The game also featured an NHL-record four goals within 49 seconds.
As a Blues power play was ending, Pietrangelo shot through a screen past Dallas goalie Kari Lehtonen for a 6-5 lead about halfway through the period.
The Stars' Travis Moen started the record-setting goal streak when he scored on a penalty shot at 19:49 of the first period. During the first 38 seconds of the second, St. Louis' Patrik Berglund and Schwartz and Dallas' Jamie Benn all scored.
Benn had two scores as the Stars rallied for four second-period goals to turn a 3-1 deficit into a 5-3 lead.
Berglund also scored two goals.