(CNN) Michael Bloomberg's campaign disclosed new information on Thursday about the health of the presidential candidate's heart, and called on Bernie Sanders, who suffered a heart attack last year, to release the same data -- a clear attempt to bring the issue of the Democratic frontrunner's health to the forefront in the 2020 race for the White House.

Bloomberg's last annual health exam was in July and included cardiac stress testing and a stress echocardiogram, according to a letter from Dr. Stephen Sisson at Johns Hopkins University that the Bloomberg campaign shared with CNN. According to Sisson, Bloomberg's left ventricular ejection fraction was "normal" at 60-65%; his left ventricular cavity size and left ventricular function were also deemed "normal"; and his exercise capacity was described as "excellent."

Bloomberg spokesman Stu Loeser said in a separate statement to CNN that Sanders should release the same left ventricular ejection fraction data.

"Releasing this single scientific number about heart health could start to put to rest any concerns about Senator Sanders' secrecy about his recent heart attack," Loeser said. "Mike Bloomberg's doctor shared Mike's number. Will Senator Sanders ask his doctor to do the same?"

"The letters that we've released are very thorough," Sanders communications director Mike Casca told CNN in response to the Bloomberg campaign's statement, referring to doctors' letters the Sanders campaign has previously released about the senator's health.

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