Background: Achieving bidirectional mitral isthmus (MI) block using radiofrequency catheter ablation (RFCA) alone is challenging, and MI reconnection is common. Adjunctive vein of Marshall (VOM) ethanol infusion (VOM-Et) can facilitate acute MI block. However, little is known about its long-term success. This study sought to evaluate the impact of adjunctive VOM-Et on MI block achievement and durability compared with RFCA alone. Methods: Patients undergoing the first attempt of posterior MI ablation were grouped according to their MI block index strategy: adjunctive VOM-Et and RFCA alone. Rates of acute MI block and MI reconnection observed during repeat procedures were compared between the 2 groups. Results: The VOM-Et group consisted of 152 patients (63.8±9.4 years) undergoing adjunctive VOM-Et for MI block. The RFCA group consisted of 110 patients (60.9±9.2 years) undergoing MI ablation using RFCA alone. Acute MI block was more frequently achieved in the VOM-Et group (98.7% [150/152] versus 63.6% [70/110]; P <0.001) with shorter RFCA duration (5.00 [3.00–7.00] versus 19.0 [13.6–22.0] minutes; P <0.001). Of the 220 patients with MI block achieved during the index procedure, 81 underwent a repeat procedure during follow-up (VOM-Et group: 23.3% [35/150] versus RFCA group: 65.7% [46/70], respectively; P <0.001). A significantly greater number of patients exhibited durable MI block in the VOM-Et group (62.9% [22/35] versus 32.6% [15/46], respectively; P =0.008). Conclusions: Beyond facilitating acute MI block, VOM-Et is associated with greater lesion durability as evidenced by higher rates of MI block during repeat procedures.

Background—: Although catheter ablation (CA) is a standard treatment for atrial fibrillation (AF), its long-term efficacy remains unclear. This study aimed to elucidate the incidences of AF recurrence and of progression from paroxysmal to persistent AF, after CA, in patients with paroxysmal AF. Methods and Results—: We examined the incidence of AF recurrence and AF progression in 1220 consecutive patients (mean age, 61 years), with symptomatic paroxysmal AF, undergoing CA, based on extensive pulmonary vein isolation and focal ablation for nonpulmonary vein foci. AF recurrence–free survival probabilities at 5 years were 59.4% after the initial CA and 81.1% after the final CA (average, 1.3 procedures). During a median follow-up period of 47.9 (range, 5.3–123.3) months after the initial CA, AF progressed from paroxysmal to persistent in 15 (1.2%) patients (0.3%/y). The duration of AF history (hazard ratio [HR], 1.03; P <0.0001), number of ineffective antiarrhythmics (HR, 1.09; P =0.005), and left atrial diameter indexed by the body surface area (HR, 1.05; P =0.001) were significant predictors of AF recurrence. Patient age (HR, 1.12; P =0.0001) and left atrial diameter indexed by the body surface area (HR, 1.26; P =0.0006) were significantly associated with AF progression. Patients aged ≤65 years and with a left atrial diameter indexed by the body surface area of ≤24.0 mm/m ² did not develop AF progression for ≤10 years after the initial CA. Conclusions—: Although the long-term follow-up revealed the effect of CA on preventing AF recurrence, repeated CA sessions might be required. The rate of progression from paroxysmal to persistent AF was 0.3%/y.