Legal and ethical aspects of driving and working in patients with an implantable cardioverter defibrillator

Legal and ethical aspects of driving and working in patients with an implantable cardioverter defibrillator Automobile driving is essential to work and leisure for many people, and patients with implantable cardioverter defibrillators (ICDs) are no exception. Whether patients who may suffer sudden incapacitation should be allowed to drive raises important ethical and legal issues. The opinion of physicians regarding when or if it is safe to drive with an ICD varies, and most countries have no regulations to assist such decisions. Such regulations can best be developed by actuarial analysis of the risks involved, although the limited volume of published data on the ICD hinders this process. A policy based on very low levels of social risk from driving by patients with ICDs or a comparison with epileptic patients suggests a ban on driving for 12 to 24 months after ICD implantation. Patients who have received therapy from the ICD within this period would not be granted a driver’s licence. As further data from actuarial studies become available, these guidelines could be relaxed for patients at low risk of therapy delivery. (AM HEART J 1994;127: 1185-93.)

Mark H. Anderson, BSc, MB, and A. John Camm, MD London, England

The development of any new therapy makes doctors and patients face new ethical dilemmas, and the implantable cardioverter defibrillator (ICD) has been no exception. Nonetheless, the legal and ethical issuesinvolved in most aspects of the development of the ICD have not been fundamentally different from those raised by many other therapies. However, the ICD treats the symptoms of the disease (ventricular arrhythmias and sudden cardiac death) without any impact on the diseasesubstrate. These symptoms are unusual by their unpredictability, suddenness of onset, and potential for rapid incapacitation of patients. In addition, the ICD, by virtue of therapy delivery, has the potential to exacerbate the symptoms. This raises import ethical and legal issues regarding whether patients should be allowed to drive or return to work after ICD implantation; these issueswill be considered further in this article. WORKING,

DRIVING,

AND THE ICD

The freedom to work and the freedom of mobility that automobile driving allows are highly prized in Western society. Illness or medical treatment that may restrict these freedoms have an adverse effect on From Reprints

St. George’s

Hospital

Medical

School.

not available.

Copyright cs 1993 0002.8703/94/$3.00

by Mosby-Year + 0 4/O/63010

Book,

Inc.

the individual’s quality of life and may also have substantial economic implications for society as a whole. Nonetheless, some restrictions are imposed on patients’ freedom to work and drive when individual incapacity or illness reduces their ability to perform and places society as a whole, at increased risk of injury or death. Assessment of chronic stable medical conditions, such as impairment of vision, is relatively straightforward. However, persons who are prone to sudden incapacitation without warning pose a particular problem. Most of the time they are fit to drive, but suddenly and unpredictably they may become unfit in a catastrophic fashion. Patients with epilepsy are one such group, and most states and countries have regulations governing driving by epileptic persons. By contrast, the problem of patients with syncope caused by arrhythmias has received much less attention. In most countries, patients are banned from vocational driving after one such episode because of the public safety implications, but the position with regard to driving private motor vehicles is more variable. The development of the ICD raises new issuesbecause, unlike other existing therapies, it does not attempt to prevent episodes of arrhythmia but just to terminate them when they occur. Of the first 48 patients to receive an ICD at St. George’s Hospital, 87% held a driver’s license and were active drivers at the time of ICD implantation. Of the 91% of patients under 65 years of age, 66% 1185

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7550250

None m

Temporary Permanent Dr ving Restrictions USA

~

Europe

Fia. 1. Pronortion of nhvsicians in the United States2and Europe recommendingpermanent, temporary, or’;lo restriction on d&&g in recipients of ICDs.

were working until ICD implantation. After ICD implantation, 56% returned to work. In 40% of the remainder, driving restrictions were a major factor in preventing return to work. Thus restrictions on driving and working can have a substantial impact on patients with ICD. CURRENT STATUS WITH AN ICD

