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Transradial Approach Interview Series
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Yutaka Tanaka, MD, PhD
Yutaka Tanaka, MD, PhD
Yutaka Tanaka, MD, PhD
The practice of transradial intervention (TRI) is common in Japanese catheterization procedures, accounting for more than 70% of the total PCIs, as compared with 25-30% in the U.S. Previous studies have shown that the use of the transradial approach significantly reduces procedure access site-related major bleeding in comparison with the femoral approach.

On the other hand, transradial PCI is reported to have certain disadvantages, including the learning curve and limitations of guiding catheter size, which may result in inadequate backup support for the guiding catheter. These negative effects limit the application of transradial PCI for complex lesions, especially in CTO cases.

Drs. Yutaka Tanaka, Shigeru Saito, and their colleagues at Shonan Kamakura General Hospital published a single center experience of "Transradial Coronary Interventions for Complex Chronic Total Occlusions" in the February 13 issue of JACC Cardiovascular Interventions (J Am Coll Cardiol Intv 2017;10:235–43). In the article, Dr. Tanaka et al concluded that transradial PCI for CTO may be feasible in noncomplex cases, although complex cases remain challenging. Angioplasty.Org’s partner site, TCROSS NEWS, recently interviewed Dr. Tanaka to understand more about this study.

Q: Can you explain the background of this study?
Dr. Tanaka: We have focused attention on the benefit of transradial (TR) access since the mid-1990s and have made an effort to expand the use of this technique through live demonstration courses throughout the world. Important advantages of TR access over transfemoral (TF) access include no bed rest due to easy hemostasis and less bleeding risk at the puncture site. These advantages are especially important for patients with obesity or those under anticoagulant therapy.

On the other hand, potential disadvantages of TR access include poor back-up support due to limited guiding catheter size (mainly 6F, but 7F at most), presence of bended and tortuous brachiocephalic and subclavian arteries, as well as the brachiocephalic artery originating distally on the aortic arch. Today, the improvement of medical devices and the advancement of technology has allowed us to perform complex intervention with TR access. However, there are inadequate data available to define limitations and the possibility of CTO-PCI through TR access. Therefore, our aim is to show a case which enables CTO-PCI via TR access.

Q: During the 10-year period between January 2005 and December 2014, a total of 10,631 PCI procedures were performed at Shonan Kamakura General Hospital. In particular, 8,379 PCI procedures (78.8%) involved transradial access, 1,573 PCI procedures (14.8%) involved transfemoral (TF) access, and 679 PCI procedures (6.4%) involved transbrachial (TB) access. When do you perform PCI via TF or TB access other than CTO lesions?
Dr. Tanaka: These numbers represent all PCI access sites used in our institution in the study period. In general, TR access is the standard approach in our institution. However, we use TB or TF approach for a patient under hemodialysis, having impalpable radial artery, or abnormality of blood flow in the radial artery. In addition, we prefer to use TB or TF access when severe bending or tortuosity in the brachiocephalic artery or/and subclavian artery has been seen during a previous catheterization in which the operator has experienced poor catheter manipulation.

Q: In looking at the baseline patient characteristics, it appears that the number of ISR lesions and the presence of moderate/severe calcification was lower in the TR group than in the TF group, indicating that less complex CTO cases were assigned to the TR group. In your practice, is the access site decision based upon J-CTO score or is it at the operator’s discretion?
Dr. Tanaka: In our study, the access site was decided upon by the individual operator, rather than J-CTO score. Most cases were performed by a single operator who has significant experience in transradial intervention. TF access was assigned when TR access was expected to limit procedure during CTO of PCI.

Q: When do you decide to terminate the procedure in your practice (e.g. procedure time, contrast volume, or radiation time.)
Dr. Tanaka: In general, we stop CTO-PCI when procedure time exceeds more than 90 minutes and/or the total amount of contrast media reaches over 300ml. Under these circumstances, the operator decides either to stop or to continue the procedure. Actually, the average fluoroscopy time and average  amount of contrast media among all subjects in the present study were relatively low, respectively 20.9 min and 184.6 ml. Success rate of CTO-PCI might be improved by increasing the amount of contrast media and/or procedure time, but might also result in increased risk of radiation injury or renal impairment for the patient.

Q: There were no significant differences in the success rates between the TR group and the TF group with J-CTO scores of 0, 1, and 2; however, in the cohort with J-CTO scores of more than 3, the TR group had a lower prevalence of technical success than the TF group (35.7% vs. 58.2%; p=0.04). Is the message from the present study that TF access is preferable in complex CTO-PCIs?
Dr. Tanaka: As mentioned in a previous question, selection bias was presented between the TR group and the TF group. Therefore a randomized control trial is required to verify the outcomes from the present study. We compared success rates between the TR group and the TF group based upon J-CTO score classification, revealing that the higher the J-CTO score, the lower the success rate in the TR group. Additionally we found that the use of guiding catheter size <7 F (OR 5.50: p = 0.008), calcification (OR 3.20: p = 0.001), occlusion length >20 mm (OR 2.97: p < 0.001), and age (OR: 1.04; p = 0.03) were associated with TR CTO-PCI failure Although current technological improvements of the sheath introducer allowed using a larger size of guiding catheter (7F+), one should prudently select access site when these predictors are presented during the procedure.

Q: Most Japanese operators who already have enough experience with transradial intervention may achieve a similar technical success rate with the present study. Please tell us any cautions for U.S. operators or any other countries who are less familiar with transradial intervention.
Dr. Tanaka: CTO-PCI with transradial access in antegrade or/and retrograde approach (bidirectional) without using transfemoral access is beneficial for the patient not only to reduce access site complications, but also to prevent protracted bed rest following the procedure. The present study included 6 hybrid cases (TR+TF) in the TR group despite the fact that the remaining cases were treated by TR access only. To master transradial approach in CTO cases, one should become familiar with transradial intervention in daily practice and also simultaneously understand the different feeling compared to TF access. Understanding potential and limitations of transradial intervention, we do not stick to TR access too much; rather we bear in mind to choose the appropriate access site in each case. To treat a CTO lesion, patient’s condition should not worsen as compared to pre-procedure period. Each operator should keep in mind the advantages and disadvantages of TR access to perform safe and effective CTO-PCI.

This interview was conducted in February 2017 by TCROSS NEWS, Tokyo, Japan