Catheter ablation and rhythm control in atrial fibrillation
THE CONTEXT
Catheter ablation offers an alternative to anti-arrhythmic drugs. Persistent atrial fibrillation (AF) can be managed with rate or rhythm control, with thromboembolism prophylaxis required for either approach.
Ablation targets, outcomes and complications
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Ablation targets left atrial connections to the pulmonary veins to prevent ectopic triggering of AF.
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Ablation prevents AF in approximately 75% of patients, although repeat procedures may be needed. It improves prognosis in some patients with coexisting heart failure and reduced ejection fraction.
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Serious complications include cardiac tamponade, stroke, phrenic nerve injury and pulmonary vein stenosis.
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Atrio-oesophageal fistula is exceptionally rare but often fatal after left atrial ablation.
Energy sources
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Radiofrequency energy produces heat injury and fibrosis.
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Cryoablation produces fibrosis by freezing tissue to approximately −40 to −50 degrees Celsius.
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Electroporation, also called pulsed field ablation, uses short bursts of DC energy to disrupt atrial myocardial cell membranes and produce fibrosis. Its non-thermal action reduces the risk of atrio-oesophageal fistula.
Persistent AF and cardioversion
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Both rate control and rhythm control require short-term or long-term prophylaxis against thromboembolism.
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Restoring sinus rhythm is appropriate when AF causes troublesome symptoms and there is a treatable underlying cause. Electrical DC cardioversion or pharmacological cardioversion may be used.
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Cardioversion succeeds initially in most patients, but relapse occurs in 25%–50% at 1 month and 70%–90% at 1 year.