EHRA EDUCATION COMMITTEE: EDUCATION IN EP
How to prevent ICD shocks: part II
1 Department of Cardiology, Thoraxcenter, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands; 2 The Interuniversity Cardiology Institute Netherlands, Utrecht, The Netherlands
Manuscript submitted 3 July 2008. Accepted after revision 4 July 2008.
* Corresponding author. Tel: +31 50 3612355; fax: +31 50 3614391. E-mail address: i.c.van.gelder{at}thorax.umcg.nl
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The patient developed persistent atrial flutter in June 2007 (Figures 2 and 3A, cycle length 230 ms). The mean ventricular rate during atrial flutter was high (mean cycle length <500 ms, i.e. >120 bpm). On the day of presentation, the patient developed a fast ventricular tachycardia (VT, cycle length 280 ms, Figure 3B). Ventricular tachycardia was treated first with a burst (cycle length 250 ms) during charging (Figure 3B), which was unsuccessful (Figure 3C). The first shock (25.4 J) was delivered sometime later and cardioverted atrial flutter into atrial fibrillation (Figure 3D). Ventricular tachycardia, however, persisted (Figure 3C and D). The second shock (34.6 J) eventually stopped the VT (Figure 3E and F).
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As is demonstrated in Figure 2, atrial flutter was continuously present since June 2007 and had induced a rise in the OptiVol index, while there was a steady decrease in the thoracic impedance since the beginning of June 2007 (Figure 4). This may indicate an increase in the pulmonary fluid congestion, which was supported by the results of physical examination. Furthermore, analysis of the patient activity (Figure 2), also indicates a small decrease in activity in the 6 weeks prior to the appropriate ICD shocks. Analysis of the cardiac compass proves that more than 10 weeks prior to the appropriate ICD shock, the OptiVol fluid index had been steadily increasing, indicating a possible fluid accumulation. Probably, this fluid index increase relates to the development of heart failure triggered by the start of persistent atrial flutter with a high ventricular rate, which eventually elicited the VT.
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The association between atrial flutter/fibrillation, heart failure, and appropriate shocks because of VT has been described earlier.1
–3 This case illustrates that due to ongoing atrial flutter with an irregular heart rate almost continuously above 100 bpm (Figure 3A), the patient developed slowly progressive heart failure, ultimately leading to the VT. Possibly, the use of home monitoring or the use of OptiVol fluid alarm might have prevented the occurrence of the VT and thus two shocks in this patient. Early detection of an increase in fluid retention and the development of atrial flutter/fibrillation, would have made an early intervention possible in order to treat heart failure.
Several studies have proven that persistent AF and new onset AF are associated with more appropriate ICD shocks and hospitalization for heart failure.1–3 There are several theories with regard to the association between AF and appropriate ICD shocks. A possible cause can be haemodynamic deterioration, as was the case in the present patient. Furthermore, high heart rates may induce ischaemia leading to ventricular arrhythmias, and last but not the least, the irregularity of AF leading to short–long–short sequences may be intrinsically pro-arrhythmic.
Currently, studies are being performed with home monitoring to determine whether the amount of hospitalization for heart failure and/or shocks can be decreased. A retrospective interim analysis by Ellery et al.4 suggested a correlation between data found by home monitoring and hospitalization.
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We report a patient with appropriate ICD shocks, in whom in retrospect the VT probably was triggered by the progression of the heart failure due to persistent atrial flutter with a high ventricular rate. With home monitoring or the use of the OptiVol alarm, the ICD shocks possibly could have been prevented by earlier intervention.
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[1] Zareba W, Steinberg JS, McNitt S, Daubert JP, Piotrowicz K, Moss AJ. Implantable cardioverter-defibrillator therapy and risk of congestive heart failure or death in MADIT II patients with atrial fibrillation. Heart Rhythm (2006) 3:631–7.[CrossRef][Web of Science][Medline]
[2] Singh JP, Hall WJ, McNitt S, Wang H, Daubert JP, Zareba W, et al. Factors influencing appropriate firing of the implanted defibrillator for ventricular tachycardia/fibrillation: findings from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II). J Am Coll Cardiol (2005) 46:1712–20.
[3] Rienstra M, Smit MD, Nieuwland W, Tan ES, Wiesfeld AC, Anthonio RL, et al. Persistent atrial fibrillation is associated with appropriate shocks and heart failure in patients with left ventricular dysfunction treated with an implantable cardioverter defibrillator. Am Heart J (2007) 153:120–6.[CrossRef][Web of Science][Medline]
[4] Ellery S, Pakrashi T, Paul V, Sack S. Predicting mortality and rehospitalization in heart failure patients with home monitoring—the Home CARE pilot study. Clin Res Cardiol (2006) 95(Suppl 3):III29–35.[CrossRef][Medline]
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