Just last week, Peverley was feeling strange after the Stars' Monday evening game and was unable to fly with the team due to his condition. Peverley also missed the entire preseason due to his heart condition.
There are several problems (several of them serious) that can stem from an irregular heartbeat. Symptoms that can lead to a collapse such as fatigue, dizziness, and shortness of breath are hard to distinguish during a game because a player is usually experiencing those during a game. The good news is that the Stars medical staff is aware of Peverley's heart condition and prepared for situations such as this.
The Stars PA announcer made an announcement that Peverley was en route to a Dallas hospital and was conscious. The game was halted by NHL officials in Toronto and postponed until further notice.
The Dallas Stars Twitter page is reporting Peverley was treated for a cardiac event and is in stable condition:
"We treated [peverley] for a cardiac event successfully." -Dr. Gil Salazar
— Dallas Stars (@DallasStars) March 11, 2014