Transitory or permanent regular wide QRS complex tachycardia induced by atrial stimulation in patients without apparent heart disease. Significance

OBJECTIVES

The purpose of the study was to evaluate the frequency of transitory or permanent bundle branch block (BBB) associated with a paroxysmal tachycardia induced by atrial stimulation in patients without heart disease and its significance.

METHODS

Esophageal atrial stimulation was performed in 447 patients suspected to have supraventricular tachycardias (SVT). Sustained regular tachycardia was induced in all of them but three, either in control state (75%) or after administering isoproterenol. In 346 patients, only narrow complex SVTs were induced (77%); in 259 of them, the reentry occurred in the AV node and in remaining patients within a concealed accessory pathway. In 62 patients, a transitory functional BBB was recorded at the onset of the tachycardia (14%). In 33 of them, the reentry occurred in the AV node and in the remaining 29 patients within a concealed accessory pathway. In 36 patients (8%), a permanently wide QRS complex tachycardia was induced. Three patients had also inducible narrow complex SVT. Atrial pacing induced a BBB similar to the aberrancy in tachycardia in 22 patients: the reentry occurred in the AV node in 17 patients, within a concealed accessory pathway in three patients and in a Mahaim bundle in two patients. In other patients, QRS complex remained normal during atrial pacing: all 14 patients had a ventricular tachycardia (VT), either a verapamil-sensitive VT (n = 7) or catecholamine-sensitive VT (n = 4) or bundle branch reentry (n = 3). Followed from 2 to 12 years, the prognosis of these patients was excellent.

CONCLUSION

Transitory BBB at the onset of an SVT is noted in 14% of the population, is more frequent in patients with accessory pathway reentrant tachycardia, but is helpful for this diagnosis in only 12% of cases. A regular tachycardia with permanent left or right bundle branch morphology induced by atrial stimulation in a patient without heart disease and without BBB during atrial pacing is due to a VT even if this patient has also narrow complex tachycardias. This mechanism does not affect the excellent prognosis of this population.

Atrial fibrillation with a very rapid ventricular response as the first clinical arrhythmia in a 76-year-old man

The interest of electrohysiological study for the prognostic evaluation of asymptomatic Wolff-Parkinson-White (WPW) syndrome remains controversial. We report the case of an asymptomatic 67-year-old man without heart disease in whom a type A WPW syndrome was noted. Because the WPW was unchanged during exercise testing, transesophageal EPS was performed. In basal state, 1/1 conduction through the Kent bundle was noted up to a rate of 210 beats/min. After infusion of 30 microg of isoproterenol, atrial pacing was associated with a 1/1 conduction throughout the Kent bundle at a rate at 300 beats/min and induced rapid atrial fibrillation which was stopped by flecainide. No treatment was indicated. Nine years later, at age 76, the patient developed syncope related to rapid atrial fibrillation requiring cardioversion. In conclusion, the occurrence of a potentially lethal supraventricular tachyarrhythmia in a previously asymptomatic patient with WPW syndrome might be encountered in elderly patients. Transesophageal electrophysiological evaluation is a useful means to predict this risk.

Postoperative ventricular arrhythmias after cardiac surgery: immediate- and long-term significance

