International Journal of Cardiology 190 (2015) 329–331

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International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard

Letter to the Editor

Cardiovascular imaging in arrhythmogenic right ventricular dysplasia/cardiomyopathy Riccardo M. Inciardi a,⁎, Andrea Rossi a, Gabriele Pesarini a, Francesco Clemenza b, Corrado Vassanelli a a b

Division of Cardiology, Department of Medicine, University of Verona, Verona, Italy Heart Failure Unit, ISMETT, Palermo, Italy

a r t i c l e

i n f o

Article history: Received 22 April 2015 Accepted 23 April 2015 Available online 24 April 2015 Keywords: ARVD/C Task Force Criteria Cardiovascular imaging Transthoracic echocardiography Cardiac MRI RV angiography

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/ C) is an inherited cardiomyopathy, usually transmitted with an autosomal dominant trait, characterized by right ventricular myocyte loss with fibrofatty replacement [1]. Clinical presentations in patients with ARVD/ C vary widely. Heart failure, ventricular arrhythmias and sudden cardiac death (SCD) are the most severe clinical manifestations of ARVD/C. It accounts for 11%–22% of cases of SCD in the young athlete population. The clinical diagnosis of ARVD/C is often difficult because of the non-specific nature of the disease and the broad spectrum of phenotypic expressions. There is no single gold-standard diagnostic test for ARVD/C, and the diagnosis relies upon a scoring system with “major” and “minor” criteria based on the evaluation of right ventricular (RV) morphology and function, characteristic depolarization/repolarization ECG abnormalities, characteristic tissue pathology, typical arrhythmias, family history, and the results of genetic testing [2]. Diagnostic criteria were revised in 2010, replacing the 1994 Task Force Criteria which had high specificity but lack sensitivity, increasing the risk of a false negative. The routine assessment of patients with suspected ARVD/C includes clinical and family history, physical examination, 12-lead ECG, 24-hour ambulatory ECG, signal-averaged ECG, and twodimensional echocardiography. Selected patients in whom non-invasive assessment is inconclusive might require further examination by cardiac magnetic resonance ⁎ Corresponding author. E-mail address: [email protected] (R.M. Inciardi).

http://dx.doi.org/10.1016/j.ijcard.2015.04.200 0167-5273/© 2015 Elsevier Ireland Ltd. All rights reserved.

(MRI), contrast angiography, and endomyocardial biopsy. The assessment of structural and functional abnormalities of the right ventricle is the most critical aspect of diagnosis (Table 1). Therefore cardiovascular imaging including transthoracic echocardiography (TTE), cardiac magnetic resonance (MR), and RV angiography represents essential tools to achieve a correct diagnosis. Echocardiography represents the first-line imaging approach for assessing index cases and family members because it is a widely available and non-invasive exam. It reveals RV structural abnormalities including global or segmental wall motion abnormalities (akinesia/ dyskinesia) with cavity dilation, hypertrophic RV trabeculation, and systolic dysfunction. On late stages, left ventricular (LV) involvement with biventricular failure is often observed. RV outflow tract (RVOT) dilation (diameter N 30 mm) has been reported to have the highest sensitivity and specificity (89% and 86%, respectively) of echocardiographic parameters in diagnosing ARVD/C [3] (Fig. 1A). In the revised Task Force Criteria, echocardiographic criteria include quantitative measures of RVOT enlargement and reduction in the RV fractional area changed (Table 1). Despite of the high specificity, in the early stage of the disease TTE could be apparently normal without the typical abnormalities. Cardiac MR imaging (MRI) is the imaging modality of choice in evaluating RV in ARVD/C (and also LV in the biventricular form of the disease). It has the benefit of providing morpho-functional evaluation of ventricle with tissue characterization and identification of intramyocardial fat and fibrosis in addition to assessment of ventricular structure and function (Fig. 1B). The noninvasive nature of MRI makes it ideal for evaluation and follow-up of asymptomatic first-degree relatives. Moreover cine-MR can be useful for estimating RV volume or structure and wall motion abnormalities giving a pivotal role to detect early and concealed cases which could escape diagnosis [4]. Sen-Chowdhry et al. [5], showed a high sensitivity and specificity (respectively 96% and 78%) in terms of identifying early abnormalities in asymptomatic gene carrier. The diagnostic criteria require the presence of akinesia, dyskinesia or aneurysm in addition to a decreased RV ejection fraction or increased ratio of RV end-diastolic volume to body surface area (Table 1). Fatty infiltration of the RV is not diagnostic of ARVD/C. Fatty tissue in the right ventricular free wall has limited diagnostic specificity in the absence of concomitant wall motion abnormalities. Actually pure fatty infiltration is common in normal hearts, particularly in obese and elderly people [6]. More recently, delayed enhancement MR has been proposed in the diagnosis of ARVD/C, specifically for the detection of fibrotic tissue, a finding that can precede functional abnormalities (Fig. 1C). In a recent

