5. Rhythm and Devices: CIEDs,Bradyarrhythmias, and Tachyarrhythmias

Patients with a history of bradyarrhythmias, tachyarrhythmias, CIED in situ, and those who require CIED implantation are at risk for incapacitation, syncope, and impaired consciousness. For example, patients with selected bradyarrhythmias including complete heart block are at high risk for syncope, and should typically undergo expedited pacemaker implantation. Similarly, patients with tachyarrhythmias such as VT might be at risk for a life-threatening recurrence.

As such, these patients might require a driving restriction because of the increased risk of incapacitation, syncope, or impaired consciousness, particularly early after these incapacitating events and/or before definitive CIED therapy.

In this section, we summarize the evidence of incapacitation, syncope, and/or impaired consciousness in these scenarios and the recommendations for driving restrictions (Tables 5 and 6).

Cardiac implantable electronic devices

Question 5a: In persons who undergo CIED implantation or procedure, or, with a history of a CIED who are considering driving, what is the rate of SCD, syncope, or impaired consciousness as a marker of SCI?

Individuals with CIEDs can be broadly categorized into patients with permanent pacemakers (including transvenous, epicardial systems, cardiac resynchronization/conduction system pacing, or leadless devices) and ICDs, either transvenous (single, dual, or resynchronization/physiologic) or extravascular types.

Patients with pacemakers. Contemporary literature suggests that patients with permanent pacemakers are at low risk for pacemaker failure. Early cohorts reported failed sensing that occurred in approximately 2% of patients after pacemaker implantation.^[87] Although contemporary registries suggest a rate of lead complications that requiring revision within the first month at approximately 2%-3%,^[88] the risk of syncope associated with such events remains very low (see Bradyarrhythmias section). In a cohort of 507 patients after permanent pacemaker implantation, syncope occurred in 3% of patients at 1 year, and was attributable to orthostatic hypotension (26%), vasovagal syncope (18%), atrial or VAs (17%), and pacemaker or lead malfunction (7%).

Patients who undergo leadless pacemaker implantation appear to be at lower risk of complications, compared with those with transvenous devices. In a systematic review and meta-analysis across 36 studies (12 studies with safety end points), the incidence of device dislodgement and overall 90-day complication rates were 0.00% and 0.46%, respectively.^[89]

The historical 1-week private and commercial driving restriction for patients who undergo permanent pacemaker implantation takes into consideration the healing of the incision and potential discomfort and for prevention of inadvertent dislodgement of newly implanted pacemaker leads that would have a clinical effect in patients with previous high-grade or complete AV block or syncope. In addition, excessive arm and activity restrictions can also affect mobility, mental health, and quality of life (Table 5).

Patients with ICDs. Traditionally, driving restrictions in patients with ICDs were because of their underlying risk for malignant VAs. Early studies in patients who presented with VT/VF showed an incidence of recurrent VF, poorly tolerated or unstable VT, syncope, SCD, or ICD shock in 4.2% in the first month, and 1.8% per month between months 2 and 7, and 0.6% per month afterward.

In a recent cohort of 2786 patients with primary and secondary prevention ICDs, the rate of appropriate shock at 1 month was 0.9% and 2.2%, for patients with primary and secondary prevention devices, respectively.^[90] Recent Canadian cohorts of patients with primary and secondary prevention ICDs (Driving Restrictions and Early Arrhythmias in Patients Receiving a Primary-Prevention Implantable Cardioverter-Defibrillator [DREAM-ICD] and DREAM-ICD II) have also been reported. In 803 patients with primary prevention ICDs, ICD therapies occurred in 0.12% at 1 month and 0.75% at 6 months.^[91] In 721 patients with secondary prevention ICDs, the cumulative incidence of appropriate therapies was also very low. Notably, most episodes of recurrent VA occurred within the first 3 months (34%) after device implantation, and decreased over time (11% between months 3 and 6, and 12% between months 6 and 12). The risk of arrhythmic syncope resulting in SCI was 1.8% within the first 3 months and 0.4% in months 4-6 after device implantation.^[92]

Together, these 3 contemporary studies support a low rate of VAs and ICD therapies in patients with primary and secondary prevention ICDs. The very low rate of ICD therapies in primary prevention patients has supported a private driving restriction to 1 week after implantation, in line with the permanent pacemaker implantation guidelines (Table 6). In addition, driving recommendations must also take into consideration whether the patient has concomitant cardiac conditions that are limiting (eg, symptomatic HF; Table 3). The low rate of ICD therapies in secondary prevention patients has supported a reduction of the private driving restriction postimplantation. Taking into consideration the risk of harm with most events occurring within the first 3 months (albeit at a very low rate), the private driving restriction has been reduced to 3 months.

