Robert Gesink (Belkin) is reportedly suffering with a stress-induced heart arrhythmia that affects his ability to race successfully, especially in major European races.
According to the Ad.nl website and other Dutch media, Gesink will hold a press conference on Tuesday evening to explain his problem and confirm that he will not ride Sunday's Amstel Gold Race. His race programme for the next few months is also unsure.
AD.nl claims that Gesink's problems also spark panic attacks and caused him to quit the 2011 national road race championships and the 2013 Giro d'Italia. The heart arrhythmia apparently forced him to quit the Vuelta al Pais Vasco last week.
The De Telegraaf newspaper suggested that the problems first occurred a few months after the death of Gesink's father in 2010. A few months before he had finished fifth in the Tour de France. Gesink has often opted to race outside of Europe to the avoid the pressure and stress that sparks his problem. However the problem apparently returns in major races in Europe.
According to Ad.nl, several sources within the team have revealed that Gesink has had a pacemaker fitted to help control his heart beat after no physical cause for the problem was found by doctors.
Last year Gesink was not a designated team leader for Belkin at the Tour de France, with that role going to Bauke Mollema. However Gesink had an excellent end of season, winning the Grand Prix Cycliste de Québec.
He told Cyclingnews that he hoped to target the overall classification in this year's Tour de France after trying to win the Amgen Tour of California in May.