[Paroxysmal junctional tachycardia and normal ECG in sinus rhythm. Is their mechanism influenced by the age of the patient at the time of the study?]

At the time of the curative treatment of paroxysmal junctional tachycardias, to determine the mechanism of the tachycardia is important. Five-hundred forty intracardiac or esophageal electrophysiological studies were performed in patients aged from 9 to 86 years and then revieved. There was no preexcitation syndrome on surface ECG. Programmed atrial stimulation was performed in basal state and if necessary repeated after infusion of isoproterenol. Atrioventricular nodal reentrant tachycardia was the most frequent cause of junctional tachycardia (72%) since childhood and in all stages of life. Concealed accessory pathway reentrant tachycardias were identified in 22% of tachycardias with a stable incidence during the course of life. Various mechanisms of tachycardia were identified in the remaining patients. In conclusion, the mechanism of paroxysmal junctional tachycardia is not correlated with the age of the patient.

[Effect of golf on sinus rate variability]

There are no or very few studies in the literature on the effects of golf on heart rate and its parameters. The purpose of the study was to evaluate the effects of a precision sport, golf, on heart rate variability (HRV). The study population consisted of six high-level golfers aged 25 to 40 years, without cardiac disease. HRV was studied three hours before a golf competition, during the four hours of the competition and three hours after the match was over. The following parameters of HRV were calculated during 12 games of golf: mean heart rate (HR), standard deviation of the mean RR intervals (SDNN), root mean square of successive differences in RR intervals among consecutive normal beats (rMSSD), percent differences between normal RR intervals that are greater than 50 ms computed over the entire 24-hour recording (pNN50), low-frequency amplitude (LF), high-frequency amplitude (HF) and LF/HF ratio: ratio of low-to-high frequency power. Analysis of the results indicates significant variations of all parameters which occur just at the beginning of the game, persist throughout the match and remain three hours after its completion: heart rate is increased; total HRV is decreased but parameters reflect parasympathetic activity; pNN50, rMSSD and 1-117 are principally decreased. In conclusion, golf significantly affects HRV just at the beginning of golf competition, probably because of stress. These changes progressively decrease but they are still significant three hours after the end of the competition.

[Curative radiofrequency ablation of paroxysmal junctional tachycardia in patients over 70 years of age. A multicenter study]

Curative radiofrequency ablation of the reentry circuit of paroxysmal junctional tachycardia is a relatively common method of treating this condition. The aim of this study was to determine whether the age of the patients should be taken into account for assessing the indication. The study population was 178 patients aged 18 to 86 years (average 56 +/- 19 years), who had paroxysmal junctional tachycardia and normal interatrial ECGs. One hundred and thirty-five patients were under 70 years of age (Group I) and 43 were over 70 (Group II). No significant differences in the mechanism of reentry, which was intranodal in 67% of cases, in the risk of immediate complications (11%) or in recurrence of tachycardia were observed between the two groups. Functional improvement was more spectacular in Group II with regression of the symptoms of associated cardiac disease and, above all, in reduction in the number of hospital admissions. The common association of cardiac disease and other pathologies in Group II should however lead to more careful management and follow-up of the more elderly patients. The authors conclude that radiofrequency ablation of paroxysmal junctional tachycardia in the over 70s is feasible and often provides better clinical results than observed in younger patients.

[Action of sotalol on high-amplification electrocardiogram]

D,l sotalol is an antiarrhythmic widely used for treating ventricular excitability, especially ventricular tachycardia (VT). The means of assessing its efficacy is 24 hour Holter monitoring and programmed ventricular stimulation. High amplification ECG has also been proposed for predicting the effects of the drug on the induction of VT. The aim of this study was to assess the results of high amplification ECG before and after taking sotalol and to compare them with those of programmed ventricular stimulation. This study was performed in 24 patients with spontaneous and inductible ventricular tachycardia due to ischaemic heart disease. The two investigations were performed under basal conditions and after treatment with 160 to 320 mg/day of d,l-sotalol for 8 days. Nine patients had VT which could not be induced after treatment. In the other 15 cases, the VT remained inducible and was not significantly slowed. Analysis of different parameters of high amplification ECG, the QRS duration, RMS 40 and LAS did not show any difference after treatment in cases with inducible VT or VT suppressed by treatment. In conclusion, d,l sotalol, even at antiarrhythmic doses, does not seem to change the parameters of high amplification ECG, and it is therefore not necessary to stop treatment to carry out this investigation. Moreover, it was impossible to predict the effect of d,l sotalol on VT by high amplification ECG.

