Right ventricular dilatation in arrhythmogenic right ventricular cardiomyopathy: need for a revision of the 2010 International Task Force criteria

This commentary refers to ‘Cardiovascular magnetic resonance imaging volume criteria for arrhythmogenic right ventricular cardiomyopathy: need for update?’, by M.Y. Khanji et al., 2020;41:1451. We read with interest the recently published expert consensus document of the European Association Cardiovascular Imaging (EACVI) which provided a comprehensive review of the cardiovascular magnetic resonance (CMR) normal value of cardiac chambers size and systolic function.1 The authors of the document appropriately raised the need for an update of the CMR imaging reference values of right ventricular (RV) cavity size and function for diagnosis of arrhythmogenic RV cardiomyopathy (ARVC). Diagnosis of ARVC relies on the International Task Force (ITF) criteria which were revised in 2010 with the intention to improve diagnostic accuracy by providing quantitative parameters for cardiac imaging diagnosis.2 The reference values of normal RV end-diastolic volumes (up to 110 mL/m2 in men and 100 mL/m2 in women) were derived from 462 healthy controls (mean age 60 years) extracted by the multiethnic study of atherosclerosis (MESA). As highlighted by Khanji et al.,3 in this study, the quantification of ventricular volumes was obtained using the old conventional gradient-echo cine technique, known to underestimate volumes because of incomplete and lower endocardial border definition. Cardiac chamber volumes are to date more accurately measured using the balanced steady-state free precession sequences, which provide superior natural contrast between blood and endocardium. We agree that the ITF criteria should be revised with regard to reference values (gender specific and indexed to body surface area) for RV cavity size and systolic function, and updated in line with current nomograms provided by the international societies of cardiovascular imaging. It should be recognized that the RV volumes ranges proposed by the EACVI document are valid for the general population aged 20–80 years, while a sizeable proportion of patients scanned because of the suspicion of ARVC are instead represented by teenagers, most often engaged in competitive sports activity. In this young population of athletes, the proposed cut-off values for RV dilatation may lack specificity because the physiologic adaptive remodelling in athlete’s heart can produce an increase of RV volume that goes well beyond the upper limit of normality reported in the general population (Figure 1). Recently, D’Ascenzi et al.4 provided proper reference values for RV volumes in athletes, including those engaged in endurance sports associated with the greatest RV dimensional remodelling. Electrocardiographic and cardiovascular magnetic resonance findings in a 22-year-old patient with arrhythmogenic right ventricular cardiomyopathy, due to a plakophilin 2-gene mutation. Basal electrocardiogram showing T-wave inversion in leads II, III, and aVF and from V1 to V4 (A). Post-contrast cardiovascular magnetic resonance images --end-diastolic frame on long-axis view (B) and short-axis view (C) --showing normal right ventricular cavity size and segmental late gadolinium enhancement of the myocardium of the basal right ventricular free-wall (white arrows). The right ventricular systolic function is preserved (not shown). Electrocardiographic and cardiovascular magnetic resonance findings in a 17-year-old endurance athlete. Basal electrocardiogram showing sinus bradycardia and early repolarization pattern in inferolateral leads (D). Post-contrast cardiovascular magnetic resonance images --enddiastolic frame in long-axis view (E) and short-axis view (F) --showing a dilated right ventricle with no signs of myocardial late gadolinium enhancement. The right ventricular systolic function is preserved (not shown). According to the 2010 ITF guidelines, either major or minor imaging criteria for diagnosis of ARVC required a combination of regional RV wall motion abnormalities (WMA) plus global RV dilatation or systolic dysfunction. These strict diagnostic criteria, despite an increased specificity, have shown low sensitivity in a sizeable proportion of ARVC patients presenting consistent RV WMA, such as akinesia, dyskinesia, or bulging, with normal global cavity size and preserved systolic function (Figure 1). This finding reflects the segmental nature of ARVC lesions, manifesting as areas of fibro-fatty myocardial replacement which may not compromise the global RV haemodynamics. To overcome this limitation, the upgraded ITF criteria should consider as diagnostic the presence of isolated RV WMA on CMR, especially when combined with underlying fatty infiltration and/or replacement fibrosis, regardless of RV dilatation and dysfunction.5 This work was supported by the Ministry of Health grant [RF\2013\02356762 and RF\2014\00000394]; University Research grants [BIRD 2016\162733 and BIRD\160519], Padua, Italy; CARIPARO Foundation 2018\0110, Padua, Italy. Conflict of interest: none declared.