Ablation index to guide AF ablation
Ablation Index (AI) is used in the context of pulmonary vein isolation with radiofrequency catheter ablation for atrial fibrillation (AF) . Pulmonary vein reconnection is an important problem which reduces the long term success rate of AF ablation. Other studies have shown that force sensing is important in AF ablation and optimal results are obtained when 90% or more of the lesions receive a local force of more than 10 grams and the time in contact force range exceeds 80%. Durability of pulmonary vein isolation depends on full thickness gap free ablation. When the gaps exceed 10 mm, there is increase in the recurrence of AF .
Ablation index is a quality marker which includes contact force and contact time in a weighted formula. High rates of persistent pulmonary vein isolation and avoidance of recurrence of arrhythmia in patients with persistent atrial fibrillation was documented in the PRAISE study (Pulmonary Vein Reconnection Following Ablation Index-guided Ablation: a Success Evaluation) . 95% of patients were in sinus rhythm at one year.
Target values of ablation index were 550 for anterior and 400 for the posterior left atrial regions. Protocol mandated 2 month restudy in the PRAISE study noted pulmonary vein reconnection in 22% of patients, affecting. In 44% ablation on the inter pulmonary venous carina was required to achieve durable pulmonary vein isolation. Among the 20% of patients who had recurrence of atrial tachyarrhythmia, only one had pulmonary vein reconnection at the repeat study. Significant factors associated with recurrence were high body mass index and excess alcohol consumption .
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