Comedian Howie Mandel is known for his snappy comebacks, but when he was diagnosed with a heart condition, he didn’t have all the answers.

He recently sat down with Dr. Manny Alvarez, senior managing health editor of FoxNews.com, to talk about life with atrial fibrillation.

Atrial fibrillation, or AFib, is a type of irregular heartbeat that is not caused by a heart valve problem. The condition affects approximately 5.8 million people in the United States.

Before he was diagnosed during a routine checkup in 2009, Mandel, 58, admitted he had never heard of the heart condition.

“I learned that it is an irregular heartbeat, but I didn’t even notice it,” he said. “And then I found out if you have it, you’re five times more likely to have a stroke.”

Although Mandel had been feeling lightheaded, dizzy and tired, he attributed it to his busy lifestyle, not suspecting something else might be wrong.

“I run seven miles a day, so I just thought I pushed it a little hard,” Mandel said. “So if I was a little dizzy or had a little flutter, I just thought that was part of my workout. I didn’t really put two and two together.”

Since his diagnosis, Mandel continues to have a healthy diet and exercise regularly and is focused on educating others about AFib. He has teamed up with Bristol-Myers Squibb and Pfizer for the Fibs or Facts campaign. Visitors to FibsOrFacts.com, can take a quiz testing their knowledge of AFib. For every quiz completed, $1 will be donated to The National Stroke Association, up to $35,000.

For more information, visit www.FibsOrFacts.com