How to prevent ICD shocks: part II

The patient developed persistent atrial flutter in June 2007 ( Figures 2 and 3 A , 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 3 B ). Ventricular tachycardia was treated first with a burst (cycle length 250 ms) during charging ( Figure 3 B ), which was unsuccessful ( Figure 3 C ). The first shock (25.4 J) was delivered sometime later and cardioverted atrial flutter into atrial fibrillation ( Figure 3 D ). Ventricular tachycardia, however, persisted ( Figure 3 C and D ). The second shock (34.6 J) eventually stopped the VT ( Figure 3 E and F ). Intra cardiac electrogram. 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. The cardiac compass trends; the OptiVol fluid Index. 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 3 A ), 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. 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.