Tachycardia Related Cardiomyopathy: Response to Control of the Arrhythmia BURT I. BROMBERG, M.D., MACDONALD DICK 11, M.D., A. REBECCA SNIDER, M.D., WILLIAM A. SCOTT, M.D., GERALD A. SERWER, M.D., EDWARD L. BOVE, M.D., and KATHLEEN P. HEIDELBERGER, M.D. From the Division of Pediatric Cardiology, C. S. Mott Children S Hospital, and the Departments of Pediatrics, Surgery, and Pathology, University of Michigan, Ann Arbor, Michigan To evaluate the clinical response of five children ingfraction (20% pre vs 34% post; P = 0.006), with automatic atrial tachycardia (AA T) and as- mean ejection fraction (36% pre vs 50% post; P sociated cardiomyopathy to arrhythmia control, < 0.01), mean velocity of’ circumferential fiber we compared pretreatment and posttreatment 24- shortening (0.62 pre vs 1.20 post; P = 0.003). hour ECG heart rates, cardiothoracic ratio by Mean E-point septa1 separation corrected for end- chest radiograph, and echocardiographic mea- diastolic dimension also showed a trend toward sures of ventricular ,function. Two children were improvement (0.25 pre vs 0.16 post; P = 0.11). treated with amiodarone, two with surgical exci- Right ventricular endocardial biopsies in four were sion and cryoablation of the ectopicfocus, and one nonspecific; an atrial biopsy from surgery showed with digoxin alone. Signijicantly slower mean a Purkinje fiber-like tissue in one patient, but was heart rates were achieved, along with a dominant nonspecijic in another. We conclude that cardio- sinus rhythm and improvement in symptoms. myopathy can be causally linked to automatic Control of the AAT resulted in improved mean atrial tachycardia and that aggressive medical cardiothoracic ratio (0.53 pre vs 0.49 post; P and/or surgical management is warranted in those = 0.021, as well as improvement in a number of patients with signs and symptoms of impaired ven- echocardiographic measurements: mean shorten- tricular function. (J Interven Cardiol 1989:2:4) Introduction matic atrial tachycardia (AAT), accounts for < 10% of SVT in children’,’ is usually slower than the more common reentrant forms of SVT, and Supraventricular tachycardia (SVT) from an ec- may be virtually incessant. At one time considered topic automatic atrial focus, herein called auto- AAT, in the absence of structural heart disease, has recently been associated with cardio- myopathy (CM). Although AAT is often refractory Presented, in part, at the 37th Annual Scientific Sessions, to conventional medical therapy, several reports American College of Cardiology, Atlanta, 1988. suggest that control of the arrhythmia improves Drs. Brombergand Scott were supported, in part, by fellowships cardiac perf~rmance.~~’In recent years, new phar- from the American Heart Association of Michigan. macologic agents8-’’ as well as surgical exci- Address for reprints: Macdonald Dick 11, MD, C.S. Mott Chil- sion 12-1 9 and catheter electrical ablation20-22have dren’s Hospital, Room FI 126, Box 0204, University of Michi- led to successful control of intractable AAT. To gan Medical Center, 1500 East Medical Center Drive, Ann Arbor, MI 48 109-0204. further examine the proposition that control of persistent AAT favorably alters cardiac function in Submitted for publication December 26, 1989; accepted with revisions January 30, 1990; revisions received February 7, some patients with cardiomyopathy, we compared 1990. the clinical course and noninvasive measures of Vol. 2, No. 4, 1989 Journal of Interventional Cardiology 21 1 BROMBERG, ET AL. ventricular function before and after therapy in sive shortening of the tachycardia cycle length five children with AAT. In addition, the findings after the initial several beats (“warm up”), atrial of two right atrial and three right ventricular biop- depolarization during the tachycardia that reset sies obtained from these patients are summarized. the atrial cycle, and failure of a single or a train of Recommendations for treatment based on this ex- atrial premature depolarizations to initiate or in- perience are outlined. terrupt the tachycardia]. In one patient the diag- nosis was made by the surface ECG and Holter tracings alone (initiating P wave of the tachycardia Methods as the same morphology of the subsequent beats, “warm-up” period, and atrioventricular dissocia- Five patients referred to the Pediatric Arrhyth- tion during SVT). Persistentjunctional reciprocat- mia Clinic at C.S. Mott Children’s Hospital, Uni- ing tachycardia was excluded by either the absence versity of Michigan, exhibited poorly controlled, of 1: 1 atrioventricular conduction during the virtually incessant SVT (Fig. 1) and had developed tachycardia or the absence of ventriculoatrial con- fatigue, exercise intolerance, increased heart size duction during ventricular pacing as well. The