"He had been experiencing some irregular heart rhythm during racing and training," team doctor Max Testa said. "We have been investigating it, first by having him evaluated by sports cardiologists in Belgium. The common decision between a specialist there and the BMC Racing Team's medical staff is to rest Klaas for an undetermined amount of time while a thorough investigation is performed."
Lodewyck, 26, has been with the team for three seasons after making his WorldTour debut with Omega Pharma-Lotto in 2011. He is yet to achieve his first professional victory, but was voted most aggressive rider in the 2012 Tour of Oman. He had only just made his comeback from injuries sustained in the Halle-Ingooigem in June, racing at the Tour de Wallonie last month.
"Mentally, it is like I am in a big nightmare," Lodewyck said. "Since my crash, it seems like there has always been something and for the last week, I have been to the hospital almost every day for tests."
Lodewyck is not the only rider to suffer from cardiac arrhythmia - former cyclo-cross world champion Niels Albert was forced to retire prematurely because of heart problems, and Belkin's Robert Gesink stopped racing in June to have an arrhythmia treated.
Other riders who have had cardiac issues in recent years include Nick Nuyens, Haimar Zubeldia, Nicolas Vogondy, Nicolas Portal and Kim Kirchen.
A 2013 medical study of cross-country skiers found an increased incidence of cardiac arrhythmia in endurance athletes. Although most arrhythmias in athletes are not life threatening, some can be more serious. Kirchen suffered a heart attack in 2010 that led to his retirement, while Belgian Rob Goris died of a heart attack at age 30 in 2012.