Highlights
- Vutrisiran therapy leads to significant improvements in biventricular systolic function and reductions in left ventricular mass in patients with transthyretin amyloid cardiomyopathy (ATTR-CM).
- Cardiovascular magnetic resonance (CMR) imaging with extracellular volume (ECV) mapping enables sensitive, noninvasive tracking of cardiac amyloid burden and treatment-related regression.
- Post hoc analysis of the UK HELIOS-B cohort demonstrates that vutrisiran associates with amyloid regression in a subset of patients and markedly reduces amyloid progression compared to placebo over three years.
- Echocardiographic secondary outcomes corroborate structural and functional cardiac benefits, underscoring vutrisiran’s impact on clinical outcomes.
Background
Transthyretin amyloid cardiomyopathy (ATTR-CM) represents a progressive infiltrative cardiomyopathy characterized by extracellular deposition of transthyretin amyloid fibrils in the myocardium. This deposition disrupts myocardial architecture and impairs cardiac function, resulting in morbidity and mortality among predominantly elderly populations. The pathogenic cascade centers on hepatic production of transthyretin (TTR), with destabilized TTR variants aggregating into amyloid fibrils. Existing therapeutic strategies target TTR stabilization, TTR gene silencing, or amyloid fibril clearance.
Vutrisiran, a subcutaneously administered RNA interference (RNAi) agent, selectively suppresses hepatic TTR synthesis, thereby reducing circulating TTR levels and downstream amyloid deposition. The pivotal HELIOS-B phase 3 trial established vutrisiran’s efficacy in reducing all-cause mortality and cardiovascular events in ATTR-CM patients. Accurate assessment of myocardial amyloid burden and associated cardiac remodeling is crucial for monitoring therapeutic effects.
Multiparametric cardiovascular magnetic resonance (CMR) imaging provides high-fidelity evaluation of cardiac morphology, volumetrics, systolic and diastolic function, and tissue characterization. Of particular interest, extracellular volume (ECV) quantification via T1 mapping reflects myocardial amyloid infiltration, enabling serial noninvasive assessment of amyloid burden.
Key Content
1. Vutrisiran Effects on Cardiac Structure and Function Assessed by Cardiovascular MRI
Razvi et al. (2026) conducted a retrospective post hoc single-center analysis of CMR data from 43 UK patients enrolled in the HELIOS-B trial who underwent imaging at baseline and up to 3 years. Participants were mostly elderly males (mean age 75 years, 95.3% male) with ATTR-CM; 21 received vutrisiran and 22 placebo.
Key CMR findings included:
- A robust and statistically significant increase in left ventricular ejection fraction (LVEF) with a least-squares mean difference of 19.18% favoring vutrisiran over placebo (95% CI 11.76%-26.60%, P < .001).
- Improvement in right ventricular ejection fraction by 16.28% (95% CI 9.58%-22.97%, P < .001).
- Increased biventricular stroke volumes, with left ventricular stroke volume rising by 27.82 mL (95% CI 13.40-42.23 mL, P < .001) and right ventricular stroke volume by 23.69 mL (95% CI 8.06-39.32 mL, P = .003).
- Reduction in left ventricular mass by 23.58 g (95% CI -38.78 to -8.39 g, P = .002), suggestive of decreased amyloid infiltration and remodeling.
- A significant decrease in myocardial extracellular volume (ECV) by 6.56% (95% CI -10.10% to -3.01%, P < .001), indicating reduced amyloid burden.
At 36 months, amyloid regression (defined as ≥5% absolute reduction in ECV) occurred in 22% of vutrisiran-treated patients compared with none in placebo, while 63% of placebo patients exhibited progression versus only 11% in the vutrisiran group.
Sensitivity analyses confirmed these findings, and no participants received background tafamidis, isolating vutrisiran’s effect.
2. Supporting Evidence from Echocardiographic Studies in HELIOS-B
Two complementary secondary analyses of the larger HELIOS-B trial echocardiographic data (n=~650) provide mechanistic and clinical corroboration:
– Nat Med (2025, PMID: 40770082) demonstrated at 30 months that vutrisiran attenuated increases in left ventricular (LV) wall thickness and LV mass index, minimized declines in LVEF and global longitudinal strain, and improved diastolic flow parameters compared with placebo, indicating favorable reversal or stabilization of pathological remodeling.
