Right bundle branch block, right precordial st-segment elevation, and sudden death in young people.

BACKGROUND: Patients with the ECG pattern of right bundle branch block and right precordial ST-segment elevation may experience sudden death in the setting of either arrhythmogenic right ventricular cardiomyopathy (ARVC) or a functional electrical disorder such as Brugada syndrome. METHODS AND RESULTS: Among a series of 273 young (

Clinical profile and long-term follow-up of 37 families with arrhythmogenic right ventricular cardiomyopathy.

OBJECTIVES: We sought to define the clinical picture and natural history of familial arrhythmogenic right ventricular cardiomyopathy (ARVC). BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy is a myocardial disease, often familial, clinically characterized by the impending risk of ventricular arrhythmias and sudden death. METHODS: Thirty-seven ARVC families of northeast Italy were studied. Probands had a histologic diagnosis of ARVC, either at autopsy (19 families) or endomyocardial biopsy (18 families). Protocol of the investigation included basal electrocardiogram (ECG), 24-hour ECG, signal-averaged ECG, stress test and two-dimensional Doppler echocardiography. Invasive evaluation was performed when deemed necessary. RESULTS: Of the 365 subjects, 151 (41%) were affected, 157 (43%) were unaffected, 17 (5%) were healthy carriers, and 40 (11%) were uncertain. Mean age at diagnosis was 31+/-13 years. By echocardiography, 64% had mild, 30% had moderate, and 6% had severe form. Forty percent had ventricular arrhythmias, 49 were treated with antiarrhythmic drugs, and two were treated with implantable cardioverter defibrillators. Sport activity was restricted in all. Of the 28 families who underwent linkage analysis, 6 mapped to chromosome 14q23-q24, 4 to 1q42-q43, and 4 to 2q32.1-q32.3. No linkage with known loci was found in four families and 10 had uninformative results. During a follow-up of 8.5+/-4.6 years, one patient died (0.08 patient/year mortality), and 15 developed an overt form of ARVC. CONCLUSIONS: Arrhythmogenic right ventricular cardiomyopathy is a progressive disease appearing during adolescence and early adulthood. Systematic evaluation of family members leads to early identification of ARVC, characterized by a broad clinical spectrum with a favorable outcome. In the setting of positive family history, even minor ECG and echocardiographic abnormalities are diagnostic.

Clinical diagnosis and management strategies in arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease, often familial, that is characterized by fibro-fatty replacement of the right ventricular (RV) myocardium. The most common clinical manifestations of ARVC consists of ventricular arrhythmias of RV origin, which may lead to sudden death mostly in young people and athletes, electrocardiograph depolarization/repolarization changes mostly localized to right precordial leads, and global and/or regional dysfunction and structural alterations of the RV. The diagnosis of ARVC may be difficult due to several problems with the specificity of the electrocardiograph abnormalities, the different potential etiologies of ventricular arrhythmias with a left bundle branch morphology, the assessment of the RV structure and function, and the interpretation of endomyocardial biopsy findings. Therefore, standardized diagnostic criteria have been proposed by the Study Group on ARVC of the European Society of Cardiology. According to these guidelines, the diagnosis of ARVC is based on the presence of major and minor criteria encompassing electrocardiograph, arrhythmic, morphofunctional, histopathologic, and genetic factors. Because the assessment of sudden death risk in patients with ARVC is still not well established, there are no precise guidelines to determine which are the patients who need to be treated and which is the best management approach. The therapeutic options include beta blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator. The implantable defibrillator is the most effective safe-guard against arrhythmic sudden death. However, its precise role in changing natural history of ARVC by preventing sudden and nonsudden death needs to be evaluated by a prospective study of a large series of patients. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In case of refractory congestive heart failure, the patients may become candidates for heart transplantation.

Signal-averaged electrocardiogram in patients with arrhythmogenic right ventricular cardiomyopathy and ventricular arrhythmias.

