UPDATE 2-Sanofi wins FDA approval for Multaq heart drug

* U.S. FDA clears Multaq for atrial fibrillation, flutter

* Sanofi says plans commercial launch this summer

* Multaq not for patients with severe heart failure

* Sanofi shares up as much as 1.7 pct, outperform peers

(Adds detail, background, shares)

By Caroline Jacobs

PARIS, July 2 (Reuters) - Sanofi-Aventis (SASY.PA) won approval to sell heart treatment Multaq in the United States, a move that should help the French drugmaker partly recoup a future sales drop as generics to several key drugs appear.

Analysts see Multaq, put forward as a blockbuster, as one of the growth drivers Sanofi has up its sleeve to drag it through the years when patents expire on multi-billion euro drugs like cancer treatment Taxotere and blood thinner Plavix.

The Food and Drug Administration cleared (FDA) Multaq twice-daily 400 mg tablets to reduce the risk of cardiovascular hospitalisation in patients with atrial fibrillation or atrial flutter, Sanofi said on Thursday. Doctors may not prescribe Multaq to patients with severe heart failure.