Craig William Dearie, 24, from Cheshunt in Hertfordshire, was found dead in a tent at Global Gathering on 28 July.
A verdict into his death ruled he died of natural causes due to Sudden Arrhythmia Death Syndrome (SADS), said Warwickshire Coroners' Office.
Up to 40,000 people are thought to have attended the event at Long Marston airfield near Stratford-upon-Avon.
The SADS Foundation website describes the condition as "heart rhythm abnormalities that can cause sudden death in young, apparently healthy people who are undiagnosed".
A man died of undiagnosed heart condition at a dance music festival in Warwickshire, an inquest heard.