The 6-year-olds parents, however, saved the child's life by doing CPR -- a successful story that may provide a lesson for anyone worried about losing a loved one to a sudden heart attack.
"I don't think that this is a call for action for not standing near a loud speaker. But I do think that any time a young person dies it is an opportunity to remind all of us that public places should have AEDs, and we all should know CPR," said Page.
In Reid's case, it seems unusual only because the music was continuous, and does not appear to have been the result of a single loud burst of sound.
"The usual description of auditory-triggered arrhythmias and death have been those that occurred suddenly such as an alarm clock or an explosion, not usually a continual loud noise," said Dr. Thomas McDonald, a cardiologist at the Albert Einstein College of Medicine in New York. "Of course, I have no idea of the tempo or volume dynamics of the music in this concert."
While diagnosing long QT syndrome can prove difficult after death, it can be important for relatives of someone who dies from sudden heart failure to get a genetic test.
One thing that should be done in the case like Reid's is "they should do post mortem genetic testing to get a definitive cause of death. This would have implications for family members," said Dr. Laurence Epstein, chief of the arrhythmia service and Brigham and Women's Hospital in Boston.
Indeed, diagnosing long QT syndrome after death can prove tricky without genetic testing.
When the coroner does the autopsy, "There's not [an] enlarged heart, there isn't necessarily plaque in their arteries," said Gordon.
In an annual screening event her group does at Madison Square Garden, where they give free ECGs to 200 children, Gordon said they ask about a history of sudden death in families as well as unexplained fainting, convulsions, seizures or dizziness in individuals.
But as shocking as the sudden death of a young person may be, long QT syndrome is not something the average person needs to worry about.
"It is infrequent and there is no reason for public alarm, if indeed this is the cause of death in this individual," said Dr. Douglas P. Zipes, editor-in-chief of HeartRhythm and a cardiologist at the Indiana University School of Medicine.
In the end, Page said, the vast majority of people at a loud nightclub should have bigger concerns than their hearts.
"I feel that people are more at risk for damage to their ears rather than heart arrhythmias from loud music," he said.
Dan Childs contributed to this report.
For more information: