McCann, a left wing, was down on the ice for several minutes before being helped to the bench and headed straight back to the Seattle locker room. There was no announcement about his injury but he did not return for the start of the second period.
McCann was hurt on a short-handed attempt midway through the first period. The shot was saved by Colorado goalie Alexandar Georgiev and appeared to go into the netting behind the goal. McCann did not seem ready for the hit by Makar.
Makar was originally given a 5-minute major penalty but it was reduced to a 2-minute minor. Seattle scored on the ensuing power play to take a 2-0 lead.
Originally selected by the Vancouver Canucks in the 2014 first round, McCann led Seattle with a career-high 40 goals and 70 points in the regular season. He had one assist in the first three games of the series.
In March of last year, McCann signed a new deal with Seattle, agreeing to a five-year extension with a $5 million average-annual value.
The Associated Press contributed to this report.
Kraken lose LW McCann to injury during Game 4 vs. Avalanche