Modern ICD programming. Despite a theoretical concern that prolonged detection might result in sustained VAs and syncope, various studies have shown that this is not the case. In the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) study, 1500 patients were randomized to 3 different ICD programming arms; there was no increase in arrhythmogenic or all-cause syncope according to programming arm.^[93] In a systematic review and meta-analysis of 6 studies and almost 8000 patients, therapy reduction programming resulted in no increase in syncope.^[94] Because ICD therapies might be deployed when the patient is sleeping, it is sometimes difficult to ascertain whether the therapies are disabling or not. Even history of previous therapies might not necessarily be representative of symptoms that the patient might experience each time, therefore not necessarily predictive of whether said therapies would be disabling. Because of this important limitation, and in erring on the side of caution, we recommend that for appropriate ICD shock or any ICD therapy occurring during sleep, driving is prohibited for 3 months.

Contemporary ICD implantation also includes the use of subcutaneous ICD technology, obviating the need for transvenous leads, and potentially reducing lead-related complications. Because there is no anticipated difference in event rates when transvenous are compared with subcutaneous ICDs, the new recommendations for driving restriction for these devices are largely the same. Specific circumstances might arise when repeated defibrillation threshold testing is performed, with previous studies suggesting a slight increase in SCD in patients who receive defibrillation testing.^[95]

Electrical storm. Patients with VA electrical storm require individualized driving restrictions, according to the severity of their clinical presentation, clinical course, and management. A greater risk of adverse events (including mortality) in patients with clustered VAs, compared with other groups has been reported.^[96] Similarly, patients with a greater number of arrhythmias per cluster and shorter cluster length are at greater risk for mortality. Clustered arrhythmias terminated with ICD shocks, compared with antitachycardia pacing, are also associated with increased mortality. The risk of VA recurrence might depend on the clinical management, correction of reversible causes or triggers, ablation, and the use of antiarrhythmic therapy.

Generator changes. Studies have shown no differences in arrhythmias or ICD therapies in the 3-6 months before and after device replacement.^[97]

Bradyarrhythmias

Question 5b: In persons with sinus node dysfunction or conduction system disease and a pacemaker who are considering driving, what is the rate of syncope or impaired consciousness as markers of SCI?

For patients with conduction disturbances, there is an important distinction as to whether these findings are isolated (absence of symptoms) or occur in the presence of symptoms (ie, syncope). In the former group, most of such cases are associated with a low risk of syncope. In the latter group (previous syncope), numerous studies have shown high rates of recurrent syncope. As such, determining the private and commercial driving restrictions for these patients is heavily dependent on a thorough history and evaluation of symptoms (Table 7).

Isolated conduction disturbances/electrocardiographic findings. The risk of incident syncope associated with isolated electrocardiographic findings (ie, first-degree AV block, right bundle branch block) is extremely low. In a Framingham study of 7575 participants, the incidence of pacemaker implantation for individuals with first-degree AV block was 140 per 10,000 person-years.^[98] This has been reported in similar cohorts of patients with isolated right and left bundle branch blocks, with a very low risk of progression to pacemaker implantation.^[99] In a contemporary cohort of 360,000 Dutch patients, the 10-year risk of syncope and third-degree AV block was reported for isolated conduction defects.^[100] The highest rates of syncope occurred in individuals with bifascicular block with first-degree AV block, approaching a 25% 10-year risk of syncope.

Low syncope rates with isolated conduction defects translates into a very low risk of SCI in these patients. Therefore, we recommend no restriction across conduction defects as long as patients remain asymptomatic. Excluded from this recommendation are those with documented high-grade AV block, including those with second-degree Mobitz II AV block, alternating bundle branch block, and acquired third-degree AV block.

