Singer Cesaria Evora has undergone open heart surgery in Paris following an emergency "coronary problem" this weekend. She is recovering in hospital and has cancelled the remainder of her 2010 concert dates.

Evora, Cape Verde's most famous musician, was in the middle of a world tour – her first major performances since suffering a stroke in 2008. She performed in Lisbon on Saturday night, but was rushed to a Paris hospital's emergency department the following day. Surgery took place on Monday night, lasting about six hours. "Everything went as well as could be expected, according to the surgeons," her record label, Lusafrica, said. "She was placed in intensive care following the surgery and she regained consciousness [on Tuesday] morning."

Sixty-eight year-old Evora is the world's best-known singer of morna, a Cape Verdean song and dance tradition that is often compared to the blues. Celebrated as the "Barefoot Diva", she has released 11 albums since 1988. The most recent of these, Nha Sentimento, was issued late last year. Recorded as Evora recovered from her stroke, it explored the Middle Eastern influence on Cape Verdean music, including a collaboration with Egyptian musician Fathy Salama. The reissue of Nha Sentimento, featuring a bonus duet with rising Cape Verde star Lura, is due shortly.

Evora appeared in London just last week with European dates scheduled for May. She has also cancelled a North American tour, and late summer visits to China, Brazil and Tunisia. was barefoot, as always, and wandered on stage wearing a brown dress and cardigan, looking as disinterested as if she were on her way to the shops. Cesaria Evora has always been an anti-star, matching simple stagecraft with exquisite vocal work, and this London comeback – the first since she had a stroke two years ago – showed she remains a powerful, distinctive singer.

Evora, who will be 69 this summer, didn't became an international star until her 50s, when she was hailed as the queen of morna, the emotional, gently melancholic songs of loss and longing for home that are the Cape Verde answer to the blues. Much earlier in her career, singing in local bars, she had specialised in more upbeat coladera dance songs, and it was this style that dominated tonight. In short bursts, on songs such as Zinha from her most recent album, her compelling, sad-edged vocals matched successfully against furious violin, cavaquinho and saxophone work from an impressive (if relentlessly cheerful) eight-piece band.

All that was lacking was variety. The musicians calmed down a little to allow a more soulful treatment of the standard Bésame Mucho, but thoughtful mornas such as Sodade would have sounded better with minimal backing. The audience were ecstatic and clapped along, but Evora wandered off stage looking bemused.

Ballaké Sissoko, the Malian kora player, opened the show with a far more delicate and unexpected set. He may have been eclipsed by the success of his friend Toumani Diabaté, but he is an adventurous virtuoso, as he proved with this collaboration with the classically trained French cellist Vincent Segal, mixing African and western themes in exquisite, trance-like improvisations.