AF is frequent after cardiac surgery. However, ventricular arrhythmias are less known. The purpose of the study was to evaluate the causes and the prognostic significance of severe ventricular arrhythmias occurring after cardiac surgery. For 10 years, among 2,100 cardiac surgeries, 16 (0.8%) patients (13 men, 3 women; age 49-71 years, mean 62 +/- 9 years) without previous ventricular arrhythmias, with preserved left ventricular ejection fraction, and without acute cause of ventricular arrhythmias, developed VF (n = 4) or a sustained VT between 3 days and 3 weeks after cardiac surgery (coronary artery bypass grafting [n = 6], valve replacement [n = 10]). Rapid AF (n = 5) or slow AF (n = 1) were present at the time of VT/VF. Programmed ventricular stimulation occurred after up to three extrastimuli in the basal state and after infusion of 20-30 micrograms of isoproterenol. An echocardiogram, coronary angiography, Holter monitoring with heart rate variability (HRV) study were performed. Ventricular stimulation was negative in six patients (with AF); sustained and clinical VT was induced in 10 patients with a left ventricular ejection fraction > 0.40, except in one patient. Valvular prothesis and coronary bypass graftings were normal. In all patients, HRV was normal before surgery and decreased after cardiac surgery; before versus after surgery, respectively, HR 69 +/- 9 and 89 +/- 30 beats/min (P < 0.01), SDNN 117 +/- 31 and 50 +/- 11 ms (P < 0.001), low frequency (LF) 474 +/- 658 and 51 +/- 40 ms2 (P < 0.05), high frequency (HF) 115 +/- 23 and 33 +/- 32 ms2 (P < 0.05), LF:HF 4 +/- 3 and 1 +/- 0.6 (P < 0.01). Follow-up lasted from 6 months to 10 years (mean 3 +/- 2 years). In patients without induced VT, 1 patient died from asystole, 1 had an ICD but no subsequent events, and the other 4 untreated patients are free of events. Patients with induced VT were treated with amiodarone and beta-blockers except in one patient who died from extracardiac complications. Six of nine patients had no inducible VT with this treatment and are alive; 3 patients had inducible VT, 1 died suddenly before implantation of ICD, and 2 patients are alive with an ICD; recurrent VTs were noted in one patient and received an ICD. In conclusion, recent heart surgery may increase the risk of ventricular arrhythmias. The reduction of indexes reflecting sympathetic and parasympathetic tone could facilitate the occurrence of atrial arrhythmias (and then VT) in patients without ventricular arrhythmogenic substrate or the development of VT/VF in patients with a latent previous ventricular arrhythmogenic substrate. In patients without inducible VT, the prognosis is excellent and an ICD is not recommended in these patients. In those with inducible VT, there is a high incidence of responders to antiarrhythmic drugs with a favorable prognosis.

Age-related changes in arrhythmias and electrophysiologic properties

There are few data on the relationships between age and arrhythmias, except for the Wolff-Parkinson-White syndrome. In clinical practice, the most frequent arrhythmia is the atrial fibrillation (AF). It is well-known, that the prevalence of AF increases with age from 2 to 4% before 70 years up to 9 to 15% in patients older than 80 years. However, it is unknown if the increased prevalence of AF is related to the increase of the cardiac and extracardiac diseases, noted in the elderly, or to atrial electrophysiological changes. Probably, the incidence and mechanism of arrhythmia do not differ between adults and elderly patients when the other clinical data are similar. Arrhythmias in elderly patients represent most of the urgencies, consultations or hospitalizations. They could become more and more frequent because we now know that the management of most of these elderly patients should be identical to that of younger patients. However, the treatment frequently is difficult. The difficulties in elderly patients are due to the associated non-cardiac and cardiac diseases which are more frequent than in adults. Therefore, the quality of management should be particularly careful in elderly patients.

[Characteristics and causes of death in 283 patients with implanted defibrillators]

The implantable automatic defibrillator has proved its superiority over pharmacological treatments for preventing mortality by serious ventricular arrhythmia. We studied the cause of death in a population of 283 consecutive patients implanted between February 1988 and December 2000 (age at implantation: 58 +/- 14.7 years; extremes: 15-78 years, 45 females, ejection fraction: 0.39 +/- 0.15) and followed up over a median of 25 months (extremes = 1 day-163 months).

RESULTS

At the end of follow up, 55 patients had died (average age: 62.7 +/- 12.6 years, extremes: 15-79 years, 7 females). All except 2 had a cardiopathy: ischaemic cardiopathy (n = 38, 36 IDDM), dilated cardiomyopathy (n = 14), arrhythmogenic dysplasia of the right ventricle (n = 1). The median interval between implantation and death was 35 months (extremes = 1 day-137 months). The causes of death were the following: cardiac insufficiency (n = 24), refractory arrhythmias (n = 13), other cardiac causes (n = 8), extra-cardiac pathologies (n = 10). The deceased patients had presented an average of 86.6 +/- 23.4 ventricular arrhythmias (extremes = 0-1309) but 18 of them (33%) did not present any during follow up.

CONCLUSIONS

Cardiac insufficiency is the prime cause of death in refractory arrhythmias; on patient in 4 dies from ventricular arrhythmia, despite the defibrillator and one deceased patient in 3 had no arrhythmia during follow up.

[Treatment with lepirudin in heparin-induced thrombocytopenia. A case report]

We report the case of a 71 old woman presenting a bilateral massive pulmonary embolism with intraventricular right thrombus complicating heparin induced thrombocytopenia (HIT) persistent after one month of conventional anticoagulant processing. We underline the effectiveness of lepirudin (Refludan) in the curative processing of pulmonary embolism allowing here to avoid a complex surgical thromboembolectomy. We evoke the place of this molecule in the curative therapeutic strategy of HIT with thrombotic phenomena.

