Driving and implantable cardioverter-defibrillator shocks for ventricular arrhythmias: results from the TOVA study.

Objectives: This study examined the risk of implantable cardioverter-defibrillator (ICD) shocks for ventricular tachycardia (VT) or ventricular fibrillation (VF) associated with driving.
Background: Concerns regarding VT/VF occurring during driving are the basis for driving restrictions in ICD patients; however, limited data are available to inform recommendations.
Methods: This study used a prospective nested case-crossover design to compare the risk of ICD shock for VT/VF both during and up to 60 min after an episode of driving as compared with that during other activities among 1,188 ICD patients enrolled in the TOVA (Triggers of Ventricular Arrhythmia) study.
Results: Over a median follow-up of 562 days, there were 193 ICD shocks for VT/VF with data on exposure to driving before ICD shock. The absolute risk of ICD shock for VT/VF within 1 h of driving was estimated to be 1 episode per 25,116 person-hours spent driving. The ICD shocks for VT/VF were twice as likely to occur within 1 h of driving a car as compared with other times (relative risk [RR] 2.24, 95% confidence interval [CI] 1.57 to 3.18). This risk was specific for shocks for VT/VF and occurred primarily during the 30-min period after driving (RR 4.46, 95% CI 2.92 to 6.82) rather than during the driving episode itself (RR 1.05, 95% CI 0.48 to 2.30).
Conclusions: Although the risk of ICD shock for VT/VF was transiently increased in the 30-min period after driving, the risk was not elevated during driving and the absolute risk was low. These data provide reassurance that driving by ICD patients should not translate into an important rate of personal or public injury.