Extracellular Volume Detects Amyloidotic Cardiomyopathy and Correlates With Neurological Impairment in Transthyretin-familial Amyloidosis

Abstract

Introduction and objectives: Cardiac involvement determines prognosis and treatment options in transthyretin-familial amyloidosis. Cardiac magnetic resonance T₁ mapping techniques are useful to assess myocardial extracellular volume. This study hypothesized that myocardial extracellular volume allows identification of amyloidotic cardiomyopathy and correlates with the degree of neurological impairment in transthyretin-familial amyloidosis.

Methods: A total of 31 transthyretin-familial amyloidosis patients (19 mean age, 49 ± 12 years; 26 with the Val30Met mutation) underwent a T₁ mapping cardiac magnetic resonance study and a neurological evaluation with Neuropathy Impairment Score of the Lower Limb score, Norfolk Quality of Life questionnaire, and Karnofsky index.

Results: Five patients had cardiac amyloidosis (all confirmed by ^99mTc-DPD scintigraphy). Mean extracellular volume was increased in patients with cardiac amyloidosis (0.490 ± 0.131 vs 0.289 ± 0.035; P = .026). Extracellular volume correlated with age (R = 0.467; P = .008), N-terminal pro-B-type natriuretic peptide (R_S = 0.846; P < .001), maximum wall thickness (R = 0.621; P < .001), left ventricular mass index (R = 0.685; P < .001), left ventricular ejection fraction (R = -0.378; P = .036), Neuropathy Impairment Score of the Lower Limb (R_S = 0.604; P = .001), Norfolk Quality of Life questionnaire (R_S = 0.529; P = .003) and Karnofsky index (R_S= -0.517; P = .004). A cutoff value of extracellular volume of 0.357 was diagnostic of cardiac amyloidosis with 100% sensitivity and specificity (P < .001). Extracellular volume and N-terminal pro-B-type natriuretic peptide were the only cardiac parameters that significantly correlated with neurologic scores.

Conclusions: Extracellular volume quantification allows identification of cardiac amyloidosis and correlates with the degree of neurological impairment in transthyretin-familial amyloidosis. This noninvasive technique could be a useful tool for early diagnosis of cardiac amyloidosis and to track cardiac and extracardiac amyloid disease.

Keywords: Amiloide; Amyloid; Cardiac magnetic resonance; Extracellular cardiac volume; Mapeo T(1); Resonancia magnética cardiaca; T(1)-mapping; Transthyretin; Transtiretina; Volumen cardiaco extracelular.