Isabel Edns Myrth, 89, long-active in the Daughters of the American Revolution and a retired Army employee, died Saturday at Washington Hospital Center after a heart attack.

Born in Brooklyn, N.Y., she came here as an infant. She was a graduate of the old Wilson Teachers College and taught is the D.C. public schools for 12 years.

In 1922, Miss Myrth joined the office of the Army adjutant general and became assistant supervisor of the correspondence department, retiring in 1950.

She was a 50-year member of the Columbia Chapter of the DAR and had served as its regent. She had been state registrar of the District of Columbia DAR. A nationally known genealogist, she also had served as head of the DAR conservation of genealogical records and lineage research.

She was a member of the state officers club, former vice chairwoman of information of the national DAR and a state promoter of the Children of the American Revolution.

Miss Myrth belonged to the Columbia Historical Society, the National Genealogical Society, the Society of Women Descendants of the Ancient and Honorable Artillery Company, the Society of the Daughters of Founders and Patriots, and the Society of Colonial Dames of the 17th Century.

She had been a leader in the Girl Scouts, a member of PEO, a philanthropic organization, and of St. Mark's Episcopal Church.