Symptoms Burden as a Clinical Outcomes Assessment in Heart Failure Patients With Atrial Fibrillation

Safe and effective pharmacologic therapy for atrial fibrillation (AF) in heart failure (HF) is an unmet need. In AF clinical trials, the standard primary endpoint of time to first symptomatic AF event (TTFSE) has several disadvantages, which could theoretically be overcome by measurement of AF-specific symptoms burden during an entire follow-up period.

The authors sought to develop and validate a method of measuring symptom burden of AF in a HF population.

The authors constructed a patient-reported outcome instrument (AFSQ [Atrial Fibrillation Symptoms Questionnaire]) to function in the setting of AF/HF, and used it to measure symptoms throughout long-term follow-up. The AFSQ queries the presence of 10 new or worsening symptoms, equally divided between those associated with AF or HF. In a 267 patient AF/HF trial comparing 2 AF prevention treatments, the AFSQ was linked to electrocardiography documented AF to form a 2-component clinical outcome assessment (SxB_AF) that was subjected to psychometric testing, anchor validation, and endpoint efficiency comparison to TTFSE.

SxB_AF exhibited greater efficiency than time to first symptomatic event for treatment difference detection, resulting in smaller projected clinical trial sample sizes. SxB_AF correlated well with device-detected AF burden (Spearman's ρ = 0.74; P < 0.0001), while permitting gradation in symptom severity. SxB_AF also identified treatment group differences in cardiovascular serious adverse events and AF interventions and in recent-onset AF provided specificity for AF- or worsening HF-associated symptoms (P < 0.001 for each).

Measurement of symptoms burden throughout clinical trial follow-up is feasible in AF/HF and should be useful for evaluating patient-centered outcomes in AF prevention trials. (Genetically Targeted Therapy for the Prevention of Symptomatic Atrial Fibrillation in Patients With Heart Failure [GENETIC-AF]; NCT01970501).