Among the risk factors, five had valvular diseases, one had valvular replacement, one had a bicuspid aortic valve and one was an intravenous drug abuser.

• 这些患者中，五位已知有心脏瓣膜疾病，一位曾接受过人工瓣膜换置手术，一位有先天性二瓣性主动脉瓣，另一位则是静脉药瘾者。