Transradial Primary Percutaneous Coronary Intervention: A Word of Caution

Dear Editor:

We read with great interest the article by Barringhaus et al, published in the February 2014 issue of the Journal of Invasive Cardiology.¹ The authors share their initial experience with primary percutaneous coronary intervention (PCI) using the transradial (TR) approach. Indeed, they are to be congratulated for both procedural and clinical outcomes, as well as quality-of-care indicators (“room-to-balloon [RTB] time”), since the latter not only reflects good clinical practice but also compares favorably with their femoral cohort data.

Nevertheless, key aspects and study limitations deserve to be underscored in order to fully appreciate their findings. First, the reported outcomes might be, at least in part, associated with their low-risk ST-elevation myocardial infarction (STEMI) population: 2.0% in-hospital mortality, mean age of 58 years, 99.1% procedural success, 1.1% crossover to femoral, 2.0% major bleeding. Indeed, these figures are similar to — and to some extent, as in the case of bleeding, better than — randomized clinical trial data,^2,3 wherein patient populations are known to be rather selected and non-high risk. Moreover, Barringhaus et al did not present clinical (eg, Zwolle⁴) or angiographic (eg, SYNTAX⁵) STEMI score data; such scoring systems could have better risk-stratified their cohort.

Second, there was a selection bias favoring under-representation of high-risk patients in the femoral cohort. In their study, 19 patients (3.9%; 17/19 were high-risk femoral patients) were excluded from the final analysis due to non-PCI related delays. Proceeding in such a manner further shifts the patient population profile toward a low-risk cohort.

Third, the authors state that none of the operators had performed >100 TR PCIs prior to participating in the study. Conversely, recent consensus recommendations on TR PCI recommend not embracing a primary PCI program until >300 TR PCIs in a (semi-)elective setting have been performed by each operator.⁶ Using radial access for primary PCI has been associated with reduced mortality, bleeding, access-site complications, and hospital stay, as compared with femoral access.^7,8 However, a steeper learning curve than the one reported by Barringhaus et al exists; the latter was not evident in their study, which was most likely due to selection bias toward a low-risk cohort.

Finally, Barringhaus et al report a statistically significant 4-minute difference favoring the radial cohort in RTB time, a key study primary outcome. This is contradictory to findings from large cohorts reporting that femoral catheterization for STEMI is less time consuming.⁹ Furthermore, the clinical relevance of such a statistically significant finding is debatable, as the largest time delays in STEMI management are attributable to patient-related factors (eg, hesitation in calling emergency responders) and logistical factors (eg, transportation), and are usually associated with hour-long delays.¹⁰

In conclusion, while the findings by Barringhaus et al are reassuring, key limitations, such as early-operator experience in their transition toward the TR approach for primary PCI together with the inclusion of a low-risk cohort, compromise the external validity of their study. Further studies — either randomized clinical trials or larger registries of all-comer STEMI patients treated at high-volume radial centers — are needed to adequately assess the feasibility and safety of primary PCI via the TR approach.

References

1. Barringhaus KG, Akhter M, Rade JJ, Smith C, Fisher DZ. Operator and institutional experience reduces room-to-balloon times for transradial primary percutaneous coronary intervention. J Invasive Cardiol. 2014;26(2):80-86.
2. Stone GW, Witzenbichler B, Guagliumi G, et al. Bivalirudin during primary PCI in acute myocardial infarction. N Engl J Med. 2008;358(21):2218-2230.
3. Armstrong PW, Gershlick AH, Goldstein P, et al. Fibrinolysis or primary PCI in ST-segment elevation myocardial infarction. N Engl J Med. 2013;368(15):1379-1387.
4. De Luca G, Suryapranata H, van’t Hof AWJ, et al. Prognostic assessment of patients with acute myocardial infarction treated with primary angioplasty: implications for early discharge. Circulation. 2004;109(22):2737-2743.
5. Sianos G, Morel M-A, Kappetein AP, et al. The SYNTAX score: an angiographic tool grading the complexity of coronary artery disease. EuroIntervention. 2005;1(2):219-227.
6. Hamon M, Pristipino C, Di Mario C, et al. Consensus document on the radial approach in percutaneous cardiovascular interventions: position paper by the European Association of Percutaneous Cardiovascular Interventions and Working Groups on Acute Cardiac Care and Thrombosis of the European Society. EuroIntervention. 2013;8(11):1242-1251.
7. Romagnoli E, Biondi-Zoccai G, Sciahbasi A, et al. Radial versus femoral randomized investigation in ST-segment elevation acute coronary syndrome: the RIFLE-STEACS (Radial Versus Femoral Randomized Investigation in ST-Elevation Acute Coronary Syndrome) study. J Am Coll Cardiol. 2012;60(24):2481-2489.
8. Jolly SS, Yusuf S, Cairns J, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial. Lancet. 2011;377(9775):1409-1420.
9. Baklanov DV, Kaltenbach LA, Marso SP, et al. The prevalence and outcomes of transradial percutaneous coronary intervention for ST-segment elevation myocardial infarction: analysis from the National Cardiovascular Data Registry (2007 to 2011). J Am Coll Cardiol. 2013;61(4):420-426. Epub 2012 Dec 19.
10. Bates ER, Jacobs AK. Time to treatment in patients with STEMI. N Engl J Med. 2013;369(10):889-892.

