Masri, A

Abstract Background Transthyretin amyloid cardiomyopathy (ATTR-CM) has a specific pathophysiology, with myocardial stiffening and systolic dysfunction only in advanced stages. Objective To investigate the response to cardiac resynchronization therapy (CRT) in ATTR-CM compared to heart failure (HF). Methods In this multicenter, international study, patients with ATTR-CM receiving CRT (n=101) were matched to patients without amyloid CM by sex, age, and implantation type (CRT with vs. without defibrillator vs. conduction system pacing, upgrade vs. first implant). We evaluated changes in QRS duration and echocardiographic parameters following CRT implantation and at the most recent available assessments. The study endpoints were all-cause mortality alone or combined with HF hospitalization. Results Patients with ATTR-CM (median age 76 years [interquartile range 72-83], 98% male, LV ejection fraction (LVEF) 30% [26-33]) showed greater QRS shortening after CRT implantation (p=0.012), but not after a median of around 1 year (p=0.152). There were no significant differences in the absolute LVEF changes immediately after implantation (+7 units [+2/+10] vs. +3 [0/+9], p=0.124), or to the last echo (p=0.796), which was performed after 1.3 years in patients with ATTR-CM and 2.9 years in patients without amyloid CM. Patients with ATTR-CM had a shorter survival than controls (p<0.001 for both endpoint). Patients with ATTR-CM experiencing an early improvement in LVEF had a longer survival (log-rank 4.3, p=0.038). Conclusions Following CRT implantation, patients with ATTR-CM show early QRS narrowing and improvement in LVEF, consistent with non-amyloid patients. Early favourable LV remodelling seems to be associated with a lower risk of all-cause mortality.