Why Radial Access for Complex Coronary Interventions?

Cath Lab Digest talks with Michael J. Martinelli, MD, Chief of Cardiology, St. Peter’s Hospital, Albany, New York.

Cath Lab Digest talks with Michael J. Martinelli, MD, Chief of Cardiology, St. Peter’s Hospital, Albany, New York.

Can you tell us about your cath lab and hospital?

St. Peter’s Hospital in Albany, New York is a large, tertiary community hospital serving the greater portion of Northeastern New York.  We have 3 active cardiac cath labs and perform approximately 3,000 cardiac and peripheral vascular procedures. 

Are you involved in a wide range of procedures? 

Yes. I perform a wide range of complex coronary procedures, including bifurcation lesions, supported percutaneous coronary intervention (PCI), left main interventions, chronic total occlusions (CTOs), peripheral interventions, transcatheter aortic valve replacement (TAVR), and other structural heart interventions.

Can you define in more detail what is meant when we discuss “complex procedures”?

That’s a great question, because “complex” has been re-defined over the years owing in large part to advances in technology that have enhanced our ability to address increasingly challenging anatomy safely. Generally speaking, complex angioplasty refers to heavily calcified vessels requiring atherectomy, complex bifurcations including the left main, saphenous vein graft intervention requiring embolic protection, CTOs, and of course, ST-elevation myocardial infarction (STEMI). 

What drew you to the idea of using radial access?

It seemed intuitive that there may be a safety advantage with radial access, and it certainly seemed to be an excellent bleeding avoidance strategy in the era of more potent anti-thrombin and anti-platelet therapy. I have been performing radial procedures for approximately 10 years and 90-95% of my procedures are via radial access.

Is there anything that might cause you to choose femoral access in complex patients?

The majority of complex coronary interventions can be performed radially. There are some limitations, such as subclavian/innominate tortuosity and vasospasm, which often can be overcome with experience. Rarely, larger catheters are necessary for certain device delivery; however, technology has overcome a great deal of the need for larger sheaths and guide catheters. I believe in the benefit of a radial-first approach and therefore, will always look to pursue radial access, whether for straightforward cardiac cath or  complex PCI.

What data/trials have you found to provide the most compelling evidence to switch from a femoral to a radial-first operator?

Some of the earlier trials demonstrated improved outcomes with regard to local vascular complications and bleeding. The RIVAL trial1 was the first major trial evaluating the radial vs femoral approach. Although RIVAL did not demonstrate a difference in the composite endpoint (death, myocardial infarction, stroke, and non-coronary artery bypass graft surgery-related major bleeding at 30 days) in the overall cohort of patients, it did strongly suggest a decrease in the primary outcome in high-volume radial centers and in patients with STEMI. Also, there appeared to be a mortality benefit in the STEMI subgroup. Given the enhanced bleeding risk secondary to the aggressive anticoagulant therapy used in treating patients with STEMI, it appeared that the significant reduction in access site bleeding afforded by the radial approach would be of significant benefit to this group of patients. Several smaller trials2,3, mostly in patients with STEMI, appeared to support the findings of these RIVAL subgroups. Recently, a large trial of 8000 patients, the MATRIX trial4, evaluated the transradial vs transfemoral approaches in acute coronary syndrome (ACS) patients at high-volume radial centers. MATRIX demonstrated a decrease in the net adverse clinical events defined as major adverse cardiovascular events plus major bleeding, driven by a decrease in major bleeding and all-cause mortality (Figure 1). They showed a number to treat for benefit of 53 patients. The MATRIX trial demonstrated a significant benefit to radial access, especially in the ACS group, with regard to major bleeding and mortality. 

More recently, two meta-analyses were published in JACC Interventions. The first evaluated multiple studies, including MATRIX, with regard to ACS patients and concluded that in ACS patients, there is not only a bleeding benefit, but a mortality benefit with radial access.5 A subsequent meta-analysis included patients with the entire spectrum of coronary disease and arrived at similar conclusions, i.e., that radial access reduced mortality and major adverse cardiovascular events, reducing major bleeding and vascular complications, again, across an entire spectrum of patients, including the non-ACS group.6 

Given the available data, it is my feeling that when starting a radial program, a dedicated effort is required to gain experience with a variety of cases in order to provide a now-proven benefit to patients. This includes the STEMI patients, who stand to receive the most benefit.

