Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

WASHINGTON — Democratic presidential hopeful Bernie Sanders has resisted calls to release additional medical information in the wake of a heart attack he suffered in October.

"We have released as much" medical information "as any other candidate," the independent senator from Vermont said on NBC News' "Meet the Press" this month.

When pressed on whether he would release more, Sanders responded that "you can start releasing medical records and it never ends."

But by releasing one simple indicator of his heart health, Sanders could address some lingering questions, Richard Kovacs, president of the American College of Cardiology, or ACC, told NBC News.

Following Sanders' heart attack, doctors inserted two stents in an artery and he was hospitalizedfor several days. After promising to release "comprehensive" records after the procedure, his campaign balked, saying no more information would be forthcoming.

"We released the full report of that heart attack," Sanders said at last week's NBC News/MSNBC debate in Las Vegas, pointing to letters from three doctors the campaign distributed in December, which aren't the same as medical records.

Kovacs, who reviewed the letters for NBC News, said they omit a "standard" measure of Sanders' heart health.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The indicator, called the left ventricular ejection fraction, is provided to any patient after a heart attack, Kovacs said. It's a measure of how much blood volume the heart pushes out with an