MATRIX: Transradial Access Benefits Maintained at 1 Year

Patrice Wendling

September 04, 2018

MUNICH — The early benefits of using transradial rather than transfemoral access during invasive treatment of patients with acute coronary syndrome persist at 1 year, final results of the MATRIX trial show.

The risk for major adverse cardiovascular events (MACE) at 1 year was similar between patients assigned to treatment via radial or femoral access (rate ratio [RR], 0.89; 95% CI, 0.80 - 1.00).

The radial-access group, however, had 13% fewer net adverse clinical events (NACE), defined as non–coronary artery bypass graft-related major bleeding or MACE (RR, 0.87; 95% CI, 0.78 - 0.97).

"Radial access reduced the 1-year NACE rates, owing to a durable effect on cardiovascular death and bleeding complications," principal investigator, Professor Marco Valgimigli, MD, University of Bern, Switzerland, said here at the European Society of Cardiology (ESC) Congress 2018.

Cardiovascular mortality was 2.1% in the radial-access group vs 3.0% in the femoral-access group, and major Bleeding Academic Research Consortium (BARC) type 3 or 5 bleeding was 2.1% vs 2.9% (for both outcomes, RR, 0.71; 95% CI, 0.54 - 0.93).

Myocardial infarction (MI), stent thrombosis, and stroke rates did not differ significantly between patients in the two groups, notes the report, published online in the Lancet to coincide with the late-breaking interventional presentation.

MATRIX is the largest trial to compare radial vs femoral access and the first to report 1-year outcomes, observed Valgimigli.

The open-label, superiority study included 8404 patients with acute coronary syndrome (ACS), including those with or without ST-segment elevation MIs, and experienced operators, who had performed at least 50% of their interventions via the radial artery in the last year. Following coronary angiography, about 80% of all patients underwent percutaneous coronary intervention (PCI).

As previously reported, MATRIX showed no difference at 30 days between the radial- and femoral-access groups regarding MACE but significant reductions in major bleeding and all-cause mortality with the transradial approach.

"I suppose many of the messages from this trial have already flown into practice," session moderator Robert Byrne, MBBcH, PhD, German Heart Center, Munich, commented to theheart.org | Medscape Cardiology.

"If you look at the guidelines, they already give a 1a recommendation for radial over femoral, based in part on the earlier 30-day results of this trial," he said. "So in that respect, you could say, 'Well, the incremental value is less,' but I think it's still important to know that there's no loss of effect between 30 days and 1 year."

Bivalirudin: "A Very Reasonable Option"

During the same session, Valgimigli also presented the 1-year results of two other studies nested within the MATRIX program: MATRIX Antithrombin and MATRIX treatment duration. A total of 7213 patients from the access-site study were included in the antithrombin study, of whom 3610 were allocated to bivalirudin and 3603 were allocated to unfractionated heparin, with or without glycoprotein IIb/IIIa inhibitors (GPI) at the discretion of the operator.

Heparin was given at 70 to 100 units/kg in patients not receiving GPI and at 50 to 70 units/kg in patients receiving GPI. Patients could receive bivalirudin during PCI only or both during and after the procedure.

Bivalirudin was given according to product labeling, with a bolus of 0.75 mg/kg followed immediately by an infusion of 1.75 mg/kg/h until completion of PCI.

For patients receiving prolonged bivalirudin treatment, the post-PCI dose could be the full dose for up to 4 hours or a reduced dose of 0.25 mg/kg/h for at least 6 hours, at the discretion of treating physicians. 

As observed at 30 days, the use of bivalirudin with or without GPIs failed to significantly reduce 1-year rates of MACE (RR, 0.94; 95% CI, 0.83 - 1.05) or NACE (RR, 0.91; 95% CI, 0.81 - 1.02), when compared with unfractionated heparin.

Interestingly, the significant interaction observed at 30 days between bivalirudin and mortality and bleeding persisted at 1 year, Valgimigli said. Bivalirudin was associated with a "robust" 32% decrease in risk for major BARC 3 or 5 bleeding events at 1 year (RR, 0.68; 95% CI, 0.51- 0.91), suggesting a complementary role in reducing bleeding risk with respect to access site selection.

Bivalirudin was also associated with lower risk for all-cause (RR, 0.79; 95% CI, 0.63 - 0.99) and cardiovascular death (RR, 0.74; 95% CI, 0.55 - 0.99) at 1 year, but these findings should be interpreted with caution as the study was not powered for mortality, the authors note.

MI rates did not differ between groups, but definite stent thrombosis continued to be higher with bivalirudin (RR, 1.72; 95% CI, 1.02 - 2.91) — a finding that has been reported in other studies.

Regarding treatment duration, post-PCI bivalirudin infusion did not reduce 1-year NACE rates compared with no post-PCI bivalirudin. However, exploratory analysis showed ischemic complications were lower with the post-PCI full-dose regimen and higher with the post-PCI low-dose regimen, Valgimigli said.

Although the results were "slightly in favor of bivalirudin, it is certainly a therapy that has fallen out of use in Europe," Byrne noted.

"I know in talking to my US colleagues that they still use it in select cases," he said. "Maybe they use it more frequently in patients where they've decided they are going to go femoral because they are concerned about bleeding, but this is probably a niche. In Europe, the penetration of bivalirudin is quite low."

In an accompanying editorial, Dominick J. Angiolillo, MD, University of Florida College of Medicine-Jacksonville, said, "The long-term benefit for net adverse clinical events, driven by a reduction in major bleeding and cardiovascular mortality, ought to change practice so that radial access should be the default approach in invasively managed patients with acute coronary syndrome."

Although it could be argued that the results leave open the controversy about the optimal antithrombotic regimen during PCI, he said, the MATRIX results are among the best available data and informative.

"In fact, although the trial was not powered for secondary endpoints, and thus so-called positive findings should be considered only nominally significant, the reduction in bleeding (access and non-access site) and mortality (all-cause and cardiovascular mortality) confirmed at 1 year cannot be ignored given the established link between these outcomes," Angiolillo argues.

"Thus, bivalirudin remains an acceptable treatment for patients with acute coronary syndrome undergoing percutaneous coronary intervention and a very reasonable option in high-bleeding-risk settings, where it might complement the benefits of radial access."

The study was funded by the Italian Society of Invasive Cardiology, The Medicines Company, Terumo, and Canada Research Chairs Programme. Valgimigli reports receiving grants from The Medicines Company and Terumo during the conduct of the study and grants and personal fees from AstraZeneca, personal fees and nonfinancial support from The Medicines Company, and personal fees from Terumo, St. Jude/Abbott Vascular, Alvimedica, and Correvio outside the study. Angiolillo reports receiving consulting fees/honoraria from Amgen, Aralez, AstraZeneca, Bayer, Biosensors, Bristol-Myers Squibb, Chiesi, Daiichi-Sankyo, Eli Lilly, Janssen, Merck, PLx Pharma, Pfizer, Sanofi, and The Medicines Company. He also reports payments for participation in review activities from CeloNova and St. Jude and institutional grants from Amgen, AstraZeneca, Bayer, Biosensors, CeloNova, CSL Behring, Daiichi-Sankyo, Eisai, Eli-Lilly, Gilead, Janssen, Matsutani Chemical Industry Co, Merck, Novartis, Osprey Medical, and Renal Guard Solutions.

European Society of Cardiology (ESC) Congress 2018.

Lancet. Published online August 2018.  Abstract, Editorial

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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