[Junctional tachycardia in adolescents: nodal reentry is the most frequent cause]

Ventricular preexcitation syndromes are classically more common in the pediatric age group than in adults, and a latent Kent bundle may explain most cases of paroxysmal junctional tachycardia (PJT). These data stem from the results of intracardiac electrophysiologic testing, which is performed only in those patients at the most severe end of the symptom spectrum. The recent introduction of transesophageal testing has expanded the indications of electrophysiologic testing for PJT. This technique was used to determine the mechanism of PJT in 23 adolescents aged 11 to 9 years (mean age, 16 +/- 3 years) with paroxysmal palpitations, accompanied in seven cases with dizziness or syncope. Only four patients had documented PJT. The basal ECG was normal, and exercise testing showed no evidence of preexcitation. Pacing at increasing rates and programmed stimulation with one then two extra-stimuli was used and repeated, if needed, under infusion of 20 to 30 micrograms of isoproterenol.

RESULTS

PJT was induced in 21 patients (91%), under basal conditions in 13 and under isoproterenol in eight. Neither of the two patients with a negative test had documented tachycardia. Based on classic criteria (position of A relative to V1, effect of a bundle branch block, and shape of A in D1 and V1), the mechanism of the PJT was shown to be nodal reentry in 17 cases (81%) and reentry into a latent left-sided Kent's bundle in four cases. Atrial fibrillation was also induced in two of the patients with nodal reentry. In six of the patients with dizziness or syncope associated with palpitations, these symptoms were due to nodal reentry.

CONCLUSION

Nodal reentry is very common in adolescents and can explain symptoms ascribed to "spasmophilia", as well as some cases of malaise or syncope.

Reproducibility of response to programmed atrial stimulation

The induction of atrial tachyarrhythmias (ATAs) is used to guide the medical or ablative treatment of these tachycardias. To date no information is available regarding the reproducibility of programmed atrial stimulation (PAS) induced ATA. The purpose of the study was to look for the reproducibility of PAS. Two baseline electrophysiological tests were performed in the drug-free state and within 6 months to 3 years of one another (mean 18 months) in 62 patients. Twenty-six patients had spontaneous documented ATAs (group I); 36 patients did not have spontaneous ATAs (group II). PAS used one and two extrastimuli delivered during three cycle lengths (sinus rhythm, 600 ms, 400 ms). The results were as follows. In group I, sustained (> 1 minute) ATA was induced in 23 patients on the first PAS and remained inducible in 22 patients in the second study. In three patients with noninducible ATA, PAS remained negative in only one; the reproducibility of PAS was 88%. In 17 (47%) group II patients, a sustained ATA was induced in the first study, and the ATA remained inducible in 10 patients in the second study. Nineteen other patients did not have inducible ATA on the first study, but 10 of them had an inducible ATA on the second PAS; the reproducibility of PAS was 53%. In conclusion, long-term reproducibility of PAS induced ATA in patients with spontaneous and documented ATA was good. In patients without spontaneous ATA, the reproducibility of PAS induced ATA was low and the induction of ATA in these patients should be interpreted cautiously in light of this observed variability in induced atrial arrhythmias.

[Transesophageal electrophysiology study, a simple method of investigation of unexplained illness in elderly patients]

Cardiac arrhythmias are common causes of syncope and malaise in elderly patients, but they are sometimes difficult to demonstrate without invasive procedures. The aim of this report was to demonstrate the value of transoesophageal electrophysiological investigation in cases of negative classical non-invasive studies. The authors report 18 cases of patients, aged 70 to 88, mainly in poor general condition, who were admitted for the investigation of malaise or syncope. The ECG was normal or subnormal and Holter monitoring non-contributive to the diagnosis. Transoesophageal electrophysiological study enabled initiation of an arrhythmia, bradycardia or tachycardia, which reproduced the symptoms of spontaneous malaise. In 10 cases, paroxysmal junctional tachycardia was demonstrated, by nodal reentry in 8 cases, and in a latent Kent bundle in 2 cases. The malaise was caused by tachyarrhythmia in 3 patients and by a vagal reaction or sinus arrest after the tachycardia in the other patients. In 6 other patients, atrial fibrillation reproduced the malaise either due to the rapid rhythm, or to bradycardia after the arrhythmia in 3 cases. In another 2 patients, conduction defects were demonstrated by atrial stimulation (alternating bundle branch block in one patient, complete atrioventricular block at the end of atrial stimulation in another patient). The authors conclude that transoesophageal electrophysiological study is a simple technique which allows diagnosis of unexplained malaise in elderly patients when non-invasive methods are unable to demonstrate the causal arrhythmia. Supraventricular arrhythmias seem to be a common and probably underestimated cause of malaise or syncope in elderly patients.