OBJECTIVE: The aim of the study was to assess the prevalence, sensitivity, specificity and predictive value of the signal-averaged ECG in patients with arrhythmogenic right ventricular cardiomyopathy and different forms of ventricular arrhythmias. METHODS: The signal averaged ECG in 138 patients and 146 healthy subjects (control group), using a three bandpass filter system (25-250, 40-250, 80-250 Hz), was considered abnormal when at least two parameters were abnormal at each filter setting. Patients were divided into three groups according to the extent of the right ventricular enlargement (mild, moderate, extensive), and into five groups according to the type of ventricular arrhythmia. RESULTS: The signal averaged ECG was abnormal in 57% of the patients and in 4% of the healthy subjects. The sensitivity was 57%, specificity 95% and positive predictive value 92%. The signal averaged ECG was abnormal in 94.4% of patients with the extensive form of the disease, in 77.7% of patients with the moderate form and in 31.8% of patients with the minor form, demonstrating good correlation with the extent of the disease. According to the type of ventricular arrhythmia, a higher correlation was found between signal averaged ECG abnormality and sustained ventricular tachycardia with superior axis (94.4%, P<0. 02); the correlation for the other arrhythmias varied from 16.6% to 55.8%. CONCLUSION: There is a closer correlation between the signal averaged ECG and extent of disease than with the presence of ventricular arrhythmias. The signal averaged ECG is not helpful in diagnosing minor forms of the disease, but since it is a non-invasive method, it may be useful in evaluating progression of the disease.

Late potentials and ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy.

We studied 38 patients (mean age 32 +/- 14 years) with arrhythmogenic right ventricular cardiomyopathy (ARVC) to evaluate the clinical significance of histologic features on endomyocardial biopsy specimens as related to signal-averaged electrocardiography (SAECG), spontaneous ventricular arrhythmias, and hemodynamic features. Fifteen patients presented with ventricular tachycardia or fibrillation (sustained ventricular arrhythmias), 23 with other minor arrhythmias. SAECG variables and right ventricular ejection fraction (RVEF) were statistically correlated with the extent of myocardial fibrosis on biopsy in ARVC. An increased percentage of fibrous tissue (> or = 30%) was a significant univariate predictor of late potentials (p = 0.004) and reduced RVEF (p = 0.02). The 18 patients with late potentials had an increased percentage of fibrous tissue (p = 0.01), a reduced RVEF (p = 0.0004), and a higher risk for sustained ventricular arrhythmias (p = 0.05) than the 20 patients without late potentials. RVEF was the most powerful predictor of late potentials (p = 0.004) at multivariate analysis. Moreover, RVEF < or = 50% was associated with an increased risk for development of sustained ventricular arrhythmias (p = 0.02). A SAECG parameter, namely the root-mean-square voltage of the terminal 40 ms at 25 Hz, was an independent predictive factor for the occurrence of sustained ventricular arrhythmias (p = 0.02). Although fibrous tissue may contribute to delayed myocardial activation in ARVC, a reduced RVEF plays an essential role for spontaneous manifestation of sustained ventricular arrhythmias.

Familial cardiomyopathy underlies syndrome of right bundle branch block, ST segment elevation and sudden death.

OBJECTIVES: We sought to assess whether structural heart disease underlies the syndrome of right bundle branch block, persistent ST segment elevation and sudden death. BACKGROUND: Ventricular fibrillation and sudden death may occur in patients with a distinctive electrocardiographic (ECG) pattern of right bundle branch block and persistent ST segment elevation in the right precordial leads. METHODS: Sixteen members of a family affected by this syndrome underwent noninvasive cardiac evaluation, including electrocardiography, Holter ambulatory ECG monitoring, stress testing, echocardiography and signal-averaged electrocardiography; two patients had electrophysiologic and angiographic study. Endomyocardial biopsy was performed in one living patient, and postmortem examination, including study of the specialized conduction system, was performed in one victim of sudden death. RESULTS: Five years before a fatal cardiac arrest, the proband had been resuscitated from sudden cardiac arrest due to recorded ventricular fibrillation. Serial ECGs showed a prolonged PR interval, right bundle branch block, left-axis deviation and persistent ST segment elevation in the right precordial leads, in the absence of clinical heart disease. Postmortem investigation disclosed right ventricular dilation and myocardial atrophy with adipose replacement of the right ventricular free wall as well as sclerotic interruption of the right bundle branch. A variable degree of right bundle branch block and upsloping right precordial ST segment was observed in seven family members; four of the seven had structural right ventricular abnormalities on echocardiography and late potentials on signal-averaged electrocardiography. A sib of the proband also had a prolonged HV interval, inducible ventricular tachycardia and fibrofatty replacement on endomyocardial biopsy. CONCLUSIONS: An autosomal dominant familial cardiomyopathy, mainly involving the right ventricle and the conduction system, accounted for the ECG changes and the electrical instability of the syndrome.

