Abstract 15165: Routine Ambulatory Heart Rhythm Monitoring in Patients With Transthyretin Cardiac Amyloidosis

Abstract

Introduction: Atrial fibrillation and flutter (AF/AFL) are common with transthyretin cardiac amyloidosis (ATTR-CM). These patients have higher risk for thromboembolism. Detection of AF/AFL may thus be especially important, but the role of routine ambulatory monitoring in asymptomatic patients is unclear. Methods: A single center observational study of patients seen at our Amyloidosis Center with wild-type or hereditary ATTR-CM diagnosed between 2005-2019. Records were reviewed to see if AF/AFL was present at baseline. In those without known AF/AFL, ambulatory monitor (duration 2-30 days) was done every 6 months when feasible as part of our routine practice. Patients with cardiovascular implantable electronic devices (CIED) instead had routine device interrogations. Results: Ninety-four patients with ATTR-CM (mean age 71.4±11.4 years, 88.3% male) had mean follow-up 2.2±1.9 years (200 patient-years). AF/AFL was seen in 62 patients (66.0%): 35 (56.5%) by symptoms, 18 (29.0%) incidentally by monitor or CIED, and 9 in whom method of AF/AFL diagnosis was unknown. Forty-one patients (66.1%) had AF/AFL before ATTR-CM diagnosis by of median 26.3 (IQR 4.3-40.9) months. New AF/AFL was diagnosed in 21/53 remaining patients with known ATTR-CM - 11 (52.4%) were incidentally diagnosed (Figure 1). Median time between ATTR-CM and AF/AFL diagnoses was 10.3 (IQR 7.0-25.8) months and 5.9 (IQR 2.2-22.3) months in symptomatic versus incidentally diagnosed patients (Mann-Whitney U=35, p=0.14). Anticoagulation (AC) was started in 9/11 (81.8%) due to incidental AF/AFL. One patient had AC for prior DVT; the other had no AC per patient preference. No strokes occurred in patients on AC. Conclusions: We found a high rate of incidentally diagnosed AF/AFL in patients with ATTR-CM. Detection of AF/AFL led to change in therapy. This finding affirms a need for routine ambulatory monitoring in asymptomatic patients with ATTR-CM. Optimal duration of monitoring needs further investigation.