Incidence and Characterization of Concealed Cardiac Amyloidosis Among Unselected Elderly Patients Undergoing Post-mortem Examination

Abstract

Background: The prevalence of cardiac amyloidosis (CA) is unknown. Aims and Methods: We sought to (a) determine the prevalence of CA in unselected patients ≥75 years undergoing autopsy, (b) characterize cardiological profiles of CA and non-CA patients by providing clinical-histological correlations, and (c) compare their cardiological profiles. After dedicated staining, the localization (interstitial or vascular) and the distribution (non-diffuse or diffuse) of amyloid deposition were analyzed. Cardiological data at last evaluation were retrospectively assessed for the presence of CA red-flags. Results: CA (50% light chains, 50% transthyretin) was found in 43% (n = 24/56) of the autopsied hearts. Atria were involved in 96% of cases. Amyloid localized both at the perivascular and interstitial levels (95.5 and 85%, respectively) with a slightly predominant non-diffuse distribution (58% of cases). Compared to the other patients, CA patients had a more frequent history of heart failure (HF) (79 vs. 47%, p = 0.014), advanced NYHA functional class (III-IV 25 vs. 6%, p = 0.047), atrial fibrillation (68 vs. 36%, p = 0.019), discrepancy between QRS voltage and left ventricular (LV) thickness (70 vs. 12%, p < 0.001), thicker LV walls (15 vs. 11 mm, p < 0.001), enlarged left atrium (49 vs. 42 mm, p = 0.019) and restrictive filling pattern (56 vs. 19%, p = 0.020). The presence of right ventricular amyloidosis seemed to identify hearts with a higher amyloid burden. Among the CA patients, >30% had ≥3 echocardiographic red-flags of disease. Conclusion: CA can be found in 43% of autopsied hearts from patients ≥75 years old, especially in patients with HF, LV hypertrophy and atrial fibrillation.