Jack's death on 'This is Us': His heart attack explained by a Temple doctor

Jack Pearson braved fire and heavy smoke to rescue his family from their burning house, then went back inside to save his daughter's dog. The character on NBC's This Is Us was then taken to the hospital, but he seemed likely to recover.

No real need for a spoiler alert here, as fans of the hit show have known since the beginning that Jack, played by actor Milo Ventimiglia, would die.

But are the details realistic?

In the episode that aired following the Super Bowl, viewers learned that Jack suffered a heart attack that was triggered by smoke inhalation. Daniel Edmundowicz, chief of cardiology at Temple University Hospital, said that certainly could happen.

Studies of firefighters suggest that the combination of smoke, elevated blood pressure, and dehydration raises the short-term risk of a heart attack, Edmundowicz said. There are scant data on civilians who enter a burning building, but it is reasonable to assume they would be at higher risk too, he said.

"The physical stress and particularly the extreme heat increases the inflammatory burden in the blood vessels," he said.

A young person in good physical shape should recover from exposure to a fire. But Jack's character was 53, an age by which people eating a typical U.S. diet have accumulated some plaque in their arteries. A heart attack occurs when some of that plaque ruptures, leading to the formation of an artery-blocking clot.

In Jack's case, the blockage occurred in the left anterior descending artery. This type of heart attack is commonly called a "widow maker," because that vessel is a vital conduit of oxygen for the heart's main pumping chamber.

"It's a devastating heart attack," Edmundowicz said.

Just how high is the risk? An online calculator from the American College of Cardiology gives a rough idea. Assume Jack has the lab results of a typical American male his age: an LDL "bad" cholesterol level of 130, a HDL "good" cholesterol level of 50, triglycerides of 150, and blood pressure of 120 over 80.

That means in the next 10 years, he had a 4.4 percent risk of suffering heart disease or a stroke. And in the short term, the extreme stress of battling a fire would have raised that risk.

Other factors not included in the online calculator can raise risk as well, Edmundowicz said. A big one is family history. Another is the level of plaque — except that is hard to measure directly.

That's why Edmundowicz, medical director of Temple's Health and Vascular Institute, is performing special tests on firefighters called coronary calcium scans. These scans measure the degree of calcification in the arteries — an indirect measure of plaque buildup — and may indicate when a patient needs further treatment. That could include the cholesterol-lowering drugs called statins. Or it could mean aerobic exercise and a healthy diet.

Though Jack is no longer, the actor who played him likely is in no immediate danger. Ventimiglia looks to be in good physical shape, and in real life he is just 40.

And if he's smart, he'll let trained professionals handle the burning buildings.