[Syncope in patients with normal EKG and without cardiac disease: value of ambulatory esophageal electrophysiology in determining etiology]

The aim of this study was to determine whether ambulatory oesophageal electrophysiological recordings are valuable in identifying the cause of syncope in patients with a normal ECG and without cardiac disease. One hundred and forty-five patients aged 16 to 88 years of age, without cardiac disease, and with a normal ECG without a documented arrhythmia, were examined for unexplained syncope: 55 patients complained of palpitations at the time of syncope. The electrophysiological study was carried out in the clinic with oesophageal recordings using a classical protocol: Wenckebach point and sinus node recovery time were determined; programmed atrial stimulation was used with delivery of 1 and 2 extra-stimuli on the basal rhythm and with 20/30 micrograms infusion of isoprenaline; blood pressure was monitored. The study was negative in 41 patients (28%). Sinus node dysfunction was observed in 9 patients (6%). A vaso-vagal reaction reproducing the symptoms was induced by isoprenaline in 21 patients (14.5%); a conduction defect was revealed in 2 cases (1%). Atrial fibrillation or tachycardia > 1 minute was induced in 22 patients (15%). Paroxysmal junctional tachycardia was induced in 50 patients (35%). Patients with a negative study were younger than those with sinus node dysfunction or atrial fibrillation (44 +/- 21, 71 +/- 9 and 63 +/- 14 years respectively). Treatment was guided by these results: cardiac pacing, antiarrhythmic therapy or radiofrequency ablation of the reentrant pathway were indicated and suppressed syncope in all but two patients. The authors conclude that electrophysiological studies in the out-patient clinic with oesophageal recordings is a safe, rapid and economic method of detecting arrhythmias (sinus node dysfunction or supraventricular tachycardia) in 60% of patients with syncope, especially if they have symptoms of palpitations.

[Antiarrhythmic drugs in atrial fibrillation]

Antiarrhythmic drugs in atrial fibrillation are relatively old and have well-specified indications. Class I antiarrhythmic drugs (IA: quinidine, disopyramide; IC: cibenzoline, flecainide, propafenone) are first indicated in patients without history of myocardial infarction and heart failure. In this last case, a b-blocker or amiodarone are indicated. Amiodarone is also indicated after failure of class I antiarrhythmic drugs. The association of class I antiarrhythmic drugs or amiodarone with a small dose of b-blocker is suitable if possible. However, the association of amiodarone with half-dose of a class I antiarrhythmic drug should remain rare, because the prognosis of chronic atrial fibrillation is unknown; the benefits to risks ratio of antiarrhythmic treatment should be discussed for each patient.

Absence of change of signal-averaged electrocardiogram identifies patients with ventricular arrhythmias who are non-responders to amiodarone

OBJECTIVES

The aim of this study was to assess the ability of a non-invasive study, the signal-averaged ECG (SAECG), to predict the effect of amiodarone at ventricular level.

BACKGROUND

Amiodarone is the main drug drug used in the treatment of ventricular arrhythmias. Standard ECG does not detect any change in QRS complex resulting from amiodarone therapy. SAECG is more sensitive than ECG for detecting changes in QRS complex.

METHODS

The study examined the effects of amiodarone on SAECG in relation to the results of programmed ventricular stimulation in 68 patients with old myocardial infarction, spontaneous and inducible sustained ventricular tachycardia (VT).

RESULTS

Amiodarone prolonged the total QRS duration (dur) (129+/-28 vs. 140+/-30 ms, P<0.05) and low amplitude signal (LAS) dur (45+/-20 vs. 51+/-20 ms, P<0.1), whereas the root-mean-square voltage of the last 40 ms of QRS complex (RMS 40) was significantly reduced (20+/-16 vs. 14+/-9 microV, P<0.05). Changes in SAECG parameters did not differ significantly in patients in whom amiodarone prevented the inducibility of VT (n=15) and those in whom VT remained inducible with amiodarone (n=53), but in baseline QRS duration was significantly shorter in patients in whom amiodarone prevented the VT induction (118+/-26 vs. 133+/-28 ms, P<0.05). In patients in whom amiodarone did not prolong the cycle length of VT (n=15), SAECG did not change significantly (QRS dur 131+/-29 vs. 132+/-27 ms, LAS 42+/-20 vs. 42+/-19 ms, RMS 40 22+/-14 vs. 19+/-11 microV). Comparison of the SAECG data in patients with no inducible VT and those with slowed VT differed significantly (P<0.05) between the control state and the recording with amiodarone.

