Design: Secondary analysis of a randomised, placebo-controlled trial (HELIOS-B)
Population: 654 patients with transthyretin amyloid cardiomyopathy
Primary outcome: All-cause mortality and recurrent cardiovascular events by concomitant therapy
Effect: No effect modification by tafamidis (P-interaction 0.95) or any HF drug class (0.59–0.92)

HELIOS-B randomised 654 patients with transthyretin amyloid cardiomyopathy to vutrisiran or placebo and showed fewer deaths and recurrent cardiovascular events. This secondary analysis, published in August, asked whether other treatments changed that effect.

At baseline 40% were on tafamidis and 77% on at least one heart failure drug. Mineralocorticoid receptor antagonists and SGLT2 inhibitors were the drugs most often started during follow-up, more so in the placebo group. There was no evidence that tafamidis, SGLT2 inhibitors, MRAs, beta-blockers or renin-angiotensin blockers modified vutrisiran's effect (all interaction P values 0.59–0.95).

For clinics already using tafamidis, this suggests the two approaches are not obviously redundant — though the trial was not designed to test the combination head to head.

Vutrisiran's effect in HELIOS-B was consistent with or without background tafamidis.
Heart failure drugs — including SGLT2 inhibitors and MRAs — did not blunt the benefit.
The placebo group started more heart failure drugs, suggesting vutrisiran slowed the need for them.
Combination treatment is still an open question; this analysis was not designed to prove additive benefit.

Why it matters

It speaks to a real decision in amyloid clinics: whether a patient on a stabiliser still gains from adding a silencer.

The statistics, in plain English

An interaction P value tests whether the treatment effect differs between groups; values from 0.59 to 0.95 mean no sign of a difference. That is not the same as proving the effect is identical — subgroups are smaller and have less power.