From the Interventional Cardiology Division, Department of Medicine, Montreal Heart Institute, Université de Montréal, Montréal, QC, Canada.

Funding: Dr Azzalini holds a grant from the Spanish Society of Cardiology. Dr Ly is a clinical research scholar from the Fonds de Recherche en Santé du Québec and receives funding from the Montreal Heart Institute Foundation and the Des Groseillers et Bérard Chair in Interventional Cardiology from the Université de Montréal.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted March 5, 2014, final version accepted March 6, 2014.

Address for correspondence: Hung Q. Ly, MD, MSc, FRCPC, Associate Professor of Medicine, University of Montreal, Interventional Cardiology Division, Dept. of Medicine, Montreal Heart Institute, 5000 Bélanger St. (East), Montréal, Québec, Canada H1T 1C8. Email: qh.ly@umontreal.ca 

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Author’s Reply

We appreciate the insightful comments and questions raised.  We agree that selection bias exists between the transradial (TR) and transfemoral (TF) groups. This was not a randomized clinical trial.  Rather, this was a study describing our experience as we transitioned to the TR approach for primary percutaneous coronary intervention (PCI). Operators intentionally favored a TF approach for high-risk cases, and we continue to exercise this judgment in our practice today. Presently, we perform over 80% of our primary PCIs transradially and are performing TR PCI on higher-risk patients than at the inception of our program. We discourage operators with limited experience from pursuing TR PCI in high-risk patients. Moreover, each center and operator should determine whether the findings of our study, conducted at an institution with a fellowship training program, strong administrative support, and high ST-elevation myocardial infarction patient volume, applies to their own settings. Nonetheless, the findings from our study are encouraging and likely will apply to many centers and operators, although they directly conflict with European recommendations published following the conclusion of the study period.¹ Conducting a randomized multicenter study of TR primary PCI among operators with limited experience would be challenging but feasible, and may aid operators in determining when to make the transition.

Regarding the learning curve, we cannot make realistic comparisons with other studies that utilize different metrics and were charted in non-emergent settings. All operators were encouraged to increase elective and urgent TR PCI prior to making the transition. Clearly, our operators gained valuable experience over that time. Additionally, newer diagnostic and guide catheters were becoming available. Over the course of 40 TR primary PCI procedures as an institution, we discovered how to optimize our room-to-balloon (RTB) times, whereupon our TR primary PCI volumes increased. We found it unnecessary to routinely adopt the left radial access site preferentially, but suggest that this approach as well as ultrasound-guided access may be useful strategies for many centers.

We agree that a 4 minute difference in RTB time likely is clinically irrelevant given recently published findings.² When viewed from this perspective, the same argument applies for contrasting studies that show only a minimal delay with TR access for primary PCI. Balanced against the gains that can be achieved in terms of fewer bleeding complications and potential mortality advantage, we believe that TR PCI will become the preferred access site for many operators who have performed fewer than 300 TR PCIs.  We concur that a clinical trial studying this question would be helpful and may accelerate the transition at many centers. Our message is not intended to embolden the foolhardy, but rather to suggest that TR primary PCI may be an acceptable option for some operators and institutions, despite having performed only a modest volume of non-emergent TR PCIs.

Sincerely,

Kurt G. Barringhaus, MD, FSCAI

Cardiovascular Division

University of Massachusetts Medical School

S3-853, 55 Lake Avenue North, Worcester, MA 01655

Email: Barringk@ummhc.org

References

1. Hamon M, Pristipino C, Di Mario C, et al. Consensus document on the radial approach in percutaneous cardiovascular interventions: position paper by the European Association of Percutaneous Cardiovascular Interventions and Working Groups on Acute Cardiac Care and Thrombosis of the European Society. EuroIntervention. 2013;8(11):1242-1251.
2. Menees D, Peterson E, Wang Y, et al. Door-to-balloon time and mortality among patients undergoing primary PCI. N Engl J Med. 2013;369(10):901-909.