There are many causes of mitral valve regurgitation, including mitral valve prolapse, infective endocarditis, rheumatic heart disease, connective tissue diseases, coronary artery disease, and dilated cardiomyopathy, among others.² Mitral valve prolapse is the most common valve abnormality in the general population, affecting between 2-3% of people, and is also the most common cause of mitral valve regurgitation in athletes.^5,6

Mitral valve disease has been a topic of particular interest in sports and exercise cardiology, gaining notoriety following the sudden cardiac death of two participants in the Chicago Marathon. Chad Schieber, a 35-year-old otherwise healthy man, and Rachael Townsend, 29, a physically fit young woman, both collapsed and died during this marathon in 2007 and 2003 respectively.¹³ Both participants were found to have mitral valve prolapse, generating much debate over the role mitral valve prolapse played in their deaths. In this analysis, we aim to define mitral valve prolapse, identify its presentation in athletes, review physical and echocardiographic findings of this abnormality, identify high risk features and the risk of adverse outcomes, and outline consensus recommendations regarding participation of athletes in competitive sports with mitral valve prolapse and also mitral regurgitation.

Mitral Valve Prolapse

Mitral valve prolapse is defined as the displacement of one or both of the leaflets of the mitral valve beyond the annulus into the left atrium during systole.¹ Historically a mitral valve prolapse syndrome has been described as patients presented with chest pain, arrhythmias, endocarditis, transient ischemic attacks, and even autonomic instability.¹⁴ Recent studies suggest that these symptoms do not occur more frequently in patients with mitral valve prolapse when compared to the general population.¹² The majority of patients remain asymptomatic, and the diagnosis is often made incidentally on physical exam and/or echocardiogram.¹²

The classic finding on physical exam is a mid-systolic click. This may be accompanied by a systolic murmur in the presence of significant mitral valve regurgitation. On echocardiography, mitral valve prolapse occurs when one or both leaflets protrude greater than 2 mm beyond the annulus into the left atrium during systole in the parasternal long axis and/or apical four chamber views.^1,7

Patients with mitral valve prolapse were classified into two groups: those with thickening and redundancy of the mitral valve leaflets ("classic") and those without ("non classic") in an attempt to identify high-risk patients.⁸ Marks et al. found that those with the classic form were more likely to develop infective endocarditis (3.5 percent vs. 0 percent), moderate-to-severe mitral valve regurgitation (12 percent vs. 0 percent) and eventually require mitral valve replacement (6.6 percent vs. 0.7 percent). However, there was a similar incidence of stroke between the two subtypes (7.5 and 5.8 percent).⁸

In patients with mitral valve prolapse without mitral regurgitation, the rate of sudden cardiac death is 2 per 10,000 per year.¹⁰ This is probably not more frequent than the general population and occurs more often in older patients with systolic dysfunction or severe mitral regurgitation.^7,16 The cause of death is thought to be due to ventricular fibrillation, although a causal relationship has not been established.

In 2015, the American Heart Association and the American College of Cardiology released the following recommendations regarding athletic participation in patients with mitral valve prolapse:⁷

1. Athletes with MVP—but without any of the following features—can engage in all competitive sports:
   1. prior syncope, judged probably to be arrhythmogenic in origin.
   2. sustained or repetitive and nonsustained supraventricular tachycardia or frequent and/or complex ventricular tachyarrhythmias on ambulatory Holter monitoring.
   3. severe mitral regurgitation assessed with color-flow imaging.
   4. LV systolic dysfunction (ejection fraction less than 50%).
   5. prior embolic event.
   6. family history of MVP-related sudden death.
2. Athletes with MVP and any of the aforementioned disease features can participate in low-intensity competitive sports only (class IA). Examples include bowling, golf, and riflery.⁴

The European Society of Cardiology released similar recommendations for participation in competitive sports but also added that those with long QT interval should not engage in competitive sports.⁴ All athletes with mitral valve prolapse should have annual follow-up with cardiology to monitor for any of the above high risk features or progression of mitral regurgitation.

