Outside advisers to the Food and Drug Administration have voted to recommend that the agency approve a new anticlotting drug developed by Johnson & Johnson and partner Bayer Healthcare.

That's despite a very negative review by FDA staff of the drug, Xarelto, released two days ago.

Nine panel members voted to recommend approval, two voted against and one person abstained. The FDA is expected to make a final decision by early November.

The recommendation, after a daylong hearing, is to allow sales of the drug for preventing strokes in patients with a common irregular heartbeat known as atrial fibrillation.

Xarelto, known chemically as rivaroxaban, has been seen as a future blockbuster drug.

The FDA had approved the drug in July for patients getting knee and hip replacements, a much smaller group that has a heightened risk of dangerous blood clots.

On Tuesday a 388-page report by FDA staff reviewers recommended against approving Xarelto for patients with atrial fibrillation, in which the heart's upper chambers quiver ineffectively -- temporarily or for years. That reduces blood flow through the heart, raising the risk of dangerous blood clots forming and triggering a stroke.

The reviewers wrote that results of a late-stage study of more than 14,000 patients, known by the acronym ROCKET, don't make clear how safe Xarelto is, or whether it's as effective as the widely used drug warfarin. They stated that an additional study of Xarelto is needed, citing questions about potential stroke and bleeding risks among other issues.

During Thursday's meeting before the FDA's Cardiovascular and Renal Drugs Advisory Committee, Johnson & Johnson officials argued their data show Xarelto is safe and effective.

Bayer Healthcare already markets rivaroxaban in 110 countries around the world. Johnson & Johnson has the U.S. marketing rights.