OF REGULATIONS

ON DRIVING

The current status of regulations in the United States governing driving after an episode of ventricular arrhythmia has been reviewed by Strickberger et a1.l They found that while 43 of the 51 states restricted patients from driving after epileptiform seizures (mean restriction, 7.4 -t 4.8 months; median restriction, 12 months), only eight states had specific restrictions covering patients with syncope caused by cardiac arrhythmias (mean restriction, 9.6 f 5.2 months; median restriction 12 months), and none of the states had specific regulations for patients with ICD. Physician awareness of existing regulations was surprisingly poor. Among cardiologists, 74% misunderstood or did not know the local regulations. The same was true among 56 % of arrhythmia specialists. The variability of advice given to patients with ICDs, even from different physicians within the same institution, has also been highlighted.2 We conducted a limited survey by facsimile of physicians in European countries. Returns were received from 11 physicians in 10 countries (see acknowledgment). The mean period of driving limitations after an epileptic seizure in all countries ranged from 12 to 24 months (mean time, 20 months). With

the exception of Great Britain, no country has specific regulations governing driving with an ICD. In Great Britain, the regulations state that “patients with implanted defibrillators should not be permitted to drive and should notify the DVLC” (Driver and Vehicle Licensing Centre).3 Physicians in Europe were more likely to recommend abstinence from driving after ICD implantation than their U.S. counterparts (Fig. 1).2 DEVELOPING A RATIONAL POLICY FOR DRIVING FOR PATIENTS WITH AN ICD

The variability of the current regulations regarding fitness to drive in patients with arrhythmias reflects the lack of any clear underlying strategy in their determination. The issue of defining sensible regulations for fitness has been addressed previously in the field of aviation medicine and is based on an assessment of the risk of sudden incapacitation and the subsequent consequences of that incapacitation.4 We advocate the application of a similar approach to enable reasonable driving policy guidelines to be established for individuals with ICDs. WHATARETHECONSEQUENCESOFSUDDEN INCAPACITATION WHILE DRIVING?

In a study of 1348 patients who died of coronary artery disease, 71 (5 % ) of these deaths occurred in patients who were driving.5 Minor accidents resulted from 24 of these deaths, all without personal injury to third parties. A study of 9330 sudden deaths6 revealed that 98 (1%) occurred in people who were driving. Accidents (all minor) resulted from 47% of

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these deaths. The consequences of sudden incapacitation while driving, particularly for third parties, are dependent to some extent on traffic density and speedsthat may have increased somewhat since these studies were conducted. Nonetheless, these studies suggest that serious accidents do result after a very small minority of sudden incapacitations. Further evidence that this is the case comes from several studies that have evaluated the proportion of accidents in which driver incapacitation appeared to be responsible. A number of studies7-g have reported figures around 0.5 to 1.5/1000 accidents causing injury, although the figure for serious accidents may be somewhat higher at 4/1000 accidents.7 Approximately half of these accidents were related to coronary or cerebrovascular disease; the remainder were caused by epilepsy or hypoglycemia. In return for the freedom that motor transport provides, society is prepared to accept a burden of deaths caused by accidents, currently just below 50,000 deaths per year in the United States, or one in 5000 population per year. lo If we accept that patients who are known to be at increased risk of incapacitation should be allowed to drive, then it is implicit that society must accept some increase in the morbidity and mortality “cost.” What level of increase would be acceptable to society to allow patients freedom of movement is not clear, but it is likely that only a very small overall increase in this burden would be acceptable. However, if the high-risk population is a relatively small proportion of the total, then a considerable increase in risk within this high-risk population may be accommodated within this limitation. CALCULATION OF AN ACCEPTABLE INCIDENCE OF SUDDEN INCAPACITATION IN PATIENTS WITH ICD

We know that the approximate rate for sudden death per year in the United States for men and women combined is 200/100,000,11 giving an actuarial risk of sudden death of one every 4.5 x lo6 hours. However, as mentioned above, cardiovascular sudden death accounts for only about half of the sudden incapacitations that cause accidents. There are approximately 25,000 patients in the United States with ICDs in a population of 250 million. If we accepted a loo-fold increase in the incidence of sudden incapacitation resulting from a cardiovascular cause in patients with ICDs to a figure of one every 4.5 X lo4 hours, and we assume that 2/1000 fatal accidents are caused by sudden incapacitation, this would produce a 0.5% rise in fatal accidents from sudden incapacitation or a net rise in fatal accidents of 0.001 $‘o. Thus a policy allowing the 25,000 patients with ICDs to drive, provided their actuarial risk of

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I. Approximate actuarial risk of epileptic seizure in the next 12 months after a variable period free of seizures Table

Period since last seizure (mo)

Actuarial risk of seizure in next 12 mo

3 6 12 24

33%* 27r;* 9rc* 125t

*Ref. 12. tRef. 13.