CONCLUSIONS

The effects of amiodarone on VT inducibility are predicted by a shorter baseline QRS duration and the degree of drug-induced prolongation of filtered QRS duration. Amiodarone prolonged the QRS duration, LAS duration and decreased RMS 40; this effect was more important in patients with no inducible VT and in those with only slowed VT, than in patients with unchanged or accelerated VT. The absence of changes of QRS duration predicted the induction of a more rapid or not slowed VT with amiodarone with a sensitivity of 87% and a specificity of 83%. Therefore, SAECG appears as an useful and simple means to predict the effects of amiodarone in patients with myocardial infarction and VT.

[Does radiofrequency ablation of the slow pathway prevent atrial fibrillation in cases of re-entrant intranodal junctional tachycardia?]

The aim of this study was to assess the effects of ablation of the slow pathway on the eventual occurrence of atrial fibrillation (AF) in cases of intranodal junctional tachycardia (INJT). Two hundred and fifty seven patients were admitted for recurrent paroxysmal junctional tachycardia. The ages ranged from 15 to 87 years (average 54 +/- 16 years). Tachycardia was induced in all patients and the mechanism shown to be INJT in 215 patients. Twelve of these (6%) also had spontaneous paroxysmal AF. It was possible to induce INJT and AF in 23 patients during electrophysiological study (11%): of these patients, 4 had a history of AF associated with INJT. Radiofrequency ablation of the slow pathway was successfully carried out. Patients were followed up for 1 to 6 years (average 3 +/- 2 years). None were prescribed antiarrhythmic drugs. The results showed that of the 12 patients with spontaneous AF before ablation, 8 had recurrence of paroxysmal AF which required reintroduction of an antiarrhythmic treatment and a ninth patient is currently in chronic atrial fibrillation. All but one of the patients were over 65 years of age. The AF recurred 1 month to 4 years after ablation. Of the 19 patients without previous AF but with inducible AF, 2 developed spontaneous paroxysmal AF. Of the patients without previous AF and without inducible AF, 4 aged over 65 went on to develop paroxysmal AF. The authors conclude that radiofrequency ablation of the slow pathway of patients with INJT does not seem to prevent future development of AF in elderly subjects.

[Does radiofrequency ablation of the bundle of Kent results in a lower risk of atrial fibrillation?]

Radiofrequency ablation of the Bundle of Kent is a common method of treating malignant forms of the Wolff-Parkinson-White syndrome and the paroxysmal junctional tachycardia which may complicate this condition. The aim of this study was to investigate the effects of ablation of a latent or patent Bundle of Kent on the prevention of atrial fibrillation. One hundred and thirty eight patients aged 15 to 81 years of age with one or more patent (Group I) (n = 96) or latent Bundles of Kent (Group II) (n = 42) underwent successful ablation of the Bundle of Kent. Five patients in Group I (5%) and 4 in Group II (9.5%) had spontaneous paroxysmal atrial fibrillation before ablation. During electrophysiological investigation, AF was induced in 7 patients, 2 of whom had spontaneous AF in Group I and 3 in Group II. During follow-up (3 +/- 1 years), 3 patients of Group I went on to develop AF: 2 of them had never had the arrhythmia before: 4 patients of Group II, including 2 with previous AF, went on to develop AF. The risk of spontaneous AF was correlated to older ages. The authors conclude that persistence of the risk of spontaneous AF after ablation of a Bundle of Kent should be investigated especially in patients over 45 years of age.

Influence of age on the potential risk of sudden death in asymptomatic Wolff-Parkinson-White syndrome

Sudden death might be the first event in patients with asymptomatic WPW. The purpose of the study was to know if the age of the patient modifies the electrophysiological characteristics of asymptomatic WPW. Transesophageal stimulation was performed on 92 asymptomatic WPW patients from the following age groups: 10-69 years (n = 14), 20-29 years (n = 33), 30-39 years (n = 15), 40-49 years (n = 17), and 50-69 years (n = 13). The procedure consisted of atrial pacing up to the second AV block, programmed atrial stimulation using one and two extrastimuli delivered on two driven rhythms in the control state, and after infusion of isoproterenol. In thefive age groups, paroxysmal junctional tachycardia occurred, respectively, in 1 (7%), 1 (3%), 2 (13%), 2 (12%) patients, and not at all in the oldest group. AF > 1 minute occurred, respectively, in 3 (21%), 9 (27%), 5 (33%), 3 (18%), and 4 (31%) patients. The dangerous form of WPW (rapid conduction in the Kent bundle > 240/min in the control state or > 300/min after isoproterenol + AF induction) occurred, respectively, in 3 (21%), 9 (27%), 4 (27%), 1 (6%), and 3 (23%) patients. In conclusion, electrophysiological data of asymptomatic WPW are not modified by age of the patient. Elderly patients remain at risk of a dangerous form of WPW; systematic evaluation of WPWis recommended in patients with an active life independent of age.

