"Most likely, it was a massive heart attack," said Dr. Theodore Christopher of Thomas Jefferson University Hospital's emergency department, who aided the effort to revive Rizzo.
There are six risk factors that predispose a person to heart disease: high blood pressure, diabetes, smoking, obesity, family history and high cholesterol levels.
Rizzo had at least two of them.
Ten years ago, he developed adult-onset diabetes, which often can be controlled through diet alone. However, seven or eight years ago, Rizzo developed a need for insulin and began injecting himself daily.
"His diabetes was controlled," said Dr. Allan Sosin, a Chestnut Hill Hospital internist who treated Rizzo. "He checked his sugars regularly."
Then there was Rizzo's hefty profile.
"Sure, he lost weight - many times," Sosin said. "He was in pretty good health, except for the diabetes.
"I always worried, but I thought he was healthy enough. It's tough campaigning 12 hours a day, but it's what he loved," Sosin said.
Citing confidentiality, Sosin declined to say whether Rizzo had his cholesterol checked or underwent a stress test - two tests that could warn of heart disease.
Some people with partially clogged arteries develop chest pain that warns them of heart disease. But many diabetics never experience this, perhaps
because they have no sensation in their heart, said Dr. J. David Ogilby of the Philadelphia Heart Institute at Presbyterian Medical Center.
Sudden cardiac arrest kills 800,000 people each year. Some can be saved if cardiopulmonary resuscitation (CPR) begins immediately and life-saving measures, including defibrillating the heart by electric shock, are given within minutes.
"As long as you're doing external cardiac compression, you have a chance," said Dr. Joseph Zeccardi, head of Jefferson's emergency department. ''But the best time to reach someone is within three to five minutes."
An estimated 15 to 20 minutes elapsed between the time Rizzo was stricken and paramedics were able to begin treating him.