Background: Signs of cardiac transthyretin (TTR) amyloidosis (ATTR) in patients with echocardiographic increase in interventricular septal thickness (IVST) are lacking.
Objectives: To identify clinical and ECG/echocardiographic signs associated with increased IVST in ATTR.
Methods: Analysis of patients with baseline echocardiography in the Transthyretin Amyloidosis Outcomes Survey (THAOS) registry (N=1682). Patients were categorised into IVST classes according to the American Society of Echocardiography classification adapted to gender (ie, normal, mild, moderate, severe); then into two combined IVST classes (normal-mild and moderate-severe).
Results: 425 patients were included: 336 with a TTR mutation (m-TTR) and 89 with wild-type TTR (WT-TTR). 72% were men. Median (25th, 75th centile) age was 62 (45, 72) years. Non-Val30Met and WT-TTR were frequent in moderate (41% and 35%) and severe (50% and 33%) IVST classes. Median IVST was 15 mm (14, 16) (moderate) and 20 mm (18, 22) (severe). In the combined moderate-severe class, 85% of patients were ≥55 years of age; 81% were men; 86% had blood pressure <140 mm Hg; and 77% had increased right ventricle thickness (≥7 mm). Up to 66% of patients had cardiac sparkling. Systolic dysfunction (left ventricular ejection fraction <50%), restrictive pattern and low voltage were less frequent, and observed in 49%, 18% and 33% of patients, respectively.
Conclusions: Increased IVST, especially in men ≥55 years with normal systolic blood pressure, increase in right ventricle free wall and valve thicknesses, and sparkling, should alert practitioners to the possibility of ATTR. Absence of restrictive pattern and low voltage should not rule out the suspicion.
Trial registration number: NCT00628745 (clinicaltrials.gov).