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MRI and Echocardiography in Cardiac Amyloid
Study Questions:
What are the functional and structural cardiac abnormalities that occur across a spectrum of cardiac amyloidosis burden? And, using cardiac magnetic resonance (CMR) imaging and echocardiography, what are the strongest cardiac functional and structural prognostic predictors in amyloidosis?
Methods:
A cohort of 322 subjects (311 systemic amyloidosis, 11 transthyretin gene mutation carriers) underwent comprehensive CMR and transthoracic echocardiography. Cardiac amyloidosis burden was quantified using CMR-derived extracellular volume. The probabilities of 11 commonly measured structural and functional cardiac parameters being abnormal with increasing cardiac amyloidosis burden were evaluated. The prognostic capacities of these parameters to predict death in amyloidosis were assessed using Cox proportional hazards models.
Results:
Left ventricular (LV) mass and mitral annular plane systolic excursion by CMR, and strain and E/e’ by echocardiography, had high probabilities of being abnormal at low cardiac amyloid burden. Reductions in biventricular ejection fractions (EFs) and elevations in biatrial areas occur at high burdens of infiltration. The probabilities of abnormal CMR-derived stroke volume index (SVI), myocardial contraction fraction (the ratio of stroke volume to myocardial volume), and tricuspid annular plane systolic excursion (TAPSE) occurred more gradually with increasing extracellular volume. During a median follow-up interval of 22 months (interquartile range, 10-38 months), 90 patients (28%) died. Univariable analysis showed that all imaging markers studied significantly predicted outcome. Multivariable analysis revealed that CMR-derived TAPSE (hazard ratio [HR], 1.46; 95% confidence interval [CI], 1.16-1.85; p < 0.01) and SVI (HR, 1.24; 95% CI, 1.04-1.48; p < 0.05) were the only independent predictors of mortality.
Conclusions:
Specific functional and structural abnormalities characterized different burdens of cardiac amyloid deposition. In a multimodality imaging assessment of a large cohort of patients with amyloidosis, CMR-derived TAPSE and stroke volume index were the strongest prognostic cardiac functional markers.
Perspective:
Cardiac involvement in light chain and transthyretin amyloidosis is a major determinant of prognosis, and therefore, influences treatment strategies. Numerous measures of cardiac structure and function can be assessed using multiple imaging modalities. Although LVEF is a conventional marker used to describe cardiac function, among patients with amyloidosis cardiac decompensation frequently precedes a reduction in LVEF. In this study, abnormal CMR-derived SVI, myocardial contraction fraction, and TAPSE occurred with increasing frequency in association with increasing cardiac amyloid burden; and prognosis was associated with CMR-derived TAPSE and SVI. These CMR-derived variables might prove useful for the assessment of risk among patients with amyloidosis.
Clinical Topics: Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Acute Heart Failure, Echocardiography/Ultrasound, Magnetic Resonance Imaging
Keywords: Amyloid Neuropathies, Familial, Amyloidosis, Familial, Diagnostic Imaging, Echocardiography, Heart Failure, Magnetic Resonance Imaging, Mutation, Myocardial Contraction, Prealbumin, Prognosis, Stroke Volume
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