Incidence of Nonsustained and Sustained Ventricular Tachyarrhythmias in Patients with an Implantable Cardioverter Defibrillator

Nonsustained ventricular tachycardia (NSVT) is a frequent phenomenon in some patients with heart disease, but its association with sustained ventricular tachycardias (ventricular tachycardia [VT]/ventricular fibrillation [VF]) is still not clear. The aim of this study was to determine whether NSVT incidence was associated with sustained VT/VF in patients with an implantable cardioverter defibrillator (ICD). Methods and Results: Retrospective data analysis was conducted in 923 ICD patients with a mean follow‐up of 4 months. NSVT and sustained VT/VF were defined as device‐detected tachycardias. The incidence rates of NSVT and sustained VT/VF as well as ICD therapies were determined as episodes per patient. The NSVT index was defined as the product of NSVT episodes/day times the mean number of beats per episode, i.e., total beats/day. The NSVT index peak was defined as the highest value on or prior to the day with sustained VT/VF episodes. Patients (n = 393) with NSVT experienced a higher incidence of sustained VT/VF (17.2 ± 63.0 episodes/patient) and ICD therapies (15.2 ± 61.4 episodes/patient) than patients (n = 530) without NSVT (sustained VT/VF: 0.5 ± 6.6 and therapies: 0.5 ± 5.6; P < 0.0001). Approximately 74% of NSVT index peaks occurred on the same day or < 3 days prior to sustained VT/VF episodes. The index was higher for peaks ≤ 3 days prior to the day with sustained VT/VF (94.3 ± 140.1 total beats/day) than for peaks > 3 days prior to the day with sustained VT/VF (32.7 ± 55.9 total beats/day; P < 0.0001). Conclusion: ICD patients with NSVT represent a population more likely to experience sustained VT/VF episodes with a temporal association between an NSVT surge and sustained VT/VF occurrence. (J Cardiovasc Electrophysiol, Vol. 15, pp. 14‐20, January 2004)