( CNN ) -- Laura Pollan , a founder of one of Cuba 's leading dissident groups , died Friday , her daughter said . Pollan suffered a heart attack and died at Calixto Garcia Hospital in Havana , Laura Maria Pollan told CNN en Espanol . The founder of Cuba 's Ladies in White had been hospitalized several days ago because of a respiratory complication . Yoani Sanchez , a Cuban blogger , told CNN that some of Pollan 's relatives , friends and fellow dissidents had gathered outside of the hospital . The Ladies in White , an opposition group , formed after the Cuban government cracked down on dissidents in 2003 . Among the activists arrested then was Hector Maseda Gutierrez , Pollan 's husband . He was freed in February . Members of the Ladies in White dress in white , carry flowers and march to demand the release of political prisoners -- many of whom are relatives and friends of the women . CNN 's Carloo Perez contributed to this report .
Laura Pollan suffered a heart attack , her daughter died . She died at the Calixto Romero Hospital in Havana . The Ladies in White demand the release of political prisoners .