Clinical Practice Guideline

for

Mitral Valve Insufficiency

Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

 

Overview: Abnormalities of the mitral valve annulus, the valve leaflets, the chordae tendinae, or the papillary muscles can cause mitral regurgitation (MR).  In the United States and much of the Western world, the most common cause is mitral valve prolapse, accounting for as much as one-half to two-thirds of MR cases.  In the aviation population clinically significant MR is also most commonly associated with mitral valve prolapse/myxomatous mitral valve disorder.  Other causes include rheumatic heart disease, endocarditis, ischemic heart disease, collagen vascular disease, and dilated cardiomyopathy.  Primary MR is mitral regurgitation in the absence of any apparent underlying etiology.  This practice guideline will focus on primary MR.  MR due to mitral valve prolapse (MVP) is discussed in a separate MVP practice guideline.  Aeromedical considerations for other etiologies of MR will be addressed per the underlying disease process and in this paper.

 

In the aircrew population, MR will typically be diagnosed on an echocardiogram (echo) done for systolic murmur evaluation or for a variety of other clinical or aeromedical indications, such as an abnormal electrocardiogram.  MR is graded on echo as trace, mild, moderate and severe.  Primary MR graded on echo as trace or mild is considered a normal variant and therefore no waiver is required.  For initial certification, echos read locally as trace or mild MR require more detailed evaluation.

 

Symptoms depend on the etiology and severity of MR.  Symptoms due to chronic MR are related to progressive severity of the volume overload with resultant pulmonary congestion and left ventricular dysfunction.  Moderate or less MR should be asymptomatic.  Expected symptoms with severe MR include reduced exercise tolerance, chronic weakness, fatigability, exertional dyspnea, dyspnea at rest, and orthopnea.  However, subjects may be asymptomatic with severe MR, even with some associated left ventricular dysfunction.  Symptom onset may be insidious and not appreciated by the patient.  A careful history is important to elicit subtle symptoms or lifestyle changes due to the patient “slowing down” as a result of progressive MR.  Atrial fibrillation may occur with severe MR.

 

In early 2007, the American Heart Association published new infective endocarditis guidelines that are dramatically different from past recommendations.  Endocarditis prophylaxis was recommended only for specified high risk groups, and only for dental procedures, respiratory tract procedures, and procedures on infected skin, skin structures or musculoskeletal tissue.  The high risk group was limited to prosthetic cardiac valves, previous endocarditis, select congenital heart conditions and cardiac transplant patients with valvulopathy.  Prophylaxis was no longer recommended for gastrointestinal or genitourinary procedures.  Conditions commonly seen by most aerospace medicine practitioners were not included in the list of high risk conditions.  Such common conditions no longer recommended for endocarditis prophylaxis included, but are not limited to, mitral valve prolapse, bicuspid aortic valve, mitral or aortic regurgitation with normal valve (e.g. primary MR) and uncorrected small defects of the atrial and ventricular septum.

 

Aeromedical Concerns: Two categories of aeromedical events must be considered with moderate and severe primary MR.  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 progression to severe mitral regurgitation (MR), requirement for surgical mitral valve repair or replacement, other thromboembolic events and nonsustained tachydysrhythmias.  Aeromedical experience with moderate and severe primary MR is very limited.  A review of an Air Force database with 404 trained aviators with MVP may be applicable, however.  This review 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.  Most of these MVP subjects did not have moderate or severe MR.  For primary MR, sudden incapacitation event rates would be comparable and likely less.  The primary concern for moderate to severe primary MR would be development of symptoms and progression to severe MR that meets published guidelines criteria for surgical repair or replacement of the mitral valve.  These surgical criteria are echocardiographic parameters that can be tracked by serial studies.  Patients who are followed closely will usually be identified for surgery before onset of symptoms.

 

Static or isometric exercises may worsen MR and thus have deleterious effects.  In general, exercise produces no significant change or a mild decrease in MR because of reduced systemic vascular resistance.  However, patients with elevation of heart rate or blood pressure with exercise may manifest increased MR and pulmonary capillary pressures.  Hence, static exercise that increases arterial pressure is potentially deleterious.  Ejection fraction usually does not change or decreases slightly with exercise, although the ejection fraction response may be completely normal in younger, asymptomatic subjects.  These concerns may be more theoretical than documented, but result in recommendation for restricted static exercise in competitive athletes with significant MR.  In the aeromedical environment, “pulling” Gs is a similar situation and thus reduced +Gz tolerance and +Gz-induced tachydysrhythmias would be concerns with severe MR.

