The beat goes on: Highlights from the new American and European A-fib guidelines

Guidance on anticoagulation

Both the American and European guidelines^3,4 recommend using the CHA₂DS₂-VASc score (1 point given for congestive heart failure, hypertension, age 65 to 74 years, ≥ 75 years [doubled], diabetes mellitus, prior stroke, transient ischemic attack, or thromboembolism [doubled], vascular disease, female sex) for thromboembolic risk assessment and warn against using currently available bleeding scores in isolation to determine eligibility for anticoagulation. However, the European guidelines⁴ discourage the use of sex to calculate the CHA₂DS₂-VASc score, seeing it as an age-related modifier and not a risk factor per se. Anticoagulation guidance for device-detected atrial high-rate episodes is appreciably more nuanced in the American guideline,³ with clear cut-offs for duration of atrial high-rate episodes and clear guidance on anti-coagulation management.

Treatment of life-threatening bleeds with specific antidotes for direct oral anticoagulants is designated a class 1 recommendation in the American guideline,³ whereas the European guidelines acknowledge the limited availability of these agents in some healthcare environments, giving their use a class 2a recommendation.⁴

Left atrial appendage occlusion

Campbell et al⁵ point out that the American guideline recommends that percutaneous placement of a left atrial appendage occlusion device is reasonable in patients experiencing atrial fibrillation with a moderate to high thromboembolic risk and contraindication to anticoagulation; this was upgraded to a class 2a recommendation owing to updated safety data on devices for left atrial appendage occlusion.³ This remains a 2b recommendation by the European guidelines, citing the lack of “solid” randomized controlled trial data and need for continued postprocedure antithrombotic treatment.⁴ Conversely, surgical left atrial appendage closure for all patients with atrial fibrillation undergoing cardiac surgery is recommended as an adjunct to oral anticoagulation to prevent ischemic stroke and thromboembolism,⁴ while the American guideline³ does not promote this technique for patients with a CHA₂DS₂-VASc score less than 2.

Catheter ablation

Catheter ablation with pulmonary vein isolation has a clear class 1 indication as first-line therapy when compared with antiarrhythmic drugs for select patients with paroxysmal and symptomatic atrial fibrillation who are younger and have fewer comorbidities.³ This upgrade in recommendation has been partially adopted by the European guidelines, which do not limit the procedure to a specific ablation method or to select groups and give it class 2a status. Only when atrial fibrillation is proven to cause symptoms or drive heart failure does catheter ablation receive a class 1b recommendation. Anticoagulation following catheter and surgical ablation is advocated for 3 months in the American guideline³ and at least 2 months in the European guidelines.⁴

Pharmacologic therapy

Further differences exist regarding pharmacologic treatment of atrial fibrillation. Unlike the European guidelines,⁴ the American guideline³ does not recommend first-line digoxin for the treatment of acute and long-term atrial fibrillation in patients with preserved left ventricular ejection fraction, owing to its slower treatment response and subsequent longer hospital stays compared with diltiazem.¹⁷

Dronedarone is mentioned by both guidelines^3,4 for maintenance of sinus rhythm. The European guidelines⁴ suggest using dronedarone for patients with heart failure with midrange and preserved ejection fraction and ischemic or valvular disease. The American guideline³ warns against its use in patients with risk factors for cardiovascular events and recent history of symptoms or hospitalization due to heart failure, noting the results of ANDROMEDA (Antiarrhythmic Trial With Dronedarone in Moderate to Severe CHF Evaluating Morbidity Decrease),¹⁸ which showed increased mortality in patients with severely symptomatic or recently decompensated heart failure.

Both American and European guidelines recommend that low-dose amiodarone is reasonable for long-term maintenance of sinus rhythm if other rhythm-control strategies are ineffective or contraindicated.^3,4 Further reversal of trigger factors and concomitant treatment of risk factors and comorbidities is encouraged as part of a complementary atrial fibrillation care pathway for patients with first-time atrial fibrillation.

Both cardiac and noncardiac surgery can trigger new-onset, incidental, acute, and recurrent atrial fibrillation, but evidence regarding preventive or therapeutic pharmacologic measures appears to be contradictory. The American guideline³ understandably argues that evidence on pretreatment of patients at high risk of atrial fibrillation is not clear due to mixed results in prior trials, with no clinical advantage seen between rate- and rhythm-control strategies in a randomized controlled trial of 2,109 patients looking at the length of hospitalization and rates of new-onset persistent atrial fibrillation after cardiac surgery.¹⁹

In comparison, the European guidelines⁴ introduced pretreatment with amiodarone (class 1) before cardiac surgery if prophylaxis is desired, owing to its ability to reduce the incidence of postoperative atrial fibrillation by 51% compared with placebo, with no difference in effect between pre- or postoperative initiation.²⁰ Conversely, pretreatment with beta-blockers is discouraged⁴ owing to a lack of efficacy prior to cardiac surgery and a recorded increase in mortality in noncardiac surgery, according to a review of 23 meta-analyses comprising 89 randomized controlled trials (19,211 patients).²¹

Guidance on treatment of postoperative atrial fibrillation is similar for both guidelines^3,4 and has not changed, with rhythm and rate control equally recommended, taking into account the hemodynamic status of the patient.

Both guidelines^3,4 note that atrial fibrillation that occurs both during and after surgery has an up to 50% risk of recurrence, putting patients at high risk of stroke, heart failure, and mortality, thereby necessitating an upgrade in recommendations regarding long-term anticoagulation (class 2a). The American guideline recommends initial treatment for 60 to 90 days followed by reassessment of thromboembolic risk and rate-control strategy at 90 days, with the possibility of lifelong anticoagulation. This is mirrored in the European guidelines.

Concomitant posterior left pericardiotomy during cardiac surgery reduces pericardial effusion post-operatively and decreases risk of postoperative atrial fibrillation (odds ratio 0.49, 95% confidence interval 0.38–0.61),²² which is similar to the reductions seen with treatment with amiodarone but without the adverse effects.

Guideline writing process

The American guideline³ was written by the ACC- and AHA-appointed Joint Committee on Clinical Practice Guidelines, which summarizes the evidence and formulates the recommendations that are then peer reviewed, approved by the governing bodies of the ACC and AHA, and endorsed by the ACCP and HRS. European guidelines are written by consensus of an appointed clinical practice guidelines committee after all evidence is reviewed.²³ Patient-reported outcomes and experiences are also measured and evaluated. The guidelines are reviewed by all national cardiac societies, at which time revisions can be incorporated.

Considerations regarding cost-effectiveness of treatment of atrial fibrillation also differ between committees. Local multidisciplinary teams evaluate cost efficiencies for the European guidelines owing to the vast differences in healthcare provision in Europe.⁴ The American guideline,³ on the other hand, acknowledges that affordability is limited for some patients in the United States due to lack of healthcare insurance and no national consensus on cost-effectiveness.²⁴ They advise taking affordability into account when recommending treatment options such as warfarin in non-valvular atrial fibrillation if direct oral anticoagulants are unaffordable for the individual.³ These differences in procedure might explain some weighting differences in the recommendations between societies.