The District of Columbia Medical Examiner released preliminary findings Sunday on the death of Sen. Lindsey Graham, revealing that the 71-year-old South Carolina Republican suffered an aortic dissection due to arteriosclerotic cardiovascular disease.

According to the ME’s office, Graham’s death was the result of this acute cardiovascular event. The death certificate will remain pending until toxicological and microscopic testing are completed. Once those results are finalized, the certificate will be updated to reflect the official cause of death and classify the manner of death.

"The death certificate will be PENDING until all the toxicological and microscopic testing are finalized and at that point the death certificate will be updated to reflect the cause of death and appropriately classify the manner of death," the statement said.

Graham was pronounced dead early Sunday morning after what his office described as a brief and sudden illness. He had been active until recently, returning from a trip to Kyiv on Friday where he met with Ukrainian President Volodymyr Zelenskyy.

The news of his passing has sent shockwaves through Washington and South Carolina, with tributes continuing to pour in from across the political spectrum, including from President Donald Trump, who called him “a true American Patriot.”

Graham had served in the Senate since 2003 and was the Republican nominee for a fifth term. His death creates an immediate vacancy in one of the Senate’s most influential voices on foreign policy and national security.