Aims: Echocardiography plays an important role in suspecting the presence of transthyretin cardiomyopathy (ATTR-CM) in patients with heart failure, based on parameters proposed as ‘red flags’ for the diagnosis of ATTR-CM. We aimed to validate those measurements in a group of patients with ATTR-CM including ATTRv and ATTRwt.
Methods and results: We tested a number of echocardiographic red flags in 118 patients with confirmed diagnosis of ATTR-CM. These variables were validated against healthy controls and patients with heart failure with left ventricular hypertrophy (LVH) but not ATTR-CM. The red flag measures outside the proposed cut-off values were also revalidated. In ATTR-CM, all conventional echocardiographic parameters were significantly abnormal compared with controls. Comparing ATTR-CM and LVH, LV wall thickness, LV diameter, E velocity, and relative apical sparing (RELAPS) were all different. Eighty-three per cent of ATTR-CM patients had RELAPS > 1.0, 73% had relative wall thickness (RWT) > 0.6, 72% had LVEF > 50%, 24% had global longitudinal strain (GLS) > −13%, 33% had LVEF/GLS > 4, and 54% had increased left atrial volume index (>34 mL/m2). Forty per cent of ATTR-CM patients had stroke volume index < 30 mL/m2 and 52% had cardiac index < 2.5 L/min/m2. RELAPS, LVEF, and RWT, in order of accuracy, were the three best measures for the presence ATTR-CM in the patient cohort, who all had thick myocardium. The concomitant presence of the three disturbances was found in only 50% but the combination of RELAPS > 1.0 and RWT > 0.6 was found in 72% of the patient cohort.
Conclusion: Increased relative apical sparing proved the most accurate independent marker of the presence of ATTR-CM followed by normal LV ejection fraction and then increased relative wall thickness. The other proposed red flags for diagnosing ATTR-CM did not feature as reliable disease predictors.