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R.M. Inciardi et al. / International Journal of Cardiology 190 (2015) 329–331

Table 1 Cardiovascular imaging criteria in ARVD/C patients. Cardiovascular imaging

Major criteria

Minor criteria

2D echocardiogram

• Regional RV akinesia, dyskinesia, or aneurysm; • and 1 of the following (measured at the end of diastole):

• Regional RV akinesia or dyskinesia; • and 1 of the following (measured at the end of diastole):

- PLAX RVOT ≥ 32 mm (corrected for body size [PLAX/BSA] ≥ 19 mm/m2) - PSAX RVOT ≥ 36 mm (corrected for body size [PSAX/BSA] ≥ 21 mm/m2) - Fractional area change ≤ 33% • Regional RV akinesia or dyskinesia or dyssynchronous RV contraction; • and 1 of the following:

- PLAX RVOT ≥29 to b32 mm (corrected for body size [PLAX/BSA] ≥16 to b19 mm/m2) - PSAX RVOT ≥32 to b36 mm (corrected for body size [PSAX/BSA] ≥18 to b21 mm/m2) - Fractional area change N 33% ≤ 40% • Regional RV akinesia or dyskinesia or dyssynchronous RV contraction; • and 1 of the following

Cardiac magnetic resonance

RV angiography

- Ratio of RV end-diastolic volume to BSA ≥ 110 mL/m2 (male) or ≥100 mL/m2 (female) - RV ejection fraction ≤ 40% • Regional RV akinesia, dyskinesia, or aneurysm

- Ratio of RV end-diastolic volume to BSA ≥100 to b110 mL/m2 (male) or ≥90 to b100 mL/m2 (female) - RV ejection fraction N40% to ≤45%

PLAX indicates parasternal long-axis view; PSAX, parasternal short-axis view; RVOT, RV outflow tract; BSA, body surface area.

study by Tandri et al. [7], this technique showed a sensitivity of 66% with a specificity of 100%. These values make this tool very important and promising in making the diagnosis of ARVD/C at an early stage. If a noninvasive workup is suggestive but non-diagnostic, further testing should be considered to establish the diagnosis, including RV angiography or electroanatomic mapping.

The Task Force Criteria include as a major criterion the presence of regional RV akinesia, dyskinesia or aneurysm by RV angiogram (Table 1). Although its specificity is 90%, this is a very subjective and observer-dependent test. RV wall motion is usually assessed by qualitative, visual impression, and has lacked a quantitative basis for defining abnormalities.

Fig. 1. Right ventricular outflow tract (RVOT) enlargement from the parasternal long axis view (A); CMR shows regional wall motion abnormalities observed at the RV mid-free wall (arrows point to the mid-free wall microaneurysms) (B), and late enhancement at the septum, free wall of RV and at the inferolateral wall of LV (C); RV angiography shows wall motion abnormalities and transverse trabeculations (D).

