NOVACOR HOME CLINICAL APPLICATIONS ATRIAL FIBRILLATION



Atrial fibrillation


CLINICAL CONTEXT

Atrial Fibrillation (AF) is the most common sustained cardiac rhythm disturbance. Its prevalence increases with age to be more than 6% in the general population over 80. The Framingham Heart prospective study showed that the prevalence of AF in case of patent stoke reached 36.2% of the population over 80.

The chief hazard of AF is STROKE. The risk of stroke among patients with AF averages 5% per year, depending on the population and the associated risk factors (age, hypertension, CHF, diabetes, …). The risk can rise up to 12% per year when these risk factors are cumulated.

The major issues in management of patients with AF are related not only to the arrhythmia itself to ensure that ventricular function is controlled, but also to prevention of thromboembolic events such as stroke. Data from trials on the efficacy of stroke prevention show that the mean risk reduction with Aspirin is approximatively 20%, while oral vitamin K antagonist reduces the rate of ischaemic stroke by 70% compared to that in untreated patient.

The diagnosis of AF requires ECG documentation by at least one-lead ECG recording during the dysrhythmia. In case of frequent episodes of paroxysmal AF, 24h Holter monitor can be used. If episodes are rare, then long-term Holter ECG or Automatic ECG event recorder is required. Automatic recording capability of the event recorder is a key feature since AF is frequently asymptomathic and avoid inconsistent use of patient triggering function, especially by elderly.

Novacor proposes 2 EXCLUSIVE solutions that both represent a major advance in paroxysmal atrial fibrillation diagnostic:
- HolterSoft Ultima, the first Holter software featuring an AUTOMATIC detection of AF episodes, fully compatible with all Novacor Holter ECG recorders (Unolter, Vista and X-Olter ranges). The detection algorithm relies on the RR analysis combining wavelet transform and fractal analysis.
- R.Test Evolution 3, the ONLY automatic ECG event recorder marketed today: 8 day recording, fully automatic, entirely programmable thus allowing the use of a program dedicated to capture events related to AF (SV events, relative pauses, …). The superiority of the R.Test Evolution 3 to 24h Holter has been established through 3 publications in peer-reviewed journal.



NOVACOR'S SCIENTIFIC PUBLICATIONS

High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals.


Frequent and Prolonged Asymptomatic Episodes of Paroxysmal Atrial Fibrillation Revealed by Automatic Long-Term Event Recorders in Patients with a Negative 24-Hour Holter.


Prevention of Atrial Fibrillation by Complete Compartmentalization of the Lef Atrium Using a Catheter Technique


Automatic Cardiac Event Recorders Reveal Paroxysmal Atrial Fibrillation after Unexplained Strokes or Transient Ischemic Attacks


Usefulness of Ambulatory 7-Day ECG Monitoring for the Detection of Atrial Fibrillation and Flutter After Acute Stroke and Transient Ischemic Attack


High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals.
 
David Duvernet, Jean-Michel Gaspoz, Vincent Pichot, Frédéric Roche, Richard Brion, Anestis Antoniadis, and Jean-Claude Barthélémy.

Duverney, D., et Al.: Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals.
Permanent and paroxysmal AF is a risk factor for the occurrence and the recurrence of stroke, which can occur as its first manifestation. Howewer, its automatic identification is still unsatisfactory. In this study, a new mathematical approach was evaluated to automate AF identification. A derivation set of 30 24-hour Holter recordings, 15 with chronic AF (CAF) and 15 with sinus rhythm (SR), allowed the authors to establish specific RR variability characteristics using wavelet and fractal analysis. Then, a validation set of 50 subjects was studied using these criteria, 19 with CAF, 16 with SR, and 15 with paroxysmal AF (PAF); and each QRS was classified as true or false sinus or AF beat. In the SR group, specificity reached 99.9%; in the CAF group, sensitivity reached 99.2%; in the PAF group, sensitivity reached 96.1%, and specificity 92.6%. However, classification on a patient basis provided a sensitivity of 100%. This new approach showed a high sensitivity and a high specificity for automatic AF detection, and could be used in screening for AF in large populations at risk. (PACE 2002; 25[Pt. I]:457-462)

Keywords: arrhythmia, automatic atrial fibrillation detection, Holter system, time frequency analysis, fractional brownian motion.