sudden incapacitation was less than 1 in 4.5 X lo4 (equivalent to an actuarial incidence of 20 % per annum), would result in one additional death every other year. This represents only a 10% increase over the figure that society accepts as a consequence of freedom of movement. In other words, if this rule were accepted, nine of 10 fatal accidents in which a patient with an ICD was responsible would not be related to the ICD. An alternative approach is to examine the actuarial risk accepted by the current regulations for drivers with epilepsy. Most states and countries require a 6- or 12-month ban on driving after an epileptic seizure; Great Britain is unusual because it has a full 24-month ban. The approximate actuarial risk represented by these restrictions can be extrapolated from actuarial studies of seizure recurrence (Table I).121l3 The risk of recurrent seizure after 6 months is approximately 25 % , settling to a figure of approximately 10% to 12% after 12 months, and with a gradual decline in actuarial risk for longer periods free of seizures.13Using the figures for annual actuarial incidence of incapacitation of 10% to 25% defined by the epilepsy regulations and our figure of 20% calculated from a hypothetic analysis of acceptable risk levels, we can examine whether some or all patients with ICDs are capable of meeting such a target. WHAT IS THE RISK OF INCAPACITATION PATIENTS WITH ICDs?

IN

Although actuarial data for the incidence of ICD therapy delivery are available, this does not necessarily equate with the incidence of incapacitation. In the series of Kou et a1.,14only 16 (15%) of 106 patients who received shock therapy from their ICD had syncope. Unfortunately, no clinical variable (including prior history of syncope with arrhythmia) was predictive of syncope in this study. With the increasing availability of third-generation ICDs, more than 70 % of spontaneously occurring ventricular arrhythmias may be terminated by antitachycardia

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SLOW

FAST

,1,,11~~~~/1~,111,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

O*

April 1994 Heart Journal

Recovery

11,,11,,,,,/, ,111 ,/,,,,,,1, ,,,,,,,,,,,/,,,1,, /,,,,,,,,,,,/,,

OP;e

Recovery

Fig. 2. Impact of 30-secondbursts of pacing at two different rates on the meanvalue of the blood pressure

(BP), carotid flow (CF), and psychomotor score (Psycho) expressedas a percentageof their baselinevalues. Mean blood pressureand carotid flow valueswere measuredat between two and four secondsand between 14 and 16 secondsafter onset of pacing. SLOW pacing has no significant impact on psychomotor function whereasFAST pacing producessignificant impairment, which persist after cerebral autoregulation has restored carotid flow to near baselinelevels,

pacing alone.15This is likely to be associated with less

incapacitation than shock therapy because of less discomfort associated with the therapy and more rapid therapy delivery. However, even in the absence of syncope or shock therapy delivery, patients may still suffer from symptoms such as dizziness, graying of vision, and chest discomfort. To evaluate the possible impact of nonsyncopal arrhythmias at St. George’s Hospital, we have developed a simple psychomotor task (a modification of the conventional pursuit rotor) to enable evaluation of short-term changes in psychomotor function.r6 Ten patients have performed this task during 30second episodes of rapid ventricular pacing at two different rates. The slower rate (SLOW) produced only minor symptoms of palpitations. The more rapid rate (FAST) produced transient hypotensive symptoms at the onset of pacing (graying of vision, chest discomfort, or dizziness). Blood pressure was monitored with a finger cuff recording system that has been shown to achieve an excellent correlation with arterial pressure. 17,l8 Internal carotid artery blood flow was measured by Doppler ultrasonography as an indicator of cerebral blood flow, a technique that has been validated elsewhere.lg The results of the pooled data for psychomotor score, blood pressure, and carotid artery flow from the 10 subjects during fast and slow pacing are shown in Fig. 2. It is clear that during the SLOW pacing,

line in the first 15 seconds and continued to decrease to 69% of baseline values during the second 15 seconds. This fall-off in performance occurred despite cerebral autoregulation returning carotid flow to near baseline values by 15 seconds. After termination of both FAST and SLOW pacing, psychomotor function returned to values close to those at baseline with

a small overshoot of blood pressure and carotid flow. The implication of this study is that episodes of ventricular arrhythmia associated with even transient hemodynamic symptoms are associated with impaired psychomotor performance, whereas arrhyth-

mias that produce symptoms of palpitation alone do not appear to have any impact on psychomotor performance. It is clear that less than 20% of arrhythmic episodes treated by the ICD are associated with syncope. However, an unknown proportion of the remaining episodes will be associated with impairment of psychomotor performance with a significantly increased accident risk. Because of the lack of specific figures on these proportions, it is safest to assume the “worst case” scenario, that is, that all episodes of arrhythmia treated by the ICD are potentially incapacitating. WHAT IS THE ACTUARIAL RISK OF THERAPY DELIVERY IN PATIENTS WITH ICDs