Regarding medical therapy, beta blockers can be used for symptom relief from premature atrial or ventricular contractions. Palpitations should be evaluated with ambulatory electrocardiographic monitoring and the detection of ventricular tachycardia should be followed by electrophysiology testing to determine the need for an ICD.¹²

Mitral Valve Regurgitation

Most athletes diagnosed with mitral valve disease have primary valvular mitral regurgitation from myxomatous disease.³ Some people may become symptomatic with dyspnea on exertion and a decrease in exercise tolerance while others may be diagnosed incidentally on physical examination. The murmur is described as a holosystolic, high pitched, blowing murmur best heard at the apex and radiating to the axilla. Mitral regurgitation is characterized on echocardiogram by measuring the area of the regurgitant jet, the PISA (proximal isovelocity surface area) method which uses the width of the jet and velocity,⁴ the left ventricular ejection fraction, and left ventricular end diastolic dimension to help determine the severity of disease. In addition, the vena contracta method uses the width of the regurgitation jet to classify patients to mild disease (<0.3 cm), moderate (0.3 to 0.6 cm) and severe (>0.6 cm).⁴ Most patients with mild to moderate disease are asymptomatic.³ Discriminating between dilation of the left ventricle caused by athletic training versus that caused by severe mitral regurgitation is difficult when the left ventricular end diastolic dimension is less than 60 mm³. Left ventricular chambers which exceed 60 mm are more likely due to severe mitral regurgitation in the presence of valvular disease. The combination of endurance training and associated high cardiac output may synergistically augment LV dilation beyond what one might see with MR alone. Therefore one needs to proceed carefully when making clinical and surgical patient care decisions based upon LV dimensions in endurance athletes with MR.

Patients with mitral valve prolapse and significant mitral valve regurgitation have an increased risk for sudden cardiac death, estimated at 0.9 to 1.9 percent annually, which is far greater than patients with only mitral valve prolapse or the population as a whole.^10,11

Athletes with mitral regurgitation should undergo annual evaluations including physical exam, echocardiogram, and exercise stress testing that simulate the amount of activity they will be participating in. Caution should also be used in patients who have mitral regurgitation from other causes such as infective endocarditis or ruptured chordae, as they may be at increased risk for sudden deterioration of their mitral valve disease.³

In 2015, the American Heart Association and American College of Cardiology released the following recommendations regarding athletes with mitral regurgitation:³

1. Athletes with MR should be evaluated annually to determine whether sports participation can continue (Class I; Level of Evidence C).
2. Exercise testing to at least the level of activity achieved in competition and the training regimen is useful in confirming asymptomatic status in patients with MR (Class I; Level of Evidence C).
3. Athletes with mild to moderate MR who are in sinus rhythm with normal LV size and function and with normal pulmonary artery pressures (stage B) can participate in all competitive sports (Class I; Level of Evidence C).
4. It is reasonable for athletes with moderate MR in sinus rhythm with normal LV systolic function at rest and mild LV enlargement (compatible with that which may result solely from athletic training [LVEDD <60 mm or <35 mm/m2 in men or <40 mm/m2 in women]) to participate in all competitive sports (stage B) (Class IIa; Level of Evidence C).
5. Athletes with severe MR in sinus rhythm with normal LV systolic function at rest and mild LV enlargement (compatible with that which may result solely from athletic training [LVEDD <60 mm or <35.3 mm/m2 in men or <40 mm/m2 in women]) can participate in low-intensity and some moderate-intensity sports (classes IA, IIA, and IB) (stage C1) (Class IIb; Level of Evidence C).
6. Athletes with MR and definite LV enlargement (LVEDD ‡65 mm or ‡35.3 mm/m2 [men] or ‡40 mm/m2 [women]), pulmonary hypertension, or any degree of LV systolic dysfunction at rest (LV ejection fraction <60% or LVESD >40 mm) should not participate in any competitive sports, with the possible exception of low-intensity class IA sports (Class III; Level of Evidence C).
7. Athletes with a history of atrial fibrillation who are receiving long-term anticoagulation should not engage in sports involving any risk of bodily contact (Class III; Level of Evidence C).

These recommendations are all Level of Evidence C and reflect expert opinion. They therefore should be used within the context of individual cases for any discussions and shared decision making on restriction from athletic participation. Further study is needed to elucidate the significance of mitral value disease in athletes.