se- on chest radiograph, and echocardiographic find- lection of medical or surgical treatment was based ings of decreased ventricular function, suggestive upon the duration of the patient’s symptoms, their of cardiomyopdthy. Four patients underwent elec- anticipated compliance with a medical regimen, trophysiologic study (EPS) using programmed ex- and, in two patients, their decision against chronic trastimulation (PES), overdrive pacing, and map- antiarrhythmic medication. ping of atrial activation during the tachycardia. Response to therapy was evaluated by pre- and Four patients had hemodynamic study and two posttreatment 24-hour ambulatory electrocardio- right ventricular endom yocardial biopsy; one had graphic tracings (CardioData Corp., Northboro, a right ventricular biopsy and two atrial biopsies at MA, USA), chest radiographs, and two-dimen- surgery. The diagnosis of automatic atrial tachy- sional and M-mode echocardiograms (Advanced cardia (AAT) was based upon the criteria of Gol- Technology Laborotones, Seattle, WA, USA and/ et al. and [initiation of the or Acuson Computer Sonography, Mountain tachycardia by spontaneous atrial depolarizations View, CA, USA). All five patients were free of val- identical to successive atrial depolarizations dur- vular, congenital, ischemic or other structural ing the tachycardia, independence of the tachycar- heart disease by two-dimensional echocardiogram, dia cycle length on AV node conduction, succes- Doppler analysis, and cineangiography (four pa- . .a . , .., .. , . .. ’ . ... 1 ‘.I I ! ; : 1 ..,. I: ;I :.I Figure 1. Representative EUG tracings from leads I1 and 111 from patient #4 before and after final treatment. Note the pretreatment heart rate of 125 bpm and the inverted P waves in both leads (left hand tracings). Following trealment the rate is 75 bpm and the P waves are upright in both leads (right hand tracings). 212 Journal of Interventional Cardiology Vol. 2, No. 4, 1989 TREATMENT OF AAT tients). Cardiac rhythm and mean 24-hour heart ity, two noted dizziness, and one had exercise in- rates were determined by computer generated tolerance. Electrophysiological study in four pa- analysis and confirmed by full disclosure tracings. tients localized the origin of the AAT at the coro- The cardiothoracic ratio (CTR) was measured nary sinus 0s in two patients and the low septal from the chest radiograph in the posterior-anterior right atrium in one. In the fourth patient, earliest projection during maximal inspiration. The left atrial activation during SVT occurred both at the ventricular shortening fraction (SF), mean veloc- mouth of the coronary sinus and the atrioventricu- ity of circumferential fiber shortening corrected lar node, suggesting that the abnormal impulse for heart rate (VCF,), E-point septal separation arose equidistant between these two points. He- normalized for end-diastolic demension (EPSS/ modynamic studies in the four patients undergo- EDD) were measured from the M-mode echocar- ing electrophysiologic study demonstrated a mean diogram; the left ventricular ejection fraction (EF) left ventricular end-diastolic pressure (LVEDP) determined from the apical four-chamber view of of 16 mmHg (range 10-26 mmHg), and a mean the two-dimensional echocardiogram was calcu- cardiac index of 2.8/min/m2 (range 1.6-3.2 lated using the Simpson's rule algorithm. All pre- L/min/m2). treatment studies were obtained within 1 week Treatment. An average of 2.3 drug trials were prior to initiation of therapy. The mean interval used in three patients before satisfactory control of between pre- and posttreatment examination was the AAT was achieved (Table I). Digoxin alone 1.5 years. Results are expressed as the mean * one provided adequate control in only one patient. standard deviation and are compared using a Beta blockade was ineffective in the two patients in paired t-test. Differences in the mean were consid- whom it was tried. Two patients, ages 9 and 11 ered significant when the P value was 10.05. years, received amiodarone therapy for control of the SVT. After initial success with amiodarone, atrioventricular block occurred in one of these pa- Results tients. Amiodarone was withdrawn and flecainide initiated with a return of control of the tachycar- Symptoms. The clinical data are summarized in dia. The remaining two patients, ages 15 and 20 Table I. All patients complained of easy fatigabil- years, who had received digoxin and propranolol Table I. Clinical, Therapeutic, Biopsy, and Follow-up Data SVT Heart Duration of Duration of Current Duration Rate Early Conventional Subsequent Myocardial Subsequent Patient Age of SVT (bgm) Symptoms Treatment Therapy Treatment Biopsy Outcome Treatment I 9.3 years 3.5 years 140 fatigue, digoxin 2 years amiodarone Not available