To enable the development

of well-founded

regu-

during which patients were aware only of palpita-

lations on fitness to drive, actuarial therapy delivery

tions, there was no significant impairment of psychomotor performance, while during FAST pacing, psychomotor performance decreased to 79 % of base-

data are required for a large population of thousands of patients with ICDs. Regrettably, no studies of this size have yet been published. The actuarial incidence

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MONTHS Fig. 3. Actuarial incidenceof appropriate therapy delivery in the first 47 patients with ICDs at St. George’s

Hospital: percent survival free of appropriate therapy delivery against time (months). II. Annual actuarial risk of first-therapy delivery in the four quarters of the first year after ICD implantation from St. George’sHospital Databaseand Fromer et a1.15 Table

Actuarial

Period o-3 3-6 6-9 9-12 Cumulative

(mo)

annualincidence

St. George’s database (%) 140 92 87 a2 68

incidence

Table Ill. Actuarial risk of first ICD therapy in the first year

and afterward Actuarial

risk

of ICD

therapy

(Wlyr)

(% lyr)

Fromer

Yr after ICD implantation

Griffith et aLzO (n = 188)

Curtis et aL2’ (n = 59)

1-2 2-3 3-4 4-6

27 7 9 10

9 9 ND ND

St. George’s database

et a1.15 (%) 88 82 45 65 55

of appropriate therapy delivery in the St. George’s Hospital population is shown in Fig. 3. Table II shows the incidence of first-therapy delivery during the four quarters of the first year after ICD implantation in this population and in a series of 102 patients published by Fromer et a1.15The figures in this table are expressed as annual actuarial incidences. For example, if 35 % of the population receive an ICD shock during the 3 months after ICD implantation, this is equivalent to a rate of 4 X 35 % = 140 % per annum, or 1 in 6.2 x lo3 hours. The actuarial incidence figures from the study of Fromer et a1.15are somewhat lower than those of the St. George’s database, because they include only the incidence of appropriate therapy for rapid ventricular arrhythmia. However, it is clear that the actuarial incidence of first-therapy delivery remains high throughout the first year after ICD implantation. Data on the risk of first-therapy delivery in subsequent years come from

0 * * *

ND, No data. *Numbers

of patients

too small

for meaningful

conclusion.

two other studies20*21 and from our database at St. George’s Hospital, as shown in Table III. There is considerable variation in the incidence of first-therapy delivery in the second year after ICD implantation, but all the studies agree that the incidence in subsequent years is low (probably 10% per year or less) in patients who have not yet received therapy from the ICD. ARE SOME

PATIENTS

WITH ICDs AT LOWER

RISK?

There has been much interest in factors that may predict a higher (or lower) incidence of therapy delivery from the ICD. Among the factors that have been identified are left ventricular function,22 coronary artery bypass grafting, and P-blocker therapy.23 After multivariate analysis, Anderson et a1.24suggested that a lower left ventricular ejection fraction is the most powerful predictor of appropriate ICD therapy delivery. Dichotomizing their population

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IV. Annual actuarial incidence of first ICD therapy delivery in the four quarters after ICD implantation stratified by ejection fraction

Table

V. Actuarial incidence of further ICD therapy delivery in the years after a first ICD therapy delivery

Table

Yr after previous ICD therapy

Actuarial incidence of first ICD therapy deliueryouer next 3 months (expressed as % lyr) Period fmo) o-3 3-6 6-9 9-12 Cumulative EF, Ejection

annual

EF > 50% (n = 22)

incidence

56 0; 23 5% 00, 0 @G 19%

EF<50% (n = 24) 132CA 145% 104 5 200% 55%

fraction

around an ejection fraction of 50% produces two populations with very different actuarial incidences of therapy delivery during the year after ICD implantation (Table IV). The high ejection fraction group also shows a rapid decline in the actuarial incidence of first-therapy delivery, with levels below 10 % per year from 6 months onward. Although there is encouraging evidence that some patients with ICDs may be at lower risk of a first-therapy delivery within 6 to 12 months after ICD implantation, such subgroup analyses are currently limited by the lack of actuarial data from large groups of patients with ICDs followed up for long time periods. ACTUARIAL RISK OF FURTHER THERAPY IN PATIENTS WHO HAVE ALREADY RECEIVED THERAPY FROM THEIR ICD

