Visual assessment of relative apical sparing pattern is more useful than quantitative assessment for diagnosing cardiac amyloidosis in borderline or mildly increased left ventricular wall thickness

Background: Relative apical sparing pattern of longitudinal strain (RapSP-LS) was suggested in advanced cardiac amyloidosis (CA). It is unclear whether it is present in less advanced CA. Methods and Results: Patients with presumptive diagnosis of CA and mean left ventricular wall thickness (LVWT) ≤14 mm were recruited. Apart from RapSP-LS visually identified, relative apical longitudinal strain index (RapLSI) was defined as [average apical LS/(average basal LS+average mid-ventricle LS)]. Among 119 patients included, 47 were finally diagnosed with CA. RapLSI was higher in the CA group compared to other causes of increased mean LVWT (P<0.001), but with a significant range of overlap noted. In contrast, RapSP-LS visually assessed was noted in most CA patients (31/47, 66.0%) except in those with preserved LV ejection fraction, normal LVWT, and mildly decreased global LS, suggesting least advanced CA. On multivariate analysis of the added diagnostic role of RapSPLS or RapLSI on top of clinical, electrocardiographic, and conventional echocardiographic parameters, addition of RapLSI produced only borderline increase in area under the curve of the multivariate model (P=0.05), whereas addition of RapSP-LS significantly increased it (P<0.001). Conclusions: Visual identification of RapSP-LS is useful in terms of added diagnostic value compared with quantitative calculation of RapLSI. Its clinical application, however, should be used with caution in patients with less advanced CA.