Implantable defibrillator event rates in patients with unexplained syncope and inducible sustained ventricular tachyarrhythmias
A comparison with patients known to have sustained ventricular tachycardia
Neil P. Andrews, BMBS, MRCPa,
Richard I. Fogel, MD, FACCa,
Gemma Pelargonio, MDa,
Joseph J. Evans, MD, FACCa and
Eric N. Prystowsky, MD, FACCa
a Electrophysiology Section, The Care Group, LLC, Indianapolis, Indiana, USA
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Figure 1 A, Comparison of CLs of monomorphic tachycardias induced at EPS and recorded by the ICD during follow-up for the syncope group (squares). B, Comparison of CLs of monomorphic tachycardias recorded at clinical presentation, induced at EPS and recorded by ICD during follow-up for control patients (circles). Monomorphic tachycardia includes sustained ventricular flutter and sustained monomorphic VT. Solid bars represent means ± SEM.
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Figure 2 Plots of relation between cycle length of monomorphic tachycardias induced at EPS and subsequent spontaneous episodes recorded by the ICD in syncope group (A, squares) and control group (B, circles). Monomorphic tachycardia includes sustained ventricular flutter and sustained monomorphic VT.
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Figure 3 Kaplan-Meier "survival" estimates for time to first appropriate ICD event in cases with unexplained syncope and control subjects with documented sustained VT. The number of patients remaining in the study at six monthly intervals are indicated below the abscissa.
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Figure 4 Surface ECGs and intracardiac electrogram (RV, right ventricular outflow tract) recorded at induction of monomorphic VT (CL, 225 ms) during baseline EPS in a patient with unexplained syncope (A). Stored ICD intracardiac electrogram recorded between proximal and distal shocking electrodes (B) in the same patient two and a half months later. This spontaneous tachycardia (rate 265 beats/min, CL 226 ms) resulted in syncope and was terminated by a 34-J shock.
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