The presence of ventricular tachycardia or fibrillation in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) constitutes an important risk factor for sudden cardiac death (SCD) in young athletes and others 35 years of age or younger. Combined endocardial and epicardial substrate guided catheter ablation show a very good short- and mid-term success rate.
In this article, we present two cases of ARVC/D that were admitted to our center for evaluation and treatment of drug-refractory ventricular tachycardia (VT) and recurrent implantable cardioverter-defibrillator (ICD) shocks.
ARVC/D is a cardiac muscle disease that is typically inherited as an autosomal dominant with variable penetrance. The main morphological feature of ARVC/D is a severely thinned right ventricular (RV) wall due to replacement of myocardium in the RV with immense fatty infiltration and fibrosis. ARVC/D causes right ventricular failure (the left side may also be affected) and various rhythm abnormalities, especially VT or ventricular fibrillation (VF) that may result in SCD, mainly among young people.1,2
The prevalence of ARVC/D is around 1:1000 to 1:1250 in the general population,3 and the annual incidence of SCD among patients with ARVC/D is estimated between 1-8%.4 ARVC/D has a major role in SCD among young people (accounting for 11% of all cases and 22% of cases among athletes).5,6
Despite significant advancements in the diagnosis of ARVC/D since the first comprehensive clinical description of the disease in 1982, the diagnosis of ARVC/D is still challenging due to the non-specific nature of clinical findings. Diagnosis is based on evaluating structural, functional, and electrophysiological abnormalities that are caused by underlying histological changes.7,8 In 1994, an International Task Force proposed criteria for the clinical diagnosis of ARVC/D; the 1994 criteria was modified in 2010 to increase sensitivity without losing specificity (Table 1).9
Patients with ARVC/D may remain asymptomatic or may present a variety of symptoms. Clinical presentations are typically related to ventricular tachycardia of RV origin, which most often develops between the second and fourth decade of life.10 The therapeutic strategy should be individualized (based on clinical presentation and risk stratification), and genetic counseling of families is recommended. The main focus of management is on preventing heart failure, malignant arrhythmias, and SCD. Patients with ARVC/D are advised to avoid competitive sports or other strenuous physical activity. ICD implantation is recommended in ARVC/D patients with prior sustained VT to prevent SCD. In patients with a high rate of appropriate ICD firing, adjunctive treatment with an antiarrhythmic drug (beta-blockers and class III antiarrhythmic drugs [sotalol, amiodarone]) and/or radiofrequency catheter ablation (RFA) may be required to reduce the burden of ventricular arrhythmia and ICD discharge.11,12 RFA should be considered as a complementary therapy to ICD implantation in patients who are unresponsive to or intolerant of antiarrhythmic drugs.13
Arrhythmia recurrence rates are reported as 48-75% at long-term follow-up (between 14 to 50 months) in ARVC/D patients who underwent endocardial RFA for VT to diffuse cardiomyopathy and the progressive nature of this disease.14,15 The combination of endocardial and epicardial mapping and ablation techniques in ARVC/D patients showed 84.6% freedom from ventricular arrhythmias or appropriate ICD therapy at long-term follow-up (1175 ± 112 days).14 Bilateral cardiac sympathetic denervation could be beneficial for patients with incessant VAs and no other pharmacologic or RFA therapy alternatives.16
A 31-year-old Hispanic male was referred to our hospital from a foreign country; this patient had a history of ARVC/D, hyperthyroidism, anxiety, and VT. The patient had been diagnosed with ARVC/D by MRI/echo about 7 years ago. The initial diagnosis was in the context of cardiac arrest secondary to VT, requiring resuscitation and hospitalization. At that time, the patient underwent ICD implantation. Since that time, he has had multiple hospitalizations for recurrent VT and has required pharmacotherapy as well as external and internal defibrillation. During the most recent hospitalization in his hometown, prior to his transfer to our hospital, he was hospitalized for 2 months with refractory VT. During this hospitalization in his hometown, the patient underwent left thoracoscopic T2-T5 sympathectomy, and was switched from sotalol to carvedilol, while IV amiodarone was continued. Despite these interventions, the patient continued to have episodes of nonsustained ventricular tachycardia (NSVT) and developed amiodarone-induced hyperthyroidism, so the cardiology committee of his hometown hospital referred the patient to us for possible ablation of sustained monomorphic VT refractory to surgical and pharmacological therapy. When we visited the patient for the first time, he was off amiodarone and having runs of hemodynamically tolerated VT at a rate of 110. His electrocardiogram showed a VT with left bundle branch block morphology and superior axis with a possible RV apex origin. Additionally, his echocardiography showed normal LV wall thickness, global LV hypokinesis, moderately decreased overall LV systolic function, severely enlarged right ventricular cavity size, depressed right ventricular global systolic function, estimated pulmonary artery (PA) systolic pressure of at least 35 mmHg, estimated right atrial pressure (RAP) of 11-15 mmHg, and an estimated left ventricular ejection fraction (LVEF) of 35-39%.
