This year’s annual meeting of the American College of Cardiology (ACC) was held recently in San Diego. I thought I’d share a round-up of some of the sports cardiology studies that caught my eye. In the months ahead, we can look forward to seeing the published reports. Here are my Top 8:
1. Life expectancy of elite long and short distance runners. In a study reported by Lee-Heidenreich D et al., the longevity of male Olympic athletes who competed in either the 100m dash or the marathon was examined. The study included the top 20 finishers in each event at the Olympic Games from 1928 to 1960. The investigators were able to determine the date of death for the majority (67%) of these athletes. At the time of their Olympic races, the short distance runners were younger than the long distance runners (23.8 vs 30.5 years). The life expectancy after their races were fairly similar (45.5 vs. 43.8 years), slightly favoring the short distance runners. But because of their older age at the time of their Olympic event, the marathoners actually enjoyed greater longevity overall.
My take: This is an interesting observation. No doubt, though, many variables influence longevity and it’s probably simplistic to think that the long- vs. short-distance issue explains all (or even most) of the longevity difference. I certainly wouldn’t encourage short distance runners to go long!
2. An assessment of the performance of pre-participation guidelines applied to novice older endurance athletes. This continues to be an important topic because there is no consensus about the best approach to screen adult recreational athletes for underlying cardiac conditions that might place them at risk. In this report by Matsumura ME et al., the use of either the American Heart Association (AHA)/American College of Sports Medicine (ACSM) Pre-Participation Questionnaire (AAPQ) or the 2001 Working Group on Masters Athletes guidelines were considered. The investigators surveyed 1457 novice runners and triathletes who were 35+ years old about the items included in the 2 screening tools. If the AAPQ criteria were applied, 42% of the athletes would be told they should have additional cardiac testing. If the Masters criteria were applied, 75% of the athletes would be told they should have additional cardiac testing.
My take: These screening questionnaires identify a rather large group of masters athletes who would require additional testing. It’s difficult to know how to find the balance here. We want to find athletes who truly have an important (hidden) heart problem, but avoid unnecessary diagnostic testing in those who don’t. It’s worth reading my previous blog post on another, recently published report on the topic of cardiac screening in adult recreational athletes.
3. Results from the coronary anomalies program at Texas Children’s Hospital. Anomalous coronary arteries (ACA, an inherited condition in which a coronary artery has an abnormal anatomy) are the 2nd leading cause of sudden cardiac death in young athletes. The investigators report on the successes of a multidisciplinary team approach to patient care, imaging studies, treatment, and long-term follow-up of pediatric patients with ACA. Among 58 patients, operation for surgical repair was recommend in 29 patients; 4 declined and 25 underwent operation. There were significant surgical complications in 4 patients. After operation, all 25 patients were able to return to exercise activities without restriction and none of these patients experienced any cardiac difficulties after operation.
My take: A multidisciplinary team that includes pediatric cardiologists, radiologists, and cardiac surgeons is almost essential to care for patients with ACA.
4. Screening with echocardiography or stress testing in asymptomatic USAF aviators–Not efficacious. The issue of cardiac screening for seemingly healthy adult athletes continues to be debated. In this study, the investigators report on an interesting experience with US Air Force (USAF) pilot applicants who, prior to 2008, underwent routine screening with echocardiogram and some form of exercise stress testing. Between 1994 and 2006, 20,208 screening echocardiograms were performed; a “permanently disqualifying diagnosis” was found in only 9 individuals (0.045%). The most common abnormalities detected were bicuspid aortic valve (in 0.76%), mitral valve prolapse (in 0.025%), and mild aortic regurgitation (in 0.29%). In a subgroup of 903 aviators who underwent stress testing, only 16% of those with an abnormal results were later found to have significant coronary artery disease with coronary arteriography. And moreover, regardless of the results of the stress testing, there was a very low rate (~0.5%) of later problems with death, heart attack, or need for revascularization (bypass surgery or coronary stent). The authors concluded that screening echocardiography and stress testing was not useful in healthy individuals without cardiac risk factors and suggested that the results could be extended to the healthy athlete population as well.
