Arrhythmia-Induced Cardiomyopathy

Cardiomyopathies include a group of diseases that affect the heart muscle.
Arrhythmia-induced cardiomyopathy refers to a condition in which the heart muscle, particularly the left ventricle, becomes weakened as a result of persistent abnormal heart rhythms.

A fundamental characteristic of this condition is its potential reversibility: when the rhythm disorder is adequately controlled, cardiac function can improve significantly.

Related article: Heart Failure – Generalities

Which Arrhythmias Can Be Responsible?

Abnormal heart rhythms are grouped under the term arrhythmias. When the heart beats too fast, they are more specifically referred to as tachycardias.

Several types of rhythm disorders may be involved:

atrial tachycardias, originating from the upper chambers of the heart;
ventricular tachycardias, arising from the lower chambers;
or very frequent premature ventricular beats.

When these arrhythmias persist over time, they place excessive strain on the heart, which can lead to a progressive decline in the contractile function of the left ventricle.
Conversely, effective control of the arrhythmia often allows for partial or even complete recovery of cardiac function, particularly when the diagnosis is made early.

Two Categories of Arrhythmia-Induced Cardiomyopathy

Two main forms of arrhythmia-induced cardiomyopathy are generally recognized:

The pure form, in which the arrhythmia is the sole cause of the weakening of the heart muscle.
The aggravating form, in which the arrhythmia occurs in the presence of pre-existing heart disease and leads to additional damage, either by further impairing cardiac function or by worsening existing symptoms of heart failure.

In both situations, the diagnosis can only be confirmed after restoration and stabilization of an adequate heart rhythm or, following strict control of heart rate when the arrhythmia persists.

Clinical Presentation and Assessment

The central feature is the simultaneous presence of:

an abnormal heart rhythm,
and an otherwise unexplained weakening of the heart muscle.

The relationship between the arrhythmia and the cardiomyopathy can be difficult to establish. The arrhythmia may progress silently for several years before being recognized, while the underlying cardiac impairment develops gradually.

Initial symptoms may therefore appear late or worsen progressively as cardiac function declines.

Most Common Findings

These findings are most often related to heart failure resulting from left ventricular dysfunction. They may include:

shortness of breath during exertion or at rest,
difficulty lying flat due to breathlessness,
swelling of the legs or abdomen,
increasing fatigue and a marked reduction in energy levels.

Signs Related to the Arrhythmia

Some signs are directly attributable to the arrhythmia itself, including:

awareness of rapid or irregular heartbeats (palpitations“Palpitation” is a symptom related to an abnormality in heartbeats. There are several types of arrhythmias. This term is like a surname that encompasses several first names.),
dizziness,
disproportionate fatigue during daily activities or physical exertion.

How Is Arrhythmia-Induced Cardiomyopathy Diagnosed?

The diagnosis of arrhythmia-induced cardiomyopathy is based on a step-by-step medical evaluation.

It begins with a clinical consultation to assess symptoms, cardiac history, and associated factors, and is then confirmed through several complementary tests, each providing essential information.

Electrocardiogram (ECG)

A persistent tachycardia can sometimes be identified on a standard 12-lead ECG. This may include atrial fibrillation, atrial tachycardia, or frequent premature beats, whether of supraventricular or ventricular origin.
However, a single ECG recording may appear normal if the arrhythmia is intermittent.

Holter Monitoring

When the arrhythmia is not captured on an ECG, a Holter monitor is used. This is an external device typically worn for at least 24 hours.

This prolonged recording makes it possible to:

assess the duration of the arrhythmia,
measure the average heart rate,
and quantify the overall arrhythmia burden over a full day.

For example, in the presence of atrial fibrillation, Holter monitoring can determine the average heart rate and the amount of time spent in arrhythmia.

When frequent premature ventricular contractions are present, it allows calculation of the percentage of abnormal beats, a key factor in assessing their impact on the heart muscle.

Transthoracic Echocardiography
Echocardiography is a central component of the diagnostic process.
Arrhythmia-induced cardiomyopathy is always associated with left ventricular dysfunction, and other cardiac chambers may also be affected.
In some patients, specific features may be observed, such as a left ventricle of relatively normal size compared with that seen in chronic pre-existing cardiomyopathies. These findings may strengthen the suspicion of an arrhythmia-induced condition.

Cardiac Magnetic Resonance Imaging (MRI)

Cardiac MRI may be used to:

exclude other potential causes of left ventricular dysfunction,
identify the presence of myocardial scars or structural damage.

In patients with frequent premature ventricular contractions, cardiac MRI may occasionally reveal a structural abnormality that would support an alternative diagnosis, thereby questioning the diagnosis of arrhythmia-induced cardiomyopathy.

Coronary Angiography

In certain situations, coronary angiography is required.

