Driving restrictions in patients with an implantable cardioverter-defibrillator

INTRODUCTION — The implantable cardioverter-defibrillator (ICD) has been instrumental in improving survival in patients resuscitated from ventricular fibrillation or unstable ventricular tachycardia (ie, secondary prevention of sudden cardiac death). There are compelling data that the ICD is also effective in the primary prevention of sudden cardiac death (SCD) in select high-risk patients. Since many patients with an ICD may be healthy enough to drive an automobile, this topic will review the concerns regarding the risk of ventricular arrhythmias and ICD shocks in this patient population while driving. (See "Secondary prevention of sudden cardiac death in heart failure and cardiomyopathy" and "Overview of sudden cardiac arrest and sudden cardiac death".)

INCREASED RISK WITH DRIVING — For patients with ICDs, driving could lead to losing control of the vehicle if there are symptomatic ventricular arrythmias or ICD shocks. Loss of vehicle control not only poses a risk to the patient, but also to other occupants of the vehicle and persons outside of the vehicle. The extension of risk to others makes this issue a public health concern. Data regarding the risks associated with driving with an ICD are primarily retrospective, with no prospective trials that have randomized patients to driving with or without restrictions. Recommendations are based primarily on expert opinion and public policy.

Causes of accidents — Both ventricular arrhythmias and ICD-delivered shock therapies can interfere with driving and lead to accidents. In patients with ICDs, causes of accidents include:

●Sudden cardiac death – Although ICDs have been shown to improve survival, they do not entirely eliminate the risk of sudden cardiac death (SCD). Data from major trials indicate that the residual rate of SCD among patients who receive an ICD for secondary prevention is one to two percent per year [1-3]. Similar or slightly lower SCD rates have been reported in major primary prevention trials [4-6].

●Syncope – Syncope may occur due to arrhythmic and nonarrhythmic causes in ICD recipients. Even rapid treatment of a ventricular arrhythmia by an ICD may not protect against driving impairment, since syncope or altered states of consciousness can still occur. In the MADIT-RIT study, which included 1500 patients who received a primary prevention ICD and who were followed for an average of 1.4 years, 64 patients (4.3 percent) experienced syncope, with similar frequency regardless of the programmed device settings [7]. (See 'Syncope' below.)

●Transient incapacitation from the shock – Even if therapy is successful and the patient remains conscious, the discomfort from an ICD discharge, either appropriate or inappropriate, may startle or briefly incapacitate the patient and disrupt safe motor vehicle operation.

Overall incidence of ventricular arrhythmias and ICD shocks — A higher incidence of ventricular arrhythmias and ICD shocks increases the likelihood of that an incident may occur during driving.

In patients treated for secondary prevention — Data on the incidence of recurrent ventricular arrhythmias and ICD therapies among patients treated with an ICD for secondary prevention comes primarily from studies performed in the 1990s and early 2000s. As such, estimates of recurrent arrhythmia from those trials are presumably higher than what is seen in contemporary practice; this likely reflects the impact of contemporary medical therapy and ICD programming strategies, which appear to significantly reduce the rates of arrhythmias and inappropriate device therapy.

●In the AVID trial, among the 449 patients assigned to ICD therapy, 35 percent of patients had an arrhythmic event (arrhythmic death, sustained ventricular arrhythmia, shock, or antitachycardia pacing) at three months, 53 percent had an event at one year, and 68 percent at two years [8]. First shocks or antitachycardia pacing after the second year were uncommon.

●Among a cohort of 256 patients who received a subcutaneous ICD (S-ICD) for secondary prevention and who were followed for an average of 21 months, 12 percent of patients received an appropriate ICD shock [9].

●In the Danish Pacemaker and ICD Register, 4580 patients with ICDs placed for secondary prevention were followed for an average of 3.6 years [10]. Thirty percent experienced appropriate ICD therapies, of which 16.8 percent were ICD shocks, and 4.6 percent of patients had an inappropriate ICD shock. There was a reduction in appropriate (28.2 to 7.9 per 100 person-years) and inappropriate (10 to 1 per 100 person-years) ICD therapy over the study period 2007 to 2016.

