Hereditary transthyretin cardiac amyloidosis (mTTR-CA) is a hypertrophic cardiomyopathy with challenging diagnosis and poor prognosis. The prevalence of m-TTR in patients with increased left ventricular wall thickness (LVWT) is unknown.

Prospective and consecutive multicenter study with systematic genetic screening for mTTR in adult patients with LVWT≥15mm included in cardiology primary clinics.

298 patients were genotyped of whom 23% were African descendant. The median (IQR) age was 62(50,74), 74% were men and 36% were in NYHA class III-IV. The median of maximal LV thickness was 18 (16, 21)mm.17 patients had TTR mutation (5.7%) of whom 15 (5.0) had confirmed mTTR-CA. All the mTTR-CA were≥55years meaning that the prevalence of mTTR-CA was 8.3% above this age. Of the 15 with mTTR-CA, 8 were Africans and 6 Caucasians. In Africans≥55 years, the prevalence was 22% and reached 35% in those over 65 years. The most frequent mutations were V142I (8), V50M (2) and I127V (2).

When adjusted to age, neuropathy (OR=20.1; 95%-CI, 5.86-69.4; P<0.001), carpal tunnel syndrome (OR=15.31; 95%-CI, 4.32-54.3; P<0.001), ECG low voltage (OR=8.8; 95%-CI, 2.67-29.1; P<0.001), symmetric hyper-trophy (OR=10.9; 95%-CI, 1.97-59.8; P=0.006), LVEF impairment (OR=10.9; 95%-CI, 1.62-15.5; P=0.005), and late gadolinium enhancement at MRI (OR=42.9; 95%-CI, 2.38-772; P=0.011) were all associated with increased odds of CA.

Conclusions mTTR-CA is frequent in HCM, particularly in African descendant and patients≥55 years. mTTR genetic screening may be warranted for patients with increased LVWT, especially with neuropathy or carpal tunnel syndrome or LGE at MRI.