Conduction disturbances might also arise secondary to surgical or percutaneous interventions, which might have different outcomes and rates of progression dependent on the underlying intervention. Driving restrictions in these cases should be tailored on the basis of the surgical or percutaneous intervention performed and are discussed separately.

Conduction disturbances with syncope. Most studies in patients with a history of syncope and known conduction disturbance have shown an increased rate of recurrent syncope in this population. As such, we have placed specific emphasis on ensuring that patients with conduction disturbances do not have a history of symptoms/syncope. In a recent trial patients 50 years of age and older with bifascicular block, preserved left ventricular function, and ≥ 1 syncope event in the preceding year were randomized to an implantable loop recorder or permanent pacemaker implantation. The primary composite outcome measure comprised cardiovascular death, syncope, bradycardia resulting in pacemaker insertion, and device complications. There were fewer primary outcomes in the pacemaker group but similar recurrent syncope in both groups reflecting other causes of syncope such as vasovagal or orthostatic hypotension, which might occur as well in this population.^[101]

In the Syncope: Pacing or Recording In The Later Years (SPRITELY) trial 115 patients with syncope and bifascicular block were evaluated and 1-year syncope rates of 20% were reported.^[102] Similarly, 52 patients with syncope and bundle branch block were enrolled in the International Study on Syncope of Uncertain Etiology-3 (ISSUE-3) study, which and showed 42% syncope recurrence between 3 and 15 months.103 Similar studies in patients with syncope and documented asystole ( 3 seconds) and first-degree AV block have shown a high rate of recurrent syncope or pacemaker implantation.^[103],[104]

Special considerations: Sarcoidosis and inherited cardiomyopathies. There are special considerations when conduction disease is present in certain inflammatory (including sarcoidosis), infiltrative or inherited cardiomyopathies that might involve the conduction system. For example, patients with sarcoidosis and a history of syncope might have rapidly progressive conduction system disease, and should be restricted from driving until CIED implantation, or an alternate explanation for syncope is determined.^[105] Similarly, patients with myotonic dystrophy are at high risk for sudden death and rapidly progressive conduction system disease and hence should be considered for early, appropriate CIED therapy.^[106]

Congenital third-degree AV block. Patients with congenital third-degree AV block might have a robust junctional rhythm preventing the onset of typical symptoms associated with acquired complete AV block. Previous studies have suggested that pacemaker implantation is appropriate in patients with symptoms (syncope, presyncope, exercise intolerance) or marked bradycardia with junctional pauses > 3 seconds, complex VAs, or marked QT prolongation.^[107]

Tachyarrhythmias

Question 5c: In persons with a history of SVT or VT, or who undergo an electrophysiological procedure, and are optimally managed with medical therapy and CIEDs (where indicated) and who are considering driving, what is the rate of incapacitation, syncope, or impaired consciousness?

Patients with supraventricular tachycardia (SVT), atrial fibrillation, and atrial flutter might experience syncope or presyncope. In a study of 300 patients with SVT, symptoms included dizziness (47%), near-syncope (50%), and syncope (14%). Women experienced symptoms more frequently than men, and more than half of the patients experienced symptoms while driving.^[108] In another study of 589 patients with paroxysmal SVT, 15% of patients experienced syncope or near-syncope during at least 1 episode of SVT.^[109] As such, the recommendations for private and commercial driving for patients with SVT are primarily dependent on satisfactory control in patients with a history of syncope or near-syncope (Table 8).

The risk of iatrogenic injury to the conduction system or AV block in patients who undergo catheter ablation is low. Although early studies reported AV node injury requiring pacemaker implantation in up to 2.3% of patients who underwent AV nodal reentry ablation, contemporary multicentre studies have shown a much lower rate of AV block (approximately 0.2%-0.4%). Case series have similarly reported a low rate of AV block with ablation of para-Hisian accessory pathways, particularly with the use of various strategies to avoid inadvertent AV node injury (eg, focal cryotherapy ablation).^{[110]–[114]} Because of the rare occurrence of conduction system injury, the treating physician should manage such patients on an individual basis.