In a large French study of people with a heart disease called wild‑type transthyretin amyloid cardiomyopathy (ATTRwt‑CM), only 16% were women. Women tended to have a slightly better heart pumping ability but a thinner heart wall, and they were three times more likely to die suddenly than men. The study suggests that using a lower cut‑off for heart wall thickness could help diagnose more women earlier.

We explored sex differences in wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) and determined survival and prognostic factors. In a retrospective cohort study at a reference centre in France from 1 January 2008 to 31 December 2022, multiple regression analyses, supervised clustering, Cox models, and a Kaplan-Meier analysis were used to compare women and men in each age quartile (Q1: &#x2264;77&#x2009;years; Q2: 78-82; Q3: 83-86; Q4&#x2009;&gt;&#x2009;86). We included 1062 patients with ATTRwt-CM (180 women, 16%). The women had a higher median [IQR] left ventricular ejection fraction (LVEF; 52% [45-60] vs. 50 [43-58] in men) and a thinner interventricular septum. 12% of women and 4.1% of men had a septum thickness &lt;12&#x2009;mm (<i>p</i>&#x2009;=&#x2009;0.004). The women in Q1 had lower LVEF and global longitudinal strain values and a higher prevalence of a septum &lt;12&#x2009;mm (15.8%, vs 2.0% in men) than men and older women (Q2-Q3-Q4). Women had a greater risk of sudden death than men (13.8% vs. 4.6%, respectively; odds ratio [95% confidence interval]: 3.24 [1.56-6.64]; <i>p</i>&#x2009;=&#x2009;0.001). In women, the ATTRwt-CM phenotype and prognosis are related to age at diagnosis. Decreasing the septum thickness cut-off would increase the frequency of ATTR-CM diagnosis in women.