Exercise Restriction to Prevent Sudden Death in Congenital Aortic Stenosis

Whom Are We Treating?

• aortic stenosis
• pediatric and congenital heart disease
• sports participation

Patients with significant congenital aortic valve stenosis are at risk for sudden death. Every pediatric cardiologist has learned this by the end of his or her first fellowship clinic session. Recommendations for exercise restriction have been a standard part of the management strategy for patients with significant aortic valve obstruction, be it untreated or persisting after valvuloplasty. Several consensus documents advocate this approach. But does exercise restriction actually result in any demonstrable benefit in patients with aortic stenosis? Amazingly, this simple question has never been addressed. In this issue of the Journal, Brown et al. (1) report on a study in which they sought to do so. They recognized that cardiologists at their center gave varying recommendations for exercise restriction after balloon valvuloplasty for aortic stenosis. Taking advantage of this variation in practice, the investigators were able to compare outcomes in 422 patients 4 years of age or older followed for a median of more than 14 years after balloon aortic valve dilation. The cohort was almost evenly split between those in whom exercise restriction was recommended and those in whom it was not. Although restricted patients were skewed slightly toward those with higher Doppler left ventricular outflow tract gradients, this difference was remarkably small. There was 1 case of sudden death in the entire cohort. This occurred in a 28-year-old exercise-restricted patient who died during sleep. To be sure, a study such as this has many limitations. Nonetheless, the information is compelling, and we are unlikely to get better data on the topic any time soon. Although these data do not allow one to conclude that exercise restriction is of no benefit in reducing the risk for sudden death in aortic stenosis, they certainly do not demonstrate such a benefit. Importantly, they suggest that if exercise restriction is of any benefit, that benefit is likely to be very small. The information demonstrates that sudden death is a very rare event in young patients (older than 4 years of age) with aortic valve stenosis managed in the current era.

Good studies raise more questions than they answer, they cause us to think about how and why we practice the way we do, and they force us to re-evaluate what we think we know. This is a good study.

There are 2 types of information relating aortic stenosis and sudden death. The first is from case series of groups of patients followed with aortic stenosis for long periods of time. From these studies, the recognition of the association between aortic stenosis and sudden death first arose; all predate the current era in the treatment of aortic valve disease. From 1958 to 1974, a total of 35 cases of sudden death in patients with aortic stenosis age 4 to 23 years were reported (2). Although direct information on the severity of obstruction was not available in most of these patients, three-quarters were symptomatic, most had ST changes on electrocardiography, and obstructions were severe in all autopsy-confirmed cases. Of the 21 instances in which activity status at death was known, only 4 patients died during organized sports; the remaining patients were either at rest or engaged in activities of daily living such as walking.

The other source of information about sudden death and aortic stenosis is from reports delineating the causes of sudden death in young competitive athletes. Aortic stenosis accounts for only 1% to 3% of cases (3–5). Although a minority of the total group of patients was known to have symptoms, no data have been presented on the subset with aortic stenosis. Furthermore, very little is known about the severity of obstruction in these patients. In sum, we know the following: 1) aortic stenosis is associated with sudden death; 2) patients with severe obstruction, particularly those with symptoms, are most at risk; and 3) although some patients died while engaged in sports, most cases of sudden death in aortic stenosis have not occurred during vigorous exercise.

It has been the recommendation of consensus groups that patients with moderate aortic stenosis (mean Doppler gradient 25 to 40 mm Hg or peak Doppler gradient 40 to 70 mm Hg) be restricted from most competitive sports (6). Underlying such recommendations is a recognition of the devastating impact of sudden death in young asymptomatic subjects, as well as the implication that restriction from sports participation is a relatively benign intervention (7). The latter deserves consideration. It is certainly possible to restrict a youngster from competitive athletics while still maintaining an active lifestyle and ideal weight, but it would be naive to think that such restrictions are always without consequences. The impact of exercise restriction on health in youngsters has not been directly examined, but there is substantial information on the benefits of competitive sports participation. Sports participation in adolescents has been associated with a decreased incidence of emotional problems (8). Adolescents who participate in competitive sports are more likely to be of healthy weight (9). There is also evidence, accruing from the experience with Title IX, that increased sports participation may result in significant decreases in adult obesity 20 to 25 years later (10). The incontrovertible evidence that we are in the midst of an epidemic of childhood obesity with predictably dire consequences on long-term health underscores the importance of this information (9,11,12). To summarize, exercise restriction has risk.

Where does the evidence lead us? First and foremost, we are led to conclude that the most effective way to prevent sudden death in aortic stenosis is to treat the obstruction where appropriate (13). If we adopt this strategy, restriction from sports participation is of unknown (but likely small) added benefit and has risk. This treatment, and restriction is a treatment, is unproven, and consequently there should be equipoise regarding its use. Published practice guidelines are powerful and useful tools. However, their utility is only as good as the evidence from which they derive. Recommendations based on limited or poorly applicable data can have the unintended effect of inappropriately limiting clinical decision making and stifling future investigation.

• American College of Cardiology Foundation