Arrhythmogenic right ventricular cardiomyopathy in young versus adult patients: similarities and differences.

OBJECTIVES: This study was designed to evaluate and compare the patterns of arrhythmogenic right ventricular cardiomyopathy in young people and adults. BACKGROUND: Few data are available on this cardiomyopathy in young people because clinical and morphologic findings considered pathognomonic are normally based on observations in adults. However, a familial occurrence with a probable genetic transmission led to the study of children and to early detection of this disease, in which sudden death has been reported even in young people. METHODS: Seventeen young patients with arrhythmogenic right ventricular cardiomyopathy diagnosed at a mean age +/- SD of 14.9 +/- 4.9 years were studied. Clinical, electrocardiographic, echocardiographic, cineangiographic and biopsy findings were compared with those of 19 adult patients whose condition was diagnosed at a mean age of 38.1 +/- 13.4 years. RESULTS: Syncope occurred in 23.5% of the young patients but in none of the adults (odds ratio of familial sudden death 5.54, p = 0.1). Ventricular couplets (odds ratio 16.0, p = 0.004) and subtricuspid bulging on echocardiography (odds ratio 5.95, p = 0.036) were prevalent in the young group. Cineangiographic data in the two groups were similar, except that more hypokinetic areas were found in adults (odds ratio 4.44, p = 0.05). Morphometric analysis of biopsy sections showed a greater amount of fibrous tissue in the young patients (p = 0.04) and a prevalence of fatty tissue in the adults (odds ratio 12, p = 0.005). During an equivalent follow-up time (mean 7 years), two young patients died suddenly, and two had ventricular fibrillation in the absence of antiarrhythmic therapy. CONCLUSIONS: The pathognomonic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in adults are also valid for young people. Sudden or aborted death occurred frequently in young untreated patients.

Correlation between cardiac involvement and CTG trinucleotide repeat length in myotonic dystrophy.

OBJECTIVES: Because sudden death due to complete atrioventricular (AV) block or ventricular arrhythmias is the most dramatic event in myotonic dystrophy, we assessed the relation of cardiac disease to cytosine-thymine-guanine (CTG) triplet mutation in adults affected with myotonic dystrophy. BACKGROUND: The myotonic dystrophy mutation, identified as an unstable deoxyribonucleic acid (DNA) sequence (CTG) prone to increase the number of trinucleotide repeats, produces clinical manifestations of the disease in skeletal muscle, the heart and many organ systems. METHODS: Forty-two adult patients underwent electrocardiography and echocardiography; in addition, signal-averaging electrocardiography was performed in 22, and 24-h Holter monitoring was recorded in 32. The diagnosis was established by neurologic examination, electromyography, muscle biopsy and DNA analysis. The patients were then classified into three subgroups on the basis of the number of CTG trinucleotide repeat expansions: E1 = 18 patients with 0 to 500 CTG repeats; E2 = 12 patients with up to 1,000 repeats; E3 + E4 = 10 patients with up to 1,500 repeats and 2 patients with > 1,500 repeats. RESULTS: The incidence of normal electrocardiographic (ECG) results was found to be significantly different in the three subgroups (55%, 50%, 17% in E1, E2, E3, + E4, respectively, p = 0.04), with the highest values in the group with fewer repeat expansions. The incidence of complete left bundle branch block was also significantly different among the groups (5% in E1, 0% in E2, 42% in E3 + E4 p = 0.01) and was directly correlated with the size of the expansion. A time-domain analysis of the signal-averaged ECG obtained in 12 patients in E1, 4 in E2, 5 in E3 and 1 in E4 showed that abnormal ventricular late potentials were directly correlated with CTG expansion (33% in E1, 75% in E2, 83% in E3 + E4, p = 0.05). Moreover, the incidence of ventricular couplets or triplets showed a positive correlation with size of CTG expansion (0 in E1, 0 in E2, 29% in E3 + E4, chi square 0.02). CONCLUSIONS: Our findings suggest that the involvement of specialized cardiac tissue, accounting for severe AV and intraventricular conduction defects, is related to CTG repeat length. In addition, the presence of abnormal late potentials directly correlates to CTG expansion. Abnormal late potentials, caused by slowed and fragmented conduction through damaged areas of myocardium, represent a substrate for malignant reentrant ventricular arrhythmias. In the future, therefore, molecular analysis of DNA should identify patients with cardiac disease at high risk for development of AV block or lethal ventricular arrhythmias.

