Are adults with CHD at risk of arrhythmias? 

Adults born with Congenital Heart Disease (CHD) are at a significantly higher risk of developing arrhythmias (abnormal heart rhythms) compared to the general population. In fact, arrhythmias are the most frequent reason for hospitalisation in the adult CHD community. These rhythm disturbances can range from a nuisance ‘fluttering’ in the chest to serious, life-threatening events. The risk often increases with age, as the long-term effects of original heart defects and the scar tissue from childhood surgeries begin to impact the heart’s electrical system. 

What We’ll Discuss in This Article 

• Why surgical scarring from childhood is a primary cause of adult arrhythmias. 

• The most common types of rhythm disorders found in adult CHD patients. 

• How ‘haemodynamic’ stress and pressure overload trigger electrical changes. 

• Identifying subtle symptoms of arrhythmias in daily life. 

• The importance of regular screening via ECG and Holter monitoring. 

• Differentiation between ‘benign’ palpitations and ‘malignant’ arrhythmias. 

• Modern treatment options, including medication, ablation, and devices. 

Why CHD Increases Arrhythmia Risk 

The heart’s electrical system is responsible for coordinating every beat. In adults with CHD, this system often faces two major challenges: structural abnormalities and surgical scarring. Most heart surgeries performed in childhood involve incisions or the placement of patches. Over time, these areas develop scar tissue, which does not conduct electricity. This can force the electrical signals to take ‘detours’, creating short circuits known as ‘re-entry’ circuits that cause the heart to beat too fast or irregularly. 

Additionally, the original heart defect may have caused certain chambers of the heart to stretch or thicken (remodelling) due to years of handling extra blood or high pressure. Stretched heart tissue is electrically unstable and much more likely to trigger extra beats or sustained rhythm disorders like atrial fibrillation or atrial flutter. 

• Surgical Scars: Act as physical barriers to normal electrical flow. 

• Chamber Enlargement: Stretched atria or ventricles are prone to ‘short-circuiting’. 

• Ageing: The natural ageing of the heart combined with CHD increases electrical sensitivity. 

Common Types of Arrhythmias in Adult CHD 

The specific type of arrhythmia often depends on the underlying heart defect. For example, those with ‘transposition of the great arteries’ or ‘Fontan circulation’ are particularly susceptible to atrial arrhythmias. 

Atrial Tachyarrhythmias 

These are fast heart rhythms starting in the upper chambers (atria). ‘Atrial flutter’ and ‘Atrial fibrillation’ (AF) are very common. They can cause a racing heart, breathlessness, and, if left untreated, can increase the risk of blood clots and stroke. 

Ventricular Arrhythmias 

These are more serious rhythms starting in the lower chambers (ventricles). They are often seen in conditions like Tetralogy of Fallot, especially if there is significant scarring or a leaky pulmonary valve. These rhythms can be life-threatening and may require the placement of an Implantable Cardioverter Defibrillator (ICD). 

Causes and Triggers of Rhythm Changes 

The ’cause’ of a new arrhythmia in adulthood is often a shift in the heart’s stability. While the scar tissue provides the ‘pathway’ for the arrhythmia, other factors act as ‘triggers’ that set it off. Lifestyle factors such as excessive caffeine, alcohol, or high levels of emotional stress can stimulate the heart and initiate a rhythm episode. 

Underlying cardiac changes are also major causes. If a heart valve starts to leak more significantly, the resulting pressure change can ‘trigger’ the electrical system to malfunction. This is why a new arrhythmia often prompts a specialist to check the structural health of the heart using an echocardiogram or MRI. 

Trigger	Impact on Heart Rhythm	Management
Alcohol/Caffeine	Can irritate the heart’s electrical nodes.	Moderate intake; track ‘trigger’ events.
Electrolyte Imbalance	Low potassium or magnesium affects cell signals.	Maintain a balanced diet; check bloods if on diuretics.
Physical Overexertion	High adrenaline can spark ventricular beats.	Follow ‘self-limiting’ exercise advice.
Sleep Apnoea	Drops in oxygen at night strain the heart.	Seek review if snoring or waking gasping.

Signs and Symptoms to Monitor 

Symptoms of an arrhythmia can be intermittent, making them easy to dismiss. However, for an adult with CHD, any new ‘thumping’ or ‘skipping’ in the chest deserves a specialist review. 

Symptom	Description	Urgency
Palpitations	Sensation of heart racing, fluttering, or skipping.	Routine Specialist Review.
Dizziness	Feeling lightheaded, especially during activity.	Urgent Specialist Review.
Syncope	Sudden loss of consciousness or fainting.	Emergency (Call 999).
Breathlessness	Difficulty breathing that is new or worsening.	Urgent Specialist Review.
Chest Pain	Tightness or aching during a ‘racing’ episode.	Emergency (Call 999).

Differentiation: Normal Palpitations vs. Arrhythmia 

It is normal for everyone to feel their heart race occasionally (e.g., when nervous or after a run), but for CHD patients, the distinction is critical. 

Normal Heart Response 

The heart rate increases gradually during exercise and slows down gradually during rest. The rhythm remains regular (like a metronome). This is a healthy response to adrenaline or exertion. 

Clinical Arrhythmia 

The heart rate often changes ‘suddenly’ starting or stopping like a light switch. The rhythm may feel ‘chaotic’ or like a ‘fish flopping in a net’. If the heart races while you are sitting still, or if it is accompanied by dizziness, it is likely a clinical arrhythmia requiring investigation. 

To Summarise 

In my final conclusion, adults with CHD are at a high risk of arrhythmias due to the combination of surgical scars and long-term structural changes in the heart. While many rhythm issues are manageable with medication or modern ‘keyhole’ procedures like ablation, they require specialist monitoring to prevent complications like heart failure or stroke. Early detection via regular check-ups at an Adult Congenital Heart Disease (ACHD) centre is the most effective way to protect your heart’s electrical health. 

If you experience severe, sudden, or worsening symptoms, such as fainting, sudden crushing chest pain, or a heart rate so fast you feel you might collapse, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This article was written by Dr. Stefan Petrov, a UK-trained physician with postgraduate certifications in Advanced Cardiac Life Support (ACLS). It provides an authoritative overview of why congenital heart defects lead to long-term electrical instability. The content is supported by the 2026 ‘Clinical Consensus on Arrhythmias in Adult Congenital Heart Disease’, which emphasizes that ‘arrhythmia management is now the most dominant aspect of long-term care for the ageing CHD population’.