"Grant died from the rupture of a slowly growing, undetected ascending aortic aneurysm with hemopericardium," his widow, physician Celine Gounder, wrote in a statement.
An aortic aneurysm is a balloon-like bulge in the aorta, the large artery that carries blood from the heart through the chest and torso, according to the Centers for Disease Control and Prevention's website.
An outpouring of support
"First and foremost, on behalf of myself and our family, I want to express our deepest gratitude for the outpouring of support, love, and sympathy from around the world," Gounder wrote.
Wahl, 48, a former Sports Illustrated writer who had moved to the Substack online publishing platform, was tweeting about the Netherlands-Argentina match on Friday when he collapsed.
His agent had earlier told Reuters that Wahl had appeared to suffer some kind of acute distress during the quarterfinal match. Attempts were made to revive Wahl in the press box before he was taken to a hospital, where he was confirmed dead.
"No amount of CPR or (defibrillator) shocks would have saved him," Gounder said on Wednesday.
Wahl wrote early last week that he had visited a hospital while in Qatar and that health officials told him he likely had bronchitis.
His body was flown back on Monday to the United States, where the New York City Medical Examiner's office performed an autopsy.
Wahl was stopped because of a rainbow shirt
"While the world knew Grant as a great journalist, we knew him as a man who approached the world with openness and love," Gounder wrote. "Grant was an incredibly empathetic, dedicated, and loving husband, brother, uncle, and son who was our greatest teammate and fan. We will forever cherish the gift of his life."
"Grant was an incredibly empathetic, dedicated, and loving husband, brother, uncle, and son who was our greatest teammate and fan."Celine Gounder
In late November, Wahl made news when he wrote that he was stopped at a World Cup stadium security screening point when he tried to enter a match while wearing a rainbow shirt in support of the LGBTQ community. He said security asked him to remove his shirt. Same-sex relations are illegal in Qatar.
Memorial services for Wahl are still being planned, his widow said.