David Crosby has undergone heart surgery and has postponed his upcoming California shows, including ones at the Great American Music Hall in San Francisco, originally scheduled for Feb. 20-21. The shows have been rescheduled for April 20-21.

Crosby's website said the 72-year-old had a cardiac catheterization on Feb. 14 to fix a blocked coronary artery because he was at-risk for a heart attack.

Crosby also had to move five shows in Los Angeles to April. He said he'll be ready to perform with the group Crosby, Stills and Nash on a tour that kicks off in Richmond, Va., on March 4.

Crosby underwent a liver transplant in 1994.

In a statement, the singer -- who just released "Croz," his first solo album in more than 20 years -- said he is "once again a very lucky man."

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