A new keyhole heart surgery device to cover a “pocket” in the heart could reduce the risk of strokes and help patients avoid the side effects of blood-thinning medication, London hospital surgeons said.

The surgery treats patients who are suffering from an irregular heartbeat, known as atrial fibrillation.

Surgeons implant an umbrella-like device known as the Watchman into the heart, preventing life-threatening blood clots from forming and entering the bloodstream, according to timesonline.co.uk.

A study of 700 patients over five years, published in The Lancet, found that the 2.5cm-diameter Watchman, designed to cover the appendage, was as protective as the medication warfarin for patients with the condition.