My take: The diagnostic yield for screening tests among healthy individuals will always be low. That’s how screening tests work, by design. We have to ask ourselves: What’s it worth to identify the 9 individuals who were disqualified from flying? Perspective matters here. If you were a member of a potential flight crew or a potential passenger, you’d want to know that your pilot was healthy!
5. Are years of training an independent predictor of atrial fibrillation in older runners? There’s plenty of evidence to suggest a link between long-term endurance sport and atrial arrhythmias like atrial fibrillation (AF). In this study, the investigators wanted to determine for runners if this relationship was independent from other known risk factors for AF such as age. They reviewed data on 2819 runners that was collected as part of the MASTERS Athletic Study, a web-based survey of endurance athletes. The data set included information about AF as well as the athletes’ run training and race participation. The mean age of the athletes was 48.4 years and the median range of running career duration was 11-15 years. The rate of reported AF was 2.4%. There was a significant correlation between the accumulated years of running and the rate of AF, with a 6.1% rate of AF among those who had run for 30 years. Independent risk factors for AF included: increasing athlete age, high blood pressure, and years of accumulated running. Variables that were not risk factors included: diabetes, average running pace, use of speed training, and participation in marathons/ultramarathons.
My take: There is ample evidence that long-term endurance sport is associated with AF. There’s no good reason not to believe that the exercise is somehow causal, even if the mechanism remains uncertain.
6. Incidence of sudden cardiac death associated with physical exertion in the Unites States military. The Armed Forces Medical Examiner Tracking System includes information about all fatalities among military service members, including autopsy reports, death certificates, and official investigations. From 2005-2010, there were 135 sudden cardiac deaths associated with exertion (SCDE) among 8,298,606 person-years of observation, giving an incidence rate of 1.63 per 100,000 person-years (p-y). The incidence rate was higher for those >35 years (3.84 per 100,000 p-y), males (1.87 per 100,000 p-y), and African-Americans (3.00 per 100,000 p-y).
My take: The US military is probably a relatively healthy cohort. Nonetheless, we shouldn’t be surprised that there would be a small rate of SCDE. Mention is not made in the abstract about what forms of exertion were involved, but we know that there is a finite rate of SCD associated with virtually any form of sporting activity, even if it doesn’t seem very strenuous.
7. Activities performed during sudden cardiac death associated with physical exertion in the United States military. This is a companion study with #6, above, using the same source of data. Here, the investigators studied the type of exercise that was associated with 200 cases of sudden cardiac death (SCD). The most common types of exercise were: running/elliptical (in 60%), generalized exercise such as furniture moving, construction, lawn mowing, dancing (in 10%), military P.T. (in 9%), walking (in 7%), swimming (in 4%), basketball (in 4%), and weight lifting (in 4%). Interestingly, 20% of SCD events occurred during mandatory physical fitness tests; of these, 32% of events occurred during the test and 68% occurred within 1 hour afterwards.
My take: Again, SCD can occur with any form of exercise. The data here also point out that SCD may occur soon after exercise. In the case of mandatory physical fitness testing, just as for athletic competition events, it’s important to organize medical support teams for the possibility of emergencies even after the event is completed.
8. QT interval in elite athletes. We know that prolonged QT interval on the ECG, either inherited or acquired, is associated with increased risk for sudden cardiac death during exercise. Here, the investigators wanted to learn if participation in sport, along with cardiac adaptations to exercise training, could itself cause prolongation of the QT interval. The investigators reviewed the medical literature and identified 10 studies on 5354 elite athletes and 448 controls for whom QT interval data were available. The QT interval in the elite athletes was, on average, 36 msec longer than for the non-athletic controls. But once the data were corrected for the slower heart rates in the elite athletes, the corrected QT, or QTc, was not significantly different for the elite athletes and the non-athletic controls.
My take: Participation is sport probably doesn’t cause prolongation of the QT interval and by itself lead to an increased risk of SCD.