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 consequent death of myocytes, especially during mechanical stress that occurs during competitive sports activity. 34 Since the RV is a cardiac chamber with greater compliance than the LV, particularly during physical exercise, it becomes more susceptible to injuries, resulting in inflammation, fibrosis and, as a consequence, arrhythmias. 7 Based on this, ITF recommends that patients with a definitive diagnosis of ARVC/D do not participate in competitive or resistance sports (class I), and may only participate in low intensity recreational sports (class IIa). The same restrictions can be applied to relatives with negative phenotype, even those that do not carry genetic mutations or with unseen genotype (class IIb). 35 Pharmacological treatment The pharmacological treatment of ARVC/D consists of the use of antiarrhythmic drugs, beta-blockers and drugs used in the treatment of heart failure. 1 Antiarrhythmic therapy The goal of antiarrhythmic treatment in ARVC/D is to prevent arrhythmic events. Literature data suggest that antiarrhythmic drugs are ineffective in preventing the occurrence of severe tachyarrhythmias in high-risk patients with ICD. 6 Thus, antiarrhythmic therapy should be indicated as adjunctive therapy to ICD in patients with multiple appropriate therapies (class I), and may also be considered in those patients with frequent ectopic activity and/or NSVT (class IIa). In patients not having ICD and with hemodynamically tolerated VT, combined ablation/antiarrhythmic therapy may be applied (class IIb). On the other hand, the use of antiarrhythmic drugs should not be considered in asymptomatic carriers of genetic mutation and without documented ventricular arrhythmia (class III). Amiodarone alone or in combination with beta-blockers (because it combines the synergistic effects of class III antiarrhythmic and beta-adrenergic blockade properties) is the most commonly used therapeutic regimen for the treatment of ARVC/D. 36 Sotalol is a good therapeutic alternative, given the side effects resulting from the chronic use of amiodarone, particularly in the younger population. 7 Although not available in our country, flecainide, when associatedwith a beta-blocker,may be aneffective antiarrhythmic strategy of control in patients that are refractory to treatment with amiodarone or sotalol and/or catheter ablation. 37 Betablockers The ventricular arrhythmia in the ARVC/D often manifests itself in a situation of increased sympathetic tone. The current consensus is that beta-blocker therapy should be empirically instituted in all patients with a clinical diagnosis of ARVC/D. 5,7 In contrast, there is no indication of prophylactic use of beta‑blockers in healthy carriers of ARVC/D. 34 Other drugs Preload reduction drug therapy (usually diuretics and nitrates) is not yet part of the regular therapeutic arsenal of ARVC/D patients. 33 Angiotensin converting enzyme inhibitors (ACE inhibitors) and angiotensin II receptor blockers have been advocated in patients with ARVC/D, especially in patients with evidence of structural impairment, although there are no studies demonstrating this indication in this specific condition. 6 Continuous oral anticoagulant use is indicated for secondary prevention in patients with documented intracavitary thrombus, atrial flutter or fibrillation type arrhythmias, or with a history of thromboembolic event. 5,34 Catheter ablation VT catheter ablation is a therapeutic option for patients with continuing VT, or appropriate ICD shocks, despite optimal pharmacological therapy, including the use of amiodarone (Figure 2). 1,4,5,38,41 Long-term VT relapses have been attributed to the progressive nature of ARVC, which leads to the development of multiple arrhythmogenic foci over time. The epicardial location of many TV reentry circuits, which reflects the propensity of the ARVC lesions to originate and progress from the epicardium, may also explain the failure of conventional endocardial mapping and catheter-only endocardial ablation. 1,2 The increasing understanding of the arrhythmogenic substrate and the possibility of an epicardial approach allowed the observation of a significant increase in the success rate of catheter ablation in the treatment of VT in ARVC/D in recent years. 27,28 The advent of three-dimensional (3D) navigation systems has enabled a significant advance in VT ablation in ARVC/D patients. This technique allows the mapping of the endocardial and epicardial substrate using a colored tissue voltage map, particularly in the areas that are adjacent to the tricuspid valve region and the RVOT (Figure 2). 27,28 Based on this latest experience, ITF proposed that, in cases of unsuccessful endocardial approach, the epicardial approach should be attempted. It also recommends an endo/epi approach, as an initial strategy, in services with experience with this type of technique. 28 The technique used for ablation depends on the patient’s hemodynamic response during tachycardia. In cases of well-tolerated VT, the electrophysiological mapping and activation mapping techniques with the 3D system are the most commonly used. In the case of a VT with hemodynamic instability, the treatment consists of modifying the arrhythmogenic substrate, with ablation being done on the possible channels between areas with different voltages in combination with the elimination of fractional endocardial and epicardial signals (Figure 2). 27,28 Implantable cardioverter-defibrillator CDI implantation is the most accepted therapeutic strategy for ARVC/D patients, because the natural history of this pathology is characterized mainly by the risk of SAD, and only secondarily by contractile dysfunction that leads to progressive heart failure. 1 Although there are no prospective randomized studies, observational studies of large registries have shown that the implantation of an ICD increases patients’ survival. These studies have shown that 48-78% of patients receive appropriate ICD therapy during long-term follow-up. 4,6,29 9