Europace Advance Access originally published online on March 29, 2008
Europace 2008 10(7):884-887; doi:10.1093/europace/eun065
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CASE REPORTS
Electrical storm in a patient with arrhythmogenic right ventricular cardiomyopathy and SCN5A mutation
Department of Cardiology, Kerckhoff Heart Center, Benekestr. 2–8, Bad Nauheim 61231, Germany
Manuscript submitted 29 October 2007. Accepted after revision 28 February 2008.
* Corresponding author. Tel: +49 6032 9962240; fax: +49 6032 9962367. E-mail address: d.erkapic{at}kerckhoff-klinik.de
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Abstract |
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We described a case of a 58-year-old man with organic changes consistent with right ventricular cardiomyopathy. He also had a loss-of-function mutation in the cardiac sodium channel gene SCN5A, described in Brugada syndrome. He first presented with non-sustained ventricular tachycardia and was implanted with an implantable cardioverter defibrillator. He remained asymptomatic for 8 years until he developed recurrent episodes of ventricular tachyarrhythmias, which required multiple shocks. The patient was treated with a combination of quinidine and verapamil and since then remained free of arrhythmias.
Key Words: ARVC, SCN5A, Ion channel mutation, Brugada syndrome, Ventricular arrhythmias, Electrical storming, ICD
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Case report |
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A 58-year-old man with intermittent monomorphic and polymorphic non-sustained ventricular tachycardias (VTs) was referred to our hospital in 1998. He complained of chest pain and dyspnoea at rest. Only one member in the family died of cardiac causes; however, it is unknown whether his death was sudden.
The resting ECG during sinus rhythm (Figure 1) showed complete right bundle branch block (RBBB) (QRS complex 140 ms) and a prolonged QT interval of 480 ms (QTc 515 ms). No ST-segment elevation was present. Coronary angiography showed coronary atherosclerosis, but no significant stenosis. On echocardiography and magnetic resonance imaging (MRI), a mild right ventricular dilatation with a reduced ejection fraction of 40% and mild hypokinesia of the right ventricular apex without left ventricular involvement were visible. Right ventricular biopsies showed cardiac hypertrophy and fibrosis, but no fatty tissue degeneration. Myocarditis was excluded. During programmed right ventricular stimulation, VTs with same morphology as spontaneous arrhythmias were induced. A diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) was made on the basis of the clinical presentation and MRI findings, and the patient was treated with a prophylactic implantable cardioverter defibrillator (ICD). Defibrillator pre-discharge tests of 30 J made an additional SQ-array necessary. Subsequently, the patient remained free of ventricular tachyarrhythmias during 8 years.
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In 2006, the patient collapsed and required cardiopulmonary resuscitation. Implantable cardioverter defibrillator interrogation showed sustained polymorphic VT that degenerated into ventricular fibrillation, which the device failed to terminate, because of ineffective shocks. The ICD was replaced by a high-energy aggregate (EntrustTM, Medtronic, Minneapolis, USA). Therapy with flecainide and mexiletine was ineffective. During continuous ECG monitoring, the patient continued to experience recurrent symptomatic monomorphic and polymorphic VTs on a daily basis (Figures 2A and C and 3). He was then started on a combination of quinidine hydrogen sulphate 250 mg and verapamil hydrochloride 80 mg (Cordichin®, Abbott, Wiesbaden, Germany) twice daily and remained arrhythmia-free. Owing to frequent polymorphic VTs and the response to quinidine/verapamil,1
–3 we looked for a possible additional ion channel disease and found a splice error in intron 21 of the SCN5A gene (nucleotide C3840 + 1 G > A), which results in a loss of function of the sodium channel.
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In 2007, Cordichin medication was stopped outside the hospital. The patient developed electrical storm, collapsed, and was rescued with an external home defibrillator. After restarting the Cordichin therapy, the patient was free of arrhythmias.
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Discussion |
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Although biopsy findings and MRI showed no fibro-fatty replacement of right ventricular myocardium, this case fulfilled several criteria for the diagnosis of ARVC because of wide QRS complex (140 ms) in the right precordial leads, recurrent VTs and right ventricular dilatation, hypokinesia, and reduced ejection fraction of 40%.4
,5 Ventricular arrhythmias and sudden death are common in ARVC. Electrical storm as a presentation of ARVC in the elderly is less usual and, to the best of our knowledge, there are only few case reports.6,7 Ventricular tachycardias in ARVC are generally monomorphic.8 Figure 2A and C shows a transition of two different monomorphic tachycardias, which is a common finding in ARVC. The initiating beat is an extrasystole with a fairly short coupling interval (the R-on-T phenomenon). Polymorphic VTs in patients with ARVC are rarely described, usually in ARVC type 2.9 In this case, recurrent VTs could not be terminated by ATP or shocks, even after the system was fitted with an SQ-array feature and upgraded to a high-energy aggregate. ICD malfunction as possible cause was excluded.
After ineffective drug therapy with flecainide and mexiletine, the patient was arrhythmia-free on a combination of quinidine and verapamil. Several authors reported that some forms of VTs, caused by re-entry, automaticity, or triggered activity can be terminated by verapamil.10–12 Quinidine is known to work especially well in preventing arrhythmias that are polymorphic and start with a short coupling interval like in patients with Brugada syndrome (BrS).1,13 Quinidine inhibits the potassium current Ito in ventricular epicardial cells, thus restoring electrical homogeneity and abolishing phase 2 re-entrant activity.14 Ito inhibition by quinidine is probably the most clinically relevant effect of this drug in BrS.13,15 In our case, the role of verapamil or quinidine in the control of the arrhythmias cannot be established with certainty because none of these drugs was given alone. Although the combined sodium and calcium channel block is suggested to be proarrhythmic in BrS,3 in this case, the patient was arrhythmia-free under a combination of verapamil and quinidine. To date, Cordichin is mainly used for the treatment of recurrent supraventricular tachycardias.
The found mutation is a known splice error in the SCN5A gene that leads to a loss of function of the sodium channel and can be found in patients with BrS.16 The BrS was described in 1992 in individuals with structurally normal hearts and characteristic morphology of the QRS complex resembling RBBB with ST-segment elevation in V1–V3.17 In the absence of ST-elevation, even during flecainide therapy, the patient's phenotype might be that of BrS with organic changes consistent with ARVC. The combination of SNC5A gene mutations and cardiomyopathies has already been reported.18
As far as we know, this is the first report of electrical storm in an elderly patient with a combination of ARVC and SCN5A mutation with effective quinidine/verapamil therapy.
Conflict of interest: none declared.
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