Long-term reproducibility of ventricular tachycardia induction with electrophysiological testing in patients with coronary heart disease and depressed left ventricular ejection fraction

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) has recently confirmed the role of programmed ventricular stimulation (PVS) to identify the high risk patients of sudden death after myocardial infarction and to prevent this risk. The purpose of this study was to evaluate the long-term reproducibility of PVS in these patients. Thirty patients with coronary heart disease without spontaneous documented sustained ventricular tachycardia (VT) underwent two programmed stimulations in the absence of antiarrhythmic drug treatment between 2 and 6 years (mean 4 years). No patient had a myocardial infarction or intervening cardiac surgery during this period. The protocol of study was similar using up to three extrastimuli in two sites of the right ventricle, delivered in sinus rhythm and driven rhythm (600 ms, 400 ms, respectively). On the first PVS, 17 patients had inducible sustained VT (group I). Thirteen patients did not have inducible VT (group II). On the second PVS all group I patients but one had inducible VT, but the cycle length was significantly modified in 11. In group II, five patients had inducible VT and in the other patients the PVS remained negative. In conclusion, in patients with coronary heart disease, but without documented VT, the long-term reproducibility of PVS was excellent in those with inducible VT (94%); the patients remain at risk of VT and a prophylactic implantable cardioverter defibrillator could be considered. In patients with initially negative study, reproducibility of PVS was lower (61.5%), probably because of the progressive remodeling after myocardial infarction. Therefore, the occurrence of new symptoms in patients with previously negative study requires a second programmed ventricular stimulation.

[Predictive value of induction of atrial flutter or fibrillation in paroxysmal junctional tachycardia]

The association of different types of tachycardia in a given patient is a well-known phenomenon and the development of ablative methods rises hopes that treatment of one of them may suppress the others. The aim of this study was to determine the significance of induction of atrial flutter or fibrillation (AF) during electrophysiological investigation of patients investigated for paroxysmal junctional tachycardia. The initial population of 500 patients was limited to 485 patients, aged 12 to 86, with a normal intercritical ECG and without a Wolff-Parkinson-White syndrome, who underwent electrophysiological investigation for junctional tachycardias since 1978 and in whom the tachycardia could be reproduced. The study was performed by the endocavitary approach in 262 cases and by the transoesophageal approach in 213 cases with a similar protocol, programmed atrial stimulation with 1 and 2 extrastimuli under basal conditions, eventually completed by the repetition of the protocol with low doses of isoproterenol. The electrophysiological study showed that the tachycardia involved a latent bundle of Kent in 103 cases, a double nodal pathway in 343 cases or another circuit in 39 cases. During this study, sustained AF was induced in 66 cases (13.5%) with a similar incidence in Kent bundles (14.5%), intranodal reentry (11%) and other forms of reentry (11%). During follow-up, ranging from 6 months to 10 years, 7 patients with induced AF and 9 without inducible tachycardia, developed permanent AF. The occurrence of the arrhythmia was significantly correlated with the mechanism of reentry (latent Kent 8/103 cases, intranodal reentry 8/343 cases, p < 0.05), and with the induction of the same arrhythmia by oesophageal investigation alone (p < 0.001). The initiation of the arrhythmia by endocavitary stimulation did not seem to have any positive predictive value. In conclusion, the induction of atrial flutter or fibrillation during investigation of a subject with paroxysmal junctional tachycardia without a patent Wolff-Parkinson-White syndrome, does not seem to be predictive of future development of atrial flutter or fibrillation, unless the investigation was undertaken by the oesophageal approach.