[Indications of atrial fibrillation regularization in 2001]

The regularisation of the first episode of atrial fibrillation should be attempted. In the case of the second episode, the indication of the regularisation should be discussed according to the data of age, tolerance, objective haemodynamic effect, adequation to the treatment and possibilities of antiarrhythmic treatment. In fact, the prognosis of a correctly treated patient (with anticoagulants and slowing drugs) remaining in atrial fibrillation, does not seem to differ from those of a patient in sinus rhythm receiving antiarrhythmic drugs.

[Contribution of the transesophageal electrophysiologic study to the etiologic diagnosis of wide QRS tachycardia]

INTRODUCTION

A wide-QRS complex tachycardia is suggestive of a ventricular tachycardia (VT). Its diagnosis requires an intracardiac electrophysiological study. That study is sometimes difficult to indicate in old or very young patients. The purpose of the study was to evaluate the interest of a rapid and noninvasive study by transesophageal route for the evaluation of the nature of a wide-QRS complex tachycardia.

PATIENTS AND METHODS

Forty patients, aged from 16 to 85 years, without bundle branch block (BBB) in sinus rhythm, were admitted for documented wide-QRS tachycardia. Transesophageal electrophysiologic study (EPS) using one and two extrastimuli was performed in control state and after infusion of 20/30 micrograms of isoproterenol. Intracardiac EPS was performed in a second time in 38 of them.

RESULTS

The study was negative six patients; intracardiac EPS remained negative in four of them, induced a VT in one and a Mahaim-reentrant supraventricular tachycardia in another one. Clinical tachycardia was induced in remaining patients: in 27 of them, the diagnosis of SVT with aberrancy was assessed; in other patients, the diagnosis of VT was assessed; The VT was a verapamil-sensitive VT or a bundle branch reentry (n = 7). The diagnosis was confirmed by intracardiac study.

CONCLUSION

Esophageal EPS was a means to reproduce the clinical tachycardia in 34 of 40 patients and to evaluate the mechanism of wide-QRS tachycardia in 33 of 34 patients; this technique easy to perform should be indicated in patients in whom intracardiac study is debatable to avoid to diagnose by excess a VT or in the opposite to miss this diagnosis.

Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias

OBJECTIVES

The purpose of the study was to look for the predictor factors of atrial proarrhythmic effects of class I antiarrhythmic drugs.

BACKGROUND

Class I antiarrhythmic drugs may induce or exacerbate cardiac arrhythmias. The predictors of ventricular proarrhythmia are known. The predictors of atrial flutter with 1:1 conduction are unknown.

METHODS

Clinical history, EGG, signal-averaged EGG (SAECG) and electrophysiologic study were analysed in 24 cases of 1:1 atrial flutter with class I AA drugs and in 100 control patients without history of 1:1 atrial flutter with class I AA drugs.

RESULTS

The ages of patients varied from 46 to 78 years. Underlying heart disease was present in nine patients. The surface EGG revealed the presence of a short PR interval (PR<0.13 ms), visible in leads V5, V6 in eight (35%) patients with normal P wave duration; in other patients with prolonged P wave duration, PR seemed normaL On SAECG recording, there was a pseudofusion between P wave and QRS complex. The electrophysiologic study revealed some signs indicating a rapid AV nodal conduction (short AH interval or rate of 2nd degree AV block at atrial pacing >200 beats/mm) in 19 of the 23 studied patients. All patients, except one, had at least one sign indicating a rapid AV nodal conduction (short PR and/or P wave-QRS complex continuity on SAECG). In the control group, seven patients (7%) had a short PR interval (P<0.01) and 11 (11%) had a pseudofusion between P wave and QRS complex on SAECG (P<0.001). The P wave-QRS complex pseudofusion on SAECG had a sensitivity of 100% and a specificity of 89% for the prediction of an atrial proarrhythmic effect with class I antiarrhythmic drug.

