What is ablation and when is it used to treat cardiac arrhythmias?

Cardiac Ablation for Arrhythmia Treatment

Cardiac ablation is a procedure that destroys small areas of heart tissue causing abnormal heart rhythms, and is indicated as first-line therapy for drug-resistant arrhythmias or when patients cannot tolerate or do not wish to take long-term medications. 1

What is Cardiac Ablation?

Cardiac ablation is a minimally invasive procedure that uses energy sources (most commonly radiofrequency energy) to destroy or scar small areas of heart tissue responsible for generating or conducting abnormal electrical signals causing cardiac arrhythmias. 1

• The procedure involves inserting catheters through blood vessels to reach the heart, then mapping the electrical activity to identify abnormal areas 1
• Once identified, energy is delivered to create controlled lesions that interrupt abnormal electrical pathways 1
• Radiofrequency ablation is the most common technique, though newer technologies like pulsed field ablation are emerging for certain arrhythmias 2

Indications for Cardiac Ablation

Class I Indications (Strongly Recommended):

• Sustained predominantly monomorphic ventricular tachycardia (VT) in patients at low risk for sudden cardiac death who are drug-resistant, drug-intolerant, or unwilling to take long-term medications 1
• Bundle-branch reentrant VT 1
• Adjunctive therapy in patients with implantable cardioverter-defibrillators (ICDs) receiving multiple shocks for sustained VT not manageable by reprogramming or medication changes 1
• Wolff-Parkinson-White syndrome patients resuscitated from sudden cardiac arrest due to atrial fibrillation with rapid conduction over accessory pathway causing ventricular fibrillation 1

Class IIa Indications (Reasonable to Perform):

• Symptomatic non-sustained monomorphic VT in patients at low risk for sudden cardiac death who are drug-resistant, drug-intolerant, or unwilling to take long-term medications 1
• Frequent symptomatic predominantly monomorphic premature ventricular contractions (PVCs) in patients who are drug-resistant, drug-intolerant, or unwilling to take long-term medications 1
• Symptomatic Wolff-Parkinson-White syndrome patients with accessory pathways having refractory periods less than 240 ms 1

Class IIb Indications (May Be Considered):

• Ablation of Purkinje fiber potentials in patients with ventricular arrhythmia storm consistently provoked by PVCs of similar morphology 1
• Ablation of asymptomatic but very frequent PVCs to prevent or treat cardiomyopathy 1

Specific Arrhythmias Treated with Ablation

Supraventricular Tachycardias:

• Atrioventricular Nodal Reentrant Tachycardia (AVNRT): Ablation success rates approach 99% and should be considered first-line therapy when the arrhythmia causes hemodynamic compromise or intolerable symptoms 1, 3
• Accessory Pathway-Mediated Tachycardias: Success rates of approximately 92-99%, particularly recommended for symptomatic Wolff-Parkinson-White syndrome 1, 3
• Atrial Flutter: First-line therapy with success rates around 92% 4, 3
• Atrial Tachycardia: Success rates of approximately 81% 3

Atrial Fibrillation:

• Catheter ablation is recommended for patients with paroxysmal or persistent atrial fibrillation who are resistant or intolerant to antiarrhythmic drug therapy 2
• Success rates range from 70-85% depending on the type of atrial fibrillation, often requiring more than one procedure 1, 4
• Particularly beneficial for patients with heart failure with reduced ejection fraction who have tachycardia-induced cardiomyopathy 2

Ventricular Arrhythmias:

• Highly effective (nearly 100%) for idiopathic ventricular tachycardias occurring in structurally normal hearts 5, 6
• Very effective for bundle-branch reentry VT, which occurs most frequently in patients with dilated cardiomyopathy 5, 6
• Variable success rates (approximately 80%) for VT due to structural heart disease 4, 6

Complications and Risks

• Overall major complication rate is approximately 1.4-3.9% 3, 7
• Cardiac tamponade (1.3%) and vascular complications (1.1%) are most common 7
• Thromboembolic events including stroke occur in approximately 0.4% of cases 7
• Inadvertent complete AV block occurs in 1.3-4.7% of AV node modification procedures 1
• Rare but serious complications include atrial-esophageal fistula (0.2%) and endocarditis (0.2%) 7
• Procedure-related mortality is very low (approximately 0.1-0.2%) 8, 7

Risk Factors for Complications

• Advanced age (≥75 years) increases complication risk (hazard ratio 3.977) 7
• Congestive heart failure is associated with higher complication rates (hazard ratio 5.174) 7

Special Considerations

• For atrial fibrillation ablation, oral anticoagulation should be given at least 3 weeks before the procedure and continued uninterrupted during the procedure 2
• Anticoagulation should continue for at least 2 months after AF ablation regardless of rhythm outcome or CHA₂DS₂-VA score 2
• After AV junction ablation, permanent pacemaker implantation is required 8
• For ventricular arrhythmias, epicardial ablation may be needed when the arrhythmia focus is not accessible from the endocardium 6

Cardiac ablation has transformed the management of cardiac arrhythmias, offering a potentially curative option with excellent success rates and acceptable safety profile when performed at experienced centers.