A teenager died of a massive heart attack the morning after attending a pre-debs party, a coroner has found.
However, coroner Dr Brian Farrell said he was unable to explain why Kaelem Hainsworth, from Newtownpark Avenue in Blackrock, south Dublin, collapsed at his friend's house on November 18, 2012.
The teenager spent the previous night at a pre-debs event in a hotel in Meath organised for students of Oatlands College, Stillorgan, and Our Lady's Grove, Goatstown.
While walking back to his friend's house following the pre-debs, Kaelem complained of pains in his chest and arm and the following morning he went into cardiac arrest.
The pathologist gave the cause of death as a massive heart attack involving both chambers of the heart but said it was unclear why this happened.
There was no heart disease, no viral infection of the heart and no reason to suspect an inherited condition.
A test for over 100 substances came back negative and there was no alcohol remaining in his system when he died.
The court had heard that Kaelem had two cans of Heineken on the bus down to the venue and his friend Cambrian Grenier told the court that he later drank another two cans and one shot of vodka.
He said that Kaelem was complaining of chest pains on the way down to the event.
He also told the court that he saw three older boys on the bus snorting drugs. His friend told how one of the older boys was "wasted" and had to be carried on to the vehicle.
The principal of Oatlands College, Caroline Garrett, asked Mr Grenier to confirm that these boys were not students of her school. Mr Grenier confirmed this.
Ms Garrett told the coroner that pre-debs events are organised by the students themselves without the school's sanction.
Dr Farrell told the court the amount of alcohol Kaelem drank was not excessive and there was no evidence of any drug use and he was unable to explain why it happened.
The coroner returned a narrative verdict outlining the facts. He told the family that he hoped they would find the strength to bear Kaelem's death.
Speaking outside the court, Ms Garrett said that principals across the country were "at their wits' end" about pre-debs events.
"They are absolutely crazy. They are not sanctioned by the schools. We do not even know that they are happening," she said. "Every principal in the country has concerns."
She also paid tribute to Kaelem as a "beautiful boy" that they "loved" dearly.
Following the inquest, Kaelem's parents, Denise Byrne and Alan Hainsworth, said that they had set up a tribute fund for the Mater Hospital in their son's name (tributefunds.materfoundation.ie) and urged people to support it.