The Limits of Traditional AFib Prediction Models in ATTR-CA

In transthyretin cardiac amyloidosis (ATTR-CA), atrial fibrillation often progresses alongside underlying infiltrative cardiomyopathy. In a recent study, Chan and colleagues provided a detailed look at how frequently atrial fibrillation and flutter occur in ATTR-CA, which patients are most vulnerable, and whether disease-modifying therapy alters that trajectory.

In this retrospective observational cohort of 419 patients, 58% already had atrial fibrillation or flutter at presentation. Among patients initially free of arrhythmia, another 41% developed incident AF during follow-up. By the end of observation, roughly 3/4 of the cohort had experienced AF, reinforcing that rhythm disturbance is embedded within the natural history of ATTR-CA rather than an isolated complication.

Why Conventional Risk Models Fall Short

One of the study’s clearest findings was the limited usefulness of traditional AF prediction frameworks in amyloidosis. The CHARGE-AF score, commonly used in broader cardiovascular populations, did not predict incident AF in this cohort. Instead, arrhythmic risk tracked more closely with ATTR disease severity itself.

The Columbia staging system emerged as the strongest clinical predictor. Each point increase in Columbia score was associated with 48% higher odds of prevalent AF and an 18% higher risk of developing new-onset AF during follow-up. Patients with AF also demonstrated more advanced NYHA functional limitation, higher natriuretic peptide levels, worse renal function, and greater diuretic requirements, suggesting that worsening systemic and cardiac burden parallels atrial instability.

The findings reinforce a recurring challenge in cardiac amyloidosis: conventional cardiovascular risk models often underestimate the physiologic consequences of infiltrative disease. ATTR-CA produces atrial remodeling, fibrosis, and mechanical dysfunction that are not fully captured by standard AF prediction tools.

Atrial Remodeling Beyond Chamber Size

Patients with prevalent AF had significantly larger left atrial volume indices than those without AF. Yet atrial size alone became less informative when predicting future arrhythmia.

That distinction suggests that atrial dysfunction in ATTR-CA may reflect infiltrative and electromechanical abnormalities beyond structural enlargement alone, as left atrial size was associated with prevalent AF but less predictive of incident AF.

The study also aligns with prior observations that amyloid-related atrial disease contributes to thromboembolic risk. Surveillance strategies based solely on symptoms or intermittent ECG assessment may therefore underestimate clinically important arrhythmia.

Tafamidis and Arrhythmic Progression

Among the study’s more clinically relevant observations was the association between tafamidis therapy and lower incident AF risk. After multivariable adjustment, tafamidis use was associated with an estimated 46% reduction in new-onset AF.

Because the analysis was retrospective, the findings should be interpreted cautiously. Tafamidis exposure was not modeled as a time-varying variable, and residual confounding remains possible. Still, the signal is biologically plausible. Prior imaging studies have shown slower deterioration in ventricular strain, atrial mechanics, and extracellular volume among treated patients. Reduced progression of infiltrative remodeling could reasonably translate into lower arrhythmic burden over time.

The findings also complement prior ATTR-ACT observations showing numerically fewer stroke and arrhythmia hospitalizations among tafamidis-treated patients, even though event counts were relatively small.

Genotype Differences and Clinical Implications

Hereditary ATTR was associated with significantly lower rates of both prevalent and incident AF compared with wild-type disease. The authors note that demographic differences may partially explain this observation, as the hereditary cohort was younger and more racially diverse. Broader epidemiologic studies have consistently shown lower clinically detected AF prevalence among Black patients, complicating direct biologic interpretation.

Even with those caveats, the study highlights how heterogeneous ATTR populations can be with respect to rhythm risk. Disease stage, phenotype, and treatment exposure all appear to influence arrhythmic progression.

For practicing clinicians, the practical implication is straightforward: AF surveillance in ATTR-CA likely requires a lower threshold and greater longitudinal vigilance than standard heart failure populations. As ATTR-CA becomes increasingly recognized and survival improves with disease-modifying therapy, long-term morbidity may depend as much on managing atrial disease as on treating ventricular dysfunction itself.

Reference:
Chan N, Brailovsky Y, Teruya S, et al. Atrial Fibrillation/Flutter in Transthyretin Cardiac Amyloidosis: Prevalence, Incidence, Clinical Predictors, and Effect of Tafamidis. JACC Adv. 2026;5(2):102470. doi:10.1016/j.jacadv.2025.102470