MATRIX: Radial Access Reduces Net Adverse Events; Bivalirudin Shows Mixed Results in ACS Patients

Two separate Late-Breaking Clinical Trials were presented on Monday, March 16 as a part of ACC.15, and looked at strategies to reduce major bleeding and mortality in patients with acute coronary syndrome (ACS). Both trials are part of the MATRIX study.

The first trial, which was also simultaneously published in the Lancet, found greater reductions in risk of major bleeding and mortality in ACS patients who underwent coronary angiography and percutaneous coronary intervention (PCI) using transradial instead of transfemoral access.

Author Marco Valgimigli, MD, PhD, et al, conducted a 1:1 randomized superiority trial to compare transradial access against transfemoral access in ACS patients who were undergoing coronary angiography and PCI. The study looked at 8,404 patients from 78 health centers in Italy, the Netherlands, Spain and Sweden.

Results demonstrated that the patient population in the transradial access group had slightly better clinical outcomes (8.8 percent) than those in the transfemoral access (10.3 percent). Investigators noted that while transradial versus transfemoral access was shown to reduce major bleeds and all-cause mortality, it was not found to reduce heat attack or stroke.

“Differences did not reach statistical significance for major adverse cardiovascular events as one of the two co-primary outcomes, and one can argue that the results for secondary outcomes, including all-cause mortality, are not definite since their α levels were not adjusted for multiple comparisons,” said Valgimigli. “However, our results need to be interpreted in the context of the updated meta-analysis (panel), which suggests highly significant benefits of radial access in acute coronary syndrome patients for major adverse cardiovascular events (p=0.0051) and all-cause mortality (p=0.0011) with no evidence of statistical heterogeneity between trials.”

Valgimigli concluded that the results “show that in patients with ACS, with or without ST-segment elevation, undergoing invasive management, the use of radial access compared with femoral access decreases net adverse clinical events.”

In the second study, Valgimigli and team found that ACS patients undergoing angioplasty did not see significant improvement in risk of cardiac events or cardiac events plus major bleeding after taking bivalirudin as compared with standard care. However, bivalirudin was shown to significantly lower the risk of complications and mortality related to bleeding.

The randomized trial included 7,200 ACS patients who were about to undergo angioplasty, from 78 hospitals in four European countries. Patients were given either bivalirudin or standard coagulation therapy—unfractionated heparin.

Results of the study found bivalirudin did not improve outcomes of cardiac events and cardiac events plus major bleeding. However, the bivalirudin group had a significantly lower rate of death, most likely due to the reduction of bleed complications especially near the catheter insertion site, which occurred in 1.7 percent of patients versus 2.3 percent of patients in the standard care group.

“We saw an impressive reduction in bleeding with bivalirudin compared to the control, which likely contributed to the reduced mortality in this group,” said Valgimigli. “I believe the study shows bivalirudin can provide additional benefits to patients as compared to unfractionated heparin in current medical practice.”

It is important to note that these results follow a series of other bivalirudin studies with inconsistent and hotly debated outcomes in the medical community. Unlike previous trials, Valgimigli and his co-authors allowed clinicians to decide whether or not glycoprotein IIb/IIIa inhibitors would complement standard protocol.

“Our study really comes at the right moment to re-evaluate the role of bivalirudin,” Valgimigli said. “Glycoprotein IIb/IIIa inhibitors were used in about one-quarter of the control patients in our study, at the operator’s discretion, which is a better reflection of current practice than the control protocol used in previous studies.”

Keywords: ACC Annual Scientific Session, Acute Coronary Syndrome, Antithrombins, Follow-Up Studies, Heparin, Hirudins, Incidence, Longitudinal Studies, Myocardial Infarction, Peptide Fragments, Percutaneous Coronary Intervention, Recombinant Proteins, Stents, Stroke, Thrombin, Thrombosis, Hemorrhage, Infarction

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