Advanced cardiac amyloidosis associated with normal interventricular septal thickness: an uncommon presentation of infiltrative cardiomyopathy.
BACKGROUND
Increased interventricular septal (IVS) thickness on echocardiography is a diagnostic criterion for cardiac amyloidosis and classically precedes decrement in left ventricular ejection fraction (LVEF). The investigators describe patients with histologically confirmed cardiac amyloidosis who had significant myocardial dysfunction (LVEF ≤ 40%) despite having normal IVS thickness.


METHODS
All patients with systemic amyloidosis and LVEFs ≤ 40% were analyzed to identify the prevalence of normal IVS thickness. Patients with known histories of cardiomyopathy or coronary artery disease were excluded. Histologic evaluation of tissue included assessment of amyloid burden and average myocyte diameter.


RESULTS
There were 255 patients with amyloidosis with LVEFs ≤ 40%, of whom seven (3%) had normal IVS thickness and histologic confirmation of cardiac involvement. Of these, six had immunoglobulin light chain amyloidosis, and one had senile amyloidosis. A majority of patients (86%) presented with new-onset cardiac dysfunction associated with edema and/or dyspnea. Electrocardiographic findings included low voltage (43%) and a pseudoinfarct pattern (29%). The 1-year survival from initial tissue diagnosis in the cohort with normal IVS thickness was similar to matched patients with amyloidosis with increased IVS thickness and LVEF ≤ 40% (21% vs 18%, respectively, P = .32). Myocardial tissue amyloid burden and average myocyte diameter were significantly reduced in cases compared with controls.


CONCLUSIONS
Cardiac amyloidosis can uncommonly present with normal IVS thickness despite significant myocardial dysfunction. The prognosis of these patients is as poor as those with increased IVS thickness. Amyloidosis should be considered in the differential diagnosis of patients with cardiomyopathy and reduced LVEFs despite normal IVS thickness.
Mayo Medical School, Mayo Clinic College of Medicine, Rochester, Minnesota.
Rahul
R
Suresh
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
Martha
M
Grogan
Division of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota.
Joseph J
JJ
Maleszewski
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
Patricia A
PA
Pellikka
Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio.
Mazen
M
Hanna
Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
Angela
A
Dispenzieri
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota. Electronic address: pereira.naveen@mayo.edu.
Naveen L
NL
Pereira
D000368:Aged; D000686:Amyloidosis / Q000150:complications / Q000000981:diagnostic imaging*; D009202:Cardiomyopathies / Q000150:complications / Q000000981:diagnostic imaging*; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006345:Heart Septal Defects, Ventricular / Q000150:complications / Q000000981:diagnostic imaging*; D006346:Heart Septum / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
Amyloid; Cardiomyopathy; Diagnosis; Echocardiography; Heart failure