BASICS
DESCRIPTION
- Mitral valve prolapse (MVP) is a systolic billowing of one or both mitral leaflets into the left atrium (LA) during systole ‚ ± mitral regurgitation (MR).
- More specifically, MVP is a single or bileaflet prolapse of at least 2 mm superior displacement into the LA during systole on the parasternal long-axis annular plane of the valve on echocardiogram ‚ ± leaflet thickening.
- Classic: prolapse with >5 mm of leaflet thickening
- Nonclassic: prolapse with <5 mm of leaflet thickening (1)
- Synonym(s): systolic click-murmur syndrome; billowing mitral cusp syndrome; myxomatous mitral valve; floppy valve syndrome; redundant cusp syndrome; Barlow syndrome
EPIDEMIOLOGY
Incidence
- Predominant age: MVP has been described in all age groups.
- Initial descriptions based on clinical examinations suggested a 2:1 female predominance. Using modern echocardiogram criteria, men and women are affected equally (2).
- The most serious consequences of hemodynamically significant MR occur in men age >50 years.
Prevalence
MVP is the most common valvular abnormality, affecting 1.0 " “2.5% of the general population, depending on the precise definition (2,3). ‚
ETIOLOGY AND PATHOPHYSIOLOGY
- The pathology causing MVP is multifactorial and includes the following:
- Abnormal valve tissue
- Myxomatous degeneration: redundant layers of leaflet "hooding " ¯ the cords, chordal elongation, and annular dilatation
- Myxoid leaflets are more elastic and less stiff than normal valves.
- Chordal rupture is more common.
- Disparity in size between the mitral valve and the left ventricle (LV)
- Connective tissue disorders (1)
- MVP is often associated with variable degrees of MR.
- Frequently, there is enlargement of the LA and LV.
- Mitral annulus is often dilated.
- Involvement of other valves may occur (tricuspid valve prolapse 40%, pulmonic prolapse and aortic prolapse 2 " “10%).
- Possible increased vagal tone
- Possible increased urine epinephrine and norepinephrine
- MVP patients often have orthostatic hypotension and tachycardia.
- Genetics causes proliferation of the spongiosa layer of the leaflets (3).
- Fibrosis on surface of leaflets (3)
- Thinning and elongation of chordae tendineae
- The mitral valve differentiates during days 35 to 42 of fetal development, the same time as differentiation of the vertebrae and ribs.
Genetics
- Familial MVP is inherited as an autosomal dominant trait but with variable expressivity and incomplete penetrance.
- Two genetic loci identified
- MMVP1 on chromosome 16p11.2 " “p12.1
- MMVP2 on chromosome 11p15.4
RISK FACTORS
- MVP is a primary cardiovascular disorder.
- MVP is more likely to occur in patients with connective tissue disorders (see "Commonly Associated Conditions " ¯).
- Physical characteristics associated with MVP
- Straight thoracic spine
- Pectus excavatum
- Asthenic body habitus
- Low body mass index (BMI)
- Scoliosis or kyphosis
- Hypermobility of the joints
- Arm span > height
- Narrow anteroposterior (AP) diameter of the chest
COMMONLY ASSOCIATED CONDITIONS
- Marfan syndrome (91% of Marfan syndrome patients have MVP, although large majority of MVP patients do not meet criteria for Marfans.) (1)
- Ehlers-Danlos syndrome
- Hypertrophic cardiomyopathy
- Pseudoxanthoma elasticum
- Osteogenesis imperfecta
- von Willebrand disease
- Primary hypomastia
DIAGNOSIS
Physical exam and echocardiography ‚
HISTORY
- Most patients are asymptomatic.
- The most frequent symptom is palpitations.
- Symptoms related to autonomic dysfunction
- Anxiety and panic attacks
- Arrhythmias
- Exercise intolerance
- Palpitations and chest pains that are atypical for coronary artery disease (CAD)
- Fatigue
- Orthostasis, syncope, or presyncope
- Neuropsychiatric symptoms
- Symptoms related to progression of MR
- Fatigue
- Dyspnea
- Exercise intolerance
- Orthopnea
- Paroxysmal nocturnal dyspnea
- Congestive heart failure (CHF)
- Symptoms occur as a result of an associated complication (stroke, arrhythmia).
PHYSICAL EXAM
- Auscultatory examination
- Mid- to late systolic click
- May vary in timing and intensity based on ventricular beat-to-beat volume variations
- At low ventricular volumes, the valve may prolapse earlier during systole and further into the LA than during volume overload.
- It may or may not be followed by a high-pitched, mid- to late systolic murmur at the cardiac apex.
- Murmur: a mid- to late crescendo systolic murmur best heard at apex, middle- to high-pitched, occasionally musical or honking in quality
- Occasionally, only the ejection click is present.
- The duration of the murmur corresponds with the severity of MR.
