Kardam, Prince of Tarnovo, Duke in Saxony was the eldest son of King Simeon II of Bulgaria and his wife Doña Margarita Gómez-Acebo y Cejuela. Kardam was born after the abolition of the Bulgarian monarchy. As such, it was only by courtesy that he was sometimes styled as if being a crown prince. He was known also as Kardam of Bulgaria and Kardam of Tarnovo, the latter being the title of the heir apparent of the Bulgarian throne. He was born in Madrid, was baptised into the Orthodox faith and had a master's degree in Agricultural Economics from Penn State University.
On 15 August 2008, Kardam and his wife were involved in a serious car accident in El Molar, near Madrid. Prince Kardam was taken by helicopter to the Doce de Octubre Hospital, while his wife was taken to the La Paz Hospital. The car they were in crashed into a tree, then turned over just ten metres away from a nearby house. Kardam suffered severe brain-skull trauma and severe injuries to his hands, while his wife suffered a broken elbow, broken ribs and a collapsed lung. She was treated and released from the hospital on 4 September. Galya Dicheva, a spokeswoman for the Saxe-Coburg-Gotha family, confirmed the information about the car accident and explained that Kardam had undergone surgery in the evening following the accident. As of 18 August 2008, Kardam was being kept in an induced coma. According to doctors at the Doce de Octubre Hospital, his hands were paralysed and reports mentioned that he had lost two fingers. A Bulgarian news agency reported on 15 October, that Kardam was in critical condition but stable and that his breathing and vital signs had improved. The news agency reported on 23 January 2009 that he had been released from the hospital and was slowly recovering at home. Kardam was now able to stand and communicate. In January 2010 however, he suffered a critical setback and was re-hospitalised. He remained in a coma until his death on 7 April 2015. In May 2010, Bulgarian authorities issued a summons to the comatose Kardam over issues relating to the management of property returned to him, to his father and to his aunt by the post-communist government. Former King and Prime Minister Simeon II and his sister Princess Maria Louisa objected to the summons on the grounds that Kardam was incapacitated.