ICDs increase traffic accident risk by 50%

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AccidentWEBThe risk of traffic accidents is increased by 50% in patients with an implantable cardioverter defibrillator (ICD) compared to age and gender matched controls, according to a Danish nationwide registry study presented at ESC Congress 2016.

“Driving after ICD implantation is an area of great debate and concern for both doctors and patients,” said lead author Dr Jenny Bjerre, a physician at Herlev and Gentofte University Hospital, Copenhagen, Denmark. “Our study provides contemporary data suggesting that the risk of motor vehicle accidents is in fact increased following ICD implantation when compared to controls.”

ICDs are widely used to prevent sudden cardiac death in patients with an increased risk of life-threatening arrhythmias (primary prevention) and in patients who have survived a life-threatening arrhythmia, including cardiac arrest (secondary prevention). The number of ICD implantations has increased dramatically over the past decades, now reaching almost 100,000 yearly implants in ESC member countries.

Due to the risk of arrhythmias and potential loss of consciousness while driving, patients with an ICD are temporarily restricted from driving following ICD implantation and/or ICD shock. However, contemporary data to support these recommendations are lacking and the restrictions have a negative influence on patients’ quality of life.

The study by Bjerre and colleagues was conducted at The Cardiovascular Research Centre at Herlev and Gentofte University Hospital in Denmark. Using nationwide registers, the researchers identified all Danish residents who received a first ICD for primary or secondary prevention between 2008 and mid-2012. Motor vehicle accidents were recorded from nationwide registers on accidents and deaths.

The study included 4,874 ICD patients and a control group of 9,748 subjects matched by age and gender. Participants were 63 years old on average. During an average follow-up period of 2.5 years, 2.3% of ICD patients were in contact with a hospital following a motor vehicle accident, compared to only 1.7% of the control population. Over time, this translated into a 51% increased risk of motor vehicle accidents in ICD patients compared to controls. There was no detectable difference in accident risk between primary and secondary prevention ICD patients.

Although higher than in the control population, the overall rate of motor vehicle accidents in ICD patients was low (1.0 to 1.4% within the first year after implantation), and the researchers observed no deaths due to motor vehicle accidents in patients with an ICD.

Bjerre said: “To date, driving recommendations for ICD patients are based on data from small studies in a few highly selected patients. The Danish nationwide registers provided a unique opportunity to investigate the subject in a ‘real world’ ICD population.”

“Due to the retrospective nature of the study we are unable to conclude that ICDs cause traffic accidents,” continued Bjerre. “However, because the control population was generally healthier and took fewer medically prescribed drugs, we speculate that the observed increased risk of motor vehicle accidents in the ICD population is likely a consequence of the underlying cardiovascular disease, rather than the ICD device itself.”

See also other ESC 2016 material:

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Background: Due to the risk of malignant arrhythmias, shocks and sudden incapacitation, patients with an implantable cardioverter defibrillator (ICD) are temporarily restricted from driving following ICD implantation and/or ICD shock. However, there is a paucity of data concerning the incidence of motor vehicle accidents (MVA) in ICD patients.
Purpose: We aimed to investigate the temporal risk of MVA in a nationwide cohort of ICD patients and matched controls.
Methods: Through nationwide registers, all Danish residents ≥18 years implanted with a first-time ICD between Jan. 1st 2008- June 30th 2012 were identified. These patients were matched 1:2 with controls on sex and age. During the study period, the Danish national recommendations for driving restriction after an ICD implantation were 1 week for primary and 6 months for secondary prevention ICD patients, provided that no ventricular arrhythmias were detected in the restricted period. The primary end-point was defined as non-fatal or fatal MVA in the period Jan. 1st 2008- Dec. 31th 2012. MVAs were identified through nationwide registers on accidents codes and death certificates according to the NOMESCO classification for external causes of injuries.
Results: We identified 4874 first-time ICD implantations and 9748 matched controls (mean age 65.5±12.2 years, 80% male, 2568 (52.7%) primary prevention ICDs). Through a mean follow-up of 2.4±1.3 years, 118 (2.4%) ICD patients and 177 (1.8%) controls experienced a total of 261 and 436 MVAs, respectively. In ICD patients, the frequency of accidents was equally distributed between primary (55 patients, 47%) and secondary (63 patients, 53%) ICD patients (p=0.192). Of the ICD patients who experienced a MVA, 59 (50%) occurred within the first 12 months after implant. No fatal MVAs were observed in ICD patients. Although higher than in the matched control group, the cumulative incidence of MVA was low over time in both primary and secondary prevention patients, with cumulative incidence of 0.3% at 3 months, <1% at 6 months and <5% at 4-years in both primary and secondary prevention patients (Figure). Compared to controls, ICD patients in general had a significantly increased risk of MVA (HR=1.42 [1.12–1.79], p=0.004). In subgroup analysis, a significantly increased risk of MVA was demonstrated in secondary prevention patients (HR=1.5 [1.2–2.1], p=0.004), but not in primary prevention patients (HR=1.3 [1.0–1.8], p=0.091), both compared to controls.
Conclusion: In a nationwide cohort of ICD patients, we found an overall increased risk of motor vehicle accidents, when compared with an age and gender matched control population. In subgroup analysis, secondary prevention ICD patients had a significantly increased risk of MVA when compared with controls, while we were unable to demonstrate a significant risk difference between primary prevention patients and controls.

J Bjerre, AK Nume, M Schou, C Jons, M Vinther, R Videbaek, HH Petersen, JB Johansen, S Riahi, JC Nielsen, G Gislason, AC Ruwald

ESC Congress 2016 material
ESC Congress 2016 abstract


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