Pulmonary vein isolation – still the cornerstone in atrial fibirillation ablation?
Atrial fibrillation (AF) is the most common cardiac arrhythmia with significant morbidity and mortality. It increases the risk of stroke 5-fold and doubles the risk of all-cause mortality (1, 2). Recent data suggest that AF hospitalizations have increased to overtake myocardial infarction and heart failure as the most common cause of cardiovascular admissions globally (3, 4). This common arrhythmia also significantly reduces the quality of life in affected patients (5). Considering the limited efficacy and possible side-effects of antiarrhythmic drugs (AAD), radiofrequency (RF) catheter ablation become a standard procedure as a second-line therapy after failure of at least one AAD, or alone as a first-line therapy in selected patients. The latter strategy is supported by numerous trials demonstrating superiority of catheter ablation over AAD therapy in maintaining sinus rhythm. For instance, multiple clinical trials report
AF free survival of 50-75% at 1-year post ablation, opposing to 10-30% with AADs only (6-11). In most of the multi-center, randomized clinical trials the ablation arm strategy was to achieve complete electrical pulmonary vein isolation, confirmed by the presence of exit and entrance block to the left atrium. In consequence, current ESC and HRS guidelines recognize PVI as “the cornerstone” in atrial fibrillation ablation. On top of pulmonary vein isolation, additional ablation targets can be considered, especially in patient with non-paroxysmal atrial fibrillation. Of these strategies, the most often applied are complex fractionated atrial electrograms (CFAE), ganglionated plexi ablation, additional linear ablation, and focal impulse or rotor modulation (FIRM).
The initial concept of electrical isolation of pulmonary veins as treatment modality for paroxysmal AF was first proposed by Haïssaguerre et al. in 1998 (12). They demonstrated than ectopic beats originating from pulmonary veins can trigger AF, and electrical isolation of ectopic foci by means of catheter ablation may prevent the recurrence of arrhythmia. Out of 45 patients they studied a single point of origin of atrial ectopic beats was found in 29 patients, two points were identified in 9 patients, and three or four ectopic sites were identified in 7 patients. The important fact was that for a total of 69 ectopic foci, 65 were localized in the pulmonary veins (94%). In this initial study, RF catheter ablation of the ectopic foci resulted in freedom from AF recurrences in 62% patients in the follow up of 8 ± 6 months. This pioneer study by Haïssaguerre and colleagues launched the era of non-farmacological treatment of atrial fibrillation, based on pulmonary vein isolation by means of catheter ablation. Numerous radnomized clinical trials comparing PVI to antiarrhythmic therapy proved PVI to be far better effective in maintaining sinus rhythm than AADs alone (6-11).
The “gold standart” to achieve complete electrical pulmonary vein isolation is to perform point-by-point ablation with irrigated-tip catheter with the support a tree-dimensional (3D) electroanatomical system (fig. 1) and usually multipolar diagnostic catheter for pulmonary vein potentials assessment (fig. 2).
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