[Cardiac syncopes]

Cardiac causes explain 5 to 30% of the syncopes and their incidence increases with age. Prognosis is poor in case of misdiagnosis. Mechanical causes are related principally to obstruction of left ventricular outflow, and responsible for exertional syncope. Diagnosis is easy through clinical examination and echocardiography. Arrhythmic causes are due either to brady-cardia (diagnosed by surface electrocardiogram, 24-hour holter monitoring and electrophysiologic study in patients with bundle branch block) or to supraventricular or ventricular tachycardia. Arrhythmic syncope is easily prevented by antiarrhythmic drugs or non medical treatments such as radiofrequency ablation of tachycardia, pace-maker or defibrillator implantation.

[Evaluation of prognosis after Q wave myocardial infarction. Comparison of invasive and noninvasive diagnostic strategies]

The predictive value of several diagnostic strategies after myocardial infarction was assessed in 178 patients (mean age 55 +/- 9 years) treated medically after a primary Q wave myocardial infarction. Within 6 weeks of onset of symptoms the authors performed exercise stress test coupled with Thallium 201 scintigraphy, isotopic left ventriculography and conventional coronary angiography with ventriculography. The average left ventricular ejection fraction was 45 +/- 12%. Two non-invasive diagnostic strategies with and without results of scintigraphy and two invasive strategies with and without ventricular volumes were studied. The average follow-up period was 58 +/- 22 months. Sixteen cardiac deaths occurred. Multivariate Cox analysis showed that, in contrast to left ventricular volumes, coronary angiography did not provide additional prognostic value compared with the non-invasive model with Thallium scintigraphy and did not appear to be essential in terms of predictive value in this population. Moreover, the size of reversible defect on Thallium scintigraphy was an independent predictive factor of cardiac death and provided additional and independent prognostic information in the non-invasive and invasive strategies. Therefore, the reduction of residual ischaemia by coronary revascularisation could improve the long-term prognosis after myocardial infarction.

Evolution of QRS duration after myocardial infarction: clinical consequences

The natural history of late potentials after acute myocardial infarction (AMI) has been studied in the first 2 years following myocardial infarction (MI). The purpose of the study was to assess the influence of some time delays since MI, including a time delay longer than 2 years on signal-averaged ECG (SAECG). SAECG was recorded at 40-Hz high pass filtering in 40 patients 10 days after acute MI (SAECG 1), then repeated 6-12 months later (mean 9 +/- 3 months) (SAECG 2), and then, 2-4 years later (mean 3 +/- 2 years) (SAECG 3). QRS duration, root mean square voltage of the last 40 ms of QRS (RMS 40), and low amplitude signal duration (LAS) were measured at the first (1), second (2), and third recording (3).

RESULTS

(***P < 0.001) [table: see text] The analysis of individual results showed a lengthening QRS duration at the third recording only in patients who had a decreased left ventricular ejection fraction (LVEF) at the third recording. In 12 patients with LVEF > 40%, QRS duration did not change at the first and third recording (104 +/- 15 vs 101 +/- 12 ms). In all 28 patients, but one with LVEF < 40%, QRS duration increased from 107 +/- 12 to 128 +/- 18 ms***. There was no correlation between QRS duration and LVEF at the second recording and no correlation between QRS duration increase at the third recording and the presence or not of late potentials at the first recording. QRS duration lengthening at the third recording was significantly correlated with a left ventricular (LV) dilatation occurrence at the two-dimensional echocardiogram. All arrhythmic events, but two, occurred in patients who developed a QRS duration prolongation and were significantly correlated (P < 0.01) to a mean longer QRS duration (132 +/- 20 ms) than in patients without arrhythmic events (113 +/- 17 ms). In conclusion, the patients with a LV impairment, and who developed a LV dilatation several months after AMI, presented a delayed lengthening of QRS duration noted only at least 2 years after infarction. These patients are at risk of arrhythmic events.

[Long-term follow up of 115 patients with ischemic heart disease and ventricular flutter induced by programmed ventricular stimulation in the absence of ventricular arrhythmia]

The clinical significance of rapid monomorphic ventricular tachycardia (VT) (> 270 beats/min), also called ventricular flutter, remains controversial in patients without documented spontaneous sustained VT. The aim of this study was to evaluate the outcome of 115 patients with ischaemic heart disease, aged 58 +/- 10 years, without spontaneous ventricular arrhythmias, but who had inducible ventricular flutter during programmed ventricular stimulation. The patients underwent stimulation to evaluate the prognosis after myocardial infarction or to investigate a malaise with or without loss of consciousness. Sustained ventricular flutter was the only inducible arrhythmia in all patients. The mean left ventricular ejection fraction (LVEF) was 42 +/- 14%. During an average follow-up period of 66 +/- 43 months, 31 deaths, including 27 of cardiac causes, were observed. The 1, 5, and 11 year survival of the whole population was 94, 79 and 64% respectively. In univariate analysis, anterior wall myocardial infarction, a low LVEF, the presence of non-sustained ventricular tachycardia (NSVT) on 24 hour Holter monitoring and Class III antiarrhythmic treatment, were poor prognostic factors (p 0.05). In multivariate analysis, the only independent predictive factors of mortality were low LVEF (p = 0.006), the presence of NSVT on Holter monitoring (p = 0.003) and the absence of betablocker therapy (p = 0.015). Medical therapy with betablockers or the implantation of an automatic defibrillator may be indicated in these patients at higher risk.

Predicting the effect of D,L-sotalol on ventricular tachycardia inducibility from the RR variability response

AIM

To find a rapid way of identifying non-responders to D, L-sotalol in patients with ventricular tachycardia.

METHODS

Programmed ventricular stimulation and RR variability were studied in the control state and 10 days after treatment with 160 to 320 mg of D,L-sotalol in 36 consecutive patients with ventricular tachycardia.

RESULTS

In 14 patients (group I) D,L-sotalol suppressed ventricular tachycardia inducibility. In 22 patients (group II) sustained ventricular tachycardia remained inducible during D,L-sotalol treatment. The ventricular tachycardia rate was slowed in eight patients and unchanged or accelerated in 14. At baseline, heart rate variability was similar in both groups. During treatment with D,L-sotalol, variables reflecting parasympathetic activity (pNN50, rMSSD, and high frequency amplitude (HF)) increased in both groups: HF increased from (mean (SD)) 75 (68) to 146 (134) in group I (p < 0.05) and from 60 (49) to 125 (79) in group II (p < 0.05). Other variables were unchanged in group I. In group II, the variables associated with sympathetic activity (coefficient of variance (CV), ratio of low frequency amplitude (LF) to HF) decreased significantly: CV decreased from 13 (4) to 9 (2) (p < 0. 001) and LF/HF from 4.74 (3.02) to 3.00 (2.02) (p < 0.05).

CONCLUSIONS

The beta blocking effect of D,L-sotalol produced a significant improvement over control values in indices of parasympathetic tone in all treated patients. However, the heart rate variability indices related to sympathetic activity were decreased only in non-responders. This effect of D,L-sotalol on heart rate variability could help detect non-responders to the drug and avoid an electrophysiological study.

Induction of sustained ventricular tachycardia after surgical repair of tetralogy of Fallot

Between 1980 and 1996, 89 unselected consecutive patients with repaired tetralogy of Fallot (TOF) underwent examination, including a prospective right ventricular programmed stimulation with the same protocol (S1 S2, S3, S4). Age at surgery was 4.2 +/- 3.5 years and age at electrophysiologic study was 10.9 +/- 6.5 years. Follow-up since surgery was 14.4 +/- 4.8 years and patient follow-up after programmed stimulation was 7.8 +/- 4.2 years. The aim of this study was to evaluate the main predictors of the inducibility of a sustained monomorphic ventricular tachycardia (VT) and its significance to identify a group of patients at risk of sudden death: 21 (group A) had and 68 (group B) had no induced sustained VT. The induction of VT was related to older age at programmed stimulation, prolonged QRS duration, presence of complex ventricular arrhythmia, symptoms, right ventricular overload, and increased right ventricular systolic pressure. Predictors of induced VT selected by multivariate analysis were age at electrophysiologic study (p <0.0001), previous palliative shunts (p <0.001), right ventricular systolic pressure (p <0.007), and symptoms (p <0.005). Among group A patients, 4 had previous sustained VT before stimulation, and 1 had sustained VT only during follow-up after stimulation. No patients of group B had clinical sustained VT. Late mortality was low but similar between both groups. A negative electrophysiologic study may be helpful for the management of patients after surgical repair of TOF, but because the arrhythmic event rate is low, the findings of even a positive electrophysiologic study should be interpreted with caution.

[Value of transesophageal programmed atrial stimulation in the evaluation of unexplained cerebrovascular accidents]

Certain embolic cerebrovascular accidents can be explained by the development of paroxysmal atrial fibrillation. When noninvasive complementary investigations are negative, programmed atrial stimulation can be proposed to detect increased atrial vulnerability. The objective of this study was to evaluate the reliability of this method performed via a transoesophageal approach in 59 subjects presenting with an embolic cerebrovascular accident and who were in sinus rhythm at the time of the accident. Seven of these patients had a history of paroxysmal atrial fibrillation (AF) or atrial tachycardia (AT) (group I). Three of these seven patients also presented AV nodal reentrant junctional tachycardia. The other 52 patients had no history of arrhythmia and their Holter recording did not reveal any episodes of sustained atrial tachycardia (group II). Transoesophageal programmed atrial stimulation used up to 2 extrastimuli under baseline conditions and during Isuprel infusion. The following results were obtained: sustained atrial tachycardia (> 1 min) was induced in all patients of group 1, 3 of them also presented inducible junctional tachycardias. 14 patients of group II (27%) presented inducible supraventricular tachycardia: atrial tachycardia in 7 cases. Patients in group II with inducible AT presented either heart disease (n = 3) or minor abnormalities on the Holter recording (runs of atrial premature complexes or sinus pauses (n = 3). Two of these patients subsequently developed sustained atrial fibrillation during follow-up. In 25 patients with normal Holter recording and no heart disease, programmed atrial stimulation induced junctional tachycardia in 4 cases. In conclusion, transoesophageal electrophysiological investigation is a useful way to identify various forms of supraventricular tachycardia able to explain an embolic cerebrovascular accident. The considerable incidence of inducible AV nodal reentrant junctional tachycardia must be emphasized, while the incidence of atrial fibrillation is much lower than during intracardiac investigations.

Increased atrial vulnerability in arrhythmogenic right ventricular disease

Supraventricular tachyarrhythmias (SVTA) may occur in patients with the arrhythmogenic right ventricular dysplasia (ARVD). The purpose of the study was to evaluate the incidence of SVTA in 47 patients with ARVD proved by right ventricular angiography. Thirty-three men and 14 women, aged 21 to 72 years (mean 44 +/- 18) were admitted for nonsustained or sustained ventricular tachycardia. Eight patients had a history of spontaneous SVTA several years before ventricular tachycardia occurrence. Protocol of the study consisted of programmed atrial stimulation with one and two extrastimuli delivered during sinus rhythm and two driven rhythms (600 and 400 msec), programmed ventricular stimulation with up to three extrastimuli and was performed in the control state and after infusion of isoproterenol. The results of programmed atrial stimulation were compared with those obtained in 36 asymptomatic subjects without heart disease and with a mean age of 50 +/- 18 years (control group). Sustained SVTA (> 1 minute) was induced in seven of eight patients with spontaneous SVTA, in 27 (69%) of those with ARVD, who did not have spontaneous SVTA, and in two control subjects (5.5%) (p < 0.001). SVTA was inducible in the control state, but ventricular tachycardia induction required isoproterenol in 11 of 27 patients. Two patients without SVTA history but with inducible SVTA developed later spontaneous SVTA. ARVD was associated with a significantly higher incidence of inducible SVTA than in a control population. Supraventricular tachycardias may precede ventricular tachycardias. This association argues for a diffuse myocardial disorder in ARVD.

[Evaluation of high amplification ECG and the study of sinus variability in the detection of patients at risk of sudden death]

In order to define the best strategy of prognostic evaluation in relation to patients in heart failure, 415 patients with impaired left ventricular function (ejection fraction < 40%) were prospectively included, between June 1993 and 1996, in a study comparing the respective value of high amplification ECG and Holter analysis of sinus variability, 308 patients in sinus rhythm and narrow QRS complexes were included. The patients were distributed into 4 groups according to the presence or absence of late potentials and altered sinus variability (group I with 2 normal examinations, group II with late potentials and normal variability, group III without late potentials, but with altered variability and group IV with 2 abnormal examinations). The sudden and overall mortality was significantly greater in groups III (28 and 11%) and IV (28 and 9%) than in group I (7 and 3%) and II (11 and 2%). The presence of potential was unable to identify patients at risk of ventricular tachycardia and sudden death. In another 60 patients with complete branch block, the prognosis was also correlated with the alteration of sinus variability. In conclusion, high amplification ECG correctly evaluated the prognosis of subjects in heart failure. However, analysis of sinus variability should be systematically proposed to detect subjects at high risk of mortality, whether the subject has large or narrow QRS complexes.

