Türk Kardiyol Dern Arş - Arch Turk Soc Cardiol 2009;37(5):337-340 337 A case of myotonic dystrophy presenting with ventricular tachycardia and atrial fibrillation Ventrikül taşikardisi ve atriyal fibrilasyon ile seyreden miyotonik distrofi: Olgu sunumu Serpil Eroğlu, M.D., Bülent Özin, M.D., Süleyman Özbiçer, M.D., Haldun Müderrisoğlu, M.D. Department of Cardiology, Medicine Faculty of Başkent University, Ankara Myotonic dystrophy type 1 (MD1) is an autosomal dominant Miyotonik distrofi tip 1 (MD1), miyotoni, ilerleyici kas güç- disorder characterized by myotonia, progressive muscular süzlüğü, katarakt ve kalp tutulumu ile seyreden otozomal weakness, cataract, and cardiac involvement. Cardiac dominant bir hastalıktır. Kardiyak tutulum sıktır ve daha involvement is common and includes conduction system çok ileti sistemi anormallikleri, supraventriküler ve ventri- abnormalities, supraventricular and ventricular arrhyth- küler aritmiler şeklinde görülür. Daha az sıklıkta miyokart mias, and less frequently, myocardial dysfunction and disfonksiyonu ve iskemik kalp hastalığı da görülebilir. ischemic heart disease. A 54-year-old woman with a previ- Daha önce MD1 tanısı konmuş olan 54 yaşında kadın ous diagnosis of MD1 was admitted with palpitation, blood hasta, çarpıntı, 157/118 mmHg kan basıncı, 220 atım/ pressure of 157/118 mmHg, and a heart rate of 220 beat/ dk kalp hızı ve elektrokardiyogramda ventrikül taşikar- min. Electrocardiography (ECG) showed ventricular tachy- disi ile yatırıldı. Hastanın hemodinamik durumunun çok cardia. Within minutes, hemodynamic collapse developed kısa sürede bozulması üzerine elektriksel kardiyoversi- and electrical cardioversion was performed. Immediately yon uygulandı. Kardiyoversiyonun hemen arkasından following cardioversion, ECG showed atrial fibrillation, a elektrokardiyogramda atriyal fibrilasyon, hafif uzamış slightly prolonged QT interval, and intraventricular con- QT intervali ve intraventriküler ileti gecikmesi gözlendi. duction delay. After intravenous infusion of amiodarone, İntravenöz amiodaron infüzyonundan sonra hasta sinüs the rhythm converted to sinus. Transthoracic echocar- ritmine döndü. Transtorasik ekokardiyografi incelemesin- diography showed significantly depressed left ventricular de sol ventrikül fonksiyonunun belirgin derecede zayıfla- function, an ejection fraction of 25%, and normal coronary dığı görüldü; ejeksiyon fraksiyonu %25 bulundu, koroner arteries. During electrophysiological study, atrium-His arterler ise normaldi. Yapılan elektrofizyolojik çalışmada, interval and His-ventricle interval were 120 msec was 54 atriyum-His intervali ve His-ventrikül intervali sırasıyla msec, respectively, and monomorphic ventricular flutter 120 msn ve 54 msn ölçüldü ve uyarıyla monometrik vent- was induced. An implantable cardioverter-defibrillator was riküler flutter oluşturuldu. Tedavi olarak kardiyak defibrila- placed. She was discharged in sinus rhythm. tör takılan hasta sinüs ritmiyle taburcu edildi. Key words: Atrial fibrillation/etiology; defibrillators, implantable; Anah tar söz cük ler: Atriyal fibrilasyon/etyoloji; defibrilatör yer- electrocardiography; myotonic dystrophy/complications; tachy- leştirme; elektrokardiyografi; miyotonik distrofi/komplikasyon; cardia, ventricular/etiology. taşikardi, ventriküler/etyoloji. Myotonic dystrophy type 1 (MD1) is an autosomal supraventricular and ventricular arrhythmias, and dominant disorder caused by the mutational expan- less frequently, myocardial dysfunction and isch- sion of a repetitive trinucleotide sequence in the emic heart disease.[2] 3’-untranslated region of the myotonic dystrophy protein kinase gene on chromosome 19q13.3.[1] CASE REPORT This disorder is characterized by myotonia, pro- A 54-year-old woman presented to the emergency gressive muscular weakness, cataract, and cardiac room with palpitation, blood pressure of 157/118 manifestations. Cardiac involvement is common mmHg, and a heart rate of 220 beats per min. and involves conduction system abnormalities, Electrocardiography (ECG) showed ventricular tachy- Received: August 7, 2008 Accepted: December 13, 2008 Correspondence: Dr. Serpil Eroğlu. Fevzi Çakmak Cad., 10. Sok., No: 45, 06490 Bahçelievler, Ankara, Turkey. Tel: +90 312 - 212 68 68 / 1419 e-mail: [email protected] 338 Türk Kardiyol Dern Arş Figure 1. Admission electrocardiogram showing ventricular tachycardia during palpitation. cardia (VT) (Fig. 1). Within minutes, hemodynamic for atrial flutter with propafenon and amiodarone, but collapse developed and electrical cardioversion with this rhythm persisted. 