A senior coroner has expressed concern about the lack of regulation of cold water immersion therapy, after ruling that a woman’s death was as a result of an undiagnosed heart condition triggered by the water. Kellie Poole, 39, died when her heart stopped shortly after entering the River Goyt in Whaley Bridge, Derbyshire, on 25 April 2022. She had been feeling well in the run-up to the cold water session and did not know she had hypertrophic cardiomyopathy, a thickening of the heart muscles. While the company running the session, Breatheolution, was not to blame for her death and could not have foreseen Poole’s adverse reaction, Peter Nieto, the senior coroner for Derby and Derbyshire said he was concerned the sector was entirely unregulated. He said he felt it necessary to write to authorities highlighting the lack of regulation covering the activity. Recording his conclusion, Nieto said: “Kellie died due to sudden cardiac arrhythmia triggered by immersion in cold water, which likely became unsurvivable due to an undiagnosed, pre-existing heart condition. “It is likely that the cold water triggered her heart to go out of rhythm, which then led her to go into sudden cardiac death. It is likely that the heart condition prevented recovery.” The two-day inquest at Chesterfield coroner’s court had heard that Poole, from Droylsden in Tameside, Greater Manchester, had a headache after entering the water before falling forward, with attempts made to revive her after she was pulled from the water. The water temperature on the day of her death was recorded as 10.7C. Nieto recorded the cause of Poole’s death as sudden cardiac arrhythmia, caused by hypertrophic cardiomyopathy due to immersion in cold water during the session led by Kevin O’Neill, who had asked Poole if she had any conditions at the start. Nieto said: “She was totally unaware. I don’t see any reason on the evidence why cold water immersion should not have proceeded.” The court also heard that cold water immersion activities were unregulated, with no legal requirement for written risk assessments or waiver forms. Nieto said this was a “concern” and he would issue a prevention of future deaths report to raise the matter after Poole’s mother called for action. He added: “Specifically, my concern is there is no regulation of people who run cold water immersion sessions, and indeed we have heard from the environmental health service that there are no statutory or regulatory requirements on people running these sessions. “It seems to me that there is a case for it being looked at, whether there can or should be any regulations of these businesses and activities.”