- Dynamic auscultation
- Maneuvers that move the click and murmur toward S1
- Arterial vasodilation
- Amyl nitrite
- Valsalva
- Augmented contractility
- Decreased venous return (which can be induced by standing up)
- Maneuvers that move the click and murmur toward S2
- Squatting
- Leg raise
- Isometric exercise
- Valsalva maneuver may help differentiate hypertrophic obstructive cardiomyopathy (HOCM) from MVP because it increases the intensity of the murmur in HOCM whereas while it makes it longer but not louder in MVP.
DIFFERENTIAL DIAGNOSIS
- MR
- Tricuspid regurgitation
- Tricuspid valve prolapse
- Papillary muscle dysfunction
- Hypertrophic cardiomyopathy
- Ejection clicks (do not change timing with systole)
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
- Echocardiogram (test of choice) (4)[B],(5)[C]
- In asymptomatic individuals with physical signs of MVP, an echocardiogram is indicated for diagnosis (4)[B].
- Follow-up echocardiograms are not indicated for asymptomatic patients who have MVP with no changes clinically, even if they had mild MR (4,5)[C].
- Parasternal long-axis view is most specific for diagnosis (4).
- Findings that may be seen with MVP
- Anterior leaflet billowing
- Leaflet thickening of ≥5 mm
- Leaflet redundancy
- MR
- Posterior leaflet displacement
- Nondiagnostic transthoracic echocardiogram: ≤10%
- Transesophageal echocardiography particularly with 3D imaging may be considered to further visualize the anatomy if an intervention is being planned (6)[B].
- Stress echocardiograms may reveal exercise-induced MR or latent LV dysfunction (1,5)[C].
- Angiography
- Rarely used for diagnostic purposes
- MVP may be incidentally seen on a catheterization.
- ECG is usually normal.
- May be nonspecific ST-T wave changes
- T-wave inversions, prominent Q waves, or prolonged QT may also occur.
- A chest x-ray (CXR) is not necessary for diagnosis.
- Typically, the CXR is normal.
- Other findings
- Possible pulmonary edema: Pulmonary edema may be asymmetric with acute chordal rupture and flail leaflet.
- Possible calcification of the mitral annulus
- Holter monitoring is optional if patient has palpitations. Order Holter monitoring as usual for syncope or dizziness
- Tilt table testing may be of value in patients with MVP who presents with syncope of unknown etiology.
Follow-Up Tests & Special Considerations
Patients with a family history of MVP should be screened with echocardiography (4)[B]. ‚
Test Interpretation
- Myxomatous proliferation of the middle layer (spongiosa) of the valve, resulting in increased mucopolysaccharide deposition and myxomatous degeneration
- By electron microscopy, the collagen fibers in the valve leaflets are disorganized and fragmented.
- With increased stroma deposition, the valve leaflets enlarge and become redundant.
- The endothelium is usually noncontiguous and a frequent site for thrombus or infective vegetation.
TREATMENT
GENERAL MEASURES
Treat MVP with orthostatic symptoms by liberalizing fluid and salt intake. If severe, mineralocorticoids may rarely be used. Support stockings may also be beneficial. ‚
MEDICATION
- Asymptomatic MVP is treated with reassurance; normal lifestyle and regular exercise is encouraged.
- MVP and transient ischemic attacks are treated with aspirin 75 to 325 mg daily (Class I recommendation) (4)[C].
- MVP with history of cryptogenic stroke, or atrial fibrillation with CHADS2 (acronym for Congestive heart failure, Hypertension, Age >75 years, Diabetes mellitus, and prior Stroke or transient ischemic attack) score <2, is generally treated with aspirin 75 to 325 mg daily (4)[C].
- MVP with atrial fibrillation with CHADS2 score ≥2 is treated with warfarin (4)[C].
- MVP with high-risk echocardiographic features (thickening >5 mm or valve redundancy) and a history of stroke, warfarin therapy may be considered (4)[C].
- MVP with palpitations is treated with ˇ ²-blockers and/or recommendation to discontinue alcohol, cigarettes, and caffeine (5)[C].
ADDITIONAL THERAPIES
- Endocarditis prophylaxis is no longer recommended for MVP.
- Patients with prior endocarditis undergoing dental, respiratory tract, infected skin, or musculoskeletal procedures should receive prophylaxis for endocarditis with amoxicillin 30 to 60 minutes prior to procedure. Ampicillin, cefazolin, or ceftriaxone IM or IV may be used if unable to tolerate oral medications (4)[B].
SURGERY/OTHER PROCEDURES
- Referral for surgery is recommended for patients with severe MR with impaired LV systolic function or flail leaflet owing to ruptured chordae tendineae (4)[C].
- Minimally invasive mitral valve repair patients have shorter postoperative hospital stay compared with conventional median sternotomy open repair for patients with bileaflet prolapse and severe MR (7)[B].
