Roger Kluge, the reigning Madison world champion with Theo Reinhardt, did not fare well in the Omnium, the first race of the UCI Track World Cup series in Glasgow, finishing 17th.

Kluge's illness was made public after the monthly German Moz published an interview with him on Saturday. He underwent surgery on October 7 to repair his patent foramen ovale (OP). Op is a congenital defect of the heart in which the opening between the right and left atria of the heart does not close after birth.

About a quarter of adults have no symptoms, but it can increase the risk of stroke. A small blood clot that would normally be filtered by the lungs can flow through the left ventricular orifice into the brain and cause a stroke.

This is exactly what happened to Kluge in mid-March 2018.

"I wanted to clean my daughter's nose, but at that moment my arm slowly dropped and I lost control. I was scared, after 30 seconds it was over," Kluge told Moz.

The day after his mild stroke (known as a transient ischemic attack, or TIA, which leaves no lasting effects), Kluge, then a Mitchelton Scott racer, headed to Belgium for the race but did not start as a precaution.

"I went to the hospital for three days for ECG [electrocardiogram] and blood tests. I was ready to race, but all of a sudden I was in the hospital with a bunch of people who were really sick."

Doctors found a blood clot, but pronounced Kluge perfectly healthy and he competed in Paris-Roubaix.

"I think my partner Judith had a harder time than I did. I didn't think more about it at the time. It just slowed me down. I swallowed it and kept running like before. Nothing has happened since," Kluge said.

However, Lotto-Soudal's team doctor recommended that Kluge undergo surgery to minimize the risk of stroke. Says Kluge, "The surgery went well, they were able to hide it, and I don't see any difference."

Kluge and Reinhardt are competing in the Ghent Six Day and are currently in fourth place with 121 points, on the same lap as leaders Kenny de Ketele and Rob Giese with 197 points.