An experimental drug designed to aid severely ill patients after hospitalization is not more effective than standard treatments for reducing the risk of blood clots, a study has confirmed.

Atrial fibrillation, a common heart arrhythmia, is generally treated with a standard drug warfarin. However, a study suggests a new drug might provide the same treatment, but with a lower risk of stroke and embolism.

A medication considered the standard for preventing stroke in heart arrhythmia patients may not be as effective as an anti-clotting drug that also boasts fewer side effects.