AtriCure (NSDQ:ATRC) said it won an investigational device exemption from the FDA for a 1st-of-its-kind clinical trial involving patients with non-paroxysmal atrial fibrillation.

The DEEP trial, a prospective, multicenter, single-arm pivotal study slated to enroll up to 220 patients, is designed to evaluate patients with persistent or long-standing persistent atrial fibrillation, AtriCure said.

The trial, named for its dual epicardial and endocardial ablation approach, will combine minimally invasive ablation outside the heart and catheter-based ablation inside the heart to treat more severe afib cases, according to a press release. The primary effectiveness endpoint is freedom from afib and freedom of Class I or III antiarrhythmic drug therapy, according to the release.

"We are pleased to be moving into this next phase of a pivotal trial for DEEP," CEO Mike Carrel said in prepared remarks. "Our goal is to start the Institutional Review Board process with many of the leading institutions right away. We intend to have our first subject enrolled in early 2015, with completion of enrollment targeted for mid-2017.”

Patients with atrial fibrillation who failed antiarrhythmic drug therapy and received up to 2 failed catheter ablations are candidates for the 2-phase DEEP study. In the 1st phase, the surgeon will perform the epicardial ablation using the 3 Bipolar system and occlude the left atrial appendage with the AtriClip system, according to the release. About three months later the patient will undergo an endocardial mapping and catheter ablation procedure performed by an electrophysiologist, AtriCure said.