Appropriate and Inappropriate Implantable Cardioverter Defibrillators Therapies in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia Patients

Abstract

Background: Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited cardiomyopathy characterized histologically by the replacement of ventricular myocardium with fibrous and fatty tissue, and clinically by ventricular tachycardia arrhythmias primarily of right ventricular (RV) origin. Implantable cardioverter defibrillator (ICD) is the only proven therapy to reduce mortality in ARVC/D patients. However, it has the risk of inappropriate anti-tachycardia pacing (ATP) or shocks. This study aimed to assess the occurrence of appropriate and inappropriate ICD therapies in ARVC/D patients who underwent ICD implantation in a single Cardiac Centre.

Methods: Retrospective analysis of the data of patients with the diagnosis of ARVC/D based on the 2010 revised Task Force Criteria, who underwent ICD implantation in the Heart Centre, at King Faisal Specialist Hospital and Research Center (KFSH&RC), Riyadh between January 1997 and May 2016. The clinical data and information about appropriate and inappropriate ICD therapies were obtained from medical records with the review of the available intra-cardiac electrograms (EGMs).

Results: Twenty-two ARVC/D patients with ICD implantation (20 males (91%), mean age at ICD implantation: 32 ± 14 years). ICD was implanted for secondary prevention of sudden cardiac death (SCD) in 15 patients (68.2%), and for primary prevention in 7 patients (31.8%). At mean follow-up of 9.4 ± 4.8 years, 11 patients (50%) had appropriate ICD therapies, and five patients (22.7%) had inappropriate ICD therapies. Out of 950 ICD therapies, 865 (91%) were appropriate (586 episodes of VT/VF treated with ATP (61.3%), and 279 episodes treated with shocks (29.37%)) and 85 (9.4%) were inappropriate (45 episodes treated with ATP (4.73%), and 40 treated with shocks (4.21%)).

Conclusion: ARVC/D patients are at risk of VT/VF arrhythmias. ICD therapy is the only proven life-saving therapy in those patients. Most of ICD therapies in our patient's population are appropriate, and ATP therapy is effective in terminating most of VT episodes. Although we do not have any patient with subcutaneous ICD, the high success rate of ATP suggests that transvenous ICD would be more appropriate in ARVC/D patients.

Keywords: Anti-tachycardia pacing; Arrhythmogenic right ventricular cardiomyopathy; Implantable cardioverter defibrillator; Shocks.

Figure 1

ECG of a patient with ARVC/D showing the presence of an epsilon wave (electric potentials after the end of the QRS complex) (red arrows) and T-wave inversion in V1 - V5.

Figure 2

ECG in a patient with ARVC/D showing ventricular tachycardia with a left bundle branch block (LBBB) morphology and superior axis suggesting a RV inferior wall origin.

Figure 3

Parasternal long axis (a) and apical four-chamber (b) echocardiographic views showing RV dilatation [13].

Figure 4

(a) Axial cine SSFP (steady-state free precession) MRI showing significant RV dilatation and (b) black-blood-prepared HASTE (half-Fourier acquired single-shot turbo spin echo) axial slice MRI at level of RVOT showing RVOT dilatation [13].

Figure 5

Implantable cardioverter defibrillator (ICD) therapy classification. ATP: antitachycardia pacing.

Figure 6

Causes of inappropriate implantable cardioverter defibrillator (ICD) therapy. AF: atrial fibrillation; EMI: elecromanganic interference; ST: sinus tachycardia; SVT: supraventricular tachycardia.