The family of a Queens grandmother who died of a heart attack during the December 2010 blizzard is suing the city for failing to clear the streets, which they say delayed emergency responders.

Faith Radvin and Robin Martucci claim in a suit filed yesterday that a day after the storm, their mother, Gail Radvin, 73, had a fatal heart attack.

“We are unable to comment on pending litigation,” said Connie Pankrat, a spokeswoman for the city.