●Another study of patients with ICD for secondary prevention is the DREAM-ICD-II Study [11]. This study observed patients from Canada from 2016 to 2020. The incidence of recurrent ventricular arrhythmia was greatest during the first three months following ICD implantation (34.4 percent) and decreased over time to 10.6 percent between months 3 and 6 and 11.7 percent between months 6 and 12. The authors also observed that the cumulative rate of sudden incapacitation resulting from syncope was 1.8 percent during the first 90 days after ICD insertion and then reduced to 0.4 percent between three to six months.

Among patients treated with an ICD for secondary prevention, single device therapy has an increased risk of additional events. In one study, the mean time to first ICD therapy was 138 days; among those with a first event, the mean time to second ICD therapy was only 66 days [12]. Patients with an initial ICD therapy had a 79 percent likelihood of another ICD therapy within one year.

Patients who do not have an ICD therapy within the first year appear to have a lower, but still appreciable, risk of future events [13,14]. One report, for example, identified 14 patients who had not received an appropriate shock at 24 months [13]. The actuarial risk of an appropriate shock in the next 24 months was still 29 percent.

In patients treated for primary prevention — Patients receiving an ICD for primary prevention have a lower risk of ventricular arrhythmias when compared with those in whom an ICD was placed for secondary prevention. Patients with primary prevention ICDs have variable rates of ICD discharge, which may be influenced by ICD programming, underlying cardiac diagnosis, and other factors [5,15-17]. (See "Implantable cardioverter-defibrillators: Optimal programming", section on 'Tachycardia therapies'.)

As examples:

●In the MADIT-RIT trial of 1500 patients with a primary prevention ICD placed between 2009 and 2011 who were randomly assigned to one of three ICD programming strategies, appropriate ICD therapy occurred in 12.4 percent over 1.4 years [16]. When compared with conventional programming, delayed therapy programming and high-rate programming reduced the risk of inappropriate and appropriate shocks without increasing the risk of death or syncope [16,18].

●In a study of 803 patients who had a primary prevention ICD placed between 2016 and 2019, the rate of ICD-delivered therapy (anti-tachycardia pacing or ICD shock) was 0.4 percent at 30 days, 1 percent at 90 days, and 1.7 percent at 180 days [17]. There were no episodes of syncope after six months of observation.

●Among 1111 patients with a low ejection fraction who underwent an S-ICD implant between 2015 and 2018 for primary prevention, 9 percent had received a shock at 18 months [19].

Predictors of events — A number of clinical features are associated with an increased risk of arrhythmic events and ICD therapies. These include the following:

●Reduced left ventricular ejection fraction (LVEF) [12,20,21]

●New York Heart Association Functional Class III or IV heart failure [12,21,22]

●Sustained monomorphic VT rather than VF as the presenting arrhythmia [12,21]

●Absence of revascularization in patients with coronary heart disease [12,21]

●Absence of beta blocker therapy after hospital discharge [12,21]

Syncope — When considering the risks associated with driving by patients with ICDs, the incidence of ventricular arrhythmias and ICD discharge are less important than the actual incidence of syncope during an arrhythmic event (since not all events lead to impaired consciousness). The incidence of syncope among patients treated with an ICD for secondary prevention ranges from 15 to 46 percent [12,23-25].

The frequency, causes of, and risk factors for syncope were evaluated in a review of 421 patients with an ICD for secondary prevention [23]. At a mean follow-up of 26 months, 62 had syncope (15 percent of all patients and 27 percent of those with recurrent ventricular arrhythmia). Syncopal episodes occurred in the following settings:

●Shortly after rapid and successful delivery of a first 34 joule shock; the mean ICD capacitor charge time was 9.4 sec (55 percent of syncopal episodes)

●VT that was initially treated with antitachycardia pacing, which may then lead to acceleration of the VT after pacing (16 percent of episodes)

●Incessant or clusters of VT (VT storm) (8 percent)

●Failure of a first shock (7 percent)

No cause could be identified in three patients.

Risk factors for syncope — Several clinical features predict an increased likelihood of syncope in patients treated with an ICD, including the following:

●Syncope during a prior episode of VT [23,26]. In one series, among ICD patients with syncope during a prior episode of VT, the median time to a first recurrent syncopal event was 376 days, suggesting that patients who present with syncope during VT are more likely to have syncope with recurrent episodes of VT, and the standard six-month driving restriction may be inadequate [26].

