Philippe Poret

Long-term prognostic value of time domain analysis of signal-averaged electrocardiography in idiopathic dilated cardiomyopathy

The aim of this study was to evaluate the long-term prognostic value of signal-averaged electrocardiography (SAECG) in idiopathic dilated cardiomyopathy (IDC). Time domain analysis of SAECG was assessed in 131 patients with angiographically confirmed IDC (age 52+/-12 years; 108 men; left ventricular ejection fraction 33+/-12%) using specific criteria in 44 patients with bundle branch block. Late potentials (LP) on SAECG were present in 27% of the patients. Patients with LP had a similar left ventricular ejection fraction and a similar left ventricular end-diastolic diameter than patients with a normal SAECG. With a follow-up of 54+/-41 months, 24 patients suffered cardiac death and 19 had major arrhythmic events (sudden death, resuscitated ventricular fibrillation, or sustained ventricular tachycardia). Patients with LP had an increased risk of all-cause cardiac death (RR 3.3, 95% confidence interval 1.5 to 7.5, p = 0.004) and of arrhythmic events (RR 7.2, 95% confidence interval 2.6 to 19.4, p = 0.0001). Using multivariate analysis, only LP on SAECG (p = 0.001), reduced SD of all normal-to-normal intervals (SDNN) (p = 0.002), increased pulmonary capillary wedge pressure (p = 0.005), and history of sustained ventricular tachyarrhythmia (p = 0.02) predicted cardiac death. A history of previous sustained ventricular tachyarrhythmia (p = 0.0001), reduced SDNN (p = 0.003), and LP on SAECG (p = 0.006) were the only independent predictors of major arrhythmic events. Results were not altered when considering separately patients with or without bundle branch block, or after exclusion of patients with a history of sustained ventricular tachyarrhythmia. This study is one of the first to suggest that LP on SAECG is an independent predictor of all-cause cardiac death and is of high interest for arrhythmia risk stratification in IDC.

Implantable loop recorder for recurrent syncope: influence of cardiac conduction abnormalities showing up on resting electrocardiogram and of underlying cardiac disease on follow-up developments

AIMS The implantable loop recorder is a useful diagnostic tool in dealing with recurrent syncope in patients. We tested to determine the influence of cardiac conduction abnormalities that turn up on resting electrocardiogram (ECG) and the impact of underlying cardiac disease on developments during follow-up. METHODS AND RESULTS Ninety-five consecutive patients received an implantable loop recorder to monitor recurrent syncope (n = 4.9+/-3.8) of unknown aetiology after cardiac investigations, including an electrophysiological study. Resting ECG was abnormal, suggesting an arrhythmic syncope, in 29 (30.5%) patients, while 21 (22.1%) patients had an underlying cardiac disease. During an average follow-up period of 10.2+/-5.2 months, 43 (45.2%) patients developed a new syncope associated in 27 of them (62.8%) with an arrhythmic event. Syncope was no more frequent in the subgroup of patients with cardiac conduction abnormalities on resting ECG, while the frequency of arrhythmic events was similar whether or not the ECG was normal. In the subgroup of patients with cardiac disease with normal left ventricular ejection fraction, the occurrence of syncope was less frequent, and the number of arrhythmic events was no greater in these patients. CONCLUSION Implantable loop recorder is a useful diagnostic tool for recurrent syncope of unknown aetiology.

Effect of verapamil on QT interval dynamicity

Using measurements of QT/RR slopes with a computerized Holter system, QT interval dynamicity was evaluated in 19 patients with normal structural heart before and 2 months after oral treatment with verapamil prescribed for paroxysmal atrioventricular nodal reentrant tachycardia. Verapamil significantly shortened QT at low heart rates, mainly in the diurnal period, and this characteristic may explain, in part, the previously reported protective effect of verapamil against torsades de pointes.

Influence of duration and hour of recording on spectral measurements of heart rate variability.

UNLABELLED Frequency-domain analysis of heart rate variability provides information about influences of autonomic nervous system on the heart and can be measured on short-term or long-term electrocardiogram recording. We compared heart rate variability on 24 h electrocardiogram recording with measurements of heart rate variability over shorter periods of 1 h and 12 h in order to determine the influence of duration and hour of recording on the heart rate variability parameters in the frequency domain. Heart rate variability was analyzed in 24 subjects with normal heart, with measurement of total power (Tot P), ULF, VLF, LF, HF and LF/HF ratio. Reference measurements over 24 h were compared with measurements over 4 periods of 1 h (2 AM-3 AM, 8 AM-9 AM, 2 PM-3 PM, 8 PM-9 PM) and over 4 periods of 12 h (2 AM-2 PM, 8 AM-8 PM, 2 PM-2 AM, 8 PM-8 AM). The correlations with measurements over 24 h were lower for the measurements over 1 h than for the measurements over 12 h. ULF had the lowest mean of correlation coefficients for measurements over 1 h and 12 h, whereas the other frequency bands had high correlations with measurements over 24 h. When using Bland and Altman method, only measurements over 2 AM-2 PM and 2 PM-2 AM periods were a reliable estimation of heart rate variability over 24 h. CONCLUSION Spectral measurements of heart rate variability over 12 h have high correlations with measurements on 24 h. ULF is the parameter the most affected by the duration of the recording. Spectral measurements over 2 AM-2 PM and 2 PM-2 AM periods are reliable appreciations of heart rate variability over 24 h.

