MITRAL VALVE PROLAPSE

MITRAL VALVE PROLAPSE

  1. 1
    Current Diagnosis

    • A midsystolic click with or without a middle- to late-peaking crescendo systolic murmur is the classic auscultatory finding of mitral valve prolapse (MVP).

    • Key examination maneuvers can help differentiate MVP from other valvular heart diseases.

    • Diagnostic echocardiographic findings of MVP are systolic billowing of the mitral valve leaflets 2 mm above the annulus into the left atrium.

    • The presence of significant myxomatous thickening of the valve leaflets (>5 mm) is significant for prognosis.

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  2. 2
    Current Therapy

    • Patients with physical findings of mitral valve prolapse (MVP) should have an echocardiogram to confirm the diagnosis, determine the severity of prolapse, determine the amount of myxomatous thickening, document the severity (if present) of mitral regurgitation, and determine left ventricular size and function.

    • Uncomplicated MVP without significant mitral regurgitation can be evaluated clinically every 3 to 5 years.

    • Complicated MVP (associated with significant mitral regurgitation, left ventricular structural changes, pulmonary hypertension, atrial fibrillation, or stroke) should be observed closely with serial clinical evaluation and echocardiography.

    • Surgery may be required for complicated MVP associated with severe mitral regurgitation. Repair rather than replacement is the procedure of choice and should be performed at surgical centers experienced with mitral valve repair.

    • Recommendations for surgery are the same for MVP as for other forms of chronic severe mitral regurgitation.

    Mitral valve prolapse (MVP) has been known by many names, including floppy valve syndrome, Barlow’s syndrome, click/murmur syndrome, myxomatous mitral valve disease, and billowing mitral cusp syndrome. MVP is a common cardiac valvular abnormality characterized by redundant, floppy mitral valve leaflets; it is often