The ex-Cherries captain was back at the Vitality Stadium for the first time with Nottingham Forest.
Former Bournemouth skipper Cook, who joined Forest for an undisclosed fee in January, said his father had had a heart attack at the Vitality Stadium in a post on Twitter congratulating his former club for sealing promotion.
kok, 31, gesê: “First of all a big congratulations to @afcbournemouth on promotion but tonight I need to thank the paramedics at the game.
“Unfortunately my dad suffered a cardiac arrest just before the game and they managed to bring him back to life. I’ll forever be grateful for their actions.”
Cook started the game for Forest, who needed to win to keep alive their own chances of automatic promotion going into the final game on Saturday.
The centre-half was substituted in the 84th minute and replaced by Forest forward Joe Lolley soon after Kieffer Moore had scored Bournemouth’s decisive goal, which clinched them a second-placed finish.
kok, who played in over 370 games in all competitions for Bournemouth during his 10-year spell at the south-coast club, was making his 17th appearance for Forest on his first return.