Clinical course after cardiac resynchronization therapy in transthyretin amyloid cardiomyopathy receiving disease-modifying therapy

The clinical course of patients with transthyretin amyloid cardiomyopathy (ATTR-CM) undergoing cardiac resynchronization therapy (CRT) remains insufficiently characterized, particularly in the era of disease-modifying therapy (DMT). We aimed to describe the clinical, electrocardiographic, echocardiographic, and long-term outcomes of ATTR-CM patients treated with CRT while receiving tafamidis or patisiran. This single-center retrospective study included 12 patients with ATTR-CM who underwent CRT between March 2020 and May 2024. All patients received DMT. After CRT implantation, QRS duration significantly decreased (161.3 ± 18.6 vs. 134.3 ± 16.8 ms, P = 0.0003). Improvement in New York Heart Association functional class was observed, although it did not reach statistical significance (P = 0.063). Marked echocardiographic reverse remodeling, including reductions in end-systolic volume and improvement in left ventricular ejection fraction, was not observed; however, echocardiographic parameters remained largely stable during follow-up. During a mean follow-up of 800 ± 97 days, MACCE occurred in 2 of 12 patients (16.7%), both representing hospitalizations for heart failure. In this contemporary series of ATTR-CM patients receiving DMT, CRT was associated with QRS narrowing, while clinical and echocardiographic status remained largely stable during follow-up, despite limited evidence of reverse remodeling. Because the effects of CRT could not be disentangled from those of concomitant DMT, these findings should be interpreted as descriptive and hypothesis-generating. This study does not qualify as a clinical trial, and it is a retrospective analysis and not classified as an interventional investigation.