Czech rider Zdenek Stybar will miss the Tour of Flanders after undergoing surgery for a heart problem, his team, Deceuninck Quick-Step, announced on Friday.
The problem emerged as the 35-year-old Stybar, usually a strong performer in one-day classics, finished a respectable 25th in Gent-Wevelgem last Sunday.
"After Gent-Wevelgem, Zdenek Stybar told the Deceuninck medical team that he was not feeling well," the Belgian team said in a statement. "The examinations carried out by our medical staff revealed that the Czech rider was suffering from heart rhythm problems.
"A surgical intervention was recommended. This was successfully carried out by Professor Pedro Brugada on Wednesday in Brussels."
Stybar has already resumed training but will take a few days off with his family, Deceuninck said.
"I am obviously disappointed to miss the Ronde on Sunday," wrote Stybar. "This period, with E3, Gent-Wevelgem, the Tour of Flanders, is my favourite of the season. I trained well and I felt that my form had not been this good for a long time."
Stybar, who also rides cyclocross, was fifth in the E3 in Harelbeke in late March. He finished in the top 10 in the Tour of Flanders in 2015, 2016 and 2018.
He was expected to be one of a trio of riders Deceuninck would hope to set up to win Sunday's race, along with French world champion Julian Alaphilippe and Belgian rider Yves Lampaert.