Complex sentence: After riding one of his favourite horses around the track, he complained of chest pains and difficulty breathing and was rushed to Martin Memorial South Hospital in Stuart, Florida, where he was pronounced dead of a severe heart attack resulting from arteriosclerosis.
Split into simpler sentences: After riding one of his favourite horses around the track, he complained of chest pains and difficulty breathing. Paramedics were called, and he was rushed to Martin Memorial South Hospital in Stuart, Florida, where he was pronounced dead of a severe heart attack resulting from arteriosclerosis.