Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a predominantly genetically determined and inheritable disease characterized by fibrofatty replacement of the right ventricular myocardium with ventricular arrhythmias and sudden death (1,2). Its prevalence has been estimated to range from 1 in 2,000 to 1 in 5,000, and men are more frequently affected than women with a ratio of 3:1. It has been reported to account for 3% to 10% of unexplained sudden cardiac death in patients less than 65 years old (3,4). Patients with symptomatic ARVC may therefore be candidates for an active therapeutic management, including antiarrhythmic medication, invasive electrophysiologic procedures, implantation of a cardioverter-defibrillator, and in some cases, cardiac transplantation (5).

It is a rare disorder, but it is the most common cause of sudden cardiac death in younger populations. Major pathologic findings are replacement of the myocardium by fatty and fibrous tissue and numerous structural abnormalities of the right ventricle including areas of wall thinning with formation of single or multiple aneurysms. These abnormalities are most often found in the subtricuspid area, the right ventricular apex, and the right ventricular outflow tract— the so-called triangle of ARVC. However, left ventricular involvement has been described especially in the posterolateral wall (6), may be age dependent and associated with arrhythmic events, cardiomegaly, and heart failure. Twelve genes have been identified which are linked to ARVC, encoding several components of the cardiac desmosome. Dysfunction of desmosomes causes defective cell adhesion, loss of electrical myocyte coupling leading to apoptotic myocyte death, fibrofatty replacement, and arrhythmias. Clinically, four stages of the disease have been proposed: (a) A concealed phase, in which anatomic changes are subtle and arrhythmias may be minor, but in which sudden cardiac death may be the first indication of the disease; (b) an overt electrical disorder presenting with ventricular tachycardias or sudden cardiac death, in which structural and functional abnormalities of the right ventricle are more apparent; (c) progressive right ventricular failure with preserved left ventricular function; and (d) biventricular dysfunction (7).

The diagnosis of ARVC can be made according to the International Task Force criteria, originally published in 1994 (8) and modified in 2010 (9). Abnormalities are divided into major and minor categories according to their specificity for ARVC. Criteria for global and regional dysfunction and/or structural alterations of the right ventricle are based on findings with transthoracic echocardiography or cardiac magnetic resonance (CMR) imaging. Further criteria include tissue characterization of myocardial walls by endomyocardial biopsy and histology, repolarization and depolarization abnormalities by ECG, arrhythmias by (Holter-) monitoring, and family history with pathologically proven ARVC. The modified ARVC Task Force criteria provide detailed cutoffs for abnormal RV size and wall motion as assessed by CMR. RV ejection fraction ≤40%, or regional akinesia, dyssynchronous RV contraction, RV end-diastolic volume/body surface area ≥110 mL/m² (male) or ≥100 mL/m² (female) are considered major criteria for ARVC.

CMR has the unique advantage to be an absolutely noninvasive technique, providing information on dimensions, geometry, shape, volumes, and function of all cardiac chambers, tissue characterization such as differentiation of fat from myocardium, and identification of fibrous formations such as myocardial scar. CMR, therefore, has been increasingly used for the evaluation of right ventricular disease and has evolved as the noninvasive imaging modality of choice in ARVC.

There is no widely accepted standard imaging protocol for the investigation of patients with suspected ARVC using CMR. The CMR imaging protocol is aimed at recognizing both, typical features of ARVC such as RV akinesia, dyskinesia, dyssynchrony, and reduced RV ejection fraction (modification of ARVC/D Task Force criteria) as well as features of other conditions with similar clinical presentation, for example, granulomas in cardiac sarcoidosis. We suggest an imaging protocol that comprises cine steady-state free precession (Cine-bSSFP) for morphology and function, T1-weighted turbo-spin-echo (T1-TSE) for morphology, and late gadolinium enhancement inversion recovery gradient recalled echo (LGE-IR-GRE) sequences acquired in axial and short-axis orientation. The right ventricle has a complex geometry, is asymmetric, and is highly trabeculated. The mean right ventricular free wall thickness in healthy individuals is 2.7 ± 0.4 mm and only 1.9 ± 1.1 mm at the right ventricular apex (8). Epicardial fat is usually present, especially in association with the right coronary artery within the right atrioventricular groove and with the left anterior descending coronary artery in the apical region. Tongues of epicardial fat may extend into the myocardium in healthy individuals (10,11). The identification of small morphologic alterations of the thin right ventricular free wall, the analysis of regional wall-motion abnormalities of a complex geometric structure, and the identification of intramural or transmural fatty infiltrates of the right ventricular myocardium require highresolution images without significant artifacts. Retrospective analysis of static magnetic resonance images of 39 patients from a ARVC registry revealed an excellent image quality in less than 10% of cases (12). Thus, basic requirements for equipment, software, imaging protocol, readout, and documentation should be fulfilled for the CMR investigation of patients with suspected ARVC. A cardiac phased array coil is preferred, and gradient coil strength should minimally be 20 mT/m. Cardiac gating and breath-hold imaging are required (13). Black blood imaging is used to depict morphologic abnormalities of the right ventricle and intramyocardial fatty infiltration. Bright blood cine imaging is used for visualizing global and regional ventricular function and to measure end-diastolic and end-systolic volumes for calculation of stroke volume and ejection fraction. In addition, significant valvular disease can be demonstrated or excluded. Diastolic dysfunction of the right ventricle can be assessed by measurement of blood-flow velocities across the tricuspid valve during the whole cardiac cycle by application of MR velocity mapping (14).