The Boston area had it's first outdoor du/triathlon this past Saturday and, unfortunately, there was another medical-related issue that lead to a participants death. The following article has the most details I've yet seen.
The swim consisted of a 1/4 point-to-point (straight line) swim with an in-water start. The water was a chilly 59 degrees but, otherwise, it was one of the best Spring mornings (weather-wise) yet this year. According to the article, the participant was a 40 year old male. It's unclear as to his racing experience.
I participated in the duathlon and we were the first wave off. As we returned to the park on the bike leg, an ambulance passed us with its sirens blaring. My race mate was in the last wave (just after his wave) and she saw the ambulance heading into transition. Unfortunately, they weren't able to save him.
He left behind three youngsters. So sad.