The gene for arrhythmogenic right ventricular cardiomyopathy maps to chromosome 14q23-q24.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVD) is a dominantly inherited disorder progressively affecting the myocardium and it is one of the major causes of juvenile sudden death. The chromosomal localization of the disease gene is reported here for the first time. A maximum lod score of 6.04 was obtained at theta = 0 for linkage with the polymorphic marker D14S42 (14q23-q24) in two families, one of which has 82 subjects (19 affected) in four generations. The pre-symptomatic identification of ARVD carriers by linkage analysis in the affected families strongly increases the possibility of prevention of life-threatening complications.

Cardiac involvement in Becker muscular dystrophy.

OBJECTIVES: The purpose of this study was to assess the incidence of myocardial involvement and the relation of cardiac disease to the molecular defect at the deoxyribonucleic acid (DNA) or protein level in Becker muscular dystrophy. BACKGROUND: Dystrophin gene mutations produce clinical manifestations of disease in the heart and skeletal muscle of patients with Becker muscular dystrophy. METHODS: Thirty-one patients underwent electrocardiographic and echocardiographic examination and 24-h Holter monitoring. The diagnosis was established by neurologic examination, dystrophin immunohistochemical assays or Western blot on muscle biopsy, or both, and DNA analysis. RESULTS: Electrocardiographic and echocardiographic findings were abnormal in 68% and 62% of the patients, respectively. Right ventricular involvement was detected in 52%. Left ventricular impairment was observed either as an isolated phenomenon (10%) or in association with right ventricular dysfunction (29%). Right ventricular disease was manifested in the teenagers, and an impairment of the left ventricle was observed in older patients. Right ventricular end-diastolic volumes were significantly increased compared with those in a control group. The left ventricular ejection fraction was significantly lower in older patients than in control subjects or younger patients. Life-threatening ventricular arrhythmias were detected in four patients. No correlations were found between skeletal muscle disease, cardiac involvement and dystrophin abnormalities. In our patients, exon 49 deletion was invariably associated with cardiac involvement. Exon 48 deletion was associated with cardiac disease in all but two patients. CONCLUSIONS: The cardiac manifestation of Becker muscular dystrophy is characterized by early right ventricular involvement associated or not with left ventricular impairment. Exon 49 deletion is associated with cardiac disease.

Right ventricular cardiomyopathy in identical and nonidentical young twins.

We describe the first sets of identical and nonidentical twins with right ventricular cardiomyopathy (RVC). Pair A: A 12-year-old boy was referred because of palpitation and syncope. Clinical and instrument examinations revealed an enlarged and depressed right ventricle (end-diastolic volume = 110 ml/m2; ejection fraction = 44%), spontaneous ventricular tachycardia, and fatty-fibrous infiltrates in the biopsy specimens. His asymptomatic, monozygotic twin showed localized involvement of the right ventricle with isolated, ventricular extrasystoles. Pair B: These 18-year-old nonidentical twin boys showed diffuse right ventricular involvement (end-diastolic volume = 110 ml/m2 and 114 ml/m2; ejection fraction = 30% and 24%, respectively), induction of sustained and nonsustained ventricular tachycardia, respectively, and fibrosis on endomyocardial biopsy. One of the boys died suddenly at rest after documented ventricular fibrillation. These cases support the hypothesis of a genetic etiology with a minor role for genotype and point to the important influence of environmental factors in determining the clinical features of the disease.

Clinical profile of concealed form of arrhythmogenic right ventricular cardiomyopathy presenting with apparently idiopathic ventricular arrhythmias.

