In the latest in a battle between the titans in transcatheter aortic valve replacement (TAVR), the European Patent Office invalidated a patent at the heart of Edwards Lifesciences’ infringement case against Medtronic.

In July 2013, a German court ruled that Medtronic infringed on Edwards’ TAVR patent and ordered Medtronic to recall its CoreValve and CoreValve Evolut systems in Germany. The technology at the center of the controversy was the Spenser patent owned by Edwards.

Medtronic challenged the patent at the European Patent Office, which in October issued a preliminary opinion that questioned the validity of the patent and opened the way for Medtronic to again market and sell CoreValve in Germany. On March 6, the patent office invalidated the Spencer patent, Minneapolis-based Medtronic announced. Irving, Calif.-based Edwards Lifesciences is entitled to appeal the ruling.

Patent skirmishes between the companies continue in the U.S. In January, a jury in an infringement case voted in favor of Edwards and awarded the company $394 million in damages. Medtronic said it would appeal.

The CoreValve received FDA approval for extreme risk patients with severe aortic stenosis in January. Edwards’ Sapien TAVR device was approved by the FDA for use in inoperable patients with severe aortic stenosis in 2011 and for high-risk patients in 2012.