NEW YORK (Reuters) - Shares of St. Jude Medical Inc. fell 5.7 percent after the closing bell on Tuesday after the heart device maker lowered its first-quarter revenue and earnings forecast.

Shares of St. Jude (down $5.00 to $36.30, Research) were trading at $38.93 on the Inet electronic brokerage network after closing at $41.30 on the New York Stock Exchange.

St. Jude reported preliminary first-quarter results that fell short of its prior outlook, citing a bigger-than-expected slowdown in the U.S. market for devices that manage irregular heartbeats. St. Jude, which competes against Medtronic Inc. (down $0.90 to $50.50, Research) and Guidant Corp. (down $0.67 to $76.48, Research) in the market for implantable defibrillators, said it now expects first-quarter earnings of 35 cents to 36 cents per share, including the impact of stock compensation expense of 3 cents, and net sales of $784 million.

In January, St. Jude had forecast first-quarter earnings of 41 cents to 43 cents a share, excluding stock compensation expense, and net sales between $799 million and $839 million.

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