Syncope While Driving
Syncope While Driving
Abstract & Commentary
By Jonathan Abrams, MD, Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque Dr. Abrams serves on the speaker's bureau for Merck, Pfizer, and Parke-Davis.
Sources: Sorajja D, et al. Syncope while driving: Clinical characteristics, causes, and prognosis. Circulation. 2009; 120:928-934; Curtis AB, Epstein AE. Syncope while driving: How safe is safe? Circulation. 2009;120:921-923.
Sudden syncope, especially while driving or during vigorous sports activity, is a widely feared, but relatively uncommon, event. This case-controlled study from the Mayo Clinic group clarifies a number of approaches to the risk of sudden death from syncope. They state that syncope is very common, estimated at 3.5% of visits to the emergency room. Although there are many causes of syncope, neurocardiogenic mechanisms and arrhythmias are responsible for the most occurrences and are unpredictable. This case-controlled study analyzes patients seen at the Mayo Clinic and outside clinics with syncope over a two-year period (January 1996 to December 1998). They defined syncope as a sudden and temporary clinical manifestation of interruption of global cerebral perfusion resulting in transient and sudden loss of consciousness and diminished postural tone, with complete spontaneous recovery without therapy.
Results: Almost 4,000 patients were seen at the Mayo Clinic for syncope within this period and, of this study population, 381 (10%) had an episode of syncope while driving (driving group). They were compared to the 3,496 remaining patients (90%) who were not driving. Prodromal symptoms of nausea, palpitations, chest pain, and dyspnea were more common in the drivers, but there were no significant differences in duration, nature, and presence of symptoms during recovery. Also, there was no significant difference in patients needing hospital care. Neurally mediated syncope was the most common cause of syncope while driving, occurring in 37% of the patients. The next most common category was cardiac arrhythmias (12%). A small number of patients had no identified cause for their syncope. The presumed causation of syncope had similar frequencies in the non-driving group. Both groups were treated conservatively with a mixture of fluid, strength training, salt, etc. Patients with neurally mediated syncope required drug therapy in about 27% of cases. A few patients in each group received pacemakers, defibrillators, or antiarrhythmic drugs. During follow-up, recurrent syncope was reported by 72 patients in the driving group, 49% of whom had a recurrence > 6 months after the initial evaluation. Recurrences during driving occurred in 10 patients in the driving group and 70% occurred > 12 months after the initial evaluation. The actuarial recurrence of syncope overall at 6 and 12 months was 12 and 14% for the driving group and 12 and 17% for the non-driving group (p = NS). Among the 72 drivers, recurrence occurred in 85% who had a prior history of syncope. The actuarial recurrence of syncope during driving was 0.7% at six months, and 1.1% in 12 months. The cumulative probability of recurrence in drivers was 7% over eight years of follow-up, with no increase in mortality when long-term survival of the driving groups was compared with age- and sex-matched patients. Long-term survival in the non-driving group was lower than in the driving group. The presence of significant cardiovascular disease, in general, was low, especially in the driving group. The authors conclude that neurally mediated syncope was the most common type of syncope while driving, and the rate of recurrence while driving is low.
Commentary
It is of interest that there is a substantial presence of syncope in free-living individuals. Although syncope is a common cause of emergency room visits, few guidelines deal with this subject. In 2001, a European task force provided guidelines for the management, diagnosis, and treatment of syncope (Eur Heart J. 2001;22:1256-1306). The peak incidence of syncope is in elderly patients. This has potential public health implications, because this peak corresponds to an age group with a higher frequency of auto accidents per year. Long-term survival in syncope patients appears to be comparable to an age/sex-matched cohort, perhaps because the actuarial recurrence of syncope while driving is low (0.7% at six months and 1.1% at 12 months). In this study, police reports and other sources of information were not investigated; thus, we are unable to discover the risk of injury to others.
Neurally mediated syncope, in this study, was presumed to be the cause of syncope in one-third of the syncopal patients during driving. Cardiac arrhythmias made up 12% of causes of syncope while driving. These observations provide strong evidence challenging our traditional views that syncope while driving is usually due to cardiac arrhythmias. The authors suggest that passive sitting without increased muscle tension, venous pooling, pre-existing dehydration, etc. could contribute to the development of syncope. Early prodromal symptoms were more common in the drivers, and provide an opportunity to prevent an accident.
Their data demonstrates that the causes of syncope and its recurrence are similar between drivers and non-drivers. Therefore, they recognize that there is no need to change clinical approaches to syncope, that current guidelines remains appropriate. Given the low overall rate of recurrence while driving, their data do not contradict the standard recommendation that driving could resume after 3 to 6 months in syncope patients who have had a medical evaluation. It is worth noting that that recurrence rates apply to patients receiving an accurate diagnosis and appropriate therapy, not the natural history in this population.
Sudden syncope, especially while driving or during vigorous sports activity, is a widely feared, but relatively uncommon, event.Subscribe Now for Access
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