'I passed out in a ditch' – a mystery heart condition at 27 hasn't stopped this rider from cycling around the world

When a trip to Italy in 2019 ignited his love of cycling, Tom Williamson began dreaming about bikepacking the world. By 2020, he was fit, trained and finally ready to begin. But before his first real adventure had even found its rhythm, he found himself at the side of the road, stopped in his tracks. “It wasn’t even a crash,” says Williamson. “I’d pulled over because my heart rate kept climbing higher and higher. Then I just passed out and toppled over. I woke up on the tarmac, confused, with a cut face.”

Williamson was riding with a friend from Land’s End to John o’ Groats (LEJOG), after Covid travel restrictions had scuppered their plans to go touring in France. Day one had gone smoothly, exactly as he’d hoped, but by the following afternoon, his heart rate was behaving strangely, spiking without warning. He assumed it was down to too much sugar and coffee, on top of the longer-than-usual hours in the saddle. On day three, it happened again – his heart rate surged, and this time he collapsed.

He ended up spending two nights in Birmingham Hospital, and had to abandon the LEJOG ride. It was a period he now describes as frightening. “I’d never passed out before,” he says. “I was thinking, what’s wrong with me? I am fit and healthy, but suddenly I am unable to keep my heart rate down.”

Outwardly, nothing appeared amiss. Williamson was 27 years old with no history of heart problems. Even medical professionals struggled to find a cause. Tests came back clear, with no abnormalities detected. And so began two years of medical limbo, during which Williamson was left questioning whether his endurance cycling ambitions were over before they had properly begun. “It felt like the rug had been pulled from under me,” he says.

On paper, Williamson was an ordinary, active young man doing all the right things to stay healthy. He cycled to his job as a marketing executive and trained regularly at his local gym – there were no warning signs. Though not a professional athlete, he grew up in a household shaped by sport: both his parents are keen runners, and he spent his childhood running and playing hockey – interests he kept up through to university. Now 32 and speaking to me from his home in Thames Ditton, Surrey, Williamson comes across as open and optimistic, someone quick to see the positive and driven by a desire to explore the world.

Back in 2019, on that trip to Italy, Williamson bought a second-hand road bike on which to explore the Lake Garda region where he was staying. At the time he had little cycling experience, but the adventure – and no doubt the fine Italian food and scenery – instilled in him a sense of freedom he did not want to leave behind. His friend’s proposal in 2020 that they ride LEJOG together was irresistible. “I joined a local cycling club for social reasons, as a way to meet people and ride with others,” Williamson remembers, “but after a while I realised that group riding is not what drew me to cycling. I wanted to plan routes and be adventurous. That sense of independence and exploration is what keeps pulling at me.”

Following his hospitalisation, Williamson underwent ECGs, echocardiograms, MRIs, 48-hour Holter monitor and exercise tolerance tests – practically every heart function test available on the NHS. The results were inconclusive. None of the doctors advised him to stop cycling, though he was told to take things easy while uncertainty remained. It was an unsettling and difficult time for Williamson. “By then, I had developed so much of my identity and happiness from endurance cycling that the uncertainty made it feel like my entire future was up in the air,” he says. “Although nobody banned me from sport outright, it felt like that possibility was on the table.”

In January 2024, he finally had a working diagnosis: supraventricular tachycardia (SVT), a type of irregular heartbeat affecting the heart's upper chambers, causing a fast or erratic heartbeat. Doctors attempted an ablation procedure, where heat is applied to create a tiny scar in the heart to block faulty heart signals. However, on this occasion the surgeon couldn’t find the location of the fault and the operation was unsuccessful. Nine months later they tried again, but alas, they once again failed to block the short-circuit, and symptoms returned.

WIlliamson was advised to keep his exertion levels low, but this didn’t stop him going on adventures – even if it meant hiding them from his doctors. “I didn’t tell them about the trips,” he says. “I knew they would advise caution, and I completely understood that. Most people would be wary of someone cycling solo in remote places, let alone with a heart condition.”

After the first surgery, determined not to put his life on hold, he cycled through Macedonia and Greece. “My approach was to take the general medical advice seriously and then apply my own understanding of how my symptoms behaved,” Williamson explains.

After the second surgery – initially thought successful – Williamson went ahead with three, almost back-to-back trips: first India, followed by Central America and India again. “Don’t tell my mum,” he jokes, “but on that trip [to India] I passed out in a ditch and ended up calling on locals to help me out.” Some might regard Williamson’s continuing to ride long distances as irresponsible, but he disagrees. “You learn that most people in this world are good,” he says. “My adventures were incredibly important to me, mentally as well as physically. I had to weigh up risk versus living fully, and I do feel I made the right decision.”

SVT affects about two in every 1,000 people, meaning it is not considered uncommon. What was uncommon, in Williamson’s case, was the location of the electrical trigger – so unusual, in fact, that he became a special case study for his cardiologist Dr Dhillon Param Deep, at King’s College Hospital, London. Williamson underwent two procedures where the surgeons couldn’t locate the trigger point in his heart, and symptoms returned almost immediately afterwards. Relief came in June last year when surgeons tried again and, after four hours probing Williamson’s heart, finally ablated the problem area. He has been symptom-free since. “For the first time in four years, I feel genuinely hopeful,” he says. “I’ve had no major symptoms and finally feel like myself again.”

Since the successful ablation, Williamson has completed a bikepacking tour of China, cycling 400 miles from Zhangjiajie National Park south to Guilin, over six days. It was the first time since 2020 he had ridden for a prolonged period without symptoms – no forced stops, no discomfort, and no need to constantly monitor his heart rate. He felt elated. “I remember flying up the hills on day six in total disbelief because I felt so strong. It was amazing.”

For Williamson, long-distance cycling is no longer just about testing his limits or chasing adventure. having benefited from life-changing medical care, he is determined to give something back. He is now planning to bikepack around the world, starting in June, to raise funds for Cardiac Risk in the Young (CRY). The charity estimates that 12 people aged 35 or under die suddenly each week in the UK from previously undiagnosed heart conditions, with 80% showing no prior symptoms. Through screening programmes and research, CRY works to reduce those numbers. “Knowing these statistics hits home how lucky I was,” Williamson reflects.

Mum’s view: ‘I won’t stop worrying!’

“I am always worried about him,” laughs Bonnie Williamson, Tom’s mother, when I ask how she feels about his bikepacking adventures. “The fact that he is alone on his trips, I worry that he might not get help when he gets into trouble.”

She recalls her panic the first time she saw Tom’s heart-rate monitor reading 200bpm. “And that was when he was just sitting still,” she exclaims. As a former NHS mental health nurse, Bonnie is not unfamiliar with hospitals and the medical profession. “When we found out he was in hospital in Birmingham, it wasn’t so much the heart that worried us first,” she remembers, “it was the picture of our healthy and fit son with cuts and bruises all over his face.”

Throughout the ordeal, Bonnie coached Tom on how to calm and slow his heart rate should the arrhythmia symptoms suddenly arise. As doctors struggled to reach a diagnosis, it was Bonnie’s suggestion to use a portable cardiac monitor to record his heart rhythms over a prolonged period. “The doctor noticed [an abnormality on] the read-out and they suddenly had proof of something being wrong. That was when they implanted an ECG to record his heart rate.”

Despite the successful surgery, Bonnie naturally still has concerns. “I am pleased about the last surgery, but I still worry about other cycling dangers like accidents. It’s his being alone that worries me more than anything.”

This feature originally appeared in Cycling Weekly magazine on 12 March 2026. Subscribe now and never miss an issue.