Transthyretin Cardiac Amyloidosis Stage and Atrial Fibrillation Prevalence and Control

Atrial fibrillation (AF) was found to be more prevalent as transthyretin cardiac amyloidosis (ATTR-CA) progressed, however, rhythm controlling strategies for AF became less effective with disease progression, according to a retrospective cohort study published in the American Journal of the College of Cardiology: Clinical Electrophysiology.

In this study, the data of 382 patients diagnosed with ATTR-CA at the Cleveland Clinic between 2004 and 2018 were examined. Patients were stratified according to ATTR-CA stage. Stage 1: estimated glomerular filtration rate (eGFR) ≥45 ml/min and N-terminal pro-B-type natriuretic peptide (NTproBNP) ≤3000 ng/L; stage 3: eGFR <45 ml/min and NTproBNP >3000 ng/L; all other patients were classified as stage 2. All patients with AF were treated with rhythm controlling methods to maintain a normal sinus rhythm (NSR).

ATTR-CA was diagnosed using biopsy (72%) or nonbiopsy (28%) criteria. Of the 69% of patients with AF, 27% had persistent AF, 15% had longstanding persistent AF, and 13% had permanent AF. The median time to AF after ATTR-CA diagnosis was 15 months (interquartile range [IQR], 4-36 months). Patients with vs without AF were significantly older (78±9 years vs 73±11 years, respectively; P <.001) and had larger left atrial diameter (4.7±0.7 cm vs 4.4±0.8 cm, respectively; P =.002).

The most common treatment for AF was direct-current cardioversion (DCCV; 45%), followed by antiarrhythmic therapy (AAT; 35%), and AF ablation (5%).

Following DCCV, 97%, 95%, and 92% of patients with stage 1, 2, and 3, respectively achieved NSR. At the 30-day follow-up, patients with advanced disease did not maintain NSR (stage 1: 90%; stage 2: 60%; stage 3: 33%; P <.0001). After 1 year, NSR was observed in 41% of the cohort.

Patients with vs without AF were more likely to be prescribed beta-blockers (39% vs 26%, respectively; P =.02). After initiating ATT, 75%, 46%, and 26% of patients prescribed sotalol, dofetilide, and amiodarone, respectively, had maintained NSR. A greater percentage of patients prescribed amiodarone had stage 3 disease (45%) than those prescribed sotalol (25%) or dofetilide (8%).

At 40 months after ablation, recurrent arrhythmia was observed in 36% of patients with stage 1 or 2, and in 90% of patients with stage 3 ATTR-CA (P =.005).

After a mean follow-up of 35±28 months, 60% of the patients had died. A greater percentage of patients who died had stage 3 disease (89%) compared with stage 1 (16%) and stage 2 (64%; P <.0001).

Study limitations include the fact that more patients (35%) with AF had an implantable cardiac device compared with patients without AF (9%), which may have led to an underestimation of the rates of AF.

“Rhythm control strategies appear to be substantially more effective when used earlier in the disease course and earl diagnosis of AF may be beneficial. In the coming years, further studies will be needed to assess incidence and prevalence of AF in the tafamidis era, in addition to the efficacy of rhythm control strategies when used concomitantly,” noted the study authors.

Reference

Donnellan E, Wazni O M, Hanna M, et al. Atrial fibrillation in transthyretin cardiac amyloidosis. Predictors, prevalence, and efficacy of rhythm control strategies. [Published online July 29, 2020] JACC Clin Electrophysiol. doi:10.1016/j.jacep.2020.04.019