In 24 subjects presenting with apparently idiopathic ventricular arrhythmias, a final diagnosis of arrhythmogenic right ventricular cardiomyopathy was formulated following global evaluation of the clinical, cross-sectional echocardiography and angiographic findings, and the observation of myocardial atrophy with fibrous-fatty substitution in right ventricular endomyocardial biopsy. All patients had good effort tolerance, and a normal cardiac silhouette. Ventricular arrhythmias with a left bundle branch block pattern were present in 23 cases (sustained ventricular tachycardia, nonsustained ventricular tachycardia, ventricular couplets, and ventricular premature complexes); 1 patient experienced an episode of ventricular fibrillation. A nearly constant electrocardiographic feature was T wave negativity in the right precordial leads. Cross-sectional echocardiography and hemodynamic studies showed that right ventricular impairment consisted only of localized structural and dynamic abnormalities; in a few cases the left ventricle was segmentally involved. Familial occurrence was present in 29% of the cases. No case of sudden death was observed during follow-up. These findings confirm that the concealed form of arrhythmogenic right ventricular cardiomyopathy is a cause of so-called "idiopathic" ventricular arrhythmias in subjects with apparently "normal hearts". Echocardiographic and angiographic investigations may lead to the correct diagnosis.

Arrhythmia development in a young subject with right ventricular cardiomyopathy (right ventricular dysplasia).

In right ventricular cardiomyopathy the relationship between the progression of structural abnormalities and arrhythmia development is not yet well known. This report describes a case in which severe ventricular arrhythmias appeared 3 years after the demonstration of right ventricular (RV) structural and dynamic abnormalities. In this interval of time structural changes were not detectable with the commonly used diagnostic methods, but endocavitary RV late fractionated QRS potentials appeared suggesting the development of an arrhythmic component of the disease.

Coexistence of kent accessory pathway, enhanced AV node conduction, and various conduction disturbances in a young athlete with tricuspid valve dysplasia.

An asymptomatic 19-year-old top-level athlete had electrocardiographic evidence of intermittent cardiac preexcitation and intermittent left bundle branch block. The electrophysiologic study demonstrated the presence of a direct accessory pathway and enhanced atrioventricular node conduction that resulted in infrahisian and intraventricular conduction disturbances. The echocardiogram disclosed tricuspid valve dysplasia.

Electrical instability in patients undergoing surgery for atrioventricular septal defect.

Postoperative 24-hour Holter monitoring was performed in 106 patients with atrioventricular septal defect in order to identify the incidence of atrial and ventricular arrhythmias. Of the patients, 72 had separate atrioventricular orifices, including 13 with a small ventricular component to the defect, and 34 patients had a common atrioventricular orifice. Two groups of abnormal patients were found. First, patients with good electrical stability characterized by isolated atrial (9 patients) and ventricular (25 patients) extrasystoles falling in classes I and II of Lown. Second, patients with marked electrical instability characterized in one patient by repetitive atrial extrasystoles, in another by atrial flutter, in 2 by polymorphic ventricular extrasystole and in 8 by couplets or triplets. Electrical instability in individual patients was then compared, by means of logistic regression analysis, with operative, surgical and postoperative variables. There was no incidence of sudden death in our series. After surgical repair, ventricular arrhythmias were more frequent than atrial arrhythmias (33% vs. 10%) and were unrelated to the type of atrioventricular septal defect. Cardiac electrical instability after operation was significantly related to larger operative body size, higher postoperative end diastolic diameter of the right ventricle, larger size of the ventricular septal defect, coexistence of postoperative right bundle branch block and left anterior hemiblock. Conversely, the risk of arrhythmias was reduced by more recent operative data and by greater shortening fraction of the left ventricle.

[Analysis of the mode of transmission of right ventricular dysplasia]. / Analyse du mode de transmission de la dysplasie ventriculaire droite.

A formal analysis of the mode of transmission of right ventricular cardiomyopathy was performed in seven families with this condition. Ninety-six subjects (81 family members, 15 connected) were studied. The index cases were family members who had died suddenly in their youth with autopsy evidence of massive fibrous-adipose right ventricular myocardial replacement. Pedigree analysis showed that 58 per cent of the family members were affected, with a male predominance (63% of men vs 53% of women). The kindreds were all normal and in none of the families were both parents affected. Carrier states were observed in both males and females and vertical transmission was demonstrated. Clinically, the disease was very variable with some cases showing widespread right ventricular involvement with or without cardiomegaly, and other cases showing localised right ventricular abnormalities. These data are consistent with a congenital disease with an autosomal dominant mode of inheritance with incomplete penetrance and variable expression.