Very little published data exist on the actuarial occurrence of further therapies after the initial occurrence of ICD therapy. In our patients with ICDs at St. George’s Hospital, 27 of 48 patients have so far received ICD therapy (appropriate, inappropriate, or both), and 22 (81%) of these patients subsequently received another therapy at least 1 week after the first therapy. Data from one published series20 on the actuarial occurrence of second-therapy delivery in the years after first-therapy delivery are summarized in Table V. This table shows that in all subsequent years the incidence of further ICD therapy is 25 % or above. EMPLOYMENT

April 1994 Heart Journal

American

AND THE ICD

The actuarial analysis techniques described above may be extended to the field of employment as well as driving. The major difference between these two situations is the duration of exposure. Most people spend on average 5 % or less of the day driving, while employment accounts for approximately 25% Of

Data

from

Actuarial risk of further ICD therapy delivery in next year (“6)

1

39

2 3 4

33 31 25

Griffith

L, et al. PACE

1988;11:887.

time. This increases the risk of incapacitation occurring during working hours. Fortunately, sudden worker incapacitation is not likely to be critical in most jobs. However, for patients with ICDs who work in dangerous environments or in posts where operator incapacitation could result in injury or death to third parties or substantial economic loss, very careful scrutiny of the risks involved should be made before the patient is allowed to resume employment. Few jobs have clearly defined actuarial incidence thresholds, but professional aircrew licensing has a defined acceptable cardiovascular event rate of 1% per year,4 which clearly is not achievable under even the most auspicious circumstances by patients with ICDs. PATIENTS WITH ARRHYTHMIAS CONVENTIONAL THERAPY

TREATED

BY

It is important to remember that patients with arrhythmias who receive conventional electrophysiologically guided drug therapy may also remain at risk of recurrent arrhythmias and sudden death. A strong case exists for driving regulations for such patients to be based on an actuarial basis similar to that for patients with ICDs. DISCUSSION

Many of the ethical issues raised by the advent of ICD therapy are common to other new medical therapies. However, while previous therapies for patients with arrhythmias have aimed to eradicate or suppress the arrhythmia, ICD therapy implies an acceptance that episodes of arrhythmia will continue. These episodes are often symptomatic and may be incapacitating. Therefore it is reasonable to question whether these patients are fit to drive or return to work. The primary responsibility of the physician is to the individual patient. However, maximizing patients’ quality of life by maintaining their freedoms and rights must not entail an unacceptable cost to the rest of society. As in other spheres of life, legal restrictions aim to define this balance between the

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individual and society and to give guidance to physicians advising their patients, In the absence of legal structures, physicians will use their best judgment and individual knowledge of the patient’s condition to guide the advice they give. Both in Europe and in the United States, most legislatures have so far avoided the definition of regulations concerning the ICD and driving, relying on the expert physician to make a considered judgment. It is also clear that physicians’ advice on this topic varies markedly. The alternative approach, adopted in Great Britain, has been to ban driving altogether for patients with ICDs pending evidence regarding its safety. If patients and physicians are to respect regulations concerning driving with the ICD, these regulations must be based on a scientific appraisal of the risks involved. The performance of such an appraisal remains limited by the lack of actuarial data on the frequency and impact of ICD therapy delivery. However, with the limited amount of data available from published studies, we have attempted an assessment of the risk involved. The definition of what constitutes an acceptable level of additional risk is essentially a decision of social perception. Therefore it is not easy to define. We postulate that it is unlikely that society would accept anything other than a negligible increase in risk to the populace as a whole as a price for additional freedom and quality of life in patients with ICD. Our calculations show that with the current size of the population of patients with ICDs, an actuarial incidence of incapacitation of 20% per year in these patients would be associated with an increase of approximately 0.001% in the number of fatal road accidents, a level that is probably acceptable. In countries (such as Great Britain) where patients with ICDs make up a smaller proportion of the total population, the impact on the overall mortality rate would be commensurately less. An alternative means of defining “acceptable risk” is to consider the regulations driving with other conditions that are associated with sudden incapacitation but in which the natural history of the conditions is better defined. Epilepsy is the obvious candidate for such a comparison. Most states in the United States and countries in Europe have regulations governing driving private motor vehicles after an epileptic seizure. Depending on whether a 6-, 12-, or 24-month period free of seizures is required, these regulations define an acceptable actuarial risk level of incapacitation of 10 % to 25 % per year. A major difficulty in defining acceptable levels of incapacitation in patients with ICDs is that only a proportion of arrhythmic episodes will result in sig-