This invasive procedure involves advancing a catheter through an artery in the wrist or groin to inject contrast dye into the coronary arteriesThe two coronary arteries, the right and the left, form the blood network that supplies the heart with oxygen and nutrients. They are located directly on the surface of the heart and branch into smaller vessels that. It allows confirmation of the absence of coronary arteryThe two coronary arteries, the right and the left, form the blood network that supplies the heart with oxygen and nutrients. They are located directly on the surface of the heart and branch into smaller vessels that obstruction, a common cause of left ventricular dysfunction that must be ruled out.

Mechanisms and Management of Arrhythmia-Induced Cardiomyopathy

The treatment of arrhythmia-induced cardiomyopathy is primarily based on effective control, or elimination, of the underlying arrhythmia.

An improvement in cardiac function following management of the rhythm disorder represents a strong argument supporting the diagnosis.

The question of whether long-term medications should be continued once cardiac function has normalized remains a matter of debate. Decisions are therefore individualized, taking into account the type of arrhythmia, the risk of recurrence, and the overall clinical context.

The chicken or the egg?

It is sometimes difficult to determine whether the arrhythmia is the initiating cause of the cardiomyopathy or a consequence of it in patients who present with both tachycardia and heart failure.

In this setting, the arrhythmia is often considered secondary and may not be treated aggressively enough. Clinical experience, however, shows that strict control of the arrhythmia is essential to achieve optimal recovery of cardiac function.

Other Important Considerations

Although an elevated heart rate may be associated with myocardial injury, several important nuances should be highlighted:

Arrhythmia-induced cardiomyopathy is rare, if not nonexistent, in individuals with inappropriate sinus tachycardia or postural orthostatic tachycardia syndrome (POTS), even when the average daytime heart rate exceeds 100 beats per minute.
In these conditions, nighttime heart rate is generally slower due to the absence of factors that promote tachycardia, which may have a protective effect.
There is no specific heart rate threshold above which arrhythmia-induced cardiomyopathy develops. Susceptibility appears to vary from one individual to another and may depend, among other factors, on age.
The factors explaining why certain patients develop this form of cardiomyopathy remain poorly understood. A genetic predisposition has nevertheless been suggested as a possible contributing factor.

Arrhythmias Involved

Atrial Fibrillation

Atrial fibrillation (AF) is the most common cause of arrhythmia-induced cardiomyopathy in adults.

To read: Atrial Fibrillation

Several mechanisms contribute to the weakening of the heart:

because of the rapid and irregular rhythm, the ventricles do not have sufficient time to fully relax between beats, which reduces ventricular filling and the amount of bloodBlood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells are responsible for transporting oxygen and carbon dioxide. White blood cells make up our immune defense system. Platelets contribute to blood pumped forward;
atrial fibrillation leads to the loss of the atrial mechanical contribution to ventricular filling, a component that normally plays an important role in cardiac output.

Both mechanisms are exacerbated as heart rate increases.

Progressive sequence

Initially, the ventricles tend to dilate in an attempt to compensate. However, when rapid atrial fibrillation persists and its control is delayed, ventricular function eventually begins to decline.

At a more advanced stage, the heart’s inability to effectively pump bloodBlood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells are responsible for transporting oxygen and carbon dioxide. White blood cells make up our immune defense system. Platelets contribute to blood forward leads to increased intracardiac pressures, with backward transmission toward the lungs. This may result in pulmonary edema, often described as “fluid in the lungs.”

To read: Water “in” the lungs

Treatment of Atrial Fibrillation

Treatment is based on pharmacological and/or interventional approaches, depending on the clinical context.

Heart Rate Control

A strategy aimed at controlling heart rate is often considered first. It relies on medications that slow the heart rate, such as beta-blockers, calcium channel blockers, and, less commonly, digoxin.

Rhythm Control

Another option consists of restoring and maintaining normal sinus rhythm, thereby terminating atrial fibrillation.

Not all patients are candidates for this approach. Restoration of sinus rhythm can be achieved through electrical cardioversion or with antiarrhythmic medications. In patients with rapid atrial fibrillation associated with heart failure, drugs such as amiodarone, sotalol, or dofetilide may be used.

Interventional Approach

In a growing number of patients, catheter ablation of atrial fibrillation represents an effective option for maintaining long-term sinus rhythm.

Alternative Interventional Option: Pacemaker and Atrioventricular Node Ablation

In patients who do not respond to pharmacological rate control or who are not candidates for rhythm restoration, a two-step strategy may be proposed:

implantation of a pacemaker;
ablation of the atrioventricular (AV) node, performed several weeks or months later.

