Heart Rhythm Disorders: Prevention, Diagnosis and When to See a Doctor
Almost everyone notices their heartbeat now and then: a thump after a strong coffee, a flutter while lying in bed. Most of these sensations are harmless. Some, however, signal a heart rhythm disorder that needs treatment, and a small number can be life-threatening. Knowing the difference, and when to act, is useful for anyone who exercises.
What a heart rhythm disorder is
The heart's rhythm is controlled by electrical impulses that start in the sinoatrial node, a natural pacemaker in the right atrium, and spread through the heart in a coordinated sequence. An arrhythmia is any disturbance of this rate or pattern.
Arrhythmias are broadly divided by speed and origin. Tachycardias are fast rhythms, bradycardias slow ones. Those arising in the upper chambers, such as atrial fibrillation or supraventricular tachycardia, are usually less immediately dangerous than ventricular arrhythmias, which can cause sudden cardiac arrest.
Atrial fibrillation is the most common sustained arrhythmia. The British Heart Foundation estimates that well over a million people in the UK have been diagnosed with it, and many more are thought to have it without knowing. Its main danger is stroke, because blood can pool and clot in the poorly contracting atria.
Ectopic beats, extra beats arising outside the normal pacemaker, are extremely common and usually benign. They are often felt as a skipped beat followed by a stronger one.
Causes and risk factors in active people
Classic risk factors include high blood pressure, coronary heart disease, heart failure, valve disease, thyroid overactivity, obesity, sleep apnoea, diabetes and heavy alcohol use. Age is a major factor for atrial fibrillation.
Exercise has a complex relationship with rhythm. Moderate activity lowers the risk of atrial fibrillation, but very high lifetime volumes of endurance exercise appear to increase it. A large Swedish study of cross-country skiers by Andersen and colleagues found that those who completed the most races or had the fastest times had a higher risk of atrial fibrillation and bradyarrhythmias.
| Factor | Possible rhythm effect |
|---|---|
| Very high endurance training volume | Atrial fibrillation, slow heart rhythms |
| Stimulants, energy drinks, pre-workouts | Palpitations, ectopic beats, tachycardia |
| Anabolic steroids and other performance drugs | Structural heart changes, ventricular arrhythmias |
| Binge drinking ("holiday heart") | Atrial fibrillation |
| Electrolyte disturbance, dehydration | Ectopic beats, arrhythmias |
| Inherited conditions (cardiomyopathies, channelopathies) | Sudden cardiac arrest in young people |
In young athletes, sudden cardiac death is rare but devastating. It is usually caused by undiagnosed inherited conditions such as hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy or long QT syndrome. Use of anabolic steroids, stimulant fat burners and other performance drugs has also been linked to cardiomyopathy and dangerous arrhythmias.
Supplements high in caffeine or other stimulants can provoke palpitations and, in susceptible people, more significant arrhythmias, especially when combined with dehydration and intense exertion.
Warning signs and when to seek help
Not all palpitations need urgent care, but some symptoms are red flags. Call 999 immediately if palpitations are accompanied by:
- chest pain or pressure;
- fainting or near-fainting, especially during exercise;
- severe breathlessness;
- signs of stroke such as facial drooping, arm weakness or speech problems.
Collapse during exercise is a medical emergency. Bystanders should call 999, start CPR and use a public access defibrillator if available. In the UK, many sports clubs, gyms and public places now have defibrillators registered on The Circuit national network.
See your GP promptly, rather than urgently, if you notice palpitations that are frequent, prolonged or increasing, an irregular pulse at rest, unexplained drops in exercise performance or dizziness, or if there is a family history of sudden death under the age of 40.
Isolated, brief skipped beats in an otherwise healthy person, especially if linked to caffeine, alcohol or poor sleep, are usually harmless, but it is still reasonable to mention them at a routine appointment.
How arrhythmias are diagnosed in the UK
The GP will usually take a history, check pulse and blood pressure, and arrange a 12-lead ECG. Blood tests often include thyroid function, electrolytes, full blood count and kidney function.
Because many arrhythmias come and go, a normal resting ECG does not rule them out. Ambulatory monitors such as 24-hour or 7-day Holter recorders, event recorders and patch monitors capture rhythm over longer periods. Smartwatch and phone-based ECG recordings can be helpful if they capture an episode, though they should be confirmed clinically.
An echocardiogram assesses heart structure and function. Exercise testing may be used to reproduce symptoms triggered by activity, and cardiac MRI is used when cardiomyopathy is suspected. For athletes, ECGs are interpreted using international athlete-specific criteria, which help distinguish normal training adaptations from disease.
NICE guidance on atrial fibrillation emphasises assessing stroke risk with the CHA2DS2-VASc score and bleeding risk before deciding on anticoagulation. Specialist cardiology or electrophysiology referral follows when needed.
Prevention and living with an arrhythmia
Many risk factors are modifiable. Controlling blood pressure, maintaining a healthy weight, treating sleep apnoea, limiting alcohol and stopping smoking all reduce the risk of atrial fibrillation and its recurrence.
For active people, sensible habits include avoiding high-dose stimulant products, staying hydrated, not training through a febrile illness and paying attention to unusual symptoms rather than "pushing through". Performance-enhancing drugs carry well-documented cardiac risks and should be avoided.
People with a diagnosed arrhythmia can often continue exercising. The 2020 European Society of Cardiology guidelines on sports cardiology support individualised recommendations, and many people with treated atrial fibrillation or supraventricular tachycardia return to sport. Treatments range from medicines to catheter ablation, pacemakers and implantable defibrillators.
If you have been prescribed anticoagulants or rhythm medicines, do not stop them without advice, and ask your cardiologist about contact sports and training intensity.
Conclusions of the editorial team
Most palpitations are benign, but rhythm disorders such as atrial fibrillation are common and carry real risks, particularly stroke.
Fainting or chest pain during exercise, and a family history of sudden death, always warrant prompt medical attention.
Diagnosis in the UK is straightforward to start, usually with a GP and an ECG, and many conditions can be treated effectively while allowing an active life.
You may also wish to read our articles on arrhythmia after caffeine, on the cardiac effects of anabolic steroids, and on how to interpret a smartwatch ECG alert.
References
- Hindricks G, Potpara T, Dagres N, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2021;42(5):373–498.
- National Institute for Health and Care Excellence. Atrial fibrillation: diagnosis and management. NICE guideline NG196. London: NICE; 2021.
- Pelliccia A, Sharma S, Gati S, et al. 2020 ESC Guidelines on sports cardiology and exercise in patients with cardiovascular disease. Eur Heart J. 2021;42(1):17–96.
- Andersen K, Farahmand B, Ahlbom A, et al. Risk of arrhythmias in 52 755 long-distance cross-country skiers: a cohort study. Eur Heart J. 2013;34(47):3624–3631.
- Drezner JA, Sharma S, Baggish A, et al. International criteria for electrocardiographic interpretation in athletes: consensus statement. Br J Sports Med. 2017;51(9):704–731.
- Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022;43(40):3997–4126.
