This document discusses the radial approach learning curve for cardiac catheterization procedures. It reviews several studies that attempted to quantify the learning curve. The studies found that procedural metrics like fluoroscopy time decreased with increased operator experience, with most operators showing improvement after 25-40 cases. While a learning curve exists, it may not be as steep as once believed. The document concludes that the learning curve is a reality, but the myth is that it is prohibitively steep.

1. Radial approach and learning curve:
myth or reality?
Robert J Applegate, M.D.
Professor of Internal Medicine-Cardiology

2. Disclosures
Advisory Boards Abbott Vascular
Research Grants Abbott Vascular
Serruys, PW. PCR 2010
The Medicines Company
Wake Forest School of Medicine AimRADIAL 2014

3. The learning curve for radial artery procedures:
historical perspective
No differences in primary entry site complications, or
MACE, but “there was a clear trend toward more
technical difficulties and more problems with the radial
approach.”
Wake Forest School of Medicine AimRADIAL 2014

4. The learning curve for radial artery procedures:
historical perspective
“In conclusion, it is evident, when reviewing
this study, that the difficulties associated with
the learning curve must be overcome
before a randomized study can be carried
out.”
Wake Forest School of Medicine AimRADIAL 2014

5. Radial “learning curve” identified early on with
attempts to quantify the “steepness” of the curve
The word in the US Interventional world
was that the radial learning curve was “steep”
But Inflection is that ??
really true?
Plateau ??
Spaulding et al: CCI 1996; 39:365-370
Wake Forest School of Medicine AimRADIAL 2014

6. A learning curve is a graphical representation of the
increase in “learning” (vertical axis) with “experience”
(horizontal axis)
The first person to describe the learning curve was Hermann Ebbinghaus in 1885, in
the field of the psychology of learning
Wake Forest School of Medicine AimRADIAL 2014

7. The learning curve for radial artery procedures:
The learning curve and outcomes
• Defining “learning” is not simple, procedural metrics often
become “outcome metric” of learning curve assessment
• Complex interaction of factors that influence the learning curve
• Establishing causality between individual learning curve
metric and outcome can be challenging
Wake Forest School of Medicine AimRADIAL 2014

8. The US adoption of radial artery procedures
• Increases in radial procedures a consequence of entry of
fellowship trained Cardiologists, as well as post graduate
training of practicing Cardiologists.
• So, evaluation of the learning curve needs to address
outcomes from both fellowship training and post
graduate training
Wake Forest School of Medicine AimRADIAL 2014

9. The learning curve for radial artery procedures
in fellowship training (new for faculty and fellows):
Wake Forest Registry data
Wake Forest School of Medicine Turner et al; CCI 2012; 80:247-257 AimRADIAL 2014

10. The US learning curve for radial artery procedures:
Wake Forest Registry data
Radial artery access metrics by period
Transition Preferred TR
Radial Radial
Metric (N = 610) (N = 897)
• Generalized decrease in procedural metrics with
Access reduced site crossover, n (%) inter quartile ranges
57 (9.3%) 80 (8.9%)
Sheath size, Fr
CATH only 5.0 (0.2) 5.0 (0.1)
PCI 6.0 (0.4) 5.7 (0.5) *
• Efforts to quantify learning curve complicated by
Procedure time intervals, minutes
affect of new fellows on monthly basis
Sheath insertion 5 (3-10) 5 (3-9) *
Intubate coronaries 7 (5-10) 6 (4-9) *
Total procedure, CATH only 26 (20-36) 24 (19-34) *
Total procedure, CATH + PCI 66 (51-85) 64 (53-83)
Total procedure, PCI only 50 (38-71) 49 (40-52)
Fluoroscopy time, minutes
CATH only 7 (5-12) 7 (5-11) *
CATH + PCI 21 (16-30) 21 (15-27)
PCI only 16 (10-24) 14 (10-19)
Contrast volume used, mL
CATH only 76 (56-98) 74 (55-99)
CATH + PCI 190 (147-250) 194 (142-246)
PCI only 132 (86-191) 111 (92-122)
Turner et al; CCI 2012; 80:247-257
Wake Forest School of Medicine AimRADIAL 2014

11. The US learning curve for radial artery procedures:
Wake Forest Registry data
Radial artery access metrics by period for operators with highest and lowest proportion of radial artery access
Attending A (HIGH) Attending B (LOW)
Transition Preferred TR Transition Preferred TR
Metric (N = 350) (N = 329) (N = 272) (N = 277)
Radial artery access, n / total volume (%) 202/350 (58%) 233/329 (71%) † 93/272 (34%) ‡ 171/277 (62%) †‡
Access site crossover, n / TR volume (%) 12/202 (6%) 12/233 (5%) 15/93 (16%) ‡ 18/171 (11%) ‡
TR procedure time intervals, minutes
Sheath insertion 6 (4-11) 6 (3-10) 6 (4-8) 5 (3-9) ‡
Intubate coronaries 6 (4-8) 5 (4-7) † 8 (5-13) ‡ 6 (5-9) †‡
Total Similar procedure, CATH to only Burzotta et 24 al (17-33) found 20 a (16-volume 28) † 29 – (21-outcome
37) ‡ 25 (21-35) ‡
Total procedure, CATH + PCI 61 (47-74) 53 (41-66) † 72 (52-95) 68 (59-89) ‡
Total procedure, PCI only 50 (43-62) 51 (28-52) 39 (36-41) 40 (40-40)
relationship among both higher and lower
TR fluoroscopy time, minutes
CATH only 5 (4-8) 5 (3-7) † 9 (6-15) ‡ 8 (6-13) ‡
CATH + PCI 18 (12-26) 15 (11-19) † 26 (20-39) ‡ 22 (16-29) ‡
PCI only 14 (10-23) 16 (10-19) 23 (21-24) 12 (12-12)
TR contrast volume used, mL
volume operators
CATH only 61 (50-83) 65 (43-83) 76 (50-98) ‡ 74 (60-91) ‡
CATH + PCI 141 (106-176) 141 (119-180) 191 (153-253) ‡ 197 (149-231) ‡
PCI only 95 (74-177) 105 (30-122) 150 (109-190) 92 (92-92)
† p<0.05 vs Transition, ‡ p<0.05 vs Attending A. CATH indicates diagnostic catheterization; PCI, percutaneous coronary intervention.
Wake Forest School of Medicine Unpublished observations AimRADIAL 2014