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nificant incapacitation. Complete incapacitation may result in only 15 % of arrhythmic episodes,14and with the advent of antitachycardia pacing therapies, only about one third of arrhythmic episodes will receive shock therapy. l5 Nonetheless, research that we have conducted at St. George’s Hospital suggests that episodes of arrhythmia associated with hemodynamic symptoms such as dizziness, graying of vision, or chest pain result in significant impairment of psychomotor performance.16 In the absence of clear evidence on the proportion of arrhythmic episodes resulting in impairment that is likely to cause an accident, we have assumed that all episodes of ICD therapy delivery are associated with such impairment. On this basis, actuarial analysis suggestsan annual incidence of first-therapy delivery throughout the year after ICD implantation in excess of the 25% per annum figure defined by a 6-month driving ban after an epileptic seizure. Figures for the incidence during the second year are more variable, and it is likely that the incidence during this period falls below the 25% per annum threshold but not sufficiently to reach the 10% per annum target defined by a 12-month ban after an epileptic seizure. This figure is only reached in the third year after ICD implantation, by which time only about 30% of patients with ICDs will have remained free of therapy delivery. Subgroup analysis suggeststhat some low-risk groups may exceed these targets at earlier stages after ICD implantation. For patients who receive ICD therapy, very limited data are available on their future risk, but it appears to remain at or above our 25% per annum threshold. Based on this analysis, it is possible to suggest a tentative structure for regulations regarding the ICD and driving. It should be stressed that this structure is based on a “worst case” scenario, and thus it may prove to be excessively cautious as more experience with the long-term follow-up of the device is gained. Patients who have not received therapy from their device could be allowed to resume driving between 12 and 24 months after ICD implantation (perhaps from 6 months in low-risk groups, such as patients with higher ejection fractions), but they would have to surrender their license if they received subsequent ICD therapy. For patients who have received ICD therapy (either before or after the intervals described above), there are currently insufficient data to say when it might be safe for them to resume driving. Because of the greater time exposures and risks involved in occupational driving, there is no evidence that any patient with an ICD should be allowed to resume vocational driving. In considering whether patients are allowed to resume an occupation that places them or others at risk, an actuarial analysis of

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the risks with use of the best available data should be performed. Such analyses are inevitably a compromise, because someone who drives for 1 hour a week has a lower risk of dying suddenly while driving than does someone driving 20 hours a week. When considering risks, it is also important to consider the known diurnal variation in the delivery of implantable defibrillator therapies,25 and any possible impact of the stress of driving on the incidence of arrhythmias. The possibility of restricting driving hours in patients at risk, perhaps by the use of a tachograph-type device, might be a reasonable means of maintaining essential mobility while minimizing risk. Whatever regulations are adopted, there will inevitably remain an ethical dilemma over their enforcement. In some countries (such as Norway), physicians are under a legal obligation to inform the local health authorities if a patient no longer meets the health requirements for driving.26 This clearly contradicts the ethical requirement of confidentiality. In Great Britain, it is the legal requirement of the patient to notify the authorities of his/her medical condition. This removes much of the ethical dilemma for the doctor whose obligation is to notify the patient of the regulations and to encourage patients to comply with those regulations. CONCLUSIONS

Most states and countries have no regulations that state when or if patients with ICDs may resuming driving private motor vehicles. The decision is usually left to the physician, with some limited guidelines on driving for patients with arrhythmias. Physicians’ opinions vary markedly. An actuarial analysis of the risks involved and comparison with regulations for epilepsy suggest that patients with ICD who have not received therapy from their device might be allowed to resume driving 12 to 24 months after ICD implantation at minimal additional risk to society. At present, there are insufficient data to suggest when or if patients who have received ICD therapy might safely resume driving. These problems highlight the need for large-scale databases containing data collected on the outcome of patients with ICDs as a whole and on subgroups within this population that may be at lower risk. Such actuarial methods of risk analysis should also be applied to the development of sensible regulations for patients with arrhythmias treated by conventional electrophysiologically guided antiarrhythmic drug therapy. We are grateful to the following individuals for responding promptly to a request for information on driving regulations in their countries and their own practices: Dr. Aliot, Central Hospital, Nancy, France; Dr. Rosenquist, Karolinska Hospital, Stock-

