A strong swimmer drowned when he suffered a cardiac episode while on holiday in the US, an inquest heard.
One of Stephen Thomas Turner's cardiac arteries was operating at only 25% efficiency when he died.
Mr Turner, 62, of Llanrwst, Conwy county, was with his partner at Lake Sutherland, Washington, when he died on 15 July 2016.
At a hearing in Ruthin, coroner Nicola Jones recorded a conclusion of accidental death.
Mr Turner, a retired civil servant, is understood to have swum into the centre of the lake before getting into difficulties.
Bystanders saw him struggling in the water before disappearing.
'Competent and confident'
The daughter of his American girlfriend and a paramedic who happened to be nearby paddled out in kayaks but were unable to find him.
His body was recovered two days later in a spot where the water was about 85ft (25m) deep.
An autopsy carried out in the US gave a provisional cause of death as freshwater drowning, but Ms Jones, assistant coroner for North Wales East and Central, said after reading of Mr Turner's heart condition she wanted to "tweak" that conclusion.
"I don't believe it was simply a case of his getting into trouble while swimming as he was a strong, competent and confident swimmer," she said.
"Underlying everything was the heart problem. It was not merely a contributory factor but actually caused the drowning."
The inquest heard Mr Turner suffered heart attacks in the past and had a stent fitted.