 

Medications to reduce afterload, such as ACE inhibitors, have documented clinical benefit in acute MR and chronic aortic insufficiency, but no studies have shown such a clinical benefit for chronic MR.  Although some studies have shown hemodynamic improvement and relief of symptoms, this has not been shown to delay the need for surgery or improve surgical outcome, as is the case for severe aortic insufficiency.  Use of these medications in asymptomatic MR may or may not be beneficial, but is probably common clinical practice.  Use in symptomatic MR is appropriate, but at that stage the aviator should be disqualified; aeromedical disposition should be secondary to consideration of proper timing of valve surgery.  The use of approved ACE inhibitors is acceptable in aviators with moderate or asymptomatic severe MR.

 

Medical Work-up: Evaluation of an aviator with MR begins with a complete history and physical examination to include detailed a description of symptoms, medications, activity level and CAD risk factors (positive and negative).  The summary needs to include complete tracings of the echo documenting primary MR along with the official report from the consulting cardiologist.  Also, copies of reports and tracings of any other cardiac tests performed locally for clinical assessment (e.g. Holter, treadmill, stress echocardiogram) are required.  Additional local cardiac testing is not routinely required but may be requested in individual cases after expert aeromedical review.

 

Aeromedical Disposition:

 

Air Force: Per AFI 48-123, primary MR graded moderate or worse is disqualifying for all classes of flying duties and ACS evaluation is required for waiver consideration.  For FC IIU and ATC/GBC personnel, symptomatic valvular heart disease or asymptomatic moderate to severe valvular disease associated with hypertrophy, chamber enlargement, or ventricular dysfunction is disqualifying.  MR is not listed as disqualifying for SMOD duties.

 

Moderate MR may be eligible for unrestricted FC II or FC III waiver.  Asymptomatic severe MR that does not yet meet published guidelines for surgery may be considered for waiver restricted to low performance aircraft.  Asymptomatic severe MR that meets published guidelines criteria for surgical repair/replacement and symptomatic severe MR are disqualifying without waiver recommendation.  ACS re-evaluations will typically be performed at 1-2 years intervals, depending on degree of MR and other related considerations, such as cardiac chamber dilation and left ventricular function.  As discussed above, the use of approved ACE inhibitors for afterload reduction is acceptable in aviators with moderate or asymptomatic severe MR.

 

Army: Mitral insufficiency is disqualifying for Army aviation and is discussed in the APL Mitral Regurgitation.  The aeromedical concerns in the Army parallel those of the Air Force. Initial flight applicants are not generally recommended for waiver if the insufficiency is greater than trace. For rated aircrew, waivers may be favorably considered for trace and mild cases of mitral regurgitation provided: 1) no association with mitral stenosis or connective tissue disease, 2) normal exercise tolerance, 3) no evidence of left atrial enlargement, 4) normal LV size and function, and 5) no dysrhythmias.

 

Navy: Waiver can be considered for mild mitral regurgitation provided it is not associated with mitral stenosis or connective tissue disease. Mild MR without abnormalities of the mitral valve, abnormalities of left atrial size or abnormalities of LV size will be Not Considered Disqualifying (NCD). Higher grades of valvular insufficiency or valvular insufficiencies with structural abnormalities will be considered for waiver recommendation on a case by case basis.

INFORMATION REQUIRED:

1.  A complete cardiology evaluation is required to confirm normal exercise tolerance, left ventricular size and function, and absence of arrhythmias or mitral stenosis.

2. A regurgitant jet must be viewed in at least two planes at 90 degrees to each other.

3. In addition, the following criteria should be used to quantify the degree of regurgitation:

a. Trivial (physiologic) MR with no structural abnormality is NCD.

b. Mild MR is defined as restriction of the regurgitant jet to less than or equal to 2 cm behind the valve leaflets. Additionally, it should be 4 cm2 or less by planimetry, or < 20% of the total LA area.

