Boston Scientific Corp yesterday said that it is acquiring start-up medical device maker Atritech, Inc, in a $375-million deal to broaden its portfolio of less-invasive cardiovascular devices.

Founded in 2000, Minnesota-based privately held Atritech has developed a novel device called 'Watchman' designed to close the left atrial appendage in patients with atrial fibrillation who are at risk for ischemic stroke.

The Watchman left atrial appendage closure technology, which was originally conceived by doctors at the Minneapolis Heart Institute and the Mayo Clinic, is the first device proved in a randomised clinical trial to offer an alternative to anticoagulant drugs, which are associated with an increased risk of bleeding, for patients experiencing atrial fibrillation who are at high risk for stroke.  

Patients with atrial fibrillation are prone to developing blood clots in an area of the heart known as the left atrial appendage.  If these clots dislodge and enter the bloodstream they may block circulation to the brain, resulting in a stroke.  

The Watchman device is designed to close the left atrial appendage, thereby preventing clots within the appendage from being dislodged into the circulation.  

The device has demonstrated a 38-per cent relative risk reduction for stroke, cardiovascular death and systemic embolism compared to long-term warfarin therapy.