CONCLUSION

We recommend avoiding class I AA drugs in patients with a short PR interval on surface EGG and to record SAECG in those with apparently normal PR interval to detect a continuity between P wave and QRS complex, which could indicate a rapid AV nodal conduction, predisposing to 1:1 atrial flutter with the drug.

Influence of age on the electrophysiological mechanism of paroxysmal supraventricular tachycardias

The purpose of this study was to evaluate the influence of age on the mechanism of paroxysmal supraventricular tachycardia (PSVT). Previous studies have shown age and sex differences between certain arrhythmias and especially changes in electrophysiological characteristics of Wolff-Parkinson-White syndrome. Four hundred and eighty five patients aged 9-86 years, with PSVT and without Wolff-Parkinson-White syndrome in sinus rhythm, were studied. The esophageal or intracardiac electrophysiological study used a standardized atrial pacing protocol. Paroxysmal junctional tachycardia was induced in 475 patients. The mechanism of tachycardia was not influenced by age and atrioventricular nodal reentrant tachycardia (AVNRT) was found as the main cause of PSVT in all ranges of age. Atrioventricular reentrant tachycardia (AVRT) using a concealed accessory pathway (AP) had a similar incidence from youth to elderly. The ratio male/female (M/F) and the inducibility of other arrhythmias (atrial flutter/fibrillation) (AF/AFl) were also found to be similar in all ranges of age. The age of the patients did not influence the mechanism of the tachycardia. Most of PVST were related to a AV nodal reentrant tachycardia. Concealed accessory pathway was identified with a similar incidence in young and old patients.

Incidence and mechanism of presyncope and/or syncope associated with paroxysmal junctional tachycardia

The objectives of this study were to: (1) define the incidence of presyncope and/or syncope in patients with paroxysmal junctional tachycardias, (2) determine their causes, and (3) determine the outcome of symptoms. Syncope is a frequent problem and is often caused by paroxysmal tachycardia. The mechanism of hemodynamic instability is unknown. The population study consisted of 281 patients, consecutively recruited because they had paroxysmal tachycardia and a sinus rhythm on a normal electrocardiogram. Fifty-two patients (group I) had presyncope and/or syncope associated with tachycardia. The remaining patients (group II) had no loss of consciousness. Transesophageal programmed atrial stimulation used 1 and 2 atrial extrastimuli, delivered in a control state, and if necessary, after infusion of 20 to 30 microg of isoproterenol. Arterial blood pressure was monitored. Vagal maneuvers and echocardiogram were performed in all patients. Paroxysmal tachycardia was induced in 51 group I patients and 227 group II patients. Comparisons of groups I and II revealed that age (50 +/- 21 vs 49 +/- 17 years), presence of heart disease (10% vs 10%), mechanism of tachycardia with a predominance of atrioventricular nodal reentrant tachycardia (70.5% vs 76%), and rate of tachycardia (196 +/- 42 vs 189 +/- 37 beats/min) did not differ between the groups. However, there were differences in both groups with regard to significantly higher incidences of positive vasovagal maneuvers (35% vs 4%, p <0.01), isoproterenol infusion required to induce tachycardia (55% vs 17%, p <0.001), and vasovagal reaction at the end of tachycardia (41% vs 4%, p <0.05). Thirty-seven group I patients underwent radiofrequency ablation of the reentrant circuit, which suppressed presyncope and/or syncope in 36 of the 37 patients. Thus, presyncope and/or syncope frequently complicated the history of patients with paroxysmal junctional tachycardia (18.5%). Several mechanisms are implicated, but vasovagal reaction was the most frequent cause. Treatment of the tachycardia typically suppressed presyncope and/or syncope.

Value of non-invasive and invasive studies in patients with bundle branch block, syncope and history of myocardial infarction

The prognosis of patients with bundle branch block (BBB) and myocardial infarction (MI) is poor, particularly for patients suffering from syncope. The purpose of this study was to investigate the diagnostic value of some techniques for the evaluation of the mechanism of syncope in patients with MI and BBB and their prognosis.

METHODS

We prospectively obtained the results of clinical history, 24 h Holter monitoring, left ventricular ejection fraction (LVEF), signal-averaged ECG (SAECG) and programmed ventricular stimulation in 130 patients with syncope, MI and BBB. 81 of them had right (R)BBB and 49-left (L)BBB.

