The 54-year-old Dantonio had surgery to put a stent in a blocked blood vessel leading to the heart. He's expected to remain in the hospital a few more days, and offensive coordinator Don Treadwell will lead the team during Dantonio's indefinite absence.
"This morning, in the very early hours, not long after the football game, Coach Dantonio began experiencing some symptoms," said Dr. Chris D'Haem, who performed the relatively common procedure to restore blood flow. "Fortunately, his heart damage is very minimal. He's going to do very well and we're very optimistic he'll have a full recovery."
The Spartans defeated Notre Dame 34-31 in a game that ended just before midnight Saturday night. After Michigan State lined up for a 46-yard field goal that could have forced a second overtime, holder Aaron Bates threw a pass to Charlie Gantt for a winning touchdown. D'Haem said Dantonio began experiencing symptoms of a heart problem around 12:30 a.m., including a squeezing sensation in his chest.
"Fortunately, he got in in a very timely fashion," D'Haem said.
The victory was among the signature moments of the young college football season, and it put Michigan State in this week's Associated Press poll at No. 25.
"This is a time for the Spartan Nation to come together, to rally, not only to Coach Dantonio and his family but in everything that we're doing here," athletic director Mark Hollis said during a news conference. "We know coach will return to the sidelines very soon."
Dantonio certainly isn't the first high-profile coach to experience health problems.
Florida coach Urban Meyer was hospitalized with chest pains in December after his Gators lost the Southeastern Conference championship game to Alabama. A couple weeks later, Meyer resigned citing health concerns, but less than 24 hours later, he took back his resignation.
Meyer was diagnosed with esophageal spasms and has taken medication.
Notre Dame's staff was also hit by health problems recently when defensive line coach and special teams coordinator Mike Elston was hospitalized for a viral illness. Irish coach Brian Kelly shook hands with Dantonio after the game at midfield, and he began his news conference Sunday by wishing Dantonio well.
"On behalf of the Notre Dame family we are in thoughts and prayers for Coach Dantonio and wish him a speedy recovery. Look forward to seeing him back on the sidelines," Kelly said. "We didn't get in until about quarter of four this morning. I went home right away. When I came back in the office Brian Hardin, our sports information director, gave me the news."
Michigan coach Rich Rodriguez also released a statement.
"The Michigan football program sends our thoughts and prayers to Coach Dantonio and his family," Rodriguez said. "We hope for a full and speedy recovery."
D'Haem said heredity can play a part in heart problems, but noted that Dantonio kept in good shape and tracked factors such as cholesterol that can lead to health issues.
"Anybody that knows Coach Dantonio knows he keeps pretty fit," the doctor said.
When Dantonio got to the hospital, "his immediate concern was to his family and then to the football program," Hollis said.
Dantonio is in his fourth season at Michigan State, with a record of 25-17 and three bowl appearances. But the victory on Saturday night might have been his most memorable, because of the opponent and the direct role he played in the outcome.
"Like we said all along, we needed one big momentum play. We just didn't know when it would come," Dantonio said after the game. "I don't really know where to start or end, but it was a big night for the Spartans."
Treadwell is in his seventh season on the Michigan State staff. He coached receivers from 2000-02 and has been the offensive coordinator since 2007, when Dantonio arrived in East Lansing after a successful three years at Cincinnati.
"There's some great carry-over that's already in place, and we will just fill the gaps, as you will," Treadwell said. "We look very forward to Mark's speedy recovery."
The Spartans host Northern Colorado on Saturday.
"They're handling it as well as they can. They love their head coach," Treadwell said of the team, which learned the news Sunday. "It's our job as assistant coaches just to keep them moving forward, to keep them focused on task."