The tech-giant husband of Facebook executive Sheryl Sandberg may have had an arrhythmia before he fell off a treadmill and died, a report said. David Goldberg, the 47-year-old SurveyMonkey CEO, died from head trauma after he slipped off the exercise machine while on vacation in Mexico.

An autopsy showed that Goldberg had an irregular heartbeat before he died, CBS News reported. It was not clear, however, if this occurred before or after he slipped from the machine and smashed his head.

A memorial service for Goldberg was held Tuesday at Stanford University, where hundreds of people gathered to honor the Silicon Valley entrepreneur.

Bono sang the U2 song “One” and Ben Affleck, who worked on philanthropy with the CEO, also was there to salute him.

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