RESULTS

Ventricular tachycardia (VT) was identified as the main cause of syncope in patients with MI and BBB: 68% of them had inducible VT. The sensitivity (se) and specificity (sp) of non sustained VT on Holter monitoring for the detection of VT were respectively 42.5 and 47% in patients with RBBB, 62 and 36% in those with LBBB; se and sp of LVEF <40% were 67.5% and 65% in patients with RBBB, 85 and 9% in those with LBBB; se and sp of the combination of 2 of the 3 SAECG criteria, QRS duration > 155 ms, LAS duration >30 ms and RMS 40 < 17 microV were respectively 50 and 57% in patients with RBBB; se and sp of the combination of 2 of the 3 criteria QRS duration >165 ms, LAS duration >40 ms and RMS 40 <17 microV were 73 and 55.5%) in patients with LBBB. During the follow-up (4.7 years +/- 2.5), 12 patients died suddenly and 12 patients died from heart failure. Univariate and multivariate analysis revealed than only the induction of VT was a significant predictor of sudden death. A long QRS duration (> 165 ms) and induction of VT were independent predictors of total cardiac mortality.

CONCLUSION

Among noninvasive studies, only the determination of filtered QRS duration was a significant predictor of cardiac mortality in the case of a prolongation (> 165 ms). Sudden death was only predicted by the induction of sustained VT. Because of the high incidence of inducible sustained VT, the low value of Holter monitoring and decreased LVEF for the prediction of ventricular arrhythmias and the poor prognosis of patients with inducible VT and low LVEF, systematic programmed ventricular stimulation is indicated in patients with MI, syncope and BBB, whatever the non-invasive studies results.

[Transformation of asymptomatic Wolff-Parkinson-White into a symptomatic form as a result of the ablation of the bundle of Kent]

We report the case of an asymptomatic young man, 19 years old, who had a Wolff-Parkinson-White syndrome. A form at risk of potentially severe arrhythmias was detected by the electrophysiological study. The Kent bundle radiofrequency ablation was performed with success. However the patient developed few weeks after, spontaneous paroxysmal junctional tachycardias. Such report indicates that we should remain careful in asymptomatic patients.

Paroxysmal tachycardia in children and teenagers with normal sinus rhythm and without heart disease

The purpose of this study was to evaluate the value of esophageal programmed stimulation in children and teenagers with normal sinus rhythm ECG and normal noninvasive studies, having palpitations and syncope, and no documented tachycardias. Paroxysmal tachycardias are frequent in children and are often related to accessory connection. These tachycardias are sometimes difficult to prove. Transesophageal atrial pacing was performed at rest and during infusion of isoproterenol in 31 children or adolescents aged 9-19 years (16 +/- 3 years) with normal sinus rhythm ECG and suspected or documented episodes of paroxysmal tachycardia. Sustained tachycardia was induced in 27 patients, at rest in 13 patients, and after isoproterenol in 14 remaining patients. Atrioventricular nodal reentrant tachycardia was found as the main cause of paroxysmal tachycardia (22 cases). Six patients were followed by a vagal reaction and dizziness. These patients had spontaneous tachycardia with syncope. In three other patients, atrial fibrillation was also induced. Concealed accessory pathway reentrant tachycardia was identified in three patients. In two patients, a regular wide tachycardia with right bundle branch block morphology was induced; the diagnosis of verapamil-sensitive ventricular tachycardia was made in a second study by intracardiac study. In conclusion, atrioventricular nodal reentrant tachycardia was found as the main cause of symptoms in children with normal sinus rhythm ECG. Syncope is frequently associated and provoked by a vagal reaction. This diagnosis could be underestimated in adolescents frequently considered as hysterical because noninvasive studies are negative.

[Does patient age influence the indications for investigating asympatomatic Wolff-Parkinson-White syndrome?]

Sudden death may be the presenting symptom of a Wolff-Parkinson-White syndrome. Electrophysiological investigation is the best method of identifying high risk cases. The aim of this study was to determine whether this investigation should be proposed to all patients, irrespective of age. Transoesophageal stimulation was performed in 85 asymptomatic patients with the Wolff-Parkinson-White syndrome. Of the 85 subjects, 13 were under 20 years of age, 30 under 30 years, 15 under 40 years, 16 under 50 years and 11 between 50 and 69 years of age. A protocol of incremental stimulation until 2nd degree AVB was attained and programmed atrial stimulation with one or two extrastimuli delivered on 2 paced cycles (600 and 400 ms) was used under basal conditions and with Isoprenaline. A malignant form of the condition was defined as the demonstration of two abnormalities: rapid conduction in the bundle of Kent (over 240/min) under basal conditions or over 300/min after Isoprenaline, and if it induced sustained atrial fibrillation (> 1 min). The results were: [table: see text] In conclusion, the number of malignant forms of the Wolff-Parkinson-White syndrome is exactly the same, irrespective of age. Elderly patients remain at risk of malignant WPW syndrome because of the increased incidence of atrial fibrillation. Therefore, the authors recommend systematic evaluation of this syndrome if the patient has an active life-style especially with regard to sporting activities.

