BACKGROUND : The tolerability and utility of combination doxycycline and ursodeoxycholic acid (ursodiol) amyloid fibril disruption therapy for transthyretin cardiac amyloidosis (ATTR CA) in clinical practice is poorly described. RESULTS : We report the clinical experience of 53 ATTR CA patients treated with doxycycline and ursodiol. Six patients (11%) did not tolerate the therapy owing to dermatologic and gastrointestinal effects. Of those remaining, the median follow-up was 22 months (range 8-30), mean age was 71 ± 11years, 41 (87%) were male, and 42 (89%) had wild-type and 5 (11%) mutant ATTR. Five patients (11%) died during follow-up. There was no significant change in New York Heart Association (NYHA) functional class, cardiac biomarkers, or echocardiographic parameters during follow-up. Left ventricular (LV) global longitudinal systolic strain (GLS) improved in 16 patients (38%) (-12 ± 4% to -17 ± 4%; P < .01). Patients whose LV GLS improved were significantly younger and had lower NYHA functional class, troponin-T, N-terminal pro-B-type natriuretic peptide (BNP), and baseline LV GLS levels compared with those whose LV GLS did not improve. Troponin-T improved in follow-up for patients whose LV GLS improved (35 ± 21 to 20 ± 14 ng/L; P = .06). CONCLUSIONS : Doxycycline and ursodiol therapy for treatment of ATTR CA was tolerable and was associated with stabilized markers of disease progression. LV GLS improved in patients with less advanced disease.