Imaging of Arrhythmogenic Right Ventricular Cardiomyopathy
Clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) remains challenging, especially in the early stages of the disease, and relies on Task Force criteria that encompass electrocardiographic, morphological (fibrofatty infiltration, wall thinning), and functional abnormalities (focal or global contraction abnormalities, right ventricle [RV] dilatation, and aneurysms).1 A 47-year-old male ARVC patient with a known plakophilin gene mutation and electrocardiographic signs of ARVC (T-wave inversion and epsilon waves in the right precordial leads, Figure, A, arrows) was scheduled for cardiac magnetic resonance and 64-slice cardiac computed tomographic imaging (MDCT) for the evaluation of coronary artery disease before implantation of an implantable cardioverter-defibrillator (ICD; Figure, B). Significant coronary artery disease was ruled out, and ICD implantation was uneventful.
In the horizontal long-axis view, both imaging techniques showed a dilated RV and intramyocardial signal changes suggestive of fibrofatty replacement. In panel C of the Figure, MDCT shows signal attenuation of the RV free wall (arrow) and RV subendocardial septum (arrowhead) as compared with normal myocardium (−40±40 versus 90±25 Hounsfield Units).2 Cardiac magnetic resonance imaging shows a high signal intensity 10 minutes after gadolinium DTPA injection on inversion recovery gradient echo images in these areas (Figure, D) and an area of low signal intensity in the RV septum on the steady-state free precession image (Figure, E, arrowhead). The effective echo time in the steady-state free precession image was 1.95 ms; this signal loss is caused by chemical shifting due to opposed intravoxel phase for fat and water signal at 1.5 Tesla. In addition, global and focal dyskinetic segments were seen during functional cardiac magnetic resonance imaging (cine). As of today, the patient’s follow-up has been unremarkable and without signs of heart failure, serious arrhythmias, or ICD shocks.
Our case shows that both imaging techniques have the ability to demonstrate structural and morphological abnormalities of the RV in ARVC patients with advanced disease. Although hampered by significant radiation, MDCT may be a useful alternative when cardiac magnetic resonance imaging is impossible in patients with ICDs, frequent arrhythmias, and claustrophobia. In selected patients, MDCT may even be preferable when coronary artery disease needs to be evaluated; however the sensitivity, specificity, and diagnostic accuracy of both techniques in all stages of ARVC need to be further addressed.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/118/12/e158/DC1.
McKenna WJ, Thiene G, Nava A, Fontaliran F, Blomstrom-Lundqvist C, Fontaine G, Camerini F. Diagnosis of arrhytmogenic right ventricular dysplasia/cardiomyopathy. Task Force of the Working Group Myocardial and Pericardial Disease of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the International Society and Federation of Cardiology. Heart. 1994; 71: 215–218.