An autopsy of elite runner Ryan Shay was inconclusive Sunday after the 28-year-old collapsed and died in Central Park at the U.S. men's marathon Olympic trials a day earlier.
"We want to take a closer look at the heart tissue," said Ellen Borakove, spokeswoman for the city medical examiner's office. She said the office likely would reach a conclusion in a week after examining Shay's tissue on microscopic slides.
Shay collapsed about 5 1/2 miles into the race Saturday, and later was pronounced dead at a city hospital.
"They know how he died ... of a cardiac arrest. What caused it is what's in question," his father, Joe Shay, told The Associated Press. "We certainly want to know that as soon as possible. When we know that we'll release that to the public as soon as we can. We're patient."
Joe Shay said Saturday that Ryan was diagnosed with an enlarged heart at age 14. But doctors had repeatedly cleared him for competition, because having a larger than normal heart is not unusual among elite athletes. Training hard in aerobic sports, such as cycling, running or swimming, tends to result in a bigger heart that pumps more blood throughout the body.
Dr. Douglas Zipes, a spokesman for the American College of Cardiology who studies sudden deaths in athletes, said it can be difficult to differentiate a normal athlete's heart from potentially deadly hypertrophic cardiomyopathy.
Cardiac echo tests and electrocardiograms can help evaluate whether the heart is healthy or not, said Zipes, a distinguished professor at the Indiana University School of Medicine. Genetic testing can also determine whether a person is at risk for certain problems.
Still, those precautions may not catch everything.
Joe Shay said doctors could not adequately test Ryan using a treadmill when he was a teenager because his heart rate was so low. Zipes said that's not uncommon among elite athletes.
Zipes will sometimes have athletes stop training for a month in an attempt to learn why their hearts are enlarged. Healthy athletes' hearts will shrink during that time. The size won't decrease if they suffer from hypertrophic cardiomyopathy.
Ryan Shay and other top athletes underwent medical testing in Flagstaff, Ariz., where he trained, last spring, his father said, and he was cleared for running.
"He said the doctors told him that because your heart rate is so low, when you're older you may need a pacemaker to make adjustments on that," Joe Shay said.
Ryan didn't complain of any problems, his father said, but he never was one to do so.
"One of the issues is athletes often ignore warning signs you or I might pay attention to," Zipes said, "because they are so pushed to achieve a particular end point."
A memorial service for Ryan Shay was to be held Sunday either at an area church or in the gymnasium at Central Lake High School in Michigan's northern Lower Peninsula, Joe Shay said. He said his son's professional coach, Joe Vigil, and his college coach at Notre Dame, Joe Piane, were to deliver eulogies.