A 12-year-old girl described as 'fit, happy and healthy' has died suddenly after collapsing at her grandparents' home in Merthyr Tydfil, Wales. Mia-Mai Grace Williams was found unresponsive in cardiac arrest with evidence of vomiting on 10 August 2024.
She was initially taken to Prince Charles Hospital before being transferred to Noah's Ark Children's Hospital in Cardiff, where her condition deteriorated and she died the following day, an inquest at Pontypridd Coroner's Court heard.
A post-mortem examination revealed that Mia-Mai had lymphocytic myocarditis, a cardiac infection that likely caused cardiac arrest. The coroner recorded death by natural causes due to multiple organ dysfunction, cardiac arrest, and lymphocytic myocarditis.
Coroner Patricia Morgan noted that Mia-Mai had shown no symptoms of illness before the incident. The inquest was concluded on 2 March 2026, with the cause of death confirmed as a cardiac infection leading to cardiac arrest.
