( CNN ) -- Singer George Hamilton IV , known as the `` International Ambassador of Country Music , '' has died at a Nashville hospital following a heart attack , the Grand Ole Opry said in a press release . He was 77 . Hamilton 's biggest hit was `` Abilene , '' which reached No . 1 on the country charts in 1963 and returned him to the pop charts , the Opry said . His other country hits were `` Before This Day Ends , '' `` Three Steps to the Phone '' and `` If You Do n't Know , I Ai n't Gon na Tell You . '' Hamilton performed around the world and became the first American country singer to appear in the Soviet Union and Czechoslovakia and was the first to record a studio album in Eastern Europe , the Grand Ole Opry said . He performed extensively in Canada and recorded songs by Canadian songwriters such as Joni Mitchell and Gordon Lightfoot . Hamilton started out as a pop singer and had a million-selling hit `` A Rose and a Baby Ruth '' in 1956 before switching to country . He 'd been a member of the Grand Ole Opry since 1960 . The singer was not related to actor George Hamilton . The North Carolina native died Wednesday Saint Thomas Midtown Hospital in Nashville . Funeral arrangements have not been announced . People we 've lost in 2014 : The lives they 've lived .
Hamilton was known as the ` ` ' Ambassador of Country . '' His biggest hit , ` ` Bells , '' reached No . 1 on the country charts in 1963 . He died at a Nashville hospital after a heart attack .