Significance of late ventricular potentials in myotonic dystrophy

In 39 patients with myotonic dystrophy, we found a high percentage of infrahissian cardiac conduction abnormalities (51%) and late potentials (46%), whereas spontaneous and inducible ventricular arrhythmias were rare. These results suggest that the prolongation of QRSD and the duration of the low-amplitude signal on the signal-averaged electrocardiogram were related to delayed activation of the His and Purkinje tissue rather than true late potentials.

Abnormal nocturnal heart rate variability and QT dynamics in patients with brugada syndrome

Background: In Brugada syndrome (BSY), most of the ventricular arrhythmic events are nocturnal, suggesting an influence of the autonomic nervous system.

Effect of Flecainide on Heart Rate Variability in Subjects Without Coronary Artery Disease or Congestive Heart Failure

Heart rate variability is a noninvasive indicator of autonomic nervous system activity. The role of the autonomic nervous system in the genesis of atrial or ventricular arrhythmias is now well established. Little is known about the effects of flecainide on heart rate variability in patients with normal heart structure, the main population receiving flecainide. This study was designed to evaluate the effects of flecainide on heart rate variability in patients without coronary artery disease or congestive heart failure. Time and frequency domain analysis of heart rate variability on 24-hour electrocardiogram recording were assessed in 40 patients with normal echocardiography and without evidence of coronary artery disease before and after 2 months of oral treatment with flecainide (321 ± 57 mg/day) prescribed for Wolff Parkinson White syndrome with circus movement tachycardia. Flecainide significantly decreased all parameters of heart rate variability in the time domain (median Δ% −10% to −25%) and in the frequency domain (median Δ% −27% to −38%), including the markers of vagal activity. There was no correlation between plasma concentrations of flecainide and reduction in heart rate variability. It was concluded that in subjects without coronary artery disease or congestive heart failure, flecainide decreases all the measurements of heart rate variability and this decrease is not related to plasma concentrations of flecainide.

Épanchement péricardique révélateur d’une insuffisance cardiaque à débit élevé par carence en thiamine chez un adulte jeune

Resume Introduction. – L’avitaminose B1 est une cause classique d’insuffisance cardiaque a debit eleve classiquement liee a l’alcoolisme en Occident, elle peut en fait etre uniquement en rapport avec une carence d’apport alimentaire. Exegese. – Nous rapportons l’observation d’un patient jeune, chez qui la mise en evidence d’un epanchement pericardique a l’echocardiogramme conduit, au cours du bilan etiologique, a la decouverte d’une insuffisance cardiaque a debit eleve en raison d’un deficit en thiamine. Le diagnostic a ete etabli apres le bilan hemodynamique et le dosage sanguin de thiamine. L’evolution a ete favorable par le traitement vitaminique, avec une regression rapide de l’insuffisance cardiaque. Conclusion. – Bien que peu frequent, le diagnostic de beriberi cardiovasculaire doit donc etre systematiquement evoque en presence d’une insuffisance cardiaque a debit eleve. Notre observation permet en outre de rappeler qu’une carence alimentaire de cette vitamine est rare, mais doit etre actuellement recherchee lorsqu’elle est associee a d’autres stigmates de denutrition.

230 Unexpected low prevalence of atrial fibrillation in cryptogenic ischemic stroke: a prospective continuous monitoring study

Introduction Ischemic stroke (IS) is a frequent pathology, burdened by high rate of recurrence and significant morbidity and mortality. There are several causes of IS, affecting prognosis, outcomes and management, but in many cases the etiology remains undetermined despite comprehensive research. We hypothezised that atrial fibrillation (AF) was largely involved in this pathology but was underdiagnosed by standard methods. The aim of this study was to determine the incidence of AF in cryptogenic IS, by using continuous monitoring of the heart rate over several months. The secondary objective was to test the predictive value of atrial vulnerability study towards spontaneous AF. Methods and results We prospectively enrolled 24 patients under 75 years: 15 men and 9 women of mean age 48.8± 13.6 years who experienced cryptogenic IS presumed of cardioembolic mechanism within the last 4 months. Any cause of IS was excluded by normal 12-lead ECG, 24-hour Holter monitoring, echocardiography, cervical Doppler, haematological and inflammatory tests. All patients underwent electrophysiological study. 7 patients (29.2%) had inducible arrhythmia during programmed atrial stimulation and 9 (37.5%) had a latent vulnerability index (LVI) Conclusion This study shows that contrary to what was expected, AF does not appear to be a common pathology in patients under 75 years with unexplained IS. The use of ILR should not be generalized in the systematic assessment of these patients because of its unprofitability. Finally this study attests the poor value of atrial vulnerability study for predicting spontaneous AF in such patients.