[Alteration of sinus variability after cardiac surgery]

Sinus tachycardia is frequent after cardiac surgery and this tachycardia is probably due to changes of the autonomic nervous system. The objective of this study was to evaluate the changes possibly induced by cardiac surgery, by studying sinus variability (SV) during a 24-hour Holter monitoring. The examination was performed in 28 patients who had undergone cardiac surgery 1 to 6 weeks previously. These patients had no alteration of left ventricular function, or any causes likely to modify SV and they had a normal postoperative course. Their results were compared to those of 4 subjects developing a postoperative complication (1 case of ventricular tachycardia and 3 cases of resuscitated cardiac arrest). The results were also compared to those of 24 age-matched adult controls without heart disease (control group). The study of SV included temporal and spectral analysis of SV with measurement of the standard deviation of normal RR intervals (SD), mean heart rate (HR), percentage of RR intervals differing by more than 50 m/sec from the adjacent interval (pNN50), coefficient of variability (CV) (SD/RR), square root of the differences between successive RR (rMSSD), spectral properties of low frequencies (LF) and high frequencies (HF) and the fractionated spectral property (LF/HF).

RESULTS

(see tables, page 151 and 152). An alteration of SV was therefore observed in the surgical group, and lasted 4 to 6 months after surgery. No difference was observed between subjects without cardiac events and those presenting a cardiac event.

IN CONCLUSION

cardiac surgery decreases all parameters of SV during the first few postoperative months. Certain unexpected cardiac accidents during this period could be explained by these changes.

[Influence of time (4 years) on the results of programmed ventricular stimulation]

The reproducibility of programmed ventricular stimulation has been previously demonstrated for periods of a few hours to several months. It has not been studied over longer intervals. The aim of this study was to assess the reproducibility of the method at long-term (> 2 years). Forty-six patients with underlying cardiac disease underwent two programmed ventricular stimulations in the absence of antiarrhythmic treatment at intervals of 2 to 6 years (mean 4 years). None of the patients had myocardial infarction or cardiac surgery during this period. The protocol was identical: up to 3 extra-stimuli were delivered in the two right ventricular sites over 3 cycles. Twenty-eight patients had inducible sustained monomorphic ventricular tachycardia during the first investigation (Group I): the investigation was negative in the remaining 18 patients (Group II). During the second investigation, 26 of the 28 patients in Group I had inducible ventricular tachycardia, the rate of which decreased from 206 +/- 50 bpm to 196 +/- 54 bpm. The induced ventricular tachycardia was slower in 15 patients and faster in 5 patients. The mode of induction was different in 12 cases. In Group II, 4 patients (22%) had inducible sustained ventricular tachycardia at the second investigation. The authors conclude that the reproducibility of programmed ventricular stimulation remains good in the long-term in subjects within inducible tachycardia, demonstrating the stability of the arrhythmogenic substrate; the frequency of this tachycardia is generally slower. In subjects with an abnormal initial investigation who became symptomatic, it may be useful to repeat programmed ventricular stimulation.

[Reproducibility of heart rate variability in the chronic phase of myocardial infarction]

Evaluation of heart rate variability is a common method of assessing autonomic nervous system function and its effects on heart rate in different conditions. The reproducibility of the technique is not known in the chronic phase of myocardial infarction. The aim of this study was therefore to assess the reproducibility of the measurement in 54 subjects who were clinically stable with no change in treatment at a distance from acute or semi-recent (> 2 years) myocardial infarction, after an interval of one month. The temporal and spectral analysis of heart rate variability included measurement of the standard deviation of the normal RR intervals (SDNN), on the mean heart rate, the percentage of RR intervals greater than 50 ms than the adjacent interval (pNN50), the coefficient of variability (CV), the square root of the differences between successive RR intervals (rMSSD), the power of low frequencies (LF) and high frequencies (HF) and of the fractional spectral power (LF/HF). No significant changes in these parameters were observed. Analysis of individual variations showed that the heart rate was the most stable parameter: for evaluation of vagal tone, the rMSSD showed less variability than the pNN50 and HF. The presence of cardiac disease did not influence these results. The authors conclude that parameters of evaluation of heart rate variability in temporal and spectral analysis are globally reproducible in stable subjects. However, individual values may change from one measurement to another. Nevertheless, abnormal variability is constantly observed at the second investigation and, similarly, normal variability also remains unchanged. These individual variations suggest that, for the demonstration of change in these parameters of variability with treatment, large population groups must be studied.