Endurance sports despite a pacemaker? - Training on a racing bike despite a pacemaker?

Question from TOUR reader Carsten B.: I (55 years old) have been cycling and taking part in ultramarathons for twelve years, including Trondheim-Oslo, completed several solo non-stop rides of between 400 and 850 kilometres and took part in Paris-Brest-Paris for the first time last year. My annual mileage is between 8,000 and 10,000 kilometres. Nine years ago, I had an ablation procedure due to reentry tachycardia. Unfortunately, something went wrong and I subsequently had a 2nd degree AV block. The last long-term ECG in January showed a nocturnal resting pulse rate of 20 beats per minute, but according to my cardiologist there was still no indication for a pacemaker because of my endurance sport. Then, in March, I had two spontaneous syncope episodes at night, one of them in hospital during an ECG, whereupon I was implanted with a pacemaker on the same day. It is set to the lowest frequency of 35 beats per minute. My question: Did my endurance sport actually delay the pacemaker indication? Or did the endurance sport perhaps lead to a further reduction in the reduced heart rate caused by the dropouts after the ablation? Another question: From your point of view, can I tackle long distances of several hundred kilometres again once I have started training?

Answer from Dr Robert Eifler: The pacemaker - a matchbox-sized device with extremely fine probes - is usually inserted under the skin below the left or right collarbone under local anaesthetic and programmed according to the arrhythmia. They are primarily used therapeutically for slow arrhythmias that are accompanied by syncope (brief loss of consciousness). Reentry tachycardia is a heart palpitation that occurs intermittently. If attempts to treat it with medication fail, it is treated with radiofrequency catheter ablation (electrical disconnection of one of the two conduction pathways from the right atrium to the ventricles). This can lead to a so-called 2nd degree AV block, an increasing delay in conduction from the atrium to the ventricle.

A resting pulse rate of less than 30 beats per minute with syncope is an indication for a pacemaker, even if there is no structural heart disease. In your case, a so-called on-demand pacemaker was apparently implanted, which is only used when the pulse rate is below 35 beats per minute and is therefore intended to protect you from loss of consciousness.

Excessive endurance sport can reduce the resting heart rate enormously. However, your pacemaker implantation was performed because of syncope, which poses a considerable risk. It is quite conceivable that your endurance sport has led to a further reduction in your heart rate after the catheter ablation. In general, there is nothing wrong with you continuing to do sport after the pacemaker has been implanted. Once the scar has healed and the correct pacemaker function has been checked, you can resume your training after just a few days. However, it is not advisable to take part in ultramarathons (risk of microsleep, fall, probe breakage).