He most recently played for the Vienna Capitals in the Austrian Hockey League. Originally drafted in 1994, round 9, #210 overall, by the Ottawa Senators. Cassivi spent several years in the minors before signing with the Colorado Avalanche in 1999 as a free agent, although he would play primarily for their minor league affiliate the Hershey Bears.
He was traded to the Atlanta Thrashers in 2002 and would actually make the Thrashers lineup for parts of two seasons.
He primarily saw ice time with their AHL affiliate, the Chicago Wolves. He played for the Chicago Wolves for 3 seasons, 2001-2002, 2002-2003 and 2003-2004.
He then played for the AHL Cincinnati Mighty Ducks for the 2004-2005 season and posted a season best save percentage of 0.924 and Georgia of 2.07 with 10 SO, while winning 25 games. Cassivi ranks fifth all-time in league wins (232) and is tied for eighth all-time in shutouts (24).
He also ranks fifth all-time in Hershey wins with 113, fifth in appearances with 246 and seventh in shutouts with nine.