●Very rapid VT (cycle length less than 300 msec) [23].

●Reduced LVEF [23].

●Chronic atrial fibrillation [23].

The authors suggested that these risk factors may be used to risk-stratify ICD patients for future syncopal events. In the study discussed above, overall actuarial survival free of syncope was 90, 85, and 81 percent at one, two, and three years after implantation; in comparison, event-free survival was better in patients with none of the above risk factors (96, 92, and 92 percent) [23].

Effect of therapy on recurrent ventricular arrhythmias — In many patients with chronic ventricular tachycardia, ventricular tachyarrhythmias can be suppressed by antiarrhythmic medications and catheter ablation, thereby preventing syncope or ICD shocks. A meta-analysis suggests that amiodarone is the most effective antiarrhythmic medication for suppression of ventricular arrhythmia [27]. Amiodarone modestly reduced the incidence of SCD in patients with or without an ICD (relative risk 0.76; 95% CI 0.66-0.88) and was superior to other antiarrhythmics with low to moderate quality of evidence.

Catheter ablation of VT has emerged as an effective treatment modality in patients with a prior documented history of VT or VF. One of the first studies to demonstrate the ability of substrate-based VT ablation to reduce future ICD therapy was the SMASH-VT study [28]. Appropriate ICD therapy occurred in 12 percent of the patients randomized to ICD implantation plus catheter ablation versus 33 percent in the ICD-implantation-alone arm over a mean follow-up of 22.5 months. Other randomized studies have also shown superiority of VT ablation over antiarrhythmic drugs to minimize outcomes of composite endpoints, which included appropriate ICD therapy [29,30].

Given the relatively high recurrence of ventricular tachyarrhythmias and ICD shocks after antiarrhythmic medications or catheter ablation over the ensuing months, these therapies may not sufficiently reduce the risk of impairment while driving.

Inappropriate ICD shocks — Inappropriate shocks, which may predispose to an accident by startling or briefly incapacitating the patient, occur less frequently with modern generations and contemporary programming of ICDs. Thus, patients who have inappropriate ICD therapies without loss of consciousness may not require restriction. Again, official recommendations vary according to location.

Examples of trials and studies that report the rate of inappropriate shocks include:

●Among 1500 patients who received an ICD for primary prevention in MADIT-RIT (average follow up 1.4 years), the annual incidence of inappropriate shocks was only 2.9 percent. The main cause is supraventricular tachyarrhythmia, in particular atrial fibrillation with rapid ventricular response. Such patients may often receive multiple inappropriate shocks. Other causes of inappropriate shocks include electrical noise from conditions such as lead fracture or external electromagnetic interference and ICD. (See "Cardiac implantable electronic devices: Long-term complications".)

●In a cohort of 4089 patients, 417 patients (65 percent with a secondary prevention indication) experienced an inappropriate shock. Less than 1 percent of patients experienced an episode of syncope associated with the inappropriate shock. The estimated maximum annual risk of harm is calculated well below the established acceptable risk threshold of 5 in 100,000 [31].

●Among 1111 patients with a low ejection fraction who underwent an S-ICD implant between 2015 and 2018 for primary prevention, 4.1 percent experienced an inappropriate shock at 18 months [19].

INCIDENCE OF ICD SHOCKS WHILE DRIVING AND ACCIDENTS — Although information regarding the general incidence of arrhythmic events and the risk factors for such events are useful, there is now increasing evidence that directly addresses the incidence of such events while driving.

ICD shocks while driving — The incidence of ICD shocks associated with driving was assessed in an analysis from the TOVA study [32]. A total of 1,188 patients treated with an ICD for a range of primary and secondary prevention indications were followed for a median of 562 days. The following findings were noted:

●The estimated risk of an ICD shock within one hour of driving was one shock per 25,000 person-hours of driving.

●The relative risk for ICD shocks for VT/VF within one hour of driving compared to other times was 2.24. However, the elevated risk was limited to the 30 minutes after driving (relative risk 4.46 compared to other times), rather than during the driving episode itself (relative risk 1.05 compared to other times).

