Medtronic plc announced positive clinical outcomes from two studies of its Affera™ family of technologies for treating atrial fibrillation (AFib) at the Heart Rhythm Society 2025 Annual Meeting in San Diego. The data highlights significant advancements in pulsed field ablation (PFA) technology for both paroxysmal and persistent AFib patients.
The one-year results for the investigational Sphere-360™ single-shot PFA catheter demonstrated impressive efficacy and safety in a prospective, single-arm, multi-center European trial. The device achieved freedom from arrhythmia recurrence in 88% of patients with paroxysmal atrial fibrillation (PAF), while maintaining chronically durable pulmonary vein isolation (PVI) in 98% of targeted veins. Notably, no safety events were reported in the subgroup treated with the most optimized waveform.
"The study results showed Sphere-360 has a promising safety and performance profile with zero serious adverse events observed," said Dr. Vivek Reddy, Director of Cardiac Arrhythmia Services for the Mount Sinai Health System in New York City. "Upon approval, Sphere-360 will be a valuable addition to Medtronic's Affera system, which has been a game changer for Afib treatment and physician workflow."
Technical Innovations in Catheter Design
The Sphere-360 catheter features several technical innovations that set it apart from other PFA technologies. It has a large, conformable lattice design that can be modified into various shapes and integrates seamlessly with the Affera Mapping and Ablation System. The device utilizes an 8.5 Fr sheath—the smallest in any single-shot PFA technology—potentially reducing procedural complications.
Dr. Reddy highlighted that the Sphere-360 "can easily create circumferential lesions without the need for catheter rotation," which may improve procedural efficiency and consistency. Medtronic plans to begin its U.S. pivotal trial for the Sphere-360 catheter later this year, though the device remains investigational worldwide and is not yet approved for sale or distribution.
Sphere-9 Catheter Shows Promise for Persistent AFib
In a separate sub-analysis from the Sphere Per-AF IDE study, Medtronic's Sphere-9™ catheter demonstrated efficacy for linear ablation in persistent AFib patients. Linear ablation is often used alongside PVI to improve outcomes in persistent AFib cases, which are typically more challenging to treat than paroxysmal cases.
The Sphere-9 catheter received FDA approval in October 2024 following the Sphere Per-AF IDE study, which evaluated its safety, efficacy, and efficiency in persistent AFib. The catheter features a wide area focal design with a 9mm lattice tip that can be used with an 8.5Fr sheath, offering physicians treatment flexibility.
"These results signify another step forward and energize us as we continue to earn and build our leadership position in electrophysiology every day," said Rebecca Seidel, president of the Cardiac Ablation Solutions business at Medtronic.
Expanding Global Reach in AFib Treatment
Medtronic now stands as the only company with two distinct PFA offerings for physicians and patients. The PulseSelect™ Pulsed Field Ablation System provides a single-shot solution for pulmonary vein isolation and is available in more than 30 countries. The Affera system with the Sphere-9 catheter is currently available in Europe, Australia, and New Zealand, with global expansion ongoing.
This portfolio expansion is particularly significant given the prevalence of AFib, which affects more than 60 million people worldwide. AFib is a progressive disease that often begins as paroxysmal (intermittent) and progresses to persistent (lasting more than 7 days without stopping). As the condition advances, patients face increased risks of serious complications including heart failure, stroke, and death.
Clinical Implications and Future Directions
The clinical significance of these advancements extends beyond the immediate efficacy data. Pulsed field ablation represents a relatively new approach to cardiac ablation that uses non-thermal electric fields to create lesions in cardiac tissue. This technology potentially offers advantages over traditional thermal-based approaches like radiofrequency ablation, including reduced risk of collateral tissue damage.
For physicians treating AFib patients, having multiple PFA options with different design characteristics allows for more personalized treatment approaches. The Sphere-360's single-shot capability may be particularly valuable for straightforward paroxysmal cases, while the Sphere-9's focal design offers precision for more complex ablation patterns needed in persistent AFib.
Medtronic's continued investment in this space reflects the growing recognition of AFib as a major public health concern requiring innovative treatment solutions. With these technologies, the company aims to address both the procedural challenges faced by electrophysiologists and the long-term outcomes for patients suffering from this common cardiac arrhythmia.
