The earliest known death in the U.S. due to complications from coronavirus occurred after an infected patient had a massive heart attack, an autopsy report obtained by the San Francisco Chronicle revealed.

A 57-year-old woman from Santa Clara County, Calif., died on Feb. 6 and had traces of the virus in her heart, trachea, lungs and intestines, the autopsy report states. The autopsy was completed on Feb. 7 but not signed until April 23.

The autopsy further states that the woman had reported flu-like symptoms in the days leading up to her death and while she had a mildly enlarged heart, she had no coronary heart disease or blot clots that would have triggered a heart attack. According to the autopsy, blood had pooled in the sac around her heart, which lead to pressure on the organ, causing it to rupture.

Until this week, it was believed that the country's first death from COVID-19 came on Feb. 28 in Washington state.

The woman's Feb. 6 death suggests that the fatal virus was circulating around the nation earlier than health experts initially believed.