UAE Team Emirates' Fabio Aru will now miss the upcoming Volta Ciclista a Catalunya, as well as May's Giro d'Italia, in order to have an operation on a constriction of the iliac artery in his left leg, his team has reported.
Aru was due to return to racing at next week's Spanish stage race having abandoned Paris-Nice in early March, but could now be away from racing for a number of months, until at least this summer.
The winner of the 2015 Vuelta a España's last victory came at La Planche des Belles Filles on stage 5 of the Tour de France in 2017, with the 28-year-old having since struggled to perform at the level he's used to.
Aru's iliac artery problem has meant that he has lacked "an adequate blood supply when trying to make a maximum effort. This problem, and resulting drop in power, during the Sardinian's most intense efforts [has] limited his performances", said a team statement released on Sunday morning.
"It is a feeling that I feel when I have to go all-out, while the symptom disappears at a medium pace – so much so that in training I get the basic numbers," Aru said.
"From a certain point of view, I can only be relieved to have found the problem; on the other hand, I am angry about the bad luck that has befallen me for the umpteenth time, and that it will force me to miss the Giro d'Italia again. I will work to try to put an end to this dark period as soon as possible.
"I thank the team for their close attention shown this year-and-a-half, and for working with me to find the solution to the problems that have plagued me," Aru continued. "We really hope this is the final chapter."
Head of the medical staff at UAE Team Emirates, Dr Jeroen Swart, gave further details of the problems Aru has encountered due to the medical condition.
"After the start of the  season, Fabio again encountered difficulties in getting up to that normal level that he and the team had hoped for," Swart said in the press release.
"Recently, Fabio developed more specific symptoms related to his left leg: he felt feelings of weakness in the limb after intense training and in race efforts. In view of these symptoms, further medical tests have shown a constriction of the iliac artery in his left leg. This relatively rare condition is found in professional cyclists given the position adopted on their bikes, and can develop progressively over a period of several years," he said.
Riders to have had iliac-artery operations in recent years include EF Education First's Joe Dombrowski, 2014 road race world champion Pauline Ferrand-Prévot and current time trial world champion Annemiek van Vleuten (Mitchelton-Scott).
"In the coming days, with a date to be determined based on the availability of the hospital, Aru will undergo angioplasty surgery at the Nuovo Ospedale di Prato [Prato hospital], after which he will have to observe an absolute rest period of one month," continued Swart.
"For something like this, the return time is estimated at three or four months," he said – meaning that Aru could potentially return in time to race at this year's Tour de France in place of the Giro.