Bayer Tests GIRK4 Inhibitor in Phase I Study for AFib Care

Key Highlights:

• Bayer begins Phase I trial for BAY 3670549, a novel GIRK4 inhibitor for atrial fibrillation.
• The drug aims to replace electric shocks with a fast-acting, drug-based cardioversion.
• It’s part of Bayer’s precision cardiology strategy to meet growing cardiovascular needs.

Bayer has initiated a Phase I clinical trial for BAY 3670549, a first-in-class, highly selective G-protein-coupled inwardly rectifying potassium channel 4 (GIRK4) inhibitor, targeting atrial fibrillation (AFib). This investigational drug aims to provide a rapid, effective pharmacological alternative to electric cardioversion (ECV), potentially eliminating the need for anesthesia, sedation, or electrical shocks in acute AFib treatment. The randomized, double-blind, placebo-controlled trial will assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of BAY 3670549 in healthy volunteers.

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AFib, affecting over 60 million people globally, is a leading cause of stroke and heart failure. Current treatment options like ECV are effective but resource-intensive, while existing anti-arrhythmic drugs have limited use due to safety concerns and contraindications. By selectively inhibiting GIRK4 channels—key regulators of the heart's electrical activity—BAY 3670549 may restore normal rhythm more safely and efficiently.

This molecule, developed through Bayer’s alliance with the Broad Institute, reflects Bayer’s strategic push into precision cardiology. According to Dr. Andrea Haegebarth, head of cardiovascular R&D at Bayer, this milestone supports the company’s broader mission to offer faster, safer, and more accessible cardiovascular treatments. With AFib prevalence projected to rise sharply in coming decades, BAY 3670549 could address a critical unmet need in cardiac care.