Giant Right Atrium in the Setting of Desmin-Related Restrictive Cardiomyopathy
A 52-year-old man who had just emigrated from Russia presented at another hospital with recent onset of right-sided heart failure. Over the past years, the patient had experienced recurring episodes of atrial fibrillation, which finally persisted. In Russia, the patient had suffered from progressive tetraparesis that had not been investigated further.
Transthoracic and transesophageal echocardiography revealed biatrial dilatation, normal ventricular function, paradoxical movement of the interventricular septum, and a loss of A wave by Doppler as a result of atrial fibrillation. However, the pericardium and the extent and detailed morphology of the atria could not be assessed by echocardiography (Figure 1). A fully animated version of Figure 1 can be viewed in the Data Supplement (Movie I and Movie II). The patient was referred to us for cardiovascular magnetic resonance (CMR) to confirm clinically suspected constrictive pericarditis. At the other hospital, skeletal muscle biopsies had been taken for neurological workup of tetraparesis, but the results of the biopsies were pending at the time of the CMR referral.
Cardiovascular MRI was performed with a 1.5-T Magnetom Sonata (Siemens Medical Systems). Fast-gradient-echo steady-state free precession cine and single-shot imaging demonstrated a distinctive constrictionlike configuration of the heart with normal-sized ventricles, normal systolic ventricular function, and enlarged atria (Figure 2). A fully animated version of Figure 2 can be viewed in the Data Supplement (Movie III through Movie V). The right atrium measured 112×82×77 mm with an estimated right atrial volume of 463 mL, which is nearly 4 times the end-diastolic volume of each ventricle (left ventricular end-diastolic volume, 113 mL; left ventricular ejection fraction, 61%; right ventricular end-diastolic volume, 139 mL; right ventricular ejection fraction, 52%). The left atrium measured 55×69×54 mm with a left atrial volume of 136 mL. However, CMR revealed no thickening or calcification of the pericardium. Thus, constrictive pericarditis as the cause of heart failure and atrial size (Figure 2) was considered to be unlikely, because constrictive pericarditis without pericardial thickening or calcification is exceedingly rare in patients without previous cardiac surgery, radiation therapy, or myocardial infarction.
Consequently, the patient underwent cardiac catheterization and endomyocardial biopsy for workup of restrictive cardiomyopathy. The hemodynamic measurements showed a systolic pressure of 45 mm Hg in the pulmonary artery and near equilibration of end-diastolic pressures in the right atrium (20 mm Hg), right ventricle (20 mm Hg), and pulmonary artery (19 mm Hg), indicating the presence of significant myocardial restriction. Histopathological analysis of myocardial biopsy specimens showed fibrosis in combination with an altered structure of myofibrils but primarily no specific cause of restrictive cardiomyopathy.
Meanwhile, the immune histology and electron microscopy of the skeletal muscle biopsies previously taken to evaluate the tetraparesis revealed desmin-associated myopathy (Figure 3, Movie VI, and Movie VII), a very rare condition that is also known to cause severe restrictive cardiomyopathy. Subsequently, the myocardial specimens were sent to the same specialized pathologist, who then confirmed the diagnosis of myocardial desminopathy. In addition, genotyping revealed a previously unknown Glu[E]245Asp[D] missense mutation in the desmin gene of this patient.
This work was supported by a grant from the Robert Bosch Foundation (Dr Mahrholdt).
The online-only Data Supplement is available at http://circ.ahajournals.org/cgi/content/full/113/4/e53/DC1.