July 10 (Reuters) - Edwards Lifesciences Corp said it would buy privately held heart device maker CardiAQ Valve Technologies Inc for up to $400 million to expand its portfolio of less-invasive mitral valve replacement devices.

The deal comes nearly two months after Edwards stopped enrolling patients for a study of its less-invasive mitral heart valve device, Fortis.

The company will pay $350 million in cash for CardiAQ and the rest will be paid on achievement of certain regulatory milestones.

Edwards launched a catheter-based aortic valve replacement device in the United States in 2011 and it is now trying to adapt the technology for mitral valves.

Transcatheter products, which allow the valve to be threaded through the arteries to the heart, provide an alternative to open-heart surgery.

Edwards said on Friday it would restart enrollment for the study. The company said it expected the CardiAQ deal to be slightly dilutive to 2015 earnings.

The Irvine, California-based company's shares closed at $147.16 on the New York Stock Exchange on Friday.

(Reporting by Rosmi Shaji in Bengaluru; Editing by Kirti Pandey)