Accidents — Among patients with an ICD, the rate of motor vehicle accidents is highest immediately following ICD implantation and then decreases over months to years. However, accidents are typically underreported and may not be properly attributed to an arrhythmia or ICD-delivered therapy, which leads to potentially inaccurate measurements of the rate and cause of accidents in this population. The following studies illustrate the range of findings:

●In a Danish registry study that included 2741 patients with an ICD implanted for any indication between 2013 and 2016, 0.2 percent of patients received a shock while driving, and there was one traffic accident [33]. The authors estimated that the risk of harm was 0.0002 percent per person-year of ICD therapy.

●In another study of 14,230 patients who received an ICD for any indication between 2008 and 2013 and who experienced at least one shock, the risk of harm while driving after the initial shock (as determined by a formula that estimates the annual risk to other road users posed by a driver with an ICD, assuming a probability of loss of consciousness with an ICD shock of 32 percent) was 12.5 events per 100,000 ICD recipients at one month and 2.7 events per 100,00 recipients at one year [34].

●Among patients enrolled in a trial of ICD placement for secondary prevention (AVID) between 1993 and 1997, 50 patients reported having at least one accident, and there were a total of 55 accidents during 1619 patient-years of follow-up after the resumption of driving (3.4 events per 100 patient-years) [35]. Of these accidents, 11 percent (0.4 events per 100 patient-years) were preceded by symptoms of arrhythmia.

RECOMMENDATIONS OF OTHERS AND GOVERNMENT LAWS

Patients with an ICD placed for secondary prevention — Guidelines for driving after an episode of sudden cardiac death (SCD) have been published by various professional societies and local governments [36-39]. The general approaches to driving restriction in 4 different regions are summarized in the table (table 1) [37]:

●Noncommercial drivers are generally advised to not drive for the first six months postimplantation (first three months in the European Union), the time of greatest risk for recurrent events [8]. If there has been no discharge from the ICD during this period, driving can be resumed (table 1).

●If highway or long-distance travel is anticipated, patients should be encouraged to have an adult companion drive, and cruise control driving should be avoided.

●The six-month driving restriction restarts if an ICD discharge occurs with or without syncope.

●For commercial drivers, the risk of harm to the public as a consequence of ICD discharge or syncope is much higher. As a result, it was recommended that all commercial driving be prohibited permanently after a life-threatening ventricular arrhythmia whether the patient is treated with an ICD or antiarrhythmic drugs.

Some patients with an ICD have frequent episodes of hemodynamically well-tolerated, asymptomatic VT that are consistently terminated (and without acceleration) by antitachycardia pacing. The guidelines recommend that decisions on noncommercial driving in such patients be made on a case-by-case basis.

However, some have considered these guidelines too conservative in light of subsequently published data and advances in the treatment of arrhythmia [40]. In a report from the AVID trial described above, 57 percent of patients resumed driving within three months; the rate of patient-reported accidents preceded by symptoms suggestive of an arrhythmia was only 0.4 percent per patient-year, which is less than the accident rate in the general driving population (0.7 percent per year) [35]. Patients in the AVID registry who were not randomized had similar clinical characteristics to those who were, suggesting that these observations can be generalized to all patients who would be eligible [41]. Reporting bias is a potential problem since patients may underreport accidents or near-accidents.

These observations have led to the suggestion that low-risk patients (LVEF >40 percent, no persistent medical condition predisposing to recurrent arrhythmia, and no recurrent ventricular arrhythmia) can begin driving after three months [40].

The 1997 ESC guidelines reached similar conclusions (table 1), although it was emphasized that, because of limited data, the recommendations do not represent practice standards [38]. Thus, clinical judgment should be considered with a given patient [42,43].

As noted above, patients with frequent ICD shocks for recurrent arrhythmia may benefit from antiarrhythmic drug therapy or catheter ablation. (See "Pharmacologic therapy in survivors of sudden cardiac arrest", section on 'Treatment of breakthrough arrhythmias'.)

Patients with an ICD placed for primary prevention — The 2007 addendum to the AHA/NASPE guidelines provided the following driving recommendations (table 1) for patients with ICDs implanted for primary prevention [39]:

●Noncommercial driving should be restricted for at least one week following ICD implantation. In the absence of symptoms potentially related to an arrhythmia, driving privileges thereafter should not be restricted.

●Patients should be instructed that impairment of consciousness is a possible future event.

