Toronto, May 15 (IANS): A simple surgery can save patients with heart arrhythmia from often-lethal strokes, a new study suggests.

The researchers, including Richard Whitlock from McMaster University, found that removing the left atrial appendage -- an unused, finger-like tissue that can trap blood in the heart chamber and increase the risk of clots -- cuts the risk of strokes by more than one-third in patients with atrial fibrillation.

Even better, the reduced clotting risk comes on top of any other benefits conferred by blood-thinner medications patients with this condition are usually prescribed.

"If you have atrial fibrillation and are undergoing heart surgery, the surgeon should be removing your left atrial appendage, because it is a set-up for forming clots," said Whitlock.

"Our trial has shown this to be both safe and effective for stroke prevention," Whitlock added.

For the study, published in The New England Journal of Medicine, the team tracked 4,811 people in 27 countries who are living with atrial fibrillation and taking blood thinners.

Consenting patients undertaking cardiopulmonary bypass surgery were randomly selected for the additional left atrial appendage occlusion surgery; their outcomes compared with those who only took medicine.

Whitlock said it was suspected since the 1940s that blood clots can form in the left atrial appendage in patients with atrial fibrillation, and it made sense to cut this useless structure off if the heart was exposed for other surgery. This is now proven to be true.

Atrial fibrillation is common in elderly people and is responsible for about 25 per cent of ischemic strokes which are caused when blood clots block arteries supplying parts of the brain.