[Electro-vectorcardiographic study of ventricular extrasystole in arrhythmogenic dysplasia of the right ventricle]. / Etude électro-vectocardiographique des extrasystoles ventriculaires dans la dysplasie arythmogène du ventricule droit.

The morphology of ventricular extrasystole (VES) in 46 cases of arrhythmogenic dysplasia of the right ventricle (ADRV) was correlated with the point of origin located by intracavitary mapping. The cases concerned 41 of left bundle-branch block (LBB) with various axes on the frontal plane (FP), 4 of right bundle-branch block (RBB), and 5 of atypical morphology (frontal plane shifted inferiorly and increased R from V1 to V6; on the horizontal plane, clockwise rotation of the loop oriented anteriorly and leftward). There is a good correlation with the site of origin: VESs which were LBB in appearance originated in the right ventricle (apex, septum, infundibulum); VESs which were RBB in appearance originated in the apex of the left ventricle, while the atypical VESs started in the upper posterior septum. A study of morphology may therefore also give an indication of the location of the disease.

Ventricular fibrillation without apparent heart disease: description of six cases.

Since 1977, six patients (five males and one female), aged 14 to 35 years, resuscitated from ventricular fibrillation, were referred to our department for detailed evaluation, after exclusion of major cardiac pathologic conditions. Four patients had a family history of heart disease. Basic ECGs showed sinus rhythm in all of them. PR interval was prolonged in one. Two patients had complete and one had incomplete right bundle branch block. One patient had inverted t waves in V1-3 and late potentials. Three had an upsloping ST-T segment elevation in V1-2. The cardiothoracic index was less than 0.5 in five and 0.50 in one. In one of the five patients studied, the clinical episode of ventricular fibrillation was reproduced by stimulation of the right ventricular outflow tract during electrophysiologic study. Results of cross-sectional echocardiography and angiography showed predominantly structural and wall motion abnormalities of the right ventricle in five patients and slight wall motion abnormalities of the left ventricle in two. Two patients also had mitral and tricuspid valve prolapse. Coronary arteries were normal in all five patients examined. Results of endomyocardial biopsy showed no abnormalities in one patient, fibrosis in two, and fibrolipomatosis in one. Two patients died during follow-up: autopsy was performed in one and results showed right ventricular cardiomyopathy. Thus in five of these selected patients with apparent idiopathic ventricular fibrillation, some abnormalities, predominantly of the right ventricle, were documented only after detailed investigation; however, clinical history and some nonspecific ECG abnormalities were factors in the diagnostic procedure.

Right ventricular dysplasia: a familial cardiomyopathy?

268 preselected subjects were extensively studied and the diagnosis of right ventricular dysplasia (RVD) was made in 108 living and 18 deceased patients, 35% of cases being familial. Subsequently we studied 72 subjects from nine families in which a case of sudden death had occurred with the autoptic diagnosis of RVD. In 42 out of 72 cases the autoptic (11 patients), clinical-echocardiographic (30 patients) and haemodynamic (15 patients) data supported the diagnosis of RVD. In all but one deceased patient, death was sudden, while in all the living family members we observed ventricular arrhythmias, mostly with left bundle branch block morphology. Both manifest and concealed forms were documented with polymorphic presentation and with clinical-pathologic findings similar to the non-familial RVD cases. This study confirms the presence of a familial form of RVD that is probably more frequent than previously thought. Preliminary data seem to indicate an autosomal dominant inheritance with incomplete penetrance and variable expression.

Isolated episode of exercise-related ventricular fibrillation in a healthy athlete.

A 19-year-old man had a documented ventricular fibrillation during a football match. He was a top-level athlete, and after successful resuscitation, he was extensively studied. Electrolytic disturbances, long QT syndrome and nervous mechanisms were all ruled out. Right and left ventriculography, coronary angiograms, electrophysiologic study and endomyocardial biopsy all proved normal. A beta-blocker was empirically given in the absence of any reliable test to guide therapy more scientifically.