Reverse Septal Contour On Cardiac Magnetic Resonance Imaging- A Mimicker Of Hypertrophic Cardiomyopathy In Transthyretin Cardiac Amyloidosis

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Introduction Transthyretin cardiac amyloidosis (ATTR) causes cardiomyopathy secondary to extracellular deposition of transthyretin protein in the heart muscle. Clinical Presentation An 86-year-old man with chronic diastolic heart failure and a recent transcatheter aortic valve replacement (TAVR) (26 mm Edwards Sapien 3 Bioprosthesis) for severe symptomatic aortic stenosis was seen in the TAVR clinic for a follow-up visit. The examination was consistent with mild volume overload. EKG showed an irregular rhythm with left axis deviation. A previous transthoracic echocardiogram showed biventricular hypertrophy with normal biventricular size and ejection fraction. For concerns of restrictive cardiomyopathy, a cardiac MRI (C-MRI) was performed which showed biventricular systolic dysfunction and right ventricular (RV) hypertrophy confirmed via RV mass index. Furthermore, tau inversion recovery imaging was normal (no intramyocardial edema). In addition, reverse septal hypertrophy of the interventricular septum (IVS) (wall thickness of 22 mm) and LV end-diastolic volume 175.61 ml, classically seen in hypertrophic cardiomyopathy patients was observed (Image 1A). Discussion The patient was diagnosed with cardiac amyloidosis based on a diminished longitudinal excursion of the basal segments, marked biventricular transmural homogenous and global amorphous Late Gadolinium Enhancement (LGE), and rapid LGE washout (Image 1 (B-C)). The diagnosis was supported by a positive via 99mTc-PYP scan and normal immunofixation electrophoresis. The patient was started on tafamidis. Transthyretin cardiac amyloidosis (ATTR) causes cardiomyopathy secondary to extracellular deposition of transthyretin protein. CMRI is used for tissue characterization and phenotyping of cardiomyopathies. CMRI methodologies such as T1 mapping, LGE, and basal-apical contractile gradient/longitudinal strain can differentiate HCM phenocopies such as ATTR amyloidosis from a typical HCM phenotype showing reverse septal contour and help in decision making and guide management Conclusion Newer imaging techniques in Cardiac MRI have helped increase diagnostic accuracy in patients with suspected cardiac amyloidosis. This has led to an increase in noninvasive diagnosis of the disease at an earlier stage which helps with prompt management. Transthyretin cardiac amyloidosis (ATTR) causes cardiomyopathy secondary to extracellular deposition of transthyretin protein in the heart muscle. An 86-year-old man with chronic diastolic heart failure and a recent transcatheter aortic valve replacement (TAVR) (26 mm Edwards Sapien 3 Bioprosthesis) for severe symptomatic aortic stenosis was seen in the TAVR clinic for a follow-up visit. The examination was consistent with mild volume overload. EKG showed an irregular rhythm with left axis deviation. A previous transthoracic echocardiogram showed biventricular hypertrophy with normal biventricular size and ejection fraction. For concerns of restrictive cardiomyopathy, a cardiac MRI (C-MRI) was performed which showed biventricular systolic dysfunction and right ventricular (RV) hypertrophy confirmed via RV mass index. Furthermore, tau inversion recovery imaging was normal (no intramyocardial edema). In addition, reverse septal hypertrophy of the interventricular septum (IVS) (wall thickness of 22 mm) and LV end-diastolic volume 175.61 ml, classically seen in hypertrophic cardiomyopathy patients was observed (Image 1A). The patient was diagnosed with cardiac amyloidosis based on a diminished longitudinal excursion of the basal segments, marked biventricular transmural homogenous and global amorphous Late Gadolinium Enhancement (LGE), and rapid LGE washout (Image 1 (B-C)). The diagnosis was supported by a positive via 99mTc-PYP scan and normal immunofixation electrophoresis. The patient was started on tafamidis. Transthyretin cardiac amyloidosis (ATTR) causes cardiomyopathy secondary to extracellular deposition of transthyretin protein. CMRI is used for tissue characterization and phenotyping of cardiomyopathies. CMRI methodologies such as T1 mapping, LGE, and basal-apical contractile gradient/longitudinal strain can differentiate HCM phenocopies such as ATTR amyloidosis from a typical HCM phenotype showing reverse septal contour and help in decision making and guide management Newer imaging techniques in Cardiac MRI have helped increase diagnostic accuracy in patients with suspected cardiac amyloidosis. This has led to an increase in noninvasive diagnosis of the disease at an earlier stage which helps with prompt management.