![]() Two antitachycardia pacing (ATP) schemes were programmed in this zone. ![]() A VT zone (lower heart rate) was programmed with a detection CL between 330 and 440 ms. The first shock ranged between 20 and 41 J and maximum energy was programmed for the remaining shocks. Between four and seven electrical shocks were programmed in this zone for all patients. 9 A ventricular fibrillation zone (upper heart rate) was set with a cut-off rate to detect a ventricular rhythm with a cycle length (CL) between 260 and 300 ms and lasting 1 s. Two zones of VT detection and therapy were programmed in all patients from both groups. ICDs were programmed empirically and not accordingly to VT responses to pacing at electrophysiological evaluation in all patients. ICD programmingĪll patients were recipients of third-generation ICD devices capable of storing intracardiac electrograms and R-R intervals. 8 Patients were followed and syncope recurrence following ICD implantation (response variable) was investigated. Programmed ventricular stimulation was performed according to a conventional protocol in all patients. Ten patients (38%) complained of more than one syncope episode before ICD implantation. Patients were divided into two groups according to the presence or absence of syncope at clinical VT presentation (exposition variable) before ICD implantation: 26 patients had a spontaneous SyMVT and the remaining 50 patients had spontaneous sustained non-syncopal monomorphic ventricular tachycardia (NSyMVT) ( Table 1). All patients who underwent ICD implantation were included in the study. This was a retrospective cohort study in the whole population of patients with spontaneous documented monomorphic VT and structural heart disease, who underwent ICD implantation in our institution since May 1995. 7 The purpose of this study was to assess the incidence, mechanisms, and time to syncope following ICD implantation in patients with spontaneous SyMVT. 5, 6 However, there is little data available about syncope recurrence in patients with spontaneous sustained VT. 3, 4 Previous studies have investigated the incidence and causes of syncope recurrence in patients with unexplained syncope and inducible ventricular tachyarrhythmias. In this setting, it has been suggested that the period with the highest risk for syncope recurrence is during the first 6 months after implantation, so driving restrictions are usually recommended during this time. Because the ICD does not prevent occurrence of life-threatening ventricular arrhythmias, ventricular tachycardia (VT) may precipitate syncope prior to termination by device therapy and could adversely affect public or private safety. 1, 2 This group of patients has high risk of arrhythmic recurrences and therefore require ICD implantation. Syncope, Tachyarrhythmias, Defibrillation Introductionĭifferent clinical trials have demonstrated that the implantable cardiac defibrillator (ICD) is associated with a reduction in mortality compared with antiarrhythmic drugs in patients with syncopal monomorphic ventricular tachycardia (SyMVT). ![]() Late syncope presentation supports reassessment of driving restrictions in this setting. Arrhythmic syncope presented after a first non-syncopal VT recurrence in six patients (75%).Ĭonclusion Syncope following ICD implantation is common in patients with SyMVT in contrast to patients with NSyMVT. Median time to the first arrhythmic syncope was 376 days. Among the former, four patients (15%) had non-arrhythmic syncope and eight patients had arrhythmic syncope (31%), which was associated with either ICD proarrhythmia (seven episodes of VT acceleration or VF degeneration by ATP or low/high-energy shocks in three patients) or spontaneous VT and VF (five episodes in five patients). Patients with SyMVT had a higher incidence of syncope (46% patients) than those with NSyMVT (2% patients) at 31☒1 and 34☒3 months follow-up, respectively (hazard ratio, 0.19 95% confidence interval, 0.04–0.42 P=0.0001). Methods and results Incidence and causes of syncope following ICD implantation in consecutive patients ( n=26) with spontaneous SyMVT were compared with those found in consecutive patients ( n=50) with spontaneous non-syncopal monomorphic ventricular tachycardia (NSyMVT). ![]() Aims We sought to determine the incidence, mechanisms, and time to syncope recurrence in patients with spontaneous syncopal monomorphic ventricular tachycardia (SyMVT) treated with an implantable cardiac defibrillator (ICD). ![]()
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