Bernie Sanders suffered “modest heart muscle damage” during his October heart attack but has since been doing well and should be able to continue campaigning for president “without limitation,” according to letters released Monday by his primary care physician and two cardiologists.

“He is currently entirely asymptomatic, his heart function is stable and well-preserved, his blood pressure and heart rate are in optimal ranges,” wrote Martin LeWinter, attending cardiologist at University of Vermont Medical Center in Sanders’ home state.

LeWinter wrote that the 78-year-old Vermont senator continues to receive “several” medications that patients commonly take after a heart attack and that he sees “no reason” why Sanders can’t campaign as normal and handle the stress of being president, should he win next year’s election.

“While he did suffer modest heart muscle damage, he has been doing very well since,” LeWinter wrote.

Sanders, the oldest candidate in the 2020 presidential race, had vowed to release detailed medical records by the end of the year, and did so the day before New Year’s Eve.

A separate letter from Brian Monahan, the congressional attending physician in Washington, said several medications that Sanders received after his heart attack, including a blood thinner and beta blocker, “were stopped based on your progress.”

“Your heart muscle strength has improved. You have never had symptoms of congestive heart failure,” Monahan wrote in a letter to Sanders. “The heart chamber sizes, wall thickness, estimated pressures, and heart valves are normal.”

He added that Sanders had a successful graded exercise treadmill examination monitoring heart function, muscular exertion and oxygen consumption that indicated “a maximal level of exertion to 92% of your predicted heart rate without any evidence of reduced blood flow to your heart or symptoms limiting your exercise performance.”

“Your overall test performance was rated above average compared to a reference population of the same age. The cardiac exercise physiologist who evaluated your results determined that you are fit to resume vigorous activity without limitation,” Monahan wrote. “You are in good health currently and you have been engaging vigorously in the rigors of your campaign, travel, and other scheduled activities without any limitation.”

Sanders suffered a heart attack while campaigning on Oct. 1 in Las Vegas and spent several days recuperating in his Vermont home. He said he had felt symptoms for weeks that he “should have paid more attention to,” including being especially fatigued after long campaign days, having trouble sleeping and sometimes feeling a “little unsteady” at the podium while speaking at events.

On the evening of the event in Las Vegas, Sanders said he asked for a chair to be brought onstage “for the first time in my life.” Afterward, he was sweating profusely when pain in his arm prompted him to head to an urgent care medical facility where “the doctor made the diagnosis in about three seconds.”

Taken by ambulance to the hospital, Sanders said he underwent surgery to insert stents for a blocked artery.

“There was some damage, but … within the next month, we’ll see what happens,” he said during a CNN interview on Oct. 10. “But so far, so very good.”

Sanders’ staff initially said stents were inserted for a blocked artery, revealing only two days later that he had suffered a heart attack. Sanders bristled at the notion that his campaign was less than forthcoming about his condition, saying that it released as much information as it could, as fast as possible, and that the full details only came later.

Scrutiny on Sanders’ health intensified after his heart attack, but it’s an issue for every Democrat age 70 or older seeking the White House.

Former Vice President Joe Biden, 77, says he will release his medical records before the Iowa caucuses on Feb. 3.

Earlier this month, 70-year-old Elizabeth Warren released a note from her doctor saying that she is “in excellent health” and that her only major medical concern is an underactive thyroid gland, which the Massachusetts senator easily treats with medication, the only kind she takes.

Michael Bloomberg’s doctor declared the 77-year-old former New York City mayor to be in “outstanding health,” though he is receiving treatment for several medical conditions, including an irregular heartbeat. Bloomberg also takes a beta blocker and medication to control his cholesterol, had “small skin cancers” removed and receives treatment for arthritis and heartburn, “both of which are well controlled.”

Additionally, Bloomberg had a stent put in his heart to clear an artery in 2000 and “has had normal cardiac stress testing annually since then.”