- Surgical repair of MR due to isolated posterior leaflet prolapse is associated with a low reoperation rate (8)[A].
- Asymptomatic patients with atrial fibrillation or pulmonary hypertension should be considered for intervention as well (3)[C].
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
- Asymptomatic MVP patients with no significant MR can be followed clinically every 3 to 5 years (4)[C].
- Patients who are symptomatic or have high-risk features on initial echocardiogram, including moderate to severe MR, may need serial echocardiograms and should be followed clinically once per year (4)[C].
- Patients with MVP and severe MR may require coronary angiography and transesophageal echocardiography if cardiac surgical referral is planned (4)[C].
PATIENT EDUCATION
- No contraindication to pregnancy
- Restriction from competitive sports if patient has MVP with one of the following features (9):
- A history of syncope associated with document arrhythmia
- A family history of MVP-related sudden cardiac death
- Sustained or repetitive and nonsustained supraventricular tachycardia or frequent and/or complex ventricular tachyarrhythmias on ambulatory Holter monitoring
- Severe MR
- A prior embolic event
- LV systolic dysfunction
- Explain the hereditary nature of familial MVP.
PROGNOSIS
- Excellent prognosis for asymptomatic patients
- For patients with severe MR or reduced ejection fraction, the prognosis is similar to that for nonischemic MR.
COMPLICATIONS
- Sudden cardiac death: not clearly established. May be secondary to ventricular arrhythmias especially if significant MR is present (1,5).
- Chordae rupture with acute mitral insufficiency (higher risk of cardiac death; up to 2% per year)
- Infectious endocarditis (risk increased if murmur present) (5)
- Cerebrovascular ischemic event (1)
- Fibrin emboli
- Heart failure with progressive MR
- Arrhythmias such as atrial and ventricular premature beats, paroxysmal supraventricular tachycardias may all be seen. Risk increases with coexistent MR (5).
- Pulmonary hypertension
REFERENCES
11 Hayek ‚ E, Gring ‚ CN, Griffin ‚ BP. Mitral valve prolapse. Lancet. 2005;365(9458):507 " “518.22 Freed ‚ LA, Levy ‚ D, Levine ‚ RA, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med. 1999;341(1):1 " “7.33 Verma ‚ S, Mesana ‚ TG. Mitral-valve repair for mitral-valve prolapse. N Engl J Med. 2009;361(23):2261 " “2269.44 Bonow ‚ RO, Carabello ‚ BA, Chatterjee ‚ K, et al. 2008 focused update incorporated into the 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 (Writing Committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2008;52(13):e1 " “e142.55 Sims ‚ JM, Miracle ‚ VA. An overview of mitral valve prolapse. Dimens Crit Care Nurs. 2007;26(4):145 " “149.66 Shah ‚ PM. Current concepts in mitral valve prolapse " ”diagnosis and management. J Cardiol. 2010;56(2):125 " “133.77 Speziale ‚ G, Nasso ‚ G, Esposito ‚ G, et al. Results of mitral valve repair for Barlow disease (bileaflet prolapse) via right minithoracotomy versus conventional median sternotomy: a randomized trial. J Thorac Cardiovasc Surg. 2011;142(1):77 " “83.88 Johnston ‚ DR, Gillinov ‚ AM, Blackstone ‚ EH, et al. Surgical repair of posterior mitral valve prolapse: implications for guidelines and percutaneous repair. Ann Thorac Surg. 2010;89(5):1385 " “1394.99 Maron ‚ BJ, Ackerman ‚ MJ, Nishimura ‚ RA, et al. Task Force 4: HCM and other cardiomyopathies, mitral valve prolapse, myocarditis, and Marfan syndrome. J Am Coll Cardiol. 2005;45(8):1340 " “1345.
ADDITIONAL READING
Zuppiroli ‚ A, Mori ‚ F, Favilli ‚ S, et al. Arrhythmias in mitral valve prolapse: relation to anterior mitral leaflet thickening, clinical variables, and color Doppler echocardiographic parameters. Am Heart J. 1994;128(5):919 " “927. ‚
CODES
ICD10
I34.1 Nonrheumatic mitral (valve) prolapse ‚
ICD9
424.0 Mitral valve disorders ‚
SNOMED
- 409712001 mitral valve prolapse (disorder)
- 250989005 Mitral cusp prolapse (disorder)
- 703359009 Degenerative mitral valve prolapse (disorder)
- 42069006 Myxoid transformation of mitral valve (disorder)
CLINICAL PEARLS
- MVP patients may have orthostatic hypotension and tachycardia.
- Asymptomatic MVP patients with no significant MR can be followed clinically every 3 to 5 years. Patients who are symptomatic or have high-risk features on initial echocardiogram, including moderate to severe MR, may need serial echocardiograms and should be followed clinically once per year.
- Endocarditis prophylaxis is no longer recommended for MVP.