PACE, Vol. 25, No. 4, April 2002, Part I

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Frequent and Prolonged Asymptomatic Episodes of Paroxysmal Atrial Fibrillation Revealed by Automatic Long-Term Event Recorders in Patients with a Negative 24-Hour Holter.

Frédéric Roche, Jean-Michel Gaspoz, Antoine Ad Costa, Karl Isaaz, David Duverney, Vincent Pichot, Frederic Costes, Jean-René Lacour and Jean-Claude Barthélémy.
Roche, F., et Al.: Frequent and Prolonged Asymptomatic Episodes of Paroxysmal Atrial Fibrillation Revealed by Automatic Long-Term Event Recorders in Patients with a Negative 24-Hour Holter.
The presence, frequency, and duration of episodes of paroxysmal atrial fibrillation (PAF) is difficult to establish. This is caused by the limited duration of standard Holter recordings and to the unsatisfactory yield of patient-triggered event recorders, because of asymptomatic events and of an inconsistent use of the patient dependent triggering function. A prospective cohort of 65 consecutive patients with recurrent palpitations and a negative 24-hour ECG Holter was investigated by means of a cardiac event recorder bearing continuous automatic arrhythmia analysis and storage. Over a mean duration of 77 +/- 36 hours, episodes of PAF were diagnosed in 20 (31%) patients, who had a total of 37 episodes; mean duration of PAF episodes was 7 hours 50 minutes +/- 8/hours 45 minutes (minimum 45 minutes, maximum 28 hours). Eleven (55%) of these 20 patients were asymptomatic and would have remained undiagnosed without the automatic mode of the event recorder. Asymptomatic PAF episodes were longer than symptomatic ones (10 hours 30 minutes +/-6 hours 30 minutes vs 4 hours 50 minutes +/-4 hours, P<0.05). In addition, episodes of sustained paroxysmal supraventicular tachycardia (PSVT) were diagnosed in 39 (57%) patients, of whom 34 (87%) were symptomatic. In this prospective cohort, a second standard 24-hour monitoring would have missed 44% of the patients with PAF or PSVT and a classical patient-triggered event recorder 13%. In patients still complaining of palpitations after one negative 24-hour Holter, numerous, prolonged, and often asymptomatic episodes of PAF can be revealed by long-term automatic event recorders. These devices should help clarify the clinical consequences of such episodes. (PACE 2002; 25:1587-1593)

Keywords: paroxysmal atrial fibrillation, arrhythmia detection, automatic cardiac event recorder.

PACE 2002; 25, No. 11, November 2002

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Prevention of Atrial Fibrillation by Complete Compartmentalization of the Lef Atrium Using a Catheter Technique


Sabine ERNST, M.D., Feifan OUYANG, M.D., Birke SCHNEIDER, M.D, and Karl-Heinz KUCK, M.D.
From Allgemeines Krankenhaus St. Georg, Hamburg, Germany.

LA Compartmentalization for AF Prevention.

Introdution
Right atrial compartmentalization has been demonstrated to only reduce the number of atrial fibrillation (AF) episodes; left atrial 'LA) fibrillation still occurs.

Methods and Results
We report successful LA compartmentalization resulting in isolation of all four pulmonary veins in a 51-year-old woman suffering from paroxysmal AF. Deployment of a complete encircling line resulted in dissociation of electrical activation within the isolated area from the remaining LA. Despite attempts at reinduction by pacing maneuvers inside and outside the isolated area, AF was no longer inducible.
During 21-week follow-up, the patient was completely free of symptoms. Antiarrhythmic therapy with sotatol (as before the last ablation) was continued during the initial 12 weeks of follow-up and then discontinued. Sequential Holter recordings showed stable sinus rhythm with rare atrial extrasystoles.
Using a continuous 7-day event recorder (R.TEST Evolution, NOVACOR, Rueil-Malmaison, France) stable sinus rhythm was documented without evidence of asymptomatic episodes of AF.

Conclusion
If reproductible, this ablation strategy could allow treatment of AF independent of suppression of any triggering event.