References

1. Jeresaty RM. Mitral valve prolapse: definition and implications in athletes. J Am Coll Cardiol 1986;7:231-6.
2. Bonow RO, Cheitlin MD, Crawford MH, Douglas PS. Task Force 3: valvular heart disease. J Am Coll Cardiol 2005;45:1334-40.
3. Bonow RO, Nishimura RA, Thompson PD, Udelson JE. Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities: Task Force 5: valvular heart disease: a scientific statement from the American Heart Association and American College of Cardiology. J Am Coll Cardiol 2015;66:2385-92.
4. Pelliccia A, Fagard R, Bjornstad HH, et al. Recommendations for competitive sports participation in athletes with cardiovascular disease: a consensus document from the Study Group of Sports Cardiology of the Working Group of Cardiac Rehabilitation and Exercise Physiology and the Working Group of Myocardial and Pericardial Diseases of the European Society of Cardiology. Eur Heart J 2005;26:1422-45.
5. Nishimura RA, McGoon MD, Shub C, Miller FA, Ilstrup DM, Tajik AJ. Echocardiographically documented mitral-valve prolapse--long-term follow-up of 237 patients. N Engl J Med 1985;313:1305-9.
6. Freed LA, Levy D, Levine RA, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med 1999;341:1-7.
7. Maron BJ, Ackerman MJ, Nishimura RA, Pyeritz RE, Towbin JA, Udelson JE. Task Force 4: HCM and other cardiomyopathies, mitral valve prolapse, myocarditis, and Marfan syndrome. J Am Coll Cardiol 2005;45:1340-5.
8. Marks AR, Choong CY, Sanfilippo AJ, Ferre M, Weyman AE. Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse. N Engl J Med 1989;320:1031-6.
9. Pelliccia, A. Risk of Sudden Cardiac Death In Athletes (9/24/2015). UpToDate.
10. Kligfield P, Levy D, Devereux RB, Savage DD. Arrhythmias and sudden death in mitral valve prolapse. Am Heart J 1987;113:1298-307.
11. Kligfield P, Devereaux RB. Is the patient with mitral valve prolapse at high risk for sudden death identifiable? In: Dilemmas in clinical cardiology, Cheitlin MD (Ed), FA Davis, Philadelphia 1990. p.143.
12. Griffin, B. Manual of Cardiovascular Medicine. Fourth Edition. 2013. 280-2.
13. ARA Staff (2011, October 13). Marathoning with Mitral Valve Prolapse. Retrieved September 11, 2016 from http://www.americanrunning.org/w/article/marathoning-with-mitral-valve-prolapse.
14. Delling, F. N., & Vasan, R. S. (2014). Epidemiology and Pathophysiology of Mitral Valve Prolapse: New Insights Into Disease Progression, Genetics, and Molecular Basis. Circulation, 129(21), 2158-2170. doi:10.1161/circulationaha.113.006702
15. Tan, T. C. (2015, January 19). Standard transthoracic echocardiography and transesophageal echocardiography views of mitral pathology that every surgeon should know. Annals of Cardiothoracic Surgery, 4(5).
16. Narayanan K, Uy-Evanado A, Teodorescu C, et al. Mitral valve prolapse and sudden cardiac arrest in the community. Heart Rhythm 2016;13:498-503.

Keywords: Athletes, Atrial Fibrillation, Axilla, Cardiac Output, High, Cardiomyopathy, Dilated, Chest Pain, Coronary Artery Disease, Death, Sudden, Cardiac, Dilatation, Dyspnea, Echocardiography, Electrocardiography, Ambulatory, Electrophysiology, Endocarditis, Exercise Test, Exercise Tolerance, Heart Atria, Heart Ventricles, Hypertension, Pulmonary, Ischemic Attack, Transient, Mitral Valve, Mitral Valve Insufficiency, Mitral Valve Prolapse, Pulmonary Artery, Rheumatic Heart Disease, Stroke, Stroke Volume, Syncope, Systole, Systolic Murmurs, Tachycardia, Supraventricular, Tachycardia, Ventricular, Ventricular Fibrillation

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