What (other) population benefits most from radial access?

Patients with potentially higher bleeding risk such as women and older individuals benefit. In addition, obese patients, in whom the femoral approach carries with it a higher risk of access site complications, benefit from both a morbidity and comfort standpoint.

Access site complications are rare. Radial artery occlusion, which is mostly “silent”, is mitigated by the use of anticoagulation, hydrophilic sheaths, aggressive treatment of spasm, and patent hemostasis at the time of sheath removal.

Tell us about your toolbox.

Initial arterial access is very important, especially in the setting of a STEMI, and I would recommend becoming comfortable with a reliable, rapid technique. I use the through and through approach, though many operators prefer a direct puncture approach. Hydrophilic sheaths are essential. The Glidesheath Slender Introducer Sheath (Terumo), which has a 5 French (F) outer diameter with a 6F inner diameter, enables us to utilize a 6F system within the smaller radial artery. Similarly, this is available in a 6/7 French size, enabling the use of larger guide catheters with lower profile access. 

Hydrophilic wires are extremely important, especially when navigating radial loops and tortuous innominate/subclavian vessels. Occasionally, one may experience difficulty manipulating a catheter once it has been placed in the ascending aorta, and a stiffer wire, such as an Amplatz wire, may help to manipulate the catheter into the coronary ostia. 

Becoming familiar with universal diagnostic (Optitorque, Jacky, Tiger [Terumo]) and guide catheters (Heartrail III, Ikari Right and Left [Terumo]) is beneficial, as this will reduce catheter exchanges, which may in turn reduce the possibility of vasospasm, as well as expedite the procedure in the emergency setting. Although the radial-specific guide catheters provide excellent backup and versatility, most of the usual array of guide catheters can be used.   

Guide extenders, such as the GuideLiner (Vascular Solutions) have become an important adjunct to complex angioplasty. 

For difficult anatomy, such as accessing radial loops and navigating tortuousity within the subclavian artery and aorta, the Glidewire Baby-J hydrophilic coated guidewire (Terumo) is, in my opinion, essential to have in the toolbox. This can allow expeditious access to the coronary arteries in the setting of tortuous, calcific vessels.

Familiarity with the use of microcatheters and specialized wires to access complex coronary anatomy is also very important. When attempting to cross tortuous, calcified vessels or chronic total occlusions, microcatheter support such as the use of the Finecross MG Coronary Micro-Guide catheter (Terumo) in conjunction with a complex lesion wire (i.e., the Terumo Runthrough NS Hypercoat coronary guidewire, or the Abbott Vascular Pilot or Fielder XT family of wires), enable the operator to perform very complex interventions radially. The microcatheters also enable exchange for more supportive wires or atherectomy wires as necessary to complete the procedure.

You mentioned earlier that subclavian tortuosity doesn’t necessarily present itself as a red flag for a radial approach. Why?

There is some tortuosity and calcification that may be impossible to navigate. Tortuosity can often be overcome with the use of hydrophilic wires, specifically the Glidewire Baby-J, owing to a tightly curved tip, which helps to avoid small branches. Once the catheter is successfully placed either in the descending aorta or the ascending aorta, stiffer wires can be used to manipulate the catheter and straighten the vessel. Many times, tortuosity can be straightened by a standard .035-inch wire; however, more supportive wires such as the Amplatz Extra Stiff wire (Cook Medical) may be necessary.

Difficulties arising from the catheter being directed into the descending aorta can often be overcome by manipulating the catheter in the direction of the ascending aorta while instructing the patient to take a deep breath and advancing the wire. This is an important point, because the deep breath can be used in many situations, one of which is to overcome subclavian/innominate tortuosity, as this will also aid in straightening the vessels. When engaging a guide or a diagnostic catheter into the coronary ostium, a deep breath will often enhance access and catheter seating for angiography and intervention.  

Can you share more about your experience using radial access in STEMI patients?

