When Tim Russert, the host of NBC’s “Meet the Press,” died at the age of 58 on June 13, it sent shockwaves not only because of his prominence as a political journalist, but because he died of a heart attack at work without any real warning.

Russert was recording voiceovers for Sunday’s “Meet the Press” broadcast when he collapsed. He was rushed to Sibley Memorial Hospital in Washington, where resuscitation efforts were unsuccessful.

Russert’s doctor said the heart attack was caused by cholesterol plaque rupturing an artery.

MSNBC said the newsman had earlier been diagnosed with asymptomatic coronary artery disease, but he was controlling it with medication and exercise and Russert had recently passed a stress test. His doctor said an autopsy revealed that he also had an enlarged heart.

Dr. Zane Darnell, MD, is a cardiologist with King’s Daughter Medical Center.

He said it is very hard in some cases to detect heart disease especially in cases like Russert’s where there are no symptoms.

“In his case, he knew he had coronary artery disease. And the biggest problem with that is the unexpected,” Darnell said.

He said people who have hard, stable plaques are easier to treat than people with soft plaque buildup. Hard plaques can grow until it blocks the artery. At 70 percent blockage, symptoms start showing and will show up on a stress test.

The trouble is that heart attacks can happen at a much lower blockage than 70 percent.

“Those occur with a buildup of what we call soft cholesterol plaques,” Darnell said. “What happens is that the plaque ruptures and goes from a 50 percent blockage to a 100 percent blockage within a few seconds. That’s the difficult thing to predict.”

Because of the difficulty of predicting a heart attack, doctors sometimes prescribe a combination of drugs including anti-platelet drugs like aspirin or Plavix with a cholesterol-lowering drug to prevent an artery from clogging.

There are numerous tests for checking blood flow “but none of this is perfect,” Darnell said.

He added research is continuing into new, non-invasive ways of dealing with plaque that can rupture an artery leading to sudden cardiac death, which kills 300,000 Americans each year.

Darnell said that prevention of plaque build-up has to start early in life because there are 20-year-olds who have the condition.

“The thought is to not worry until you are older, when sometimes by then it is too late,” he said.

He said for most people, if it is found in the early stages it is treatable with medicine and lifestyle changes.

“In Russert’s case, it wasn’t enough for him,” Darnell said.

One important thing to have in these cases is a defibrillator on hand.

“So if it does happen, it gives them a much better chance of survival,” he said.