The scan that finds it is quick, safe, and has been around for years. Almost no cardiologist used it until a drug gave them a reason to look.
A non-invasive scan could spot ATTR cardiac amyloidosis, a common, deadly, long-overlooked cause of heart failure in the elderly, years before doctors used it. Diagnoses only surged after tafamidis (Vyndaqel) was approved for the heart in 2019. The treatment didn't create the disease; it created the diagnosis. The backstory, the economics, and why it matters.
Alnylam's two siRNA drugs hit the same liver target. One failed an FDA review in 2023. Two years later the other was approved for both forms of ATTR amyloidosis. The mechanism didn't change. The trial design did.
In September 2023 an FDA advisory committee voted 9-3 that patisiran's benefit supported approval for cardiac ATTR amyloidosis. The FDA rejected it anyway. Eighteen months later it approved vutrisiran — a near-identical Alnylam siRNA against the same liver target — for both forms of ATTR at once. Patisiran's APOLLO-B was 360 patients, 12 months, a six-minute-walk endpoint (+14.7 m, p=0.0162) with a secondary composite that missed at a win ratio of 1.27. Vutrisiran's HELIOS-B was 655 patients, up to 36 months, a hard mortality-plus-CV-events composite cut by 28%. Same mechanism, opposite verdicts — the molecule never changed, the trial did.
