Introduction

Arrhythmia is defined as any disturbance in the rate, rhythm, site of origin, or conduction of the heart’s electrical impulses. Normal cardiac rhythm (sinus rhythm) arises from the sinoatrial (SA) node at a rate of 60–100 beats per minute. Deviations from this pattern, whether due to structural heart disease, systemic disorders, or primary electrical abnormalities, may result in arrhythmias.

Arrhythmias range from asymptomatic benign conditions (such as isolated premature atrial complexes) to life-threatening events (such as ventricular fibrillation). They contribute significantly to cardiovascular morbidity and mortality worldwide, with atrial fibrillation alone affecting an estimated 37 million people globally and carrying a five-fold risk of stroke [1].

Types of Arrhythmia

Supraventricular Arrhythmias (originating above the ventricles)

• Atrial fibrillation (AF): Chaotic atrial activity, leading to an irregularly irregular ventricular response.

• Atrial flutter: Rapid, organized atrial activity with a characteristic “saw-tooth” pattern on ECG.

• Paroxysmal supraventricular tachycardia (PSVT): Includes AV nodal reentrant tachycardia (AVNRT) and AV reentrant tachycardia (AVRT).

• Multifocal atrial tachycardia (MAT): Often seen in pulmonary disease.

Ventricular Arrhythmias

• Premature ventricular contractions (PVCs): Usually benign but may indicate structural heart disease.

• Ventricular tachycardia (VT): Sustained or non-sustained; often associated with ischemic heart disease.

• Ventricular fibrillation (VF): Chaotic activity without effective cardiac output—medical emergency.

Bradyarrhythmias

• Sinus bradycardia: May be physiologic (athletes) or pathologic.

• Sinoatrial block or sick sinus syndrome.

• Atrioventricular (AV) block: First-degree, second-degree (Mobitz type I/II), and third-degree (complete) block.

Symptoms

• Palpitations: Awareness of heartbeat (fluttering, pounding, irregular).

• Dizziness/lightheadedness: Due to reduced cerebral perfusion.

• Syncope: Suggests hemodynamically significant arrhythmia.

• Dyspnea and fatigue: Common in AF due to loss of atrial contraction (“atrial kick”).

• Chest pain: Particularly if arrhythmia occurs in patients with coronary artery disease.

• Sudden cardiac arrest: In malignant ventricular arrhythmias.

• Note: Asymptomatic presentations are common, especially in AF detected incidentally during ECG.

Etiology and Risk Factors

Cardiac causes:

• Coronary artery disease, prior myocardial infarction

• Cardiomyopathy (dilated, hypertrophic, restrictive)

• Valvular disease (e.g., mitral stenosis in AF)

Systemic factors:

• Thyroid disorders (hyperthyroidism → AF)

• Electrolyte disturbances (hypokalemia, hypomagnesemia)

• Pulmonary disease (e.g., COPD, sleep apnea)

Lifestyle and external triggers:

• Alcohol (“holiday heart syndrome”)

• Excess caffeine or stimulant use

• Certain drugs (antiarrhythmics, digoxin, cocaine, amphetamines)

Genetic predisposition:

• Long QT syndrome, Brugada syndrome, catecholaminergic polymorphic VT.

Diagnosis

• Electrocardiogram (ECG): Gold standard for arrhythmia detection.

• Ambulatory monitoring: Holter (24–48 hr) or event recorder for intermittent symptoms.

• Echocardiography: Evaluates structural heart disease and atrial/ventricular size and function.

• Exercise stress test: For arrhythmias induced by exertion or ischemia.

• Electrophysiological study (EPS): Invasive, maps conduction pathways, guides ablation therapy.

• Blood tests: Thyroid function, electrolytes, cardiac biomarkers when indicated.

Management

1. General Measures & Lifestyle

• Avoid arrhythmia triggers (alcohol, excess caffeine, stimulant drugs).

• Weight management and regular exercise reduce AF recurrence.

• Treat sleep apnea to improve rhythm control.

• Blood pressure, diabetes, and lipid management as per guidelines.

2. Pharmacological Therapy

Rate control (especially in AF):

• Beta-blockers (e.g., metoprolol)

• Non-dihydropyridine calcium channel blockers (diltiazem, verapamil)

• Digoxin (less preferred, mainly in sedentary patients)

Rhythm control:

• Class IC (flecainide, propafenone) in selected patients without structural heart disease

• Class III (amiodarone, sotalol, dofetilide) in patients with structural heart disease

• Anticoagulation (AF/flutter):

• Based on CHA₂DS₂-VASc score

• Warfarin (INR 2–3) or DOACs (dabigatran, rivaroxaban, apixaban, edoxaban).

3. Electrical and Interventional

• Cardioversion: Electrical or pharmacological (preferred in recent-onset AF or VT).

• Catheter ablation: Curative in many cases of SVT, AF, and VT.

• Pacemakers: For sinus node dysfunction or AV block causing bradycardia.

• Implantable cardioverter-defibrillators (ICDs): For secondary prevention after cardiac arrest, or primary prevention in cardiomyopathy with reduced ejection fraction.

• Cardiac resynchronization therapy (CRT): For heart failure patients with arrhythmia and LBBB.

Prognosis

• Atrial fibrillation: Increases risk of stroke (5x) and heart failure (3x).

• Ventricular arrhythmias: Sustained VT or VF carries a high risk of sudden cardiac death.

• Bradyarrhythmias: Often well-managed with pacing, prognosis depends on underlying heart disease.

• Timely diagnosis and treatment significantly improve survival and quality of life. Multidisciplinary care (cardiologist, electrophysiologist, internist) is essential.

References

• Hindricks G, Potpara T, Dagres N, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. Eur Heart J. 2021;42(5):373–498.

• Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. Circulation. 2018;138(13):e272–e391.

• January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update on Atrial Fibrillation. J Am Coll Cardiol. 2019;74(1):104–132.

• Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay. J Am Coll Cardiol. 2019;74(7):e51–e156.

• Braunwald E, Zipes DP, Libby P, Bonow RO, Mann DL. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia: Elsevier; 2021.