UPDATE 1-Tenet says U.S. probing Medicare claims for ICDs

* Says Justice Dept seeks documents under False Claims Act

* Says expects more hospitals will get similar demands

* Tenet shares down 3.3 percent

CHICAGO, Aug 3 (Reuters) - Tenet Healthcare Corp (THC.N) said the U.S. Department of Justice is investigating whether one of its hospitals fraudulently billed Medicare for heart defibrillator implant surgeries.

The Dallas-based hospital company, in a regulatory filing on Tuesday, said the department in March issued a demand under the federal False Claims Act for documents detailing its Medicare submissions for implantable heart defibrillator procedures dating back to 2002.

Tenet said it believes the Justice Department is requesting patient records and other information to determine if ICD procedures that were performed followed Medicare coverage requirements.

ICDs are implanted in a patient's chest and detect and treat abnormally fast heart rhythms that could result in sudden cardiac death.

Tenet said it anticipates that more of its hospitals may receive similar information requests and that the investigation involves ICD manufacturers as well as other hospital operators.

"We understand that the DOJ has submitted similar requests to a number of other hospitals, as well as to the ICD manufacturers themselves," the company said in the filing.

Tenet said it is cooperating with the probe.

ICD makers Medtronic Inc (MDT.N) and St Jude Medical Inc (STJ.N) previously disclosed in separate regulatory filings that they also received Justice Department demands in March for information related to Medicare claims for ICD implants. Both companies said they are cooperating with the investigation.

Shares of Tenet fell were down 3.3 percent to $4.44 in afternoon trading on the New York Stock Exchange. (Reporting by Susan Kelly; Editing by Tim Dobbyn)