LONDON – Bivalirudin did not prove superior to unfractionated heparin in reducing the rate of major adverse cardiovascular events in two nested, open-label, randomized clinical trials involving patients presenting with acute coronary syndrome who were expected to undergo percutaneous coronary intervention, Dr. Marco Valgimigli reported.
In addition, post-PCI infusions of bivalirudin for 4 hours or longer did not reduce the rate of adverse bleeding events, compared with no infusion.
Dr. Marco Valgimigli
These findings add important data to the understanding of antithrombotic therapy in ACS patients undergoing invasive treatment, but they do not resolve the persistent question of which method is best for preventing thrombotic complications while limiting the risk of bleeding during and after such procedures, said Dr. Valgimigli of Erasmus University in Rotterdam.
Previous studies comparing bivalirudin, a direct thrombin inhibitor, against unfractionated heparin, an indirect thrombin inhibitor, have yielded conflicting results regarding ischemic and bleeding outcomes, so Dr. Valgimigli and his fellow investigators in the MATRIX (Minimizing Adverse Hemorrhagic Events by Transradial Access Site and Systemic Implementation of Angiox) trial conducted two industry-sponsored superiority trials to try to settle the question.
The findings of one of these trials were reported by Dr. Valgimigli at the annual congress of the European Society of Cardiology on Sept. 1, when the results of both were simultaneously published online (N Engl J Med. 2015 Sept 1. doi: 10.1056/NEJMoa1507854).
The MATRIX studies were conducted at 78 medical centers in Italy, the Netherlands, Spain, and Sweden. They involved 7,213 patients who presented with either ST-elevation MI or non-STEMI ACS and were expected to undergo PCI. The first trial, MATRIX Antithrombin, assessed outcomes in 3,610 of these participants who were randomly assigned to receive bivalirudin and 3,603 assigned to receive unfractionated heparin. In the second trial, MATRIX Treatment Duration, the bivalirudin group was further randomized to receive either a post-PCI bivalirudin infusion (1,799 patients) or no post-PCI infusion (1,811 patients).
MATRIX Antithrombin
At 1-month follow-up, the rate of major adverse cardiovascular events (MACEs) – a composite of death from any cause, myocardial infarction, or stroke – was no lower in the bivalirudin group (10.3%) than in the heparin group (10.9%), for a rate ratio of 0.94. Similarly, the rate of net adverse clinical events was not significantly lower with bivalirudin (11.2%) than with heparin (12.4%), for a rate ratio of 0.89.
MATRIX Treatment Duration
The primary outcome in the MATRIX Treatment Duration study – a composite of urgent target-vessel revascularization, definite stent thrombosis, or net adverse clinical events at 30 days – occurred in 11.0% of patients who received post-PCI bivalirudin infusions and 11.9% of those who did not, a nonsignificant difference (rate ratio, 0.91). However, the rate of subacute definite stent thrombosis was significantly higher in the post-PCI infusion group, at 0.7%, compared with 0.2% in the group that didn’t receive post-PCI infusions (RR, 4.37).
“I believe the option to prolong or stop bivalirudin infusion after PCI remains open for clinicians, who will have to decide based on the ischemic and bleeding risk of individual patients as well as, perhaps, based on type of acute coronary syndrome, timing of loading dose, and type of oral P2Y12 inhibitors,” Dr. Valgimigli said, noting that this is in keeping with the current labeling of the drug in Europe and the United States.
The MATRIX study was sponsored by the nonprofit Italian Society of Invasive Cardiology and financially supported by the Medicines Company and Terumo Medical. Dr. Valgimigli reported ties to AstraZeneca, the Medicines Company, Terumo Medical, St. Jude Vascular, Alvimedica, Abbott Vascular, and Correvio; his associates reported ties to numerous industry sources.
Mary Ann Moon contributed to this report.