Shedding Light on Bridging Therapy: A Deeper Dive into the AMBER Trial

Alfonso J Tafur interviews McMaster University’s Dr. Alexander Godoy and Medical Student Tegvir Singh Grewal at ISTH 2025:

At the forefront of clinical research in cardiovascular medicine, Dr. Alejandro Godoy and medical student Tegvir Singh Grewal from McMaster University sat down to share key findings from the AMBER trial and its recent sub-analysis. Their work addresses a critical, understudied question in thrombosis care: What is the safest and most effective way to manage anticoagulation in patients with mechanical heart valves—particularly during procedures such as colonoscopies and endoscopies?

Why Was the AMBER Trial Necessary?

Discontinuing anticoagulation in patients with mechanical heart valves, especially those with aortic mechanical valves, has long been a gray area in medicine. According to Dr. Godoy, previous data on this topic were limited to small sub-analyses and low-quality retrospective studies with conflicting results. Recognizing this knowledge gap, the AMBER team launched a multi-center international study to better understand optimal management strategies.

A Closer Look at the Study Design

The AMBER trial compiled five years of retrospective data from five hospitals—three in Canada and two in the U.S. Researchers scoured electronic health records, tracking 30-day outcomes in patients who temporarily discontinued warfarin. The goal: to determine the rates of thrombotic and bleeding events when bridging anticoagulation was used.

Key Findings from the AMBER Trial

The team discovered that using low molecular weight heparin (LMWH) as a bridging therapy during temporary warfarin interruptions may be associated with increased bleeding—particularly when it’s not carefully tailored to the patient’s individual risk. That said, thrombotic events were low in both bridged and non-bridged patients. While the results are promising, Dr. Godoy emphasized the need for a randomized controlled trial to confirm these findings.

Introducing the AMBER-GI Sub-Analysis

Tegvir Singh Grewal, a medical student contributing to the AMBER project, spearheaded a novel sub-analysis focusing on patients with aortic mechanical heart valves undergoing gastrointestinal procedures. This included 190 patients from the overall AMBER cohort who had colonoscopies or endoscopies.

“This is the first analysis of its kind,” said Grewal. “There is a notable lack of evidence and weak guideline support for managing anticoagulation in this patient subset. Our goal was to fill that gap.”

The AMBER-GI sub-analysis provides much-needed insight into clinical practice patterns, acting as a foundation for future trials. Given how common GI procedures are, Grewal emphasized the importance of ensuring safety and clarity in anticoagulation strategies for patients who may undergo these procedures multiple times throughout their lives.

What’s Next?

Both Godoy and Grewal hope that their findings will serve as a springboard for future research and guideline development. As Grewal aptly noted, “The current landscape is highly anecdotal. We need stronger data so clinicians can make evidence-based decisions and deliver the safest care.”

Their work is a timely reminder of the pressing need for targeted, high-quality data in complex patient populations—and a testament to the impact of collaborative, cross-disciplinary research.