J Cardiovasc Electrophysiol, Vol 11, pp 686-690, June 2000

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Automatic Cardiac Event Recorders Reveal Paroxysmal Atrial Fibrillation after Unexplained Strokes or Transient Ischemic Attacks
 
Jean-Claude Barthélémy, M.D., Ph. D., * Séverine Féasson-Gérard, M.D., * Pierre Garnier, M.D., ** Jean-Michel Gaspoz, M.D., M.S.c., *** Antoine Da Costa, M.D., **** Daniel Michel, M.D., Ph.D., ** and Frédéric Roche, M.D., Ph.D. *

From the * Service d'Exploration Fonctionnelle CardioRespiratoire, Laboratoire de Physiologie, CHU Nord, France; ** Service de Neurologie, CHU Bellevue, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, France; *** Clinique de Médecine II et Division de Cardiologie, Département de Médecine Interne, Hôpitaux Universitaires, Switzerland; * Service de Cardiologie, CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, France.

Background
The etiology of stroke or transitory ischemic attack (TIA) remains frequently unknown. While paroxysmal atrial fibrillation (PAF) is often suspected, its presence remains difficult to establish. Therefore, we investigated the occurence of PAF episodes in such a population using a long-term automatic cardiac event recorder.

Method
We prospectively investigated 60 consecutives subjects admitted in our university hospital for stroke (n=44) or TIA (n=16), adding long-term automatic cardiac event recorders, with a target duration of 4 days, to standard investigations, which included 12-lead ECGs and 24-hour Holter recordings.

Results
In 28 patients no etiology was found for their stroke or TIA. Howewer, one or more than one PAF episode was found in 4 of them (14.3%) using the long-term automatic event recorder. In the 32 remaining patients, 8 presented with PAF, and this was considered as the cause of their stroke. In both groups, AF was paroxysmal. The PAF episodes' duration went from 1 to 96 hours (mean +- standard deviation, 18 hours and 30 minutes +- 30 hours).

Conclusions
Patients suffering PAF episodes after ischemic stroke or TIA were statistically less often recognized using the 24-hour Holter ECG recording alone than the R.TEST Evolution alone.

A.N.E. 2003; 8(3):194-199

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Usefulness of Ambulatory 7-Day ECG Monitoring for the Detection of Atrial Fibrillation and Flutter After Acute Stroke and Transient Ischemic Attack


Denis Jabaudon, MD, PhD; Juan Sztajzel, MD; Katia Sievert; Theodor Landis, MD; Roman Sztajzel, MD From the Department of Neurology (D.J, T.L, R.S.) and Cardiology Center, Department of Internal Medicine, (J.S., K.S.), University Hospital Geneva, Geneva, Switzerland.
Correspondence to Denis Jabaudon, Department of Neurology, University Hospital Geneva, Rue Micheli-du-Crest 24, 1211 Genève 4, Switzerland. Email denis.jabaudon@hcuge.ch

Background and Purpose
Although atrial fibrillation is the most frequent cause of cardioembolic stroke, this arrhythmia remains underdiagnosed, as it is often asymptomatic or intermittent and, thus, may not be detected on standard 12-lead ECG or even 24-hour ECG recording (Holter). In this study, we hypothesized that 7-day ambulatory ECG monitoring using an event-loop recording (ELR) device would detect otherwise occult episodes atrial fibrillation and flutter (AF) after acute stroke or transient ischemic attack (TIA).

Methods
One hundred forty-nine consecutive patients admitted to our neurology department with an acute stroke or TIA were systematically screened for emboligenic arrhythmias using standard ECG. In the absence of AF on standard ECG, patients underwent 24-hour ECG recording (Holter), which was followed by a 7-day ambulatory ECG monitoring (ELR) in patients with a normal Holter. Patients with previously documented persistent AF, with primary hemorrhagic stroke, or with acute large vessel dissection were not included in the study.

Results
AF was detected in 22 patients. Standard ECG identified AF in 2.7% of the cases at admission (4/149 patients) and in 4.1% of remaining patients within 5 days (6/145). Holter disclosed AF in 5% of patients with a normal standard ECG (7/139 patients), whereas ELR detected AF in 5.7% of patients with a normal standard ECG and normal Holter (5/88 patients).

Conclusions
Following acute stroke or TIA, ELR identified patients with AF, which remained undetected with standard ECG and with Holter. ELR should, therefore, be considered in every patient in whom a cardioembolic mechanism is suspected.

Key Words
atrial fibrillation, diagnostic tests, electrocardiography, prevention and control, stroke, cardioembolic

Stroke, 2004, 35: 1647 - 1651

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