R.M. Inciardi et al. / International Journal of Cardiology 190 (2015) 329–331

There are features other than wall motion abnormalities that may be seen in the right ventriculogram, such as aneurysms in the right ventricular outflow tract region, the coexistence of small bulges in the subtricuspid valve region and anterior wall, as well as heavy transverse trabeculations that are greater than 4 mm in the apical and moderator band region (Fig. 1D). Indik JH et al. [8], attempt to quantify RV wall motion based on contrast ventriculography in patients with ARVD/C and to specify the severity and location of wall motion abnormalities. They showed a primarily reduction movement, distinguished from normal patients, in the tricuspid, subtricuspid, and inferior wall regions. Three-dimensional electroanatomical mapping can reveal delayed potentials that can lead to tachycardic events. These areas correspond to fibrofatty replacement and the electroanatomical study could assist in the differential diagnosis with diseases that mimic ARVD/C, such as inflammatory cardiomyopathy and idiopathic right ventricular outflow tract tachycardia [9]. Scar tissue can be identified by voltage mapping, and validation studies have confirmed that low voltage corresponds to the presence of scar defined by delayed enhanced MRI. Integration of both imaging modalities has been used to focus on the arrhythmogenic substrate that is predominantly confined to scar tissue [10]. The stepwise approach of using TTE, cardiac MR, and RV angiography increases the diagnostic performance. However the clinician should be aware that ARVD/C cannot be excluded by the absence of structural abnormalities at initial examination, because arrhythmias often occur in the concealed phase without structural abnormalities, which may evolve years later. Conflict of interest The authors report no relationships that could be construed as a conflict of interest.

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References [1] H. Calkins, Arrhythmogenic right ventricular dysplasia, Curr. Probl. Cardiol. 38 (3) (Mar 2013) 103–123. [2] F.I. Marcus, W.J. McKenna, D. Sherrill, et al., Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria, Circulation 121 (2010) 1533–1541. [3] D.M. Yoerger, F. Marcus, D. Sherrill, Multidisciplinary study of right ventricular dysplasia investigators, et al., Echocardiographic findings in patients meeting task force criteria for arrhythmogenic right ventricular dysplasia: new insights from the multidisciplinary study of right ventricular dysplasia, J. Am. Coll. Cardiol. 45 (2005) 860–865. [4] H. Tandri, H. Calkins, D.A. Bluemke, MR and CT imaging, in: F.I. Marcus, A. Nava, G. Thiene (Eds.), Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: Recent Advances, Springer Verlag, Milano 2007, pp. 135–146. [5] S. Sen-Chowdhry, S.K. Prasad, P. Syrris, et al., Cardiovascular magnetic resonance in arrhythmogenic right ventricular cardiomyopathy revisited: comparison with task force criteria and genotype, J. Am. Coll. Cardiol. 48 (2006) 2132–2140. [6] H. Tandri, R. Macedo, H. Calkins, et al., Role of magnetic resonance imaging in arrhythmogenic right ventricular dysplasia: insights from the North American arrhythmogenic right ventricular dysplasia (ARVD/C) study, Am. Heart J. 155 (2008) 147–153. [7] H. Tandri, M. Saranathan, E.R. Rodriguez, et al., Noninvasive detection of myocardial fibrosis in arrhythmogenic right ventricular cardiomyopathy using delayedenhancement magnetic resonance imaging, J. Am. Coll. Cardiol. 45 (2005) 98–103. [8] J.H. Indik, T. Wichter, K. Gear, W.J. Dallas, F.I. Marcus, Quantitative assessment of angiographic right ventricular wall motion in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), J. Cardiovasc. Electrophysiol. 19 (2008) 39–45. [9] D. Corrado, C. Basso, L. Leoni, et al., Three-dimensional electroanatomical voltage mapping and histologic evaluation of myocardial substrate in right ventricular outflow tract tachycardia, J. Am. Coll. Cardiol. 51 (2008) 731–739. [10] M. Yokokawa, G. Mueller, F. Bogun, Role of imaging in ablation therapy of ventricular arrhythmias, Circ. J. 76 (2012) 1292–1298.

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