cite This Study

Kim et al. (2026) conducted an observational in Patients scheduled for elective or urgent coronary angiography and percutaneous coronary intervention via distal radial access (n=800). Distal radial access performed by inexperienced operators (no prior DRA experience) vs. Distal radial access performed by experienced operators (≥ 1,000 prior DRA procedures) was evaluated on Successful coronary procedures without access-site crossover across four sequential 50-case quartiles (and overall rate) (p=<0.001 for trend in inexperienced operators (0.714 for overall between-group difference)). Inexperienced operators performing distal radial access improved procedural success from 83.0% in the first 50 cases to 99.0% in cases 151-200, matching experienced operators after 50 cases.

synapsesocial.com/papers/6af5cd33a40bbe8669e89c7b https://doi.org/10.1038/s41598-026-79379-0

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Learning curve of distal radial access for coronary procedures: prospective, multicenter, observational study (IDEAL-BOX)

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Learning curve of distal radial access for coronary procedures: prospective, multicenter, observational study (IDEAL-BOX)

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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