The following are key points to remember from this review on restrictive cardiomyopathy (RCM):

1. The authors propose a new definition for RCM that includes persistent presence of restrictive pathophysiology with atrial dilatation, nondilated ventricles irrespective of ventricular wall thickness, and systolic function.
2. The classic hemodynamic finding of dip and plateau or square root sign in RCM is characterized by elevated diastolic filling pressure and a rapid equalization of filling pressures of all cardiac chambers during diastole.
3. Constrictive pericarditis can be differentiated from RCM by presence of ventricular interdependence. With RCM, there is little change in peak ventricular pressures with respiration and they move in the same direction.
4. An echocardiogram for RCM shows biatrial dilatation, normal or mildly reduced left ventricular (LV) and right ventricular ejection fraction, and nondilated ventricles. Doppler imaging shows a restrictive filling pattern with tissue Doppler showing an elevated E/e’ ratio.
5. Treatment for RCM centers on relieving congestion with loop diuretics. However, hypovolemia may cause a fall in stroke volume.
6. Cardiac output in RCM is dependent on heart rate due to a fixed stroke volume. Therefore, beta-blockers can worsen hemodynamic function. Atrial fibrillation is poorly tolerated due to loss of atrial contribution to ventricular filling, and therefore, rhythm control should be preferred when possible.
7. LV assist devices are challenging due to a small LV size. Heart transplant maybe considered for select patients.
8. Disease-modifying treatment for light chain (AL) amyloidosis includes autologous stem cell transplant after bortezomib conditioning. For patients not eligible for transplant, a combination of daratumumab, bortezomib, cyclophosphamide, and dexamethasone is second line.
9. For TTR amyloidosis, tafamidis reduces further formation of TTR and prolongs survival. Small interfering RNA (siRNA) patisiran and antisense oligonucleotide inotersan are approved for patients with stage 1 and 2 familial TTR with polyneuropathy. Patients on patisiran and inotersen agents need vitamin A supplementation and side effects include glomerulonephritis and thrombocytopenia.
10. For sarcoidosis, immunosuppression with steroids for suppression of acute inflammation is central with use of guideline-directed therapies for heart failure and arrhythmias.
11. Familial RCM displays autosomal dominant inheritance usually. There is considerable phenotype and genotype overlap between RCM and hypertrophic cardiomyopathy (HCM) with the same mutations phenotypically manifesting as either HCM or RCM. Genetic conditions associated with RCM include desminopathies, hereditary hemochromatosis, and Danon disease.
12. Anderson Fabry is an X linked recessive disorder caused by absence of alpha galactosidase. Early-onset type is characterized by heart failure, arrhythmias, mitral regurgitation, increased LV mass, episodic pain in extremities, decreased sweating, and gastrointestinal abnormalities. Later-onset type is characterized by increased LV mass or HCM and renal disease in older age. Treatments include enzyme replacement and migalastat, which promotes proper folding and trafficking of the abnormal substrate.
13. Diagnostic workup for etiology of RCM includes the electrocardiogram (low voltage for infiltrative cardiomyopathies) and an echocardiogram. Cardiac magnetic resonance imaging should be performed when possible with consideration for genetic testing.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Pericardial Disease, Valvular Heart Disease, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Heart Transplant, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Mitral Regurgitation

Keywords: Amyloidosis, Arrhythmias, Cardiac, Atrial Fibrillation, Cardiomyopathy, Hypertrophic, Diagnostic Imaging, Echocardiography, Electrocardiography, Genetic Testing, Genotype, Geriatrics, Heart Failure, Heart Transplantation, Immunosuppression, Magnetic Resonance Imaging, Mitral Valve Insufficiency, Pericarditis, Constrictive, Phenotype, Polyneuropathies, RNA, Small Interfering, Sarcoidosis, Stem Cell Transplantation, Steroids, Stroke Volume, Thrombocytopenia, Ventricular Function

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