ABC | Volume 112, Nº1, January 2019

Elias Nero et al ARVC/D - Diagnosis and treatment Arq Bras Cardiol. 2019; 112(1):91-103 Review Article Figure 2 – Two examples of voltage mapping for ventricular tachycardia ablation in patients with ARVC/D. 1A) Mapping of epicardial voltage showing (in red) areas of scar in the outflow tract and basal region of the RV. 1B) Mapping of endocardial voltage showing the presence of more extensive scar areas in the same region. 1C) Perspective showing the correlation of the scar areas with the coronary tree. 2A and 2B) Voltage mapping used for substrate ablation in a patient with ICD with multiple therapies. Radiofrequency applications (white and red circles) distributed in the endocardial and epicardial regions. 3C) Mapping image showing scar presence affecting the LV. evaluation of patients with suspected ARVC/D (class IIa) and may also be used in the risk stratification of asymptomatic patients (class IIb). 18 Recent studies using electroanatomic voltage mapping (bipolar and unipolar) to assess the existence and extent of the scar area in the RV have added interest in the use of EFS in the evaluation of ARVC/D (Figure 2). This mapping technique proved to be useful in directing the region to be biopsied, as it is more sensitive than the CMR to identify myocardial scar areas, and in the differential diagnosis between an idiopathic VT of the RVOT, and a VT in a patient with ARVC/D. Nevertheless, due to the fact that it is an invasive, high cost and dependent operator, this diagnostic method should be reserved for cases with a high index of suspicion and an indefinite diagnosis. 5 Differential diagnosis The main differential diagnoses that should be considered in suspected cases of ARVC/D include: idiopathic RVOT VT, VT originating from the aortic cusps, and cardiac sarcoidosis. 6 The idiopathic RVOT VT is a generally benign form of ventricular arrhythmia without association with cardiac structural alteration. 27 The differential diagnosis is based on the fact that idiopathic VT is a non-familial arrhythmia and that the patient does not present the classic ARVC/D electrocardiographic alterations. 28 An evaluation with the CMR should be carried out in all cases. Another differential diagnosis is sarcoidosis. This granulomatous disease, when it involves the heart, may be very similar to ARVC/D. Cardiac sarcoidosis should be suspected when cardiac manifestations are associatedwithmediastinal lymphadenopathy, extracardiac sarcoidosis, especially the pulmonary one, to severe atrioventricular conduction disturbances, and the presence of a scar in the interventricular septum in the imaging evaluation. 6 In addition, more advanced age at onset of symptoms, presence of cardiovascular comorbidities, and non-familial disease pattern should also raise suspicion of cardiac sarcoidosis. 4 Cardiac position emission tomography may be useful for differential diagnosis. 29 Other less frequent pathologies are: myocarditis; Brugada syndrome; 30 dilated cardiomyopathy, in cases with biventricular dysfunction; myocardial infarction with involvement of both cardiac chambers; pulmonary hypertension (RV pressure overload), and/or significant tricuspid regurgitation (RV volume overload); congenital heart defects such as Uhl’s anomaly and corrected Fallot’s tetralogy; and left-right intracardiac shunts (usually interatrial septal defect and anomalous drainage of the pulmonary veins) that may cause right ventricular overload. Recently, there has been much discussion of the phenotypic overlap between ARVC/D and Brugada syndrome. 30 The ultrastructural changes that result from mutations in the desmosomes may explain this observation. From the clinical point of view, both conditions may manifest as abnormalities in the ventricular repolarization in right precordial leads, right bundle branch conduction disorder, and ventricular arrhythmias stemming from the RV. 31 Pathologically, fatty myocardial infiltration has been reported in both conditions. 4,32,33 As a consequence, ARVC/D and Brugada syndrome may be part of a subgroup of structural myopathies due to changes in the sodium current, due to the involvement of the inter-cellular connection. 30 Risk stratification The natural history of ARVC/D is predominantly related to electrical instability that can lead to arrhythmic SAD, especially in young athletes. At a later stage of the disease, progressive RV impairment and left ventricular involvement may result in right and/or left failure. 1,6 Data regarding the clinical progress come from small cohorts performed in tertiary centers and with a relatively short clinical follow-up. The total mortality estimated in these studies 7