Helen Schwimmer Lefkowitz, the wife of former New York State Attorney General Louis J. Lefkowitz, died of cardiac arrest yesterday at Lenox Hill Hospital. She was 77 years old and lived in Manhattan.

She had been a member since 1963 of the board of trustees of the Fashion Institute of Technology - part of the State University. For the last 20 years, she had also had been a director of the institute's Student-Faculty Corporation, which allocates funds for special student and faculty activities.

Mrs. Lefkowitz, who was born in Brooklyn and attended Hunter College, was a member of the administrative board of the Society of the Memorial Sloan-Kettering Cancer Center, a fund-raising group run by volunteers.

Besides her husband, the Attorney General from 1957 to 1978, she is survived by a daughter, Joan Feinbloom of Rochester; a son, Stephen, of Manhattan; a brother, Charles Schwimmer of Valley Cottage, N.Y., and two grandsons.