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A Closer Look at Radial Access Data: Important Questions Remain

Issue: July/August 2013

ByMichael S. Lee, MD, FACC, FSCAI

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In January, three European associations, including the European Association of Percutaneous Cardiovascular Interventions and the Working Group on Thrombosis of the European Society of Cardiology, issued a consensus document that advocates the transradial approach over the transfemoral approach in PCI.

This endorsement was based on randomized trials, such as RIVAL, RIFLE-STEACS and STEMI-RADIAL, which reported the superiority of radial access compared with femoral access for PCI in ACS, with a reduction in bleeding and vascular complications. Radial access was also associated with a significantly lower mortality in STEMI patients in RIVAL and lower cardiac mortality in RIFLE-STEACS. Transradial intervention may also decrease access-site bleeding complications and therefore the risk for death and need for blood transfusions, and allow patients to continue cardioprotective post-procedural anticoagulation that otherwise might have been discontinued had major bleeding occurred.

Accounting for Antithrombotic Regimens

Although the data are supportive of PCI in ACS, the consensus document endorsed transradial intervention in both elective and ACS patients. However, these trials included suboptimal antithrombotic regimens, including high doses of heparin and a high percentage of patients on glycoprotein IIb/IIIa receptor antagonists. In patients with STEMI being referred for primary PCI, the American College of Cardiology Foundation/American Heart Association guidelines recommend 50 IU/kg to 70 IU/kg bolus to achieve an activated clotting time of 200 to 250 seconds when a glycoprotein IIb/IIIa receptor antagonist is planned and 70 U/kg to 100 U/kg to achieve an activated clotting time of 250 to 300 seconds (as measured by the HemoTec device) when no glycoprotein IIb/IIIa receptor antagonist is planned. Heparin doses in excess of this amount have not been associated with improved pre-procedural patency or post-procedural outcomes.

Michael S. Lee

Although the amount of heparin administered was not presented in the RIVAL study, one-quarter of all patients and one-third of STEMI patients received glycoprotein IIb/IIIa inhibitors. In the RIFLE-STEACS trial, the heparin dose of 71 IU/kg was in excess of what is recommended given that more than two-thirds received glycoprotein IIb/IIIa inhibitors. Patients in the STEMI-RADIAL trial received an average heparin dose of more than 100 IU/kg despite nearly half the patients being treated with glycoprotein IIb/IIIa inhibitors.

There is a paucity of patients on bivalirudin (Angiomax, The Medicines Company), a direct thrombin inhibitor shown to decrease bleeding and improve outcomes compared with heparin and glycoprotein IIb/IIIa receptor antagonists. Bivalirudin was used in 3.1% of patients who underwent transfemoral intervention in the RIVAL trial and 7.3% in the RIFLE-STEACS trial. A significantly lower percentage of femoral-access patients received smaller gauge arterial sheaths compared with radial-access patients (≤6F in 81.4% vs. 90.8%; P<.001).

Final Considerations

Without a well-designed randomized trial, the applications of these trial findings are minimal. In addition to inappropriate antithrombotic therapy, these trials were carried forth in high-volume transradial centers, further limiting the ability to generalize the findings to most PCI centers where PCI is performed primarily with transfemoral access. These are important considerations, especially for high-risk and ACS patients, in whom the negative implications of major bleeding are even greater. Ultimately, a trial comparing femoral vs. radial access in patients on bivalirudin, potent antiplatelet medication and without adjunctive glycoprotein IIb/IIIa inhibitor therapy, as well as possibly incorporating ultrasound guidance and the use of a micropuncture kit, is needed to assess outcomes based on access site alone.

Disclosure: Lee reports receiving honoraria from Abiomed, Boston Scientific, Janssen, Medtronic and St. Jude Medical.