[Can the supraventricular proarrhythmic effects of class 1C antiarrhythmic drugs be prevented with the association of beta blockers?]

Due to their electrophysiological characteristics, class 1 antiarrhythmic drugs can induce an auricular flutter with a 1/1 response. In addition to antiarrhythmic treatment, several authors have therefore considered using drugs capable of slowing auriculoventricular nodal conduction and preventing the 1/1 response. Beta-blockers have been proposed as candidate drugs. In this study, two patients were treated with an association of class 1 antiarrhythmic drugs (cibenzoline in one case, flecainide in the other) and beta-blockers. The administration of these drugs resulted in an atrial proarrhythmic response, and wide QRS tachycardia. Although both subjects had underlying heart disease, the tachycardia was relatively well tolerated in both instances. It was concluded that although beta-blockers may not suppress the risk of atrial proarrhythmia, they at least permit an improved tolerance to this complication.

[Prolongation of the averaged QRS complex. A simple prognostic factor in patients with post-infarction bundle branch block and a history of syncope]

Patients with a history of myocardial infarction and complete bundle branch block with syncopal episodes have a high risk of sudden death: the identification of the cause of the syncope is therefore essential. The aim of the study was to assess the diagnostic value of non-invasive techniques used in the investigations of syncope: 24 hour Holter recording, high amplification ECG and measurement of left ventricular ejection fraction. The results of these investigations were compared with those of complete electrophysiological investigation evaluating atrioventricular conduction and the inducibility of tachycardia. The patient population was 134 patients, 83 with right bundle branch block and 51 with left bundle branch block. Ninety one patients had inducible sustained ventricular tachycardia and 24 had atrioventricular conduction defects: of these, 14 also had ventricular tachycardia. During follow-up, there were 12 sudden deaths and 13 deaths from cardiac failure. Uni- and multivariate analysis showed induction of ventricular tachycardia to be a significant risk factor for global mortality and sudden death but prolongation of the averaged QRS complex (> 165 msec) was also an independent risk factor of global cardiac mortality. The authors conclude that simple prolongation of the averaged QRS duration > 160 ms in patients with right bundle branch block and > 170 ms in patients with left bundle branch block after myocardial infarction and syncope is a significant poor prognostic factor. However, this sign is not predictive of sudden death.

[Incidence and prognosis of atrioventricular block induced by radiofrequency ablation of intranodal reentrant tachycardia. A multicenter study]

The object of this study was to assess the incidence and significance of atrioventricular block (AVB) induced by radiofrequency ablation of intranodal reentrant tachycardias. The study population was 18 patients aged 44 to 83, selected from a total population of 144 patients treated for recurrent, refractory tachycardias. These patients developed complete AVB (9 cases), 2nd degree ABV (3 cases) and 1st degree AVB (6 cases) either immediately or in the chronic phase after radiofrequency ablation. The outcomes were as follows: 1. In the 9 patients with complete AVB, the block regressed in a period ranging from 7 seconds to 5 minutes. It recurred as complete AVB 1 to 4 days later in 2 patients, and regressed again after a maximum of 10 days. One 47 year old woman had definitive complete AVB; 2. In the 3 patients with 2nd degree AVB, the block regressed within 7 days; 3. In the 6 cases of 1st degree AVB, 2 patients developed transient complete AVB the following day. The possible causes of AVB were: increased vagal tone in 1 case, ablation of the rapid pathway located in a postero-septal site in 8 cases and, in the remainder, pre-existing conduction defects. The authors conclude that transient complete AVB is common and usually has a good prognosis. Definitive complete AVB is a rare but possible (0.7%) complication of radiofrequency ablation of reentrant intranodal tachycardias; other forms of AVB generally regress quickly and, although they may recur within days, they carry a good prognosis in the following months. However, long-term follow-up remains necessary.