The patient was scheduled for endo-epicardial ablation under general anesthesia. After informed consent was obtained, the patient was taken to the electrophysiology laboratory. After local anesthetic infiltration with 1% lidocaine, sheaths and catheters were placed. An intracardiac echocardiography catheter (ICE) was placed in the right atrium (Figure 1). The baseline rhythm was sinus rhythm. Epicardial access was obtained under fluoroscopic guidance; an 8 French (Fr) sheath was left in place in the pericardial space anteriorly. Three-dimensional electroanatomic mapping of the left ventricle was performed using the Carto 3 system (Biosense Webster, Inc., a Johnson & Johnson company) and ThermoCool SmartTouch catheter (Biosense Webster, Inc., a Johnson & Johnson company). Voltage mapping showed extensive scar on the RV lateral wall. We were able to induce tachycardia during mapping, which we pace-mapped at the mid lateral RV; we had concealed entrainment at this area. We ablated at this spot (Figure 2) and continued to modify the whole scar using the ThermoCool SmartTouch catheter. After we completed modifying the scar, we attempted VT induction by ventricular pacing including ventricular extrastimuli (VES). Upon a stringent pacing protocol including 5 VES, the clinical VT was not inducible. As the VT was not inducible after the endocardial ablation, we did not proceed to map and ablate epicardially. At the end of the case, there was no pericardial effusion by ICE. The patient was in sinus rhythm and in good condition. The patient discharged from the hospital with a beta-blocker.
A 45-year-old female with a history of ARVC/D was admitted to our hospital with VT and recurrent shocks. The patient had been diagnosed with ARVC/D by MRI/echo approximately 8 years ago, and an ICD had been implanted at that time. Prior to the shocks, she had indicated that she felt lightheaded and had palpitations.
Echocardiography showed no visualized pericardial effusion, moderately decreased overall LV systolic function, estimated LVEF of 30-34%, global LV hypokinesis, mildly reduced right ventricular global systolic function, estimated PA systolic pressure of 20-25 mmHg, and an estimated RAP of 6-10 mmHg.
The patient was scheduled for an endo-epicardial substrate based mapping and ablation under general anesthesia. After local anesthetic infiltration with 1% lidocaine, sheaths and catheters were placed under fluoroscopic guidance. An ICE catheter was placed in the right atrium. We then proceeded to obtain epicardial access using an epidural needle and micropuncture needle. The anterior orientation of the wire was confirmed. The wire was in the pericardial space wrapping left to right, with freedom of the wire and lack of any adhesions. A 9Fr was left in place. The baseline rhythm was sinus rhythm. Three-dimensional electroanatomic mapping of the right ventricle was performed endocardially using the Carto 3 system, first with DecaNAV catheter (Biosense Webster, Inc., a Johnson & Johnson company) and then with the ThermoCool SmartTouch catheter.
Late potentials and scar were mapped endocardially in the right ventricular outflow tract (RVOT) septal and posterior area as well as epicardially in the outflow tract anteroseptal region, where we obtained 99% match pace-mapping. By using the ThermoCool SmartTouch catheter, we ablated in both these regions. We then attempted to induce VT by ventricular pacing including VES. Upon a stringent pacing protocol including 3 VES, we were able to induce a very fast VT (cycle length: 280msec) but the patient’s clinical VT (inferior axis, L bundle, V3 transition, negative aVL) was no longer inducible. The patient was in sinus rhythm and in good condition at the end of the procedure.
Ventricular arrhythmias are common in patients with ARVC/D. The major goal of ARVC/D treatment is preventing SCD. An ICD should be implanted in ARVC/D patients who have experienced sustained VT or VF. Antiarrhythmic drugs are often used to reduce the arrhythmia burden and to decrease firing of the ICD. Our patients had sustained VT refractory to antiarrhythmic drugs, so we considered an endo-epicardial based ablation strategy to manage the VT. The ablation was acutely successful to terminate VT in both cases. The endo-epicardial substrate based mapping and ablation could be considered as an effective method to control VT in patients with ARVC/D. ■
Disclosure: The authors have no conflicts of interest to report regarding the content herein.
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