A doctor has called on Bernie Sanders to release a key indicator of his heart health - months after the presidential candidate suffering a heart attack on the campaign trail.
Sanders says he doesn't plan to divulge additional information about his health after releaseing 'comprehensive' medical records.
The campaign waited until New Year's Eve to put out letters from three doctors attesting to his health - a move traditionally deployed to avoid scrutiny.
But the three letters are not the same as medical records.
The president of the American College of Cardiology, Richard Kovacs, tells that if Sanders released one simple indicator of his heart health, it could put to rest any lingering questions.
The indicator, known as the left ventricular ejection fraction, is given to any patient after a heart attack and is a measure of how much blood volume the heart pushes out with an individual heartbeat.
It can correlates with the risk for future cardiac events and mortality rate.
Questions about Sanders' health have lingered ever since he checked into a Las Vegas hospital with chest discomfort on October 1 and had two stents inserted
'Normally the heart will push out 60 percent,' Kovacs said.
'If you go down to 40 or 50 percent, we regard that as mild impairment of the left ventricle. Thirty to 40 percent would be moderate. If you get to 30 percent, that would be severe.'
Sanders has not revealed what his number was at the time of his heart attack or what it is currently.
The three letters, Kovacs says, 'imply with the heart attack that he (Sanders) had diminished heart muscle strength,' or a lowered fraction.
'It's a patient's personal private information but there's the importance of the number,' Kovacs said.
'They've chosen not where to buy lisinopril without dr prescription reveal the ejection fraction.'