Sib Hashian's cause of death has been revealed. He died of a heart attack according to a report by TMZ.
Hasbian joined Boston in 1975 to replace original drummer Jim Maseda whose chops were deemed unfit for recording by Epic Records. Sib recorded all of the drum parts on Boston's acclaimed self-titled debut album except for one track.
Hasbian also recorded all of the drum parts on Boston's second album, 1978's Don't Look Back, but was replaced by Maseda in 1983.
He was 67.