The Lightning defeated the New York Islanders in six games in the Eastern Conference Final, winning Game 6 2-1 in overtime on Thursday.
Hedman is averaging 26:31 of ice time in 19 games, the most of any skater to make it to at least the conference finals. He leads NHL defensemen with nine goals, and his 15 points are tied for fifth among defensemen with Cale Makar of the Colorado Avalanche. Hedman scored six points (four goals, two assists) in the six games against the Islanders.
Duncan Keith of the 2015 Chicago Blackhawks is the only defenseman to win the Conn Smythe since Scott Niedermayer won it with the Anaheim Ducks in 2007.
Heiskanen leads NHL defensemen in the playoffs with 22 points (five goals, 17 assists) in 21 games, but had one point, an assist, in the series win against the Golden Knights.
The 21-year-old has set the Stars record for points by a defenseman in a single postseason (Craig Hartsburg, 15, 1981).
Heiskanen also is the eighth defensemen to score at least 22 points in his first 21 or fewer playoff games in one postseason, joining Paul Coffey of the Edmonton Oilers (37 points in 18 games, 1985; 22 points in 19 games, 1984), Brian Leetch of the New York Rangers (32 points in 21 games, 1994); Al MacInnis of the Calgary Flames (29 points in 21 games, 1989); Denis Potvin of the New York Islanders (25 points in 18 games, 1981); Ray Bourque of the Boston Bruins (25 points in 19 games, 1991; 23 points in 17 games, 1983); Bobby Orr of the Bruins (24 points in 15 games 1972); and Brent Burns of the San Jose Sharks (22 points in 21 games, 2016).
If Heiskanen were to win the award, he would become the youngest defenseman to do so. Orr was 22 when he won it in 1970.