Gail Williams was 15 when her mother died of a heart attack. “The world seemed like it got dimmer, a shade darker than it was,” said Williams, now 60, of New Haven. The death of Shirley Mae Burgess, Williams’ mother, at age 41 was a shock and a tragedy for her family. But it also is a story of how economic and social determinants of health shape lives. Even though deaths from heart disease have been falling, it is still the No. 1 killer for both men and women, reports the Centers for Disease Control and Prevention (CDC).