200 joules was immediately performed. Immediately Physical examination showed ptosis, and cataract, following cardioversion, ECG showed atrial fibril- and manual strength test of symmetric upper and lower lation (AF), a slightly prolonged QT interval, and extremities showed muscular weakness of grade 4/5. intraventricular conduction delay (Fig. 2). After intra- Electroneuromyographic assessment was compatible venous infusion of amiodarone, the rhythm converted with MD. Transthoracic echocardiography showed to sinus rhythm. significantly depressed left ventricular function and The patient had a 12-year history of myotonic an ejection fraction of 25%. No signs of dyssynchrony muscular dystrophy for which she had been treated were found. On cardiac catheterization, pulmonary with mexiletine. Two months earlier, she was treated capillary wedge pressure was 23 mmHg, left ventricu- Figure 2. Electrocardiogram following cardioversion showing atrial fibrillation, prolonged QT interval, and intra- ventricular conduction delay. A case of myotonic dystrophy presenting with ventricular tachycardia and atrial fibrillation 339 Figure 3. Surface and intracardiac electrocardiograms showing tachycardia during electrophysiological study. lar end-diastolic pressure was 19 mmHg, and systolic, In patients with MD1, a pacemaker should be diastolic, and mean pulmonary artery pressures were implanted according to the recommended guide- 45, 20, and 30 mmHg, respectively. Cardiac index lines.[5] Asymptomatic atrioventricular conduction was 2.03 l/min/m2 according to the Fick method. delay, especially in the presence of a prolonged H-V Coronary arteries were normal. Intracardiac electro- interval, represents one of the major therapeutic chal- cardiogram was obtained during electrophysiological lenges in MD1, as data on the rate of progression to study (EPS). On EPS, atrium-His interval was 120 complete atrioventricular block are inconsistent. The msec and His-ventricle (H-V) interval was 54 msec, presence of a prolonged H-V interval exceeding 70 and monomorphic ventricular flutter was induced by msec may require prophylactic pacemaker implanta- a single programmed stimulus from the right ventricu- tion, even in the absence of symptoms.[6] lar apex (at a coupling interval of 260 msec) (Fig. 3). Tachyarrhythmias can occur in MD1 patients. Ventricular flutter was terminated by overdrive pacing. Supraventricular tachyarrhythmias are common and An implantable cardioverter-defibrillator (ICD) (VVIR may be asymptomatic.[2] The most common arrhyth- mode, Ovatio VR 6250, Ela Medical, Plymouth, MN, mias are atrial flutter and AF.[2] Atrial fibrillation was USA) was implanted. The patient was discharged in present in our patient. sinus rhythm and on medical treatment. Ventricular arrhythmias are also frequent in MD1. DISCUSSION Monomorphic or polymorphic VT and ventricular Conduction system abnormalities are commonly fibrillation (VF) have been reported.[7] Monomorphic observed in MD1. Fibrosis and fatty infiltration are VT may be associated with re-entry around areas of observed together in the conduction system and may fibro-fatty degeneration of the myocardium, bundle be a possible underlying mechanism of the develop- branch re-entry (typical), or triggered activity.[2] ment of conduction system defects.[3,4] The most fre- During EPS, VF can be induced in the form quent involvement is in the His-Purkinje system, but of unsustained or sustained polymorphic VT, VF, any part of the conduction system may be affected.[2] or both sustained and unsustained monomorphic A long PR interval and/or a wide QRS complex may VT.[2] Sustained monomorphic ventricular flutter was accompany delayed impulse propagation along the induced in our case. conduction system. Late potentials which result from delayed myocardial activation usually associated with Treatment of ventricular arrhythmias in MD1 is abnormal tissue predict ventricular arrhythmias.[2] difficult. Implantation of an ICD should be considered A long PR interval (220 msec) and wide QRS (124 to treat VT because massive fatty fibrosis in cardiac msec) were present in our patient. muscle is often responsible for VT and numerous phar- 340 Türk Kardiyol Dern Arş macological treatments have been found not to improve myotonic dystrophy: a study of 12 cases. J Am Coll the condition.[8] There are also several reports of suc- Cardiol 1988;11:662-71. cessful catheter ablation of VT in MD1 patients.[8,9] 4. Grigg LE, Chan W, Mond HG, Vohra JK, Downey WF. Ventricular tachycardia and sudden death in myotonic Sudden death accounts for 2% to 30% of mortality dystrophy: clinical, electrophysiologic and pathologic in MD1 patients, possible mechanisms being ven- features. J Am Coll Cardiol 1985;6:254-6. tricular asystole, degeneration of VT, VF, or electro- 5. Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA mechanical dissociation.[2] Groh et al.[10] investigated 3rd, Freedman RA, Gettes LS, et al. ACC/AHA/HRS