Incremental benefits of echocardiographic indices over clinical parameters for screening cardiac amyloidosis in patients with left ventricular hypertrophy

Abstract

Abstract Background Cardiac amyloidosis (CA), characterized by amyloid protein deposition in the heart, is a treatable disease. Although left ventricular (LV) wall thickness is the most established imaging predictor for CA, several echocardiographic indices including deformation parameters also contribute to the screening of CA. However, it is unclear whether additive values of echocardiographic indices have greater benefit over the conventional clinical predictors for the screening of CA. Therefore, we sought to compare the incremental benefits of echocardiographic indices over the clinical parameters for the screening of CA and externally validate their incremental benefits. Methods We retrospectively studied 295 consecutive patients (median age, 67 years; male, 65%; mean LV wall thickness (MWT), 12 mm) with LV hypertrophy who underwent echocardiography as well as the detailed work-up for myocardium (Biopsy, technetium pyrophosphate scintigraphy (99mTc-PYP) or cardiac magnetic resonance imaging). CA was diagnosed through biopsy or 99mTc-PYP. The clinical model considers patients' age and the low-voltage in electrocardiography in reference to previous studies. Continuous echocardiographic variables were represented in binary through generally accepted external cutoff points. The incremental benefits of the echocardiography findings over the clinical model were assessed using with the help of both receiver-operated characteristic curve analysis and comparison of area under the curves. Furthermore, these incremental benefits were validated in the external validation sample (median age, 70 years; male, 69%; MWT, 12 mm). Results Among the enrolled patients, CA was observed in 18% of cases. Table presents the results of this study. Of the echocardiographic parameters, relative apical sparing pattern (RASP) was the greatest contributor for improvement of diagnostic accuracy of the clinical model. The next greatest contributor was LV wall thickness, followed by left atrial reservoir strain (LAS), E/e', left atrial volume index, ejection fraction strain ratio, and pericardial effusion, respectively. Similarly, RASP, LV wall thickness, global longitudinal strain, ejection fraction, LAS, and granular sparkling showed significant incremental benefit in the validation cohort. Only mean wall thickness, LV wall thickness, LAS, E/e' and RASP consistently improved the diagnostic accuracy of the clinical model. Conclusion During the screening process, adding LV wall thickness, LAS, and RASP to the clinical parameters may be useful for the accurate diagnosis of CA in patients with LV hypertrophy. Figure 1 Funding Acknowledgement Type of funding source: None