12. The learning curve for radial artery procedures
In fellowship training:
Vanderbilt Registry data
Kasasbeh et al; JIC 2012; 24:599-604
Wake Forest School of Medicine AimRADIAL 2014

13. The learning curve for radial artery procedures:
Vanderbilt Registry data
60% radial
Wake Forest School of Medicine Kasasbeh et al; JIC 2012; 24:599-604 AimRADIAL 2014

14. The learning curve for radial artery procedures:
Vanderbilt Registry data
Room time (min)
Wake Forest School of Medicine Kasasbeh et al; JIC 2012; 24:599-604 AimRADIAL 2014
Procedure time (min) Floro time (min)
“Incorporation of radial access to our cardiac
catheterization laboratory led to a decrease in
fluoroscopy time in each operator, operator
group, and institute-wide over the last 3 years.
This improvement was seen after
approximately 25 cases and further improved
after 75 cases.”

15. The learning curve for radial artery procedures
In fellowship training:
UC Davis Registry data
Balwanz et al; AHJ 2013; 165:310-6
Wake Forest School of Medicine AimRADIAL 2014

16. The learning curve for radial artery procedures:
UC Davis Registry data
• June 2010 to July 2011 402 CATH, 205 PCI
• 35% TR CATH, 28% TR PCI
• TR new to faculty and fellows
Balwanz et al; AHJ 2013; 165:310-6
Wake Forest School of Medicine AimRADIAL 2014

17. The learning curve for radial artery procedures:
UC Davis Registry data
• For CATH, there was minimal improvement in procedural metrics
for either TR or TF (contrast volume less with TR in 2nd half
of year)
• However, there were significantly lower procedural metrics with
TF than TR during the 2nd half of the year
• No difference in procedural metrics for PCI with either TR or TF
over the year, and no difference between TR or TF
• Authors conclude that “the learning curve for trainees appears
slower for TR-CATH than for TF-CATH”
Balwanz et al; AHJ 2013; 165:310-6
Wake Forest School of Medicine AimRADIAL 2014

18. Post graduate learning curve assessment
Wake Forest School of Medicine Hess et al Circ 2014; 129:2277-86 AimRADIAL 2014

19. The learning curve for radial artery procedures:
NCDR
Hess et al Circ 2014; 129:2277-86
Wake Forest School of Medicine AimRADIAL 2014

20. The learning curve for radial artery procedures:
NCDR
More complex cases performed by
higher volume operators
Hess et al Circ 2014; 129:2277-86
Wake Forest School of Medicine AimRADIAL 2014

21. The learning curve for radial artery procedures:
NCDR
Procedural metrics reduced by
higher volume operators
Hess et al Circ 2014; 129:2277-86
Wake Forest School of Medicine AimRADIAL 2014

22. The learning curve for radial artery procedures:
NCDR
Floroscopy time Contrast volume
Procedural success
Wake Forest School of Medicine Hess et al Circ 2014; 129:2277-86
AimRADIAL 2014

23. The learning curve for radial artery procedures:
NCDR
Hess et al Circ 2014; 129:2277-86
Wake Forest School of Medicine AimRADIAL 2014

24. The learning curve for radial artery procedures:
NCDR
Conclusions
• As operator experience increases, higher risk patients and
more technically complex cases are selected for TRI
• There is a learning curve for TRI procedures with a
threshold of about 40 cases
• Improvements continue after the initial learning curve is
overcome (volume-outcome relationship)
Hess et al Circ 2014; 129:2277-86
Wake Forest School of Medicine AimRADIAL 2014

25. The learning curve for radial artery procedures:
Fellowship vs Post Graduate
• Circumstances of learning very different-probably easier
and more complete in fellowship training (but hard to measure)
• Limited studies evaluating learning curve as part of
a fellowship training program: learning metrics reflect the
learning curves of both fellows and attendings
• The available data indicate that the radial learning curve may not
be as “steep” as once believed. With a threshold for initial
“competence” 25-40 cases
• Need data addressing the issue of competence/proficiency
Wake Forest School of Medicine AimRADIAL 2014

26. The learning curve for radial artery procedures:
Myth or reality?
• Reality- there is a learning curve
• Myth-the learning curve is prohibitively
steep
Wake Forest School of Medicine AimRADIAL 2014

27. Wake Forest School of Medicine Hamon et al, Eurointervention 2013; 8:1242-51 AimRADIAL 2014

28. Wake Forest School of Medicine Hamon et al, Eurointervention 2013; 8:1242-51 AimRADIAL 2014