Clinical Practice Guideline

for

MITRAL VALVE PROLAPSE

Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

 

Overview: The prevalence of mitral valve prolapse (MVP) is reported to be 2-5% in the general U.S. population.  In the US Air Force database of Medical Flight Screening echocardiograms (echo) performed on pilot training candidates, the prevalence of MVP has been about 0.5% in males and females.  This lower prevalence may partly be due to the young age of this population and also due to elimination of some more obvious cases in the initial pilot training examination process.  MVP may be diagnosed or suggested by the typical auscultatory finding of a midsystolic click with or without late systolic murmur, but by current standards it is more typically an echo diagnosis.  Echo criteria have evolved significantly over the years, but current standards are widely accepted and unlikely to change significantly in the near future.  These criteria have been followed at the US Air Force’s Aeromedical Consultation Service (ACS) for over a decade, since their earliest acceptance in the academic cardiology community.

 

 

Aeromedical Concerns: Two categories of aeromedical events may be considered with MVP.  Events which might occur abruptly and impact flying performance include sudden cardiac death, cerebral ischemic events, syncope/presyncope and sustained supraventricular and ventricular tachydysrhythmias.  Other aeromedical concerns include infective endocarditis risk, progression to severe mitral regurgitation (MR), requirement for surgical mitral valve repair or replacement, other thromboembolic events and nonsustained tachydysrhythmias.  Review of the ACS experience with 404 trained aviators with MVP yielded event rates of 1.5% per year for all aeromedical endpoints examined.  However, most of these could be readily tracked by serial evaluations and presented a low risk for sudden incapacitation.  For those events which might suddenly impact flying performance, the rate was 0.3% per year.  A subset of this cohort had MVP by auscultation only; all available echos on these aviators did not meet current criteria for MVP.  In this group there were no potentially incapacitating events in the first ten years of follow-up and none of them progressed to severe MR or mitral valve surgery.  In the echo-positive subset, annual event rate at ten years was about 0.5% per year.  None of the 404 had infective endocarditis.  By multivariate analysis the only factors independently predictive of subsequent events were dilation of the left ventricle or left atrium and age older than 45 years at time of initial diagnosis.

 

Reduced +Gz tolerance and +Gz induced dysrhythmias are a consideration and centrifuge assessment was previously required for return to high performance aircraft.  In the ACS database, 95 aviators had a monitored centrifuge assessment.  Nonsustained supraventricular tachycardia and nonsustained ventricular tachycardia each occurred in one individual (1/95, 1%).  G-loss of consciousness occurred in two individuals (2/95, 2%) without associated dysrhythmia in either case.  These occurrences are less than that reported for several cohorts of apparently healthy centrifuge subjects or trainees.  A slight reduction in +Gz tolerance has previously been reported for MVP but was operationally nonsignificant.  Monitored centrifuge assessment is thus no longer required for MVP.

 

 

Medical Work-up: The primary modality in the work-up of possible MVP is a good auscultatory exam of the chest.  The critical testing modality is echocardiography with evaluation by an experienced cardiologist.  If the aviator is returned to flying status, regular exams and echo testing will need to be done to follow the progress of this condition.  An electrocardiogram is also an essential part of this work-up due to the association of supraventricular and ventricular arrhythmias with MVP.

 

Aeromedical Disposition (military): MVP is disqualifying for all classes of flying duties.  Expert review is required for waiver consideration.  Determination of waiver is dependent on the flying duty of the aviator and whether or not they are already trained and experienced.  In the case of a positive finding on auscultation without echo findings, the aviator can be given an indefinite flying waiver if there are three consecutive negative echo tests.

 

Additional considerations for waiver recommendation include but are not limited to: normal left ventricular and left atrial size, normal left ventricular function, no prior thromboembolic events, no associated tachydysrhythmias and no symptoms attributable to MVP.

 

If the disease process appears mild and stable, waiver for all classes of flying duties will generally be valid for three years with consultative reevaluation/review at that time for waiver renewal.  Each waiver recommendation will specify requirements and timing for waiver renewal. 

 

Aeromedical Disposition (civilian): Mitral valve prolapse unto itself without significant mitral insufficiency can be granted medical certification in civil aviation.  In such cases yearly status reports and echocardiograms are requested and a special issuance (waiver) is granted.  Once there is chamber enlargement the airman is denied medical certification until they have valve repair or replacement.  Airmen who have had associated arrhythmias have been granted medical certification depending on the severity of the rhythm disturbance. 

 

Waiver Experience (military): Query of a US Air Force database resulted in 76 submissions for flying waivers of all classes for the diagnosis of MVP.  Of that number, 70 were granted a waiver for an acceptance rate of 92%.

 

Waiver Experience (civilian):  As of March 2006 there were 750 first-, 571 second- and 1,383 third-class airmen with varying degrees of mitral valve prolapse who were currently issued medical certificates.  This does not include those airmen who may have had valve repair or replacement. 

 

References:

 

Kruyer WB.  Cardiology.  In: Rayman RB, ed. Clinical Aviation Medicine, 4th ed. New York: Graduate Medical Publishing, LLC, 2006; 196-99.

 

Kruyer WB, Gray GW, Leding CJ.  Clinical aerospace cardiovascular medicine.  In: DeHart RL, Davis JR eds.  Fundamentals of Aerospace Medicine, 3rd ed.  Philadelphia: Lippincott Williams & Wilkins, 2002; 352-354.

 

Osswald SS, Gaffney FA, Kruyer WB, Pickard JS, Jackson WG. Analysis of aeromedical endpoints and evaluation in USAF aviators with mitral valve prolapse.  Submitted for publication.

 

Osswald SS, Gaffney FA, Hardy JC.  Mitral Valve Prolapse in Military Members: Long-term Follow-up and Clinical Risk Analysis.  J Am Coll Cardiol. 1997 Feb;29 (Suppl A):506A.

 

Whinnery JE.  Acceleration Tolerance of Asymptomatic Aircrew with Mitral Valve Prolapse. Aviat Space Environ Med. 1986; 57:  986-92.

 

Whinnery JE, Hickman JR.  Acceleration Tolerance of Asymptomatic Aircrew with Mitral Valve Prolapse and Significant +Gz-induced Ventricular Dysrhythmias.  Aviat Space Environ Med.  1988; 59:  711-7.

 

Whinnery JE.  Acceleration-Induced Ventricular Tachycardia in Asymptomatic Men: Relation to Mitral Valve Prolapse.  Aviat Space Environ Med.  1983; 54(1):  58-64.

 

Whinnery JE.  Dysrhythmia comparison in apparently healthy males during and after treadmill and acceleration stress testing. Am Heart J.  1983; 105:  732-737.

 

McKenzie I, Gillingham KK.  Incidence of Cardiac Dysrhythmias Occurring During Centrifuge Training.  Aviat Space Environ Med. 1993; 64:  687-91.

 

 

April 23, 2007