●Patients who have received an ICD for primary prevention who subsequently receive an appropriate therapy for VT or VF, especially with symptoms of cerebral hypoperfusion, should be managed according to the recommendations for patients with ICDs for secondary prevention.

●These recommendations do not apply to the licensing of commercial drivers.

The ESC guidelines recommended no restriction for noncommercial driving, beyond the two-week restriction immediately following implantation to allow for wound healing, but total restriction for commercial driving when an ICD was implanted for primary prevention (table 1) [38,43]. As in low-risk patients who receive an ICD for secondary prevention, resumption of driving may be safe after three months in patients who receive an ICD for primary prevention if they have had no sustained ventricular tachyarrhythmias [40,44].

Patients with nonsustained arrhythmias but without an ICD — The 1996 AHA/NASPE guidelines also made recommendations for driving in patients with ventricular tachyarrhythmias (nonsustained VT and idiopathic VT) not associated with loss of consciousness not treated with ICDs [37]:

●No restrictions for either noncommercial or commercial driving for patients with nonsustained VT without impaired consciousness.

●Noncommercial driving should be restricted for three months and commercial driving for six months in patients with nonsustained VT and impaired consciousness or with idiopathic VT (ie, no apparent structural heart disease) without impaired consciousness. Driving must cease if there are disabling symptoms. Driving is only allowed after specialist assessment and satisfactory control of the arrhythmia. If there is an indication for an ICD, the respective rules apply. (See "Ventricular tachycardia in the absence of apparent structural heart disease" and "Catecholaminergic polymorphic ventricular tachycardia".)

Governmental laws — Legal restrictions on driving for patients with a history of cardiac arrhythmias, non-seizure syncope, and seizure syncope differ among local, regional, and national governments (table 1), and there is generally no distinction between patients managed medically or with an ICD [25,43]. It has been estimated that, as of 1992, only about 30 percent of clinicians who implanted an ICD were aware of governmental regulations regarding driving [45]. Furthermore, among those aware of governmental regulations, 20 percent admitted to making recommendations that were not consistent with the regulations.

Clinicians must be aware of and adhere to the strictest legal regulations covering the area in which they practice (and also the areas in which their patients reside, if different from the practice location). It may be helpful for the clinician to point out to the patient that the issue affects public safety as well as patient safety.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac implantable electronic devices".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Implantable cardioverter-defibrillators (The Basics)" and "Patient education: Time to stop driving? (The Basics)")

●Beyond the Basics topic (see "Patient education: Implantable cardioverter-defibrillators (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Background – Data regarding the risks associated with driving with an ICD are primarily retrospective, and there are no trials of driving with or without restrictions. Recommendations are based primarily on expert opinion and public policy. Although restricting driving for a short period of time after implantable cardioverter-defibrillator (ICD) implantation may be necessary, excessive restrictions or a total ban may be unwarranted. (See 'Increased risk with driving' above.)

●Predictors of events – We consider the following factors when deciding about driving restrictions (see 'Predictors of events' above):

•Number of arrhythmic events

•Presence of syncope

•Low left ventricular ejection fraction (LVEF)

•Other cardiac diagnosis

•Treatment with antiarrhythmic drug or catheter ablation treatment

●Treatment of underlying factors – All reversible factors that might cause or exacerbate ventricular arrhythmia should be corrected (eg, coronary ischemia, drug toxicity, and electrolyte imbalance, particularly hypokalemia or hypomagnesemia). (See "Sustained monomorphic ventricular tachycardia in patients with structural heart disease: Treatment and prognosis", section on 'Treatment of associated conditions'.)

●Shared decision-making discussions – When making therapeutic decisions for life-threatening ventricular arrhythmias, the clinician should make it clear to the patient and family members that driving restrictions may be independent of whether the patient is treated with an ICD or antiarrhythmic drugs as other medical conditions may also contribute to the need to restrict driving. Such discussions can be difficult because of the importance of driving for both independence and quality of life. (See 'Recommendations of others and government laws' above.)

●Knowledge of legal considerations – Clinicians must be aware of and adhere to the strictest legal regulations covering the area in which they practice (and also the areas in which their patients reside, if different from the practice location) (table 1). It may be helpful for the clinician to point out to the patient that the issue affects public safety as well as patient safety. (See 'Governmental laws' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Ann Garlitski, MD, who contributed to earlier versions of this topic review.