In patients with transthyretin amyloid cardiomyopathy (ATTR-CM), treatment with vutrisiran is associated with favorable changes in cardiovascular magnetic resonance (CMR) parameters related to cardiac structure, function and amyloid burden, according to a retrospective post hoc analysis of the HELIOS-B trial published Aug. 12 in JAMA Cardiology.

Yousuf Razvi, MBChB, BSc, et al., included 43 participants (mean age 75 years, 95% male) who underwent baseline CMR imaging: 39, 26 and 17 patients underwent one-, two- and three-year CMR imaging, respectively. CMR parameters of cardiac structure, volumetrics, function and amyloid burden were considered. The authors defined amyloid regression and progression as absolute reductions and increases in extracellular volume (ECV) of 5% or more.

CMR parameters at baseline were comparable for those in the treatment vs. placebo groups. Patients in the treatment group saw favorable changes in biventricular ejection fractions (LVEF least-squares mean difference, 19%; 95% CI, 12-27%; p<0.001; right ventricular (RV) EF, 16%; 95% CI, 10-23%; p<0.001) and stroke volumes (LV stroke volume, 27.82 mL; 95% CI, 13.4-42.23 mL; p<0.001; right ventricular stroke volume, 23.69 mL; 95% CI, 8.06-39.32 mL; p=0.003). Vutrisiran was also associated with reductions in LV mass (−23.58 g; 95% CI, −38.78 to −8.39 g; p=0.002) and ECV (−6.56%; 95% CI, −10.10% to −3.01%; p<0.001).

At the three-year follow-up, 22% of patients taking vutrisiran exhibited amyloid regression. No patients receiving placebo experienced regression. Meanwhile, 63% of patients in the placebo group saw amyloid progression vs. 11% in the vutrisiran group.

"Although echocardiographic analyses in the HELIOS-B trial have generally indicated attenuation of disease progression with vutrisiran, the greater precision of CMR imaging in this selected cohort provides preliminary potential insights into changes in myocardial structure and function in patients receiving vutrisiran," write the authors. "The observation of amyloid regression in a subset of patients who received vutrisiran...supports the hypothesis that effective, sustained suppression of TTR production can shift equilibrium between amyloidogenesis and clearance, permitting disease modification and net reduction in myocardial amyloid."