A radial-first approach is essential in the development of a successful radial STEMI program. I perform the vast majority of STEMIs from the radial approach. When instituting this approach, we must consider the timing as it pertains to radial artery access, angiography, guide catheter engagement, and successful revascularization. The literature suggests considering aborting the radial approach in the following circumstances: more than 3 minutes taken to obtain radial access, more than 10 minutes to access the infarct-related artery with a guide, and more than 20 minutes taken to application of the first device.7 Although these are merely suggested “guidelines”, they are important to keep in mind when starting a program and require a level of experience to accomplish in order maintain excellent door-to-balloon times. 

It is important to master a vascular access strategy. Once access is obtained, universal catheters are extremely helpful in advancing the radial-first approach. Imaging the non-infarct-related artery with a universal guide catheter, followed by engagement and intervention of the infarct-related artery, can reduce procedure time as well as the incidence of vasospasm by limiting catheter exchanges. Current data suggests that the radial artery should be the default access in the STEMI patient.4 It is therefore important for a program to embrace the radial technique in order to gain the necessary experience to safely and expeditiously perform PCI in this patient population.

One reason for the slow uptake of the radial approach in the U.S. is that a learning curve exists, even for experienced operators. We have seen more recently, however, an increase in the use of radial access and a decrease in the number of cases which appear to be required to master the procedure. Anecdotally, this has been confirmed by feedback I have received from proctoring experience in cath labs across the country, in institutions embracing a dedicated, programmatic approach. With the evidence building regarding mortality benefit of radial access in the setting of ACS and STEMI, experience is essential in order to achieve excellent door-to-vessel-open times, equivalent to current standards.

How does your team help you achieve radial access in complex cases?

A radial program is truly a team effort. Buy-in from the entire staff is essential, especially in the emergency setting. Our cath lab is dedicated to the “radial first” approach. For example, the procedure set up for STEMI includes a radial and femoral prep. The femoral prep is primarily for the potential need for support devices such as an intra-aortic balloon pump (IABP) or Impella (Abiomed), as well as the less likely need for bailout from the radial approach. When we are performing supported angioplasty, we will also pursue a radial-first approach in order to minimize femoral access. This is to avoid multiple femoral access sites, thereby reducing the potential for access site bleeding.

Do you have a preference as to which side you prefer for radial access, left or right?

Generally, I prefer the right radial approach. Using the right radial enables simulation of the positioning used in femoral access, as the arm is placed alongside the patient. I will often, but not always, choose the left radial approach to access a left internal mammary artery (LIMA) graft, as it is often easier and less time consuming to access the LIMA from the left side. As I noted, there are some anatomic considerations involving the right upper extremity anatomy that may necessitate left radial access.

Do you use the Allen’s test as a method to rule out radial access?

There are certainly patients who have significant peripheral arterial disease and diminished radial pulses. An Allen’s test may be beneficial in these situations, in deciding right vs left access. However, I do not feel that an abnormal Allen’s test is necessarily a contraindication to a radial procedure, owing to the rich vascular supply to the hand and an extremely low rate of access site complications. 

Can we predict vasospasm?

We do see an increase in the incidence of vasospasm in women with smaller vessels, smokers, and those patients with peripheral arterial disease. It is usually easier to attempt prophylaxis for vasospasm than to treat it as it occurs, and to that end, we pre-treat for vasospasm with nitrates and/or calcium blockers.

What if vasospasm does occur?

The use of additional nitrates and calcium blockers is often required in this setting. Sedation is very important and will enhance the effect of anti-spasm medication. If untreated, vasospasm will persist, necessitating aggressive treatment. Angiography is often helpful in order to assess whether placement of the catheter is in an accessory vessel requiring repositioning, or in identifying dissection or perforation, which will often exacerbate spasm.  

What advantages do you see for the team by using radial access in complex PCI procedures?

As a team of health care providers, our primary interest is the patient. A robust radial program not only has the potential to improve outcomes, but also enhances patient comfort while reducing cost. 

With regard to the staff, the radial approach requires less dedicated post-op hours given the significant reduction in access site issues. Significant bleeding, especially retroperitoneal bleeding, is no longer a concern. Also, with the use of the radial approach, we are seeing an increase in the use of same-day angioplasty, which is not only associated with decreased cost, but with an increase in patient satisfaction.8

Can you talk more about recovery process for complex PCI patients who receive radial access?