To understand this strategy, it is important to recall that electrical conduction from the atriaThe atria are the two upper chambers of the heart. They act as reservoirs for blood that will fill the ventricles. to the ventricles can occur through only one pathway, the atrioventricular node. This structure acts as a true “checkpoint,” limiting the rate at which impulses reach the ventricles.

Prior implantation of a pacemaker is essential to ensure adequate ventricular pacing after intentional destruction of this conduction pathway. Only after a period of stabilization can AV node ablation be performed safely.

Atrial Flutter

Atrial flutter is often described as the “twin sister” of atrial fibrillation.

To read: Atrial Flutter

The mechanisms responsible for cardiac weakening are similar to those described above.

The same rate- and rhythm-control strategies may be used. However, from an interventional standpoint, outcomes are particularly favorable.

A Preferred Interventional Approach

Although the mechanisms leading to arrhythmia-induced cardiomyopathy are comparable to those seen in atrial fibrillation, treatment differs.

Radiofrequency ablation of typical right atrial flutter has a very high success rate (greater than 96%), with a low risk of complications. For this reason, it is generally considered the treatment of choice.

Frequent Premature Ventricular Contractions

Frequent premature ventricular contractions may lead to arrhythmia-induced cardiomyopathy in individuals without known heart disease. They may also worsen cardiac function in patients with pre-existing heart disease.

In this context, the arrhythmia is often perceived as secondary and may not be treated aggressively enough. However, clinical experience shows that strict control of the arrhythmia is essential to achieve optimal recovery of cardiac function.

Mechanisms

The exact mechanisms leading to this form of cardiomyopathy are not fully understood, although several hypotheses have been proposed.

Important Clinical Indicators

The most critical factor is a high daily PVC burden, typically defined as:

more than 10,000 to 25,000 PVCs per day, or
a proportion exceeding 10% to 24% of total daily heartbeats.

Improvement in ventricular function is often observed when the number of PVCs decreases below approximately 5,000 per day.
In general, a higher PVC burden recorded on electrocardiography is associated with an increased risk of arrhythmia-induced cardiomyopathy.

Treatment of Premature Ventricular Contractions

Treatment aims to reduce or eliminate PVCs, either through medication or intervention.

Pharmacological Treatment

Initial therapy usually consists of a beta-blocker or a calcium channel blocker, given their favorable safety profile, although their effectiveness may be limited.

When these measures are insufficient, antiarrhythmic medications may be considered. The most effective agents include dofetilide, mexiletine, sotalol, and amiodarone. Their use, however, is associated with a higher risk of side effects, including proarrhythmic effects.

These medications are generally reserved for patients who cannot undergo catheter ablation or who are reluctant to pursue an interventional approach.

Interventional Therapy

Catheter ablation is now considered a definitive therapy for PVC-mediated arrhythmia-induced cardiomyopathy. Reported success rates range from 50% to 90%, depending on the site of origin of the premature beats and their frequency at the time of the procedure.

Prognosis and Long-Term Follow-Up

Arrhythmia-induced cardiomyopathy differs from many other forms of cardiomyopathy by its generally favorable prognosis, provided that the underlying arrhythmia is properly identified and adequately treated.

-Evolution After Treatment

When the rhythm disorder is controlled or eliminated, a progressive improvement in cardiac function is usually observed.

Recovery may begin within the first few weeks but most often extends over several months. In some patients, left ventricular function may return to normal.

The extent and speed of recovery depend on several factors:

the duration of exposure of the heart to the arrhythmia,
the type of arrhythmia involved,
the effectiveness and timeliness of treatment,
the presence or absence of underlying heart disease.

-Risk of Recurrence

Even after satisfactory recovery, the risk of arrhythmia recurrence remains present. A recurrence of the rhythm disorder may once again lead to weakening of the heart muscle, sometimes more rapidly than during the initial episode.

For this reason, long-term monitoring remains essential, even in patients whose cardiac function has normalized.

Clinical and Paraclinical Follow-Up

Follow-up is based on:

regular clinical assessment of symptoms,
periodic monitoring of heart rhythm and heart rate using electrocardiography or prolonged rhythm recording when necessary,
follow-up echocardiography to document changes in left ventricular function over time.

The frequency of follow-up is individualized, depending on the type of arrhythmia, the treatment strategy used, and overall clinical stability.

Long-Term Treatment

Decisions regarding the continuation of therapy, particularly medications used for heart failure or arrhythmia prevention, are made on a case-by-case basis.

In some patients, a gradual reduction in medication may be considered after complete and sustained recovery, whereas in others, long-term treatment remains necessary to prevent recurrence.

Key Message

Arrhythmia-induced cardiomyopathy highlights the importance of early diagnosis and targeted treatment of cardiac rhythm disorders.

When recognized and appropriately managed, this form of cardiomyopathy is often reversible, allowing a return to satisfactory cardiac function and an improved quality of life.