ARB therapy improves ablation outcome
NAGOYA, JAPAN. There is growing evidence that the renin-angiotensin system (RAS) is involved in the development and progression of atrial fibrillation (AF). Thus it is not surprising that angiotensin-converting enzyme inhibitors (ACE inhibitors) and angiotensin receptor blockers (ARBs) have received considerable attention as possible candidates for use in therapy aimed at preventing AF. Now Japanese researchers report that treatment with ACE inhibitors and/or ARBs helps prevent AF recurrence following pulmonary vein isolation (PVI) procedures.

Their retrospective study included 94 paroxysmal afibbers and 170 patients with persistent AF. The average age of the participants was 63 years, 74% were male, less than 5% had structural heart disease, but 42% had been diagnosed with hypertension. Prior to their PVI procedure, 76% were taking a class I antiarrhythmic (most likely propafenone or flecainide) and 33% were taking an ACE inhibitor or ARB to control blood pressure.

The study participants all underwent an anatomically-guided PVI procedure and a right atrial flutter ablation. After the procedure antiarrhythmic agents were prescribed for all patients to be taken for at least 3 months. They were discontinued at the 3-month mark if the left atrial diameter had decreased by more than 10% from the pre-procedure value (an indication of reverse structural remodeling).

Following the PVI the study participants were divided into 2 groups – group 1 (145 patients) was prescribed treatment with renin-angiotensin system blockers (ARBs: 129 patients, ACE inhibitors: 13 patients, both: 3 patients). The remaining 119 patients (group 2) received no renin-angiotensin system blockers (RAS-Bs). After an average 6.5 months of follow-up, AF had recurred in 13.8% of group 1 as compared to 26.1% in group 2. An assessment by Cox regression analysis showed that patients who had taken RAS-Bs after their PVI had a 59% reduced risk of recurrence. The beneficial effect of RAS-B therapy was only statistically significant after the first 3 months post-ablation. After these first 3 months the recurrence rate in the RAS-B group was 79% lower than in the group that had not taken RAS-Bs.

The Japanese researchers speculate that the antiarrhythmic properties of RAS-Bs may be due to their anti-inflammatory properties and their ability to decrease atrial wall stress, modulate atrial refractoriness, produce favourable changes in autonomic tone, stabilize electrolyte concentrations, and promote reverse structural remodeling of the left atrium. They suggest that their findings need confirmation in a larger, prospective, randomized study.

Ishikawa, K, Hirayama, H, et al. Renin-angiotensin system blocker use may be associated with suppression of atrial fibrillation recurrence after pulmonary vein isolation. PACE, Vol. 34, March 2011, pp. 296-303

Editor's comment: The finding that renin-angiotensin system blockers markedly reduces the recurrence of AF after a PVI procedure is welcome news indeed and certainly would seem to warrant a larger and longer-lasting trial to confirm it. Such a trial should however keep a careful watch on overall and cancer-specific mortality in the RAS-B group and the placebo group in view of a recently published meta-analysis suggesting that therapy with angiotensin receptor blockers may modestly increase the risk of cancer[1].
[1] Sipahi, I, Fang, JC, et al. Angiotensin-receptor blockade and risk of cancer: meta-analysis of randomised controlled trials. The Lancet Oncology, Vol. 11, July 2010, pp. 627-36