Assuming that the procedure is successful and there are no intra-procedural issues, the recovery is very simple, which is one of the major advantages of the radial approach. Usually we will ambulate the patients 1-2 hours after the procedure depending on the level of sedation. The sedation level generally depends on the length of the procedure, and whether or not significant vasospasm has occurred. We are much less concerned about potential bleeding complications that may arise with the use of more intensive anticoagulation in complex interventions. 

Do you see a greater potential use for transradial access in complex PCI?

Yes, operators are realizing the potential to perform most procedures safely with continued advances in available equipment. Additionally, there is an increasing body of evidence demonstrating significant bleeding reduction and consequently, mortality benefit. Radial use in complex PCI will likely continue to increase, especially in the STEMI population.

Any final thoughts?

Our goal is to be a radial-first institution, and we have, over the last several years, improved our overall radial access rate to over 70%. The radial approach improves patient satisfaction, comfort, and safety. The most benefit appears to be demonstrated in the higher risk patients, thus providing the incentive to pursue complex PCI via the radial approach.

Cost is also important, and a clear cost benefit has been shown with the use of the radial approach.9 Of course, patient satisfaction remains very important and has been shown across the board to be positive.10


  1. Mehta SR, Jolly SS, Cairns J, Niemela K, Rao SV, Cheema AN, et al; RIVAL Investigators. Effects of radial versus femoral artery access in patients with acute coronary syndromes with or without ST-segment elevation. J Am Coll Cardiol. 2012 Dec 18; 60(24): 2490-2499. 
  2. Romagnoli E, Biondi-Zoccai G, Sciahbasi A, Politi L, Rigattieri S, Pendenza G, 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 Dec 18; 60(24): 2481-2489.
  3. Bernat I, Horak D, Stasek J, Mates M, Pesek J, Ostadal P, et al. ST-segment elevation myocardial infarction treated by radial or femoral approach in a multicenter randomized clinical trial: the STEMI-RADIAL trial. J Am Coll Cardiol. 2014 Mar 18; 63(10): 964-972.
  4. Valgimigli M, Gagnor A, Calabró P, Frigoli E, Leonardi S, Zaro T, et al; MATRIX Investigators. Radial versus femoral access in patients with acute coronary syndromes undergoing invasive management: a randomised multicentre trial. Lancet. 2015 Jun 20; 385(9986): 2465-2476.
  5. Andò G, Capodanno D. Radial access reduces mortality in patients with acute coronary syndromes: results from an updated trial sequential analysis of randomized trials. JACC Cardiovasc Interv. 2016 Apr 11; 9(7): 660-670.
  6. Ferrante G, Rao SV, Jüni P, Da Costa BR, Reimers B, Condorelli G, et al. Radial versus femoral access for coronary interventions across the entire spectrum of patients with coronary artery disease: a meta-analysis of randomized trials. JACC Cardiovasc Interv. 2016 Jul 25; 9(14): 1419-1434.
  7. Rao SV, Tremmel JA, Gilchrist IC, Shah PB, Gulati R, Shroff AR, et al; Society for Cardiovascular Angiography and Intervention’s Transradial Working Group. Best practices for transradial angiography and intervention: A consensus statement from the society for cardiovascular angiography and intervention’s transradial working group. Catheter Cardiovasc Interv. 2014 Feb; 83(2): 228-236.
  8. Shroff A, Kupfer J, Gilchrist IC, Caputo R, Speiser B, Bertrand OF, Pancholy SB, Rao SV. Same-day discharge after percutaneous coronary intervention: current perspectives and strategies for implementation. JAMA Cardiol. 2016 May 1; 1(2): 216-223.
  9. Amin AP, House JA, Safley DM, Chhatriwalla AK, Giersiefen H, Bremer A, et al. Costs of transradial percutaneous coronary intervention. JACC Cardiovasc Interv. 2013 Aug; 6(8): 827-834.
  10. Surveys indicate greater patient satisfaction with radial approach. February 3, 2015. Available online at er Accessed September 8, 2016.

This article is published with support from Terumo.

Disclosure: Dr. Michael Martinelli reports consulting honoraria from Terumo and speaker’s honoraria from AstraZeneca, and Terumo.

Dr. Michael Martinelli can be contacted at