European Heart Journal Advance Access originally published online on September 25, 2006
European Heart Journal 2006 27(20):2481-2482; doi:10.1093/eurheartj/ehl263
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Incidence of syncope after ICD implantation: low or high?
Department of Cardiology
University Hospital Valladolid
Ramon y Cajal, sn
Valladolid 47005
Spain
Tel: +34 983244251
Fax: +34 983255305
E-mail address: egarmo{at}yahoo.com or egarmo{at}egarmo.com
Arrhythmia Unit
Hospital Clinic
Barcelona, Spain
We read with great interest the article by Abello et al.1 reporting the incidence of syncope in implantable cardioverter recipients with spontaneous syncopal monomorphic ventricular tachycardia.
They make a distinction between patients who presented with syncopal ventricular tachycardia and those with non-syncopal ventricular tachycardia. In the former, eight out of 26 suffered syncope (11 episodes). Syncope presentation, therefore, appears to confer high risk of syncope after ICD implantation.
ICD was developed to protect patients from sudden death, but they also may help to control other symptoms such as syncope. Our previous work assessing the risk of syncope in ICD recipients2 in a population who presented with syncope showed strikingly different results, compared with the results from Abello et al. In our series, only three out of 37 patients had syncope recurrence and in none of them was it due to arrhythmias. To date, the largest report on the matter is that from Bansch et al.3 They found recurrence of syncope after ICD implantation in 14.7% of patients. Likewise, an older article by Kou et al.4 reports syncope in 13 of 180 patients.
How can we explain the results of Abello et al. in a particular subset of ICD recipients? First, their population corresponds to a selected group of patients with syncopal tachycardia. Secondly, ICDs can be programmed in a wide variety of ways. In our series, we found a high effectiveness of anti-tachycardia pacing and adjusted energy shocks after a short charging time. We think that this fact would explain the low incidence of syncope when compared with previous reports. The programming features in our patients are similar to those of Abello et al. with one exception. Abello et al. describe the use of ‘low energy shocks’ (LESs) as a therapy in the VT zone aimed at suppressing organized rhythms. As a matter of fact, there is evidence of arrhythmia acceleration after such LESs.5 Abello et al. describe the sequence of facts in seven episodes of syncope related to proarrhythmia, and in four out of those seven, LES was present in the sequence of therapies.
In conclusion, the true incidence of syncope in ICD recipients remains controversial. Reports on the incidence of syncope in large populations of ICD recipients are lacking. Previously known proarrhythmic therapies such as LESs should probably be avoided.
References
- Abello M, Merino JL, Peinado R, Gnoatto M, Arias MA, Gonzalez-Vasserot M, Sobrino JA. (2006) Syncope following cardioverter defibrillator implantation in patients with spontaneous syncopal monomorphic ventricular tachycardia. Eur Heart J 27:89–95.
[Abstract/Free Full Text] - Garcia Moran E, Mont L, Cuesta A, Matas M, Brugada J. (2002) Low recurrence of syncope in patients with inducible sustained ventricular tachyarrhythmias treated with an implantable cardioverter-defibrillator. Eur Heart J 23:901–907.
[Abstract/Free Full Text] - Bansch D, Brunn J, Castrucci M, Weber M, Gietzen F, Borggrefe M, Breithardt G, Block M. (1998) Syncope in patients with an implantable cardioverter-defibrillator: incidence, prediction and implications for driving restrictions. J Am Coll Cardiol 31:608–615.
[Abstract/Free Full Text] - Kou WH, Calkins H, Lewis RR, Bolling SF, Kirsch MM, Langberg JJ, de Buitleir M, Sousa J, El-Atassi R, Morady F. (1991) Incidence of loss of consciousness during automatic implantable cardioverter-defibrillator shocks. Ann Intern Med 115:942–945.[ISI][Medline]
- Lauer MR, Young C, Liem LB, Ottoboni L, Peterson J, Goold P, Sung RJ. (1994) Ventricular fibrillation induced by low-energy shocks from programmable implantable cardioverter-defibrillators in patients with coronary artery disease. Am J Cardiol 73:559–563.[CrossRef][ISI][Medline]
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