Unexplained Syncope - Implantable Recorders

3/17/2003

Question: How effective are implantable loop recorders in the diagnosis of unexplained syncope?

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Unique Identifier:11687776

Authors: Boudet G. Chaumoux A.

Institution: Laboratoire Performance Motrice, UFR STAPS, Universite Blaise Pasal, Aubiere, Cedex, France. Gil.Boudet@wanadoo.fr

Title: Ability of new heart rate monitors to measure normal and abnormal heart rate.

Source: Journal of Sports Medicine & Physical Fitness. 41(4):546-53, 2001 Dec.

Abstract: BACKGROUND: The extended use of heart rate monitors to non sportive people, and older ones increases the risk to be facing heart rate troubles. Questions exist upon the ability of this devices to detect such abnormalities. The purpose of the investigation was to evaluate the accuracy of two third generation heart rate monitors, Accurex Plus and Vantage NV and to compared these data with those of an older one, PE 4000. Then we investigate responses of this monitors to abnormal heart rate. METHODS: EXPERIMENTAL DESIGN: The three heart rate monitors were tested in the laboratory, wired in parallel to an ECG simulator under two modes: a normal heart rate program (7 stable heart rate stages with two marked transitions) and an automatic arrhythmia one. MEASURES: 1st program: Values generated by the ECG simulator were compared to the values produced by the three devices. Particular attention was paid to the transition phases (heart rate drop and heart rate fall). Results of heart rate monitors accuracy were expressed at the exact value (devices value=simulator value) and at approximated value of +/-3 beats x min(-1) (devices value=simulator value +/-3 beats x min(-1)); 2nd program: Abnormal rhythms were analysed using an ambulatory ECG recorder (Synesis) as control data, and compared to the data from the three devices. Statistics: Correlation between simulator generated true values and HRMs read values were calculated. RESULTS: In the 1st normal heart rate program, with an accuracy of exact value, Accurex Plus and Vantage NV, were more accurate than the PE 4000 (94% and 89% of values respectively versus 33% for the PE4000). At +/-3 beats x min(-1), the three devices gave good results: over 98% of total values. In transition phases: the three devices showed a smoothing effect, which was stronger in decelerating heart rate than in accelerating heart rate. In the 2nd program: isolated heart rhythm troubles (missing beat, pause <4 sec, supra-ventricular ectopic activity, and ventricular ectopic activity) were either not detected or were rejected. Signal changes such as changes in QRS (ventricular bigeminy) may cause detection losses, and so modify calculated heart rate. The HR signal rising/dropping slopes caused by sudden heart rhythm disorders, were notably attenuated, with a consequent loss of HR accuracy. CONCLUSIONS: In laboratory stable heart rate conditions, third generation HRMs are more accurate than earlier ones. Heart rate monitors are less accurate in transient phases and have not been improved in that domain. The three HRMs ignore isolated heart rate troubles. As expected, the usefulness of HRMs in detecting HR disorders is limited. Nevertheless, these devices have some value with serious troubles, like pause, bradycardia or tachycardia, lasting longer than 4 sec, and especially if they coincide with functional symptoms. The use of such even more accurate devices may consequently be recommended to healthy public for which they were built.

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Unique Identifier:11359733

Authors: Brignole M. Menozzi C. Moya A. Garcia-Civera R. International Study on Syncope of Uncertain Etiology (ISSUE) Investigators.

Title: Implantable loop recorder: towards a gold standard for the diagnosis of syncope?.

Source: Heart (British Cardiac Society). 85(6):610-2, 2001 Jun.

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Unique Identifier:10092573

Authors: Kenny RA. Krahn AD.

Institution: Cardiovascular Investigation Unit, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK. R.A.Kenny@ncl.ac.uk

Title: Implantable loop recorder: evaluation of unexplained syncope.

Source: Heart. 81(4):431-3, 1999 Apr.

 Link Directly to Fulltext Article at Publisher

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Unique Identifier:9918528

Authors: Krahn AD. Klein GJ. Yee R. Takle-Newhouse T. Norris C.

Institution: Division of Cardiology, University of Western Ontario, London, Ontario, Canada. akrahn@julian.uwo.ca

Title: Use of an extended monitoring strategy in patients with problematic syncope. Reveal Investigators.

Source: Circulation. 99(3):406-10, 1999 Jan 26.

Abstract: BACKGROUND: The conventional investigation of patients who present with syncope involves short-term ECG monitoring or provocative testing with head-up tilt and electrophysiological testing. A symptom-rhythm correlation is often difficult to obtain during spontaneous syncope because of its sporadic, infrequent, and unpredictable nature. METHODS AND RESULTS: We used a prolonged monitoring strategy to determine the cause of syncope in 85 patients (age, 59+/-18 years; 44 men) with recurrent undiagnosed syncope with an implantable loop recorder capable of cardiac monitoring for up to 18 months. During a mean of 10.5+/-4.0 months of follow-up, symptoms recurred in 58 patients (68%) 71+/-79 days (2.3+/-2.6 months) after implantable loop recorder insertion. An arrhythmia was detected in 42% of patients who recorded a rhythm during recurrent symptoms, with bradycardia present in 18 and tachycardia in 3. Five of the 18 bradycardic patients and 2 additional sinus rhythm patients received a clinical diagnosis of neurally mediated syncope. Patients who experienced presyncope were much less likely to record an arrhythmia during symptoms compared with recurrence of syncope (24% versus 70%, P=0.0005). There were no adverse events associated with recurrent symptoms, and there were no sudden deaths. Inability to freeze after an event occurred in 8 patients, and pocket infection occurred in 3. CONCLUSIONS: The strategy of prolonged monitoring is effective and safe in patients with problematic syncope.

 Link Directly to Fulltext Article at Science Direct

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Unique Identifier:9671019

Authors: Krahn AD. Klein GJ. Yee R. Norris C.

Institution: Division of Cardiology, University of Western Ontario, London, Canada.

Title: Final results from a pilot study with an implantable loop recorder to determine the etiology of syncope in patients with negative noninvasive and invasive testing.

Source: American Journal of Cardiology. 82(1):117-9, 1998 Jul 1.

Abstract: Twenty-four patients with recurrent unexplained syncope and negative tilt and electrophysiologic testing underwent implantation of the implantable loop recorder, with recurrence of syncope in 21 patients 5.1+/-4.8 months after device implantation. Eighteen of the 21 had a treatable diagnosis, with arrhythmias in 11. Treatment resulted in resolution of syncope in most patients during long-term follow-up.

 Link Directly to Fulltext Article at Science Direct

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Unique Identifier:9193028

Authors: Fogel RI. Evans JJ. Prystowsky EN.

Institution: Indiana Heart Institute, Indianapolis 46260, USA.

Title: Utility and cost of event recorders in the diagnosis of palpitations, presyncope, and syncope.

Source: American Journal of Cardiology. 79(2):207-8, 1997 Jan 15.

Abstract: In 184 patients given an event recorder for the evaluation of palpitations, syncope or presyncope, we found that event recorders are useful and relatively inexpensive in the initial evaluation of patients with palpitations regardless of the presence of heart disease, and of syncopal or presyncopal patients without heart disease. In patients with presyncope or syncope who have heart disease and a negative electrophysiology evaluation, event recorders have less utility and are more costly.

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