title: Quantification of myocardial extracellular volume fraction in systemic AL amyloidosis: an equilibrium contrast cardiovascular magnetic resonance study.
abstract: BACKGROUND
  Cardiac involvement predicts outcome in systemic AL amyloidosis and influences therapeutic options. Current methods of cardiac assessment do not quantify myocardial amyloid burden. We used equilibrium contrast cardiovascular magnetic resonance (EQ-CMR) to quantify the cardiac interstitial compartment, measured as myocardial extracellular volume (ECV) fraction, hypothesizing it would reflect amyloid burden.
  
  
  RESULTS
  Sixty patients with systemic AL amyloidosis (65% men, median age 65 years) underwent conventional clinical cardiovascular magnetic resonance, including late enhancement, equilibrium contrast cardiovascular magnetic resonance, and clinical cardiac evaluation, including ECG, echocardiography, assays of N-terminal pro-brain natriuretic peptide and Troponin T, and functional assessment comprising the 6-minute walk test in ambulant individuals. Cardiac involvement in the amyloidosis patients was categorized as definite, probable, or none, suspected by conventional criteria. Findings were compared with 82 healthy controls. Mean ECV was significantly greater in patients than healthy controls (0.25 versus 0.40, P<0.001) and correlated with conventional criteria for characterizing the presence of cardiac involvement, the categories of none, probable, definite corresponding to ECV of 0.276 versus 0.342 versus 0.488, respectively (P<0.001). ECV was correlated with cardiac parameters by echocardiography (eg, Tissue Doppler Imaging [TDI] S-wave R=0.52, P<0.001) and conventional cardiovascular magnetic resonance (eg, indexed left ventricular mass R=0.56, P<0.001). There were also significant correlations with N-terminal pro-brain natriuretic peptide (R=0.69, P<0.001) and Troponin T (R=0.53, P=0.006). ECV was associated with smaller QRS voltages (R=0.57, P<0.001) and correlated with poorer performance in the 6-minute walk test (R=0.36, P=0.03).
  
  
  CONCLUSIONS
  Myocardial ECV measurement has potential to become the first noninvasive test to quantify cardiac amyloid burden.
authors.affiliation: The Heart Hospital, London, UK.
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Banypersad
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sado
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Flett
authors.forename: Simon D J
authors.initials: SD
authors.lastname: Gibbs
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Pinney
authors.forename: Viviana
authors.initials: V
authors.lastname: Maestrini
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Cox
authors.forename: Marianna
authors.initials: M
authors.lastname: Fontana
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Whelan
authors.forename: Ashutosh D
authors.initials: AD
authors.lastname: Wechalekar
authors.forename: Philip N
authors.initials: PN
authors.lastname: Hawkins
authors.forename: James C
authors.initials: JC
authors.lastname: Moon
mesh_terms: D000368:Aged; D000682:Amyloid / Q000378:metabolism*; D000686:Amyloidosis / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D003287:Contrast Media; D003937:Diagnosis, Differential; D015150:Echocardiography, Doppler; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D019786:Gadolinium DTPA; D006331:Heart Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D000075363:Immunoglobulin Light-chain Amyloidosis; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013318:Stroke Volume
chemical_list: D000682:Amyloid; D003287:Contrast Media; D019786:Gadolinium DTPA