    Should be reassessed by yearly echocardiography

c. Moderate MR is defined as extension of the jet to the mid-atrium.

d. Severe MR is defined as a flow velocity of 1.5 m/s. Severe MR should also show a jet area greater than or equal to 8 cm2, or > 40% of LA size. The flow should extend through more than 2/3 of

    systole. Prevalvular acceleration of the MR jet implies more significant regurgitation as well.

4. Because numerous variables can affect the apparent size of the jet and the assessment of severity is only semi-quantitative, moderate to severe MR diagnoses should be reviewed by NAMI (Naval

    Aerospace Medical Institute).

 

Civilian: If an AME hears a murmur that on echocardiography turns out to be MR the airman will be placed on an Authorization for Special Issuance and be required to provide yearly echocardiograms. Should the airman then develop tachydysrhythmias or cardiac chamber enlargement this may result in denial of certification. 

 

The FAA grants waivers to airmen with both mitral valvuloplasty and replacement.  Once the procedures are completed the airman is not considered for 6 months.  All first and second-class airmen must have their cases reviewed by an FAA Cardiology Consultant.  Valvuloplasty can be considered locally.  The airman must provide the hospital admission and discharge summaries, initial echocardiogram results, cardiac catheterization report if accomplished, and operative reports.  The airman must then provide a maximal nuclear stress test in the case of first and second-class airmen or Plain Bruce protocol for third-class, current echocardiogram, fasting lipid panel and blood sugar. A 24 hour Holter monitor test may also be required if the airman had dysrhythmias.  If a mechanical valve is inserted, the airman will need to provide the International Normalized Ratio (INR) levels.  The FAA requires 80% of these values to be between 2.5 and 3.5.

 

Waiver Experience:

 

Air Force: AIMWITS search revealed a total of 151 individuals with an aeromedical summary containing the diagnosis of mitral regurgitation.  Of the total, there were 8 FC I/IA cases (3 disqualifications), 90 FC II cases (9 disqualifications), 50 FC III cases (6 disqualifications), 1 FC IIU case (waiver approved), 1 ATC cases and 1 SMOD case (both of the latter were disqualified).  Most of the disqualified cases were disqualified for issues related directly to the mitral valve issue or another cardiac issue.

 

Army: Mitral Insufficiency has been a relatively uncommon diagnosis among rated Army aviators.  Between 2009 and 2011 there was an average rated aviator population of 14919 as identified by having an annual flight physical.  During this period, there was an average of 1 case carrying the diagnosis of mitral insufficiency in any given year, yielding an average one year period prevalence of 0.67 case per 10,000 aircrew.  During the period of the study there were 6 applicants and 3 rated aviators discovered with mitral insufficiency; 2 of the applicants were found not qualified.  Of the rated aircrew, 1 was suspended due to the significance of his pathology.

 

Navy: Not available at this time

 

Civilian: Current statistics are maintained that include all forms of waivers for mitral valve disease.  As of December 2011 there are 385 first-class, 284 second-class, and 1,434 third-class airmen currently issued with mitral valve disease.  This includes those airmen who have had surgical repair and replacement.

 

ICD 9 code(s) for

394.1

Rheumatic mitral insufficiency

424.0

Mitral valve disorders

746.6

Congenital mitral insufficiency

 

References:

 

Kruyer WB.  Cardiology.  In: Rayman RB, ed.  Clinical Aviation Medicine, 4th ed.  New York: Graduate Medical Publishing, LLC.  2006; 199-201.

 

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; 349-350.

 

Wilson W, chair.  Prevention of infective endocarditis: Guidelines from the American Heart Association.  Circulation.  2007; 115:1-19.

 

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; 29 (Suppl A): 506A.

 

Bonow RO, Cheitlin MD, Crawford MH, Douglas PS.  36th Bethesda conference: Eligibility recommendations for competitive athletes with cardiovascular abnormalities.  Task force 3: Valvular heart disease.  J Am Coll Cardiol, 2005; 45: 1334-40.

 

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.

 

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.

 

Bonow RO, chair.  ACC/AHA 2006 guidelines for the management of patients with valvular heart disease.  A report of the American College of Cardiology/American Heart Association task force on practice guidelines.  J Am Coll Cardiol, 2006; 48): e1-e148.

 

 

Dr. Dan Van Syoc

May 29, 2012