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Implantable Cardioverter–Defibrillators and Driving—Current Perspectives
a descending exponential curve, with the highest risk for a recurrence of patients with recent implants reported that they drove at least once daily,
being the period immediately following an event. Following a period of despite recommendations at that time to avoid driving for the first six
three months, the curve significantly flattens, and at six months it is months after device implantation. Patients who had received an ICD for
completely flat. primary prophylaxis were more likely to continue driving after implantation
than those who received devices after an episode of sudden cardiac death.
However, the years following the development of these guidelines saw the
rise of ICDs used for prophylactic purposes, where the risk for experiencing During an average follow-up period of 562 days, patients reported
a shock was far lower than that of the previous ICD population. A second experiencing a total of 414 ICD shocks, of which 324 (74.6%) were for VT
set of guidelines was then issued concerning these patients, which and/or VF. This corresponded to a person suffering a shock within one hour
recommended that driving needed to be restricted only for a period of time of driving, occurring at a frequency of approximately one episode per 25,116
sufficient to allow the implantation wound to heal (commonly felt to be person-hours of driving. Interestingly, almost 10% of these patients received
around one week).
2
three to four shocks, and about 6% received more than four shocks.
The principal problem with all of these recommendations was that they Due to the lack of information on exposure to driving, not all episodes of
were significantly hampered by the relative dearth of good data available for ICD shocks could be included in the final analyses. Of the 44 shocks
assessing the actual risk for experiencing an ICD shock while operating a confirmed to have occurred during and within 60 minutes of driving, seven
motor vehicle. Driving is considered to be one of the more stressful activities episodes occurred during driving, 30 occurred in the first 30 minutes after
a person encounters in day-to-day life. The associated increase in driving, and seven episodes occurred in the following 30 minutes
catecholamine levels noted to occur while driving would intuitively seem to after driving. Of particular note was the fact that of the seven patients in
predispose patients to a higher risk for ventricular tachyarrhythmias. the group who experienced an ICD shock while driving, none reported
However, the actual incidence of and causal relationship between driving having experienced light-headedness or syncope, and only one of these
and ICD shocks have never been fully studied. episodes resulted in a motor vehicle accident. The study concluded that
there was a significant increase in the risk for ICD shocks in the first 30
In the Antiarrhythmics Versus Implantable Defibrillators
3
(AVID) study, minutes after driving a motor vehicle, but the increase in risk during driving
approximately 8% of patients reported having experienced ICD shocks and in the period after the first 30 minutes was not significant.
while driving. Although this was an interesting observation, it did not
prove a causal relationship between the two. Another major problem was In the TOVA study, although the majority of ICD discharges occurred after
that many patients simply ignored their doctor’s advice regarding driving, driving rather than during it, the reasons for this were not apparent.
as being unable to drive often represented a significant hardship. Indeed, However, there was speculation that either exposure to particulate matter
in much of the US today, the inability to drive places significant limitations while driving or autonomic nervous system changes that occurred in the
on an individual’s potential for either employment or education, and aftermath of driving may have played a role. There were some important
renders them for the most part ‘functionally disabled.’ Finally, the risk limitations to the study. Principal among these was that it was an
for sudden cardiac death in the patient population receiving an ICD for observational study that was not intended to demonstrate causality. Also,
primary prophylaxis—although higher than the general population—is the data concerning driving were limited to non-anonymous self-reporting
far lower than for sudden cardiac death survivors. Thus, restrictions in by patients. Other studies have shown that patients are far less apt to report
driving after implantation of prophylactic ICDs in such patients appeared episodes when they suspect that the information may be used to restrict
to be unduly excessive. their ability to operate a motor vehicle. This would suggest that under-
reporting may have occurred to some extent. Another potentially
The situation has improved following the publication of the Triggers of compounding factor is that patients in the TOVA study who have resumed
Ventricular Arrhythmia (TOVA)
4
study in 2007. This was a prospective driving may have been significantly healthier than the average patient who
multicenter cohort study that evaluated both the driving habits and undergoes ICD placement.
frequency of ICD discharges in a group of 1,188 patients with ICDs
implanted in both sudden cardiac death survivors and for primary Where do we go from here? Given the sum total of information currently
prophylaxis in high-risk groups in accordance with the 1998 American available, it would appear prudent to continue to follow the most recent set
College of Cardiology (ACC)/American Heart Association (AHA) guidelines of AHA guidelines in addition to any and all federal, state, and local
for ICD implantation. The study was designed to compare the risk for ICD requirements concerning the operation of a motor vehicle when an individual
shocks during and up to 60 minutes after an episode of driving with the risk has an ICD.
2
Continued studies will be necessary to help better define the
for ICD shocks during other activities. Of the patients included in the study, exact risks that patients with an ICD pose to themselves and others, and to
approximately 80% said they drove a car at least once per week, and 75% evolve guidelines that are just and adequate for all concerned. ■
1. Olshansky B, Grubb BP, Driving and syncope. In: Grubb BP, recommendations: a medical/scientific statement from the 2001;345:391–7.
Olshansky B (eds), Syncope: Mechanisms and Management, American Heart Association and the North American Society of 4. Albert CM, Rosenthal L,Calkins H, et al., for the TOVA
Malden, MA: Blackwell Press, 2005:322–42. Pacing and Electrophysiology, Circulation, 2007;115:1170–76. Investigators. Driving and implantable cardioverter-defibrillator
2. Epstein A, Baessler C, Curtis A, et al., Addendum to: personal and 3. Akiyama T, Powell JL, Mitchell LB, et al., Antiarrhythmics Versus shocks for ventricular arrhythmias: results from the TOVA study,
public safety issues related to arrhythmias that may effect Implantable Defibrillators Investigators, Resumption of driving J Am Coll Cardiol, 2007:50:2233–40
consciousness: implications for regulation and physician after life threatening ventricular tachyarrhythmias, N Engl J Med,
US CARDIOLOGY 27
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