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holm, Sweden; Dr. den Dulk, Academic Hospital, Maastricht, The Netherlands; Dr. Steinbeck, Med. Hospital I, University of Munich, Germany; Dr. Ohm, Haukeland Sykehus, Bergen, Norway; Dr. Forfang, Rikshospitalet, Oslo, Norway; Dr. Dominguez and Professor Almendral, Madrid, Spain; Dr. Kappenberger, Lausanne-CHUV, Switzerland; Dr. Brugada, Aalst, Belgium; Professor Kremastinos, Onassis Cardiac Surgery Center, Athens, Greece: and Dr. Capucci, Bologna, Italy.

REFERENCES

1. Strickberger SA, Cantillon CO, Friedman PL. When should patients with lethal ventricular arrhythmia resume driving? Ann Intern Med 1991;115:560-3. 2. DiCarlo LA, Winston SA, Honoway S, Reed P. Driving restrictions advised by midwestern cardiologists implanting cardioverter defibrillators: present practices, criteria utilized and compatibility with existing state laws. PACE 1992; 15:1131-6. 3. Gold R, Oliver M. Fitness to drive: updated guidance on cardiac conditions in holders of ordinary driving licences. Health Trends 1990;22:31-2. 4. Joy M. Cardiological aspects of aviation safety-the new European perspective. Eur Heart J 1992;13:H21-H6. 5. Myerburg RJ, Davis JH. The medical ecology of public safety. I: sudden death due to coronary heart disease. AM HEART J 1964;68:586-95. 6. Bowen DA. Deaths of drivers of automobiles due to trauma and ischaemic heart disease, a survey and assessment. Forensic Sci 1973;2:285-90. I. Grattan E, Jeffcoate GO. Medical factors and road accidents. Br Med J 1968;1:75-9. 8. Herner B, Smedby B, Ysander L. Sudden illness as a cause of motor-vehicle accidents. Br J Indust Med 1966;23:37-41. 9. Baker SP, Spitz WU. An evaluation of the hazard created by natural death at the wheel. N Enel J Med 1970:283:405-9. 10. Baker SP, O’Neill B, Ginsburg MJ:Li G. The in&v fact book, 2nd ed. New York: Oxford U&versity Press, 199%212. 11. Gillum RF. Sudden coronarv death in the United States 1980-1985. Circulation 1989;7&756-65. 12. Shorvon SD, Reynolds EH. Early prognosis of epilepsy. Br Med J 1982;285:1699-701. 13. Medical Research Council Antiepileptic Drug Withdrawal Study Group. Prognostic index for recurrence of seizures after remission of epilepsy. Br Med J 1993;306:1374-8. 14. Kou WH, Calkins H, Lewis RR, Bolling SF, Kirrsch MM, Langberg JJ, de Buitleir M, Sousa J, El-Atassi R, Morady F. Incidence of loss of consciousness during automatic implantable cardioverter-defibrillator shocks. Ann Intern Med 1991: 115:942-5. 15. Fromer M, Brachman J, Block M, Siebels J, Hoffman E, Almendral J, Ohm OJ, den Dulk K. Coumel P. Camm AJ. Touboul PI Efficacy if automatic m&imodal device therap; for ventricular tachyarrhythmias as delivered by a new implantable pacing cardioverter-defibrillator. Circulation 1992; 86:363-74. 16. Anderson MH, Katritsis D, Gibson SA, Ross DJ, Pickering A. Automobile driving and ventricular arrythmias: implications of a study of motor performance during rapid ventricular pacing [Abstract]. Circulation 1992;86:1313. 17. Parati G, Casadei R, Groppelli A, Di Rienzo M, Mancia G. Comparison of finger and intra-arterial blood pressure monitoring at rest and during laboratory testing. Hypertension 1989;13:647-55. 18. Friedman DB, Jensen FB, Matzen S, Secher NH. Noninvasive blood pressure monitoring during head-up tilt using the Penaz principles. Acta Anaesth&iol SC&d 1990;34:519-22. 19. Leopold PW. Shandall AA. Feustel P. Corson JD. Shah DM. Popi AJ, F&tune JB, Leather RP, ‘Karmody AM. Duplex scanning of the internal carotid artery: an assessment of cerebral blood flow. Br J Surg 1987;74:630-3. 20. Griffith L, GuarnieriT, Mower M, Grunwald L, Reid P, Levine

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Sak-sena

J, Juantaquay J, Watkins L, Veltri E. Does an AICD generator need replacement when the battery is depleted? [Abstract] PACE 1988;ll:SSi’.

