Author + information
- Mladen I. Vidovich, MD∗ ()
- Department of Medicine, Division of Cardiology, University of Illinois at Chicago, Chicago, Illinois
- Division of Cardiology, Jesse Brown VA Medical Center, Chicago, Illinois
- ↵∗Address for correspondence:
Dr. Mladen I. Vidovich, University of Illinois at Chicago, 840 South Wood Street, Suite 935, Chicago, Illinois 60613.
Imagine for a moment you are a stock analyst. You are trying to predict the future price of a large British company. The company sells a relatively new “product”—radial percutaneous coronary intervention (PCI) in patients with previous coronary artery bypass grafts (CABG). Their main competitor is an established company that offers a traditional product—femoral PCI in CABG.
This radial product has become a global phenomenon and de facto standard of care in the United Kingdom and Sweden. The radial market share in the United Sates is about one-half of the United Kingdom/Sweden but seems to be steadily growing.
In this issue of JACC: Cardiovascular Interventions, Kinnaird et al. (1) present a large retrospective analysis of the British Cardiovascular Interventions Society National Database (BCIS) describing trends of radial PCI in CABG from 2005 to 2014, and they compare it with femoral PCI from 2012 to 2014.
The authors unequivocally show that adoption of radial PCI in CABG has significantly lagged the adoption of radial PCI in native coronaries. Although over the same period, the use of radial PCI in native coronaries has reached ∼80%, bypass grafts seem to deter interventionalists so that only 42% of CABG PCIs are performed radially. Although CABG PCI could be called a “niche product,” wearing your stock analyst hat, you clearly need to determine why the adoption rates are so low.
The authors further confirm that radial PCI in CABG does not save lives, but provides the same technical success rates while reducing the need for blood transfusion and reducing access site complications. These findings are in line with what we already know about radial PCI in native coronaries (2).
The study introduces several findings that go beyond current knowledge about radial PCI in CABG. It comes as no surprise that patients with prior CABG are older and sicker in every aspect. As is true in many other areas of interventional cardiology, the sickest patients are those who usually benefit from the radial approach. And yet, disappointingly, the authors show that when the going gets tough, interventionalists seem to choose the femoral over the radial approach. Fewer women and fewer acute coronary syndrome patients benefited from radial access. What seems to be happening in the trenches is that chronic total occlusions (CTO) and graft interventions sway the interventionalists to choose femoral access.
What are the weaknesses of this study? We do not have data on diagnostic procedures preceding the PCI. This likely introduced a bias. It is plausible that the initial diagnostic and subsequent PCI were not performed via same access route (radial vs. femoral or left vs. right radial). Procedures might have been staged for reasons other than access site considerations: renal insufficiency, oral anticoagulant agents or anticipated technical reasons (e.g., guide support, bilateral access, large equipment). Similarly, there remain additional confounders that were not captured in this dataset: for instance, prior radial artery harvesting, arteriovenous fistulae, or known previous radial access failure (41% of patients had prior PCI). Additionally, we do not know whether the interventionalists had access to the surgical report or whether the patients had graft markers in the aorta.
The BCIS dataset does not capture contrast dye use nor radiation dose. The authors elegantly used the black-box approach and report that acute kidney injury was similar between radial and femoral PCI. This is very encouraging. Although the published reports suggest equipoise between contrast use in radial and femoral CABG PCI, exact dye use information would be most valuable for clinical practice. Even a perception that radial CABG PCI may be associated with higher contrast dye use may be one of the barriers to its wider adoption. Radiation and radial access have received detailed scrutiny, and although recent data suggest what we may be reaching equipoise with the increase in radial skills and operator volume, as the interventional community, we should redouble our efforts to minimize exposure (3). Similar to dye use, higher radiation doses with radial CABG PCI are likely in low-volume operators, adding another potential barrier to wider adoption. Hopefully, the BCIS group will consider collecting these data points and capture dye use and radiation exposure onward.
Now, back to the stock analyst trying to predict the next 10 years (Figure 1). The good news for radial access is that we now have robust evidence that radial PCI saves lives (ST-segment elevation myocardial infarction), reduces access site complications, and saves money by causing fewer bleeding complications and allowing for faster discharge. One could expect the share of radial access in CABG PCI to grow because this population is sicker, older, and likely to benefit from radial access.
With increase in experience, British operators seem to perform more radial PCIs in CABG. We do have the data on the learning curve for radial PCI, and analyzing the study by Kinnaird et al. (1), it is attractive to conjecture that the learning curve for radial CABG PCI requires considerably more cases. Nowadays, newly trained cardiologists enter the workforce with substantially better radial training and may be more likely to perform radial CABG PCI. Some may never reach the optimal number on the learning curve to be facile with radial CABG PCI. Low-volume centers may not have enough cases to maintain proficiency in this niche segment. This magic number for radial CABG PCI is uncertain.
Concurrent with the rapid adoption of radial PCI, we are seeing a growth in CTO techniques. CTO today is not the CTO of 10 years ago. The authors demonstrate that CTO clearly is a major factor affecting the choice of femoral over radial access. CTO equipment size requirements may limit its use in patients with smaller radial arteries. The need for bilateral access or repeated access is not a trivial consideration with radial PCI. The rates of radial artery occlusion have decreased dramatically with contemporary closure techniques but remain stubbornly in the low single digits even in the best centers using best practices (4).
Lastly, femoral access continues to evolve due to competitive pressure from radial access. In 2018, the way we practice femoral access has been refined, owing to better understanding of ultrasound guidance, micropuncture needles, and closure devices. This is a healthy competition, and it is conceivable that in the near future, this “new and improved femoral access” might be able to compete with radial access when it comes to access site complications (5).
In conclusion, as a stock analyst, I give radial CABG PCI a buy recommendation as a long-term investment. To increase the proportion of radial PCI in CABG, we will require additional operator proficiency, new equipment, and unequivocal confirmation about equipoise when it comes to radiation dose, contrast use, and procedure time. Continued growth of CTO PCI along with improvement in femoral access may well leave this a niche PCI procedure in a 50/50 radial/femoral zone. We hope to read the follow-up BCIS analysis in a JACC: Cardiovascular Interventions issue in 2024.
↵∗ Editorials published in JACC: Cardiovascular Interventions reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Interventions or the American College of Cardiology.
Dr. Vidovich has received royalty payments from Merit Medical.
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