SAN JOSE, Costa Rica -- Doug Hamilton, president and general manager of the defending MLS champion Los Angeles Galaxy, died Thursday after an apparent heart attack while flying back from the team's CONCACAF Champions Cup match in Costa Rica. A two-time Major League Soccer Executive of the Year, Hamilton died aboard a Lacsa Airlines flight after it left San Jose airport Thursday evening, airline spokeswoman Sofia Valverde said. "He appeared to have symptoms similar to a heart attack," Valverde said. One of the Galaxy's team doctors, Dr. Howard Liebeskind, tried to resuscitate him as the pilot returned the plane to San Jose, according to Michael Roth, vice president of communications for AEG, the investor-operator of the Galaxy. Hamilton was returning to the United States after the Galaxy played Saprissa of Costa Rica during a second leg of a CONCACAF Champions Cup quarterfinal Wednesday. He had turned 43 on Monday, Roth said. "We are deeply saddened by the loss of one of the leaders of American soccer and a truly terrific individual," MLS Commissioner Don Garber said. "The thoughts and prayers of all of MLS, our teams, our players and our fans are with the Hamilton family. Doug will be dearly missed as his legacy of passion and dedication to the sport will always be remembered." The Galaxy had planned to remain in Costa Rica for training, but decided to return to Los Angeles on Friday. Hamilton joined the Galaxy four seasons ago after spending two years as executive vice president and GM of the Miami Fusion. He previously worked for adidas America for six years. He graduated from the University of North Carolina-Greensboro. Hamilton is survived by his wife, Paige, and a 5-year-old son.