21. Curtis JJ, Walls JT, Boley TM, StephensonHE, Schmaltz RA, Nawarawrong W, Flaker GC. Time to first pulse after automatic implantable cardioverter defibrillator implantation. Ann Thorac Surg 1992;53:984-7. 22. Reiter MJ, Fain ES, Senelly KM. Determinants of recurrent ventricular arrhythmias in patients with implantable pacemaker/defibrillators [Abstract]. Circulation 1991;84(suppl 11):426. 23. Levine JH, Mellits D, Baumgardner RA, Veltri EP, Mower M, Grunwald L, Guarnieri T, Aarons D, Grifsth LSC. Predictors of first discharge and subsequent survival in patients with au-

tomatic implantable cardioverterdefibrillators. Circulation 1991;84:558:66. 24. Anderson M, Poloniecki J, Stein T, Ward DE, Rowland E, Camm AJ. Ejection fraction alone predicts recurrence of arrhythmias in implantable cardioverter defibrillator patients [Abstract]. Eur Heart J 1993;14(suppl):167. 25. Behrens S, Andresen D, Bruggemann T, Galecka M, Schroder R, Stegiltz K. Circadian variation of appropriate shocks in patients with implantable defibrillator [Abstract]. Eur Heart J 1993;14(suppl):168. 26. Steen T, Gjerstad L. Traffic medicine: formal and practical aspects. Tidsskr Nor Laegeforan 1993;113:2277-80.

The impact of implantable cardioverter defibrillator therapy on health care systems lmplantable cardioverter defibrillators (ICDs) are now widely used for the secondary prevention of sudden cardiac death and are being offered as a primary preventive therapy. This technology has potential for significant fiscal impact on health care budgets. Technologic innovation will result in more complex devices that are more effective and better accepted by patients and physicians. The clinical impact of these devices will be predicated, in part, by absolute survival benefits but also by their relative advantages over alternative therapies in terms of survival, safety, morbidity, quality of life, and cost. The impact on public health will depend on the efactiveness of screening methods for identification of populations likely to benefit from primary prevention. Risk stratification algorithms are now being tested in several ongoing clinical trials. Dilution of benefit by competing illnesses may occur to different extents in indlvidual patient populations. The economic impact is predicated on the future cost of ICD systems, limitation of hospitalization costs associated with this therapy, and accurate prospective stratification in primary prevention populations. Cost efficacy analyses and quality of life assessment in ongoing and future clinical trials are essential to the development of this therapy and its diffusion into different health care systems. Achievement of clinical benefits, functional independence, and a return to gainful employment by patients will be important determinants of the support lent by health care systems to the dissemination of this therapy. (AM HEART J 1994;127:1193-200.)

Sanjeev Saksena, MD Newark and Passaic, N.J.

Implantable cardioverter defibrillators (ICDs) are now widely used for the secondary prevention of sudden cardiac death. Whereas current data have been obtained from studies of patients who have already manifested malignant ventricular tachyarrhythmias, clinical trials are now assessing applications for primary prevention of sudden death in patients with coronary heart disease. Additional future

From the Arrhythmia and Pacemaker University of Medicine and Dentistry-New Heart Institute, and Children’s Hospital Reprint requests: Sanjeev Saksena, MD, vard, Passaic, NJ 07055. Copyright @ 1994 by Mosby-Year Book, 0002-8703/94/$3.00

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Service, Divisions of Cardiology, Jersey Medical School, Eastern of New Jersey. Reid Building, 4th Fl., 350 BouleInc.

applications include treatment of atria1 arrhythmias or other heart diseases in which the risk of sudden cardiac death or cardiovascular morbidity is deemed significant. The potential impact of ICD technology on a health care system is likely to be significant; its clinical impact is already evident from its widespread application for secondary prevention of sudden death.r ICDs are now being offered as a solution for the enormous public health problem of sudden cardiac death.2 In its June 1992 congressional report, the Prospective Payment Assessment Commission of the United States Government3 identified ICDs as one of the three new technologies likely to have a significant impact on Medicare costs. This article will consider the extent of this effect. To achieve this goal, a set of reasonable assumptions designed to project the de1193