– J Am Coll Cardiol (2025, PMID: 40769673) found that baseline biventricular systolic and diastolic echocardiographic parameters predicted clinical outcomes. Vutrisiran treatment attenuated progressive declines in LV and right ventricular systolic function at 18 months. Changes in cardiac function correlated with clinical endpoints, suggesting that vutrisiran’s cardiac functional improvements underlie better morbidity and mortality profiles.
3. Methodological and Translational Insights
The integration of multiparametric CMR imaging and echocardiography allows comprehensive evaluation of the cardiac amyloid burden and functional status. CMR-derived ECV is a sensitive biomarker of amyloid infiltration, enabling detection of disease progression or regression over time and therapeutic response. Vutrisiran’s RNAi mechanism effectively reduces systemic TTR supply, consequentially decreasing myocardial amyloid deposition. The observed reductions in LV mass and ECV align with histopathological evidence of amyloid clearance or halted fibril accumulation.
Functionally, improvements in biventricular ejection fractions and stroke volumes indicate myocardial recovery and improved hemodynamic performance, which translate to better clinical outcomes.
Expert Commentary
Vutrisiran offers a novel targeted intervention that modifies the pathogenic substrate of ATTR-CM by silencing hepatic TTR production. This contrasts with TTR stabilizers like tafamidis that prevent further misfolding but do not reduce existing amyloid burden. In the selected cohort analyzed by Razvi et al., the demonstration of amyloid regression by CMR is particularly compelling, signifying disease modification rather than mere stabilization.
This evidence corroborates and extends the primary HELIOS-B clinical results, with multiparametric CMR providing detailed insights into structure-function relationships. The significant improvements in biventricular function highlight the importance of comprehensive assessment beyond LVEF alone.
However, limitations include the relatively small, single-center cohort for CMR analysis and a predominance of male patients, potentially limiting generalizability. Longer follow-up and real-world studies will be essential to confirm durability and safety.
Furthermore, no patients received concomitant tafamidis, which limits understanding of combinatorial therapy effects. Current guidelines do not yet incorporate RNAi therapeutics, but these emerging data warrant updates emphasizing precision imaging-guided management.
Future research should focus on combining RNAi agents with amyloid clearance approaches, exploring predictors of response, and expanding investigations into early-stage and hereditary ATTR-CM.
Conclusion
Accumulating evidence from the HELIOS-B trial and its detailed imaging sub-analyses establishes vutrisiran as an effective RNA interference therapy for transthyretin amyloid cardiomyopathy. Multiparametric cardiovascular MRI, particularly ECV mapping, reveals that vutrisiran treatment significantly improves cardiac structure and function and is associated with amyloid regression in a subset of patients. Echocardiographic data complement these findings, associating functional cardiac improvements with superior clinical outcomes.
These data signify a substantial advance in amyloidosis management, shifting the therapeutic paradigm from stabilization to active disease modification. Careful integration of RNAi therapies and advanced cardiac imaging in clinical practice may optimize patient outcomes and guide personalized treatment strategies.
References
- Razvi Y, Sheikh A, Patel RK, et al. Vutrisiran Treatment and Changes in Cardiac Parameters and Amyloid Burden Assessed by Cardiovascular MRI. JAMA Cardiol. 2026 Aug 12. PMID: 42584913. https://pubmed.ncbi.nlm.nih.gov/42584913/
- Martinez-Naharro A, Hawkins PN, Fontana M. Effects of vutrisiran on cardiac structure and function in patients with transthyretin amyloidosis with cardiomyopathy: secondary outcomes of the HELIOS-B trial. Nat Med. 2025 Oct;31(10):3560-3568. PMID: 40770082. https://pubmed.ncbi.nlm.nih.gov/40770082/
- Patel RK, Solomon SD, Gillmore JD, et al. Effects of Vutrisiran on Cardiac Function and Outcomes in Patients With Transthyretin Amyloidosis With Cardiomyopathy. J Am Coll Cardiol. 2025 Aug 12;86(6):444-455. PMID: 40769673. https://pubmed.ncbi.nlm.nih.gov/40769673/
