Use of irbesartan to maintain sinus rhythm in patients with long-lasting persistent atrial fibrillation: a prospective and randomized study.

BACKGROUND: Data from studies of angiotensin-converting enzyme inhibitors provide evidence that the renin-angiotensin-aldosterone system plays a role as a mediator of atrial remodeling in atrial fibrillation. The present study has evaluated the effect of treatment with the angiotensin I type 1 receptor blocker irbesartan on maintaining sinus rhythm after conversion from persistent atrial fibrillation. METHODS AND RESULTS: To be included in the present study, patients must have had an episode of persistent atrial fibrillation for >7 days. The patients were then randomized and scheduled for electrical cardioversion. Two groups of patients were compared: Group I was treated with amiodarone, and group II was treated with amiodarone plus irbesartan. The primary end point was the length of time to a first recurrence of atrial fibrillation. From a total of 186 patients assessed in the study, 154 were analyzed with the use of intention-to-treat analysis. Seventy-five patients were randomly allocated to group I and 79 to group II. After 2 months of follow-up in the intention-to-treat analysis, the group treated with irbesartan had fewer patients with recurrent atrial fibrillation (Kaplan-Meier analysis, 84.79% versus 63.16%, P=0.008). The Kaplan-Meier analysis of time to first recurrence during the follow-up period (median time, 254 days [range, 60 to 710]) also showed that patients treated with irbesartan had a greater probability of remaining free of atrial fibrillation (79.52% versus 55.91%, P=0.007). CONCLUSIONS: Patients treated with amiodarone plus irbesartan had a lower rate of recurrence of atrial fibrillation than did patients treated with amiodarone alone.

[Lesions produced by radiofrequency ablation of the cavotricuspid isthmus in an experimental model]. / Lesiones producidas por la ablación con radiofrecuencia del istmo cavotricuspídeo en un modela experimental.

INTRODUCTION AND OBJECTIVES: Experimental studies have shown that deeper and wider lesions (up to 10 mm long or deep) can be safely created using an 8 mm or irrigated tip catheter for ablation to treat atrial flutter. However, potential damage to the tricuspid valve or inferior cava vein has not been systematically evaluated. PATIENTS AND METHOD: The cavotricuspid isthmus was ablated in 26 pigs (body weight 26-52 kg), with a total of 187 radiofrequency pulses. Standard 4 mm, 8 mm and irrigated tip catheters were used at random. For each ablation, energy, impedance and temperature were recorded continuously. RESULTS: The lesions were larger with irrigated tip and 8-mm catheters than with standard ones. In 7 animals (1 with an irrigated tip, 4 with an 8-mm, and 2 with a standard tip) the tricuspid valve was damaged. The tricuspid valve was severely damaged in 3 pigs and lesions were moderate in 4. In animals with tricuspid valve lesions, maximal energy was higher (59 +/- 27 vs. 51 +/- 24 W; p=0,03) and higher temperatures were reached (63 +/- 4 vs. 55 +/- 11 degrees C; p<0.001). Low energy pulses measured before ablation were also more intense in animals in which damage was produced (0.55 +/- 0.24 vs. 0.35 +/- 0.29; p=0.001), indicating greater contact pressure. CONCLUSIONS: The tricuspid valve may be severely damaged during the ablation of the cavotricuspid isthmus for atrial flutter: damage was seen most often with high energy pulses and with 8-mm catheters, but can also occur with usual energy levels and standard catheters. To minimize damage this technique should not be used from the inside of the right ventricle just above the tricuspid valve.

Lesiones producidas por la ablación con radiofrecuencia del istmo cavotricuspídeo en un modelo experimental / Lesions produced by radiofrequency ablation of the cavotricuspid isthmus in an experimental model

Introducción y objetivos. El empleo de catéteres con punta de 8 mm o irrigados para la ablación del aleteo auricular produce lesiones más anchas y profundas que los estándares, hasta de 10 mm de longitud y profundidad. El daño potencial sobre la válvula tricúspide o la vena cava inferior no se ha evaluado de forma reglada. Pacientes y método. Se hizo ablación del istmo cavotricuspídeo en 26 animales (cerdos, con un peso de 2652 kg) con un total de 187 aplicaciones, empleando aleatoriamente catéteres estándar de 4 y 8 mm, y catéteres irrigados, con control de la potencia, la impedancia y la temperatura. Resultados. Los catéteres irrigados y de 8 mm produjeron lesiones de mayor tamaño. En 7 animales (uno con catéter irrigado, 4 con catéter de 8 mm y 2 con catéter estándar) se dañó la válvula tricúspide, la lesión fue severa en 3 casos y moderada, en 4. Los casos con lesión valvular habían recibido mayor potencia (59 ñ 27 frente a 51 ñ 24 W; p = 0,03) y alcanzado temperaturas más altas (63 ñ 4 frente a 55 ñ 11 °C; p < 0,001). La medición del pulso de baja energía preablación fue también mayor cuando se produjeron lesiones (0,55 ñ 0,24 frente a 0,35 ñ 0,29; p = 0,001), lo que indicó una mayor presión de contacto del catéter. Conclusiones. El daño valvular durante la ablación del istmo cavotricuspídeo puede ser más frecuente con el uso de alta energía y con catéteres de 8 mm e irrigados, pero también se puede producir con catéteres estándares y energías habituales. Para evitarlo, no se deben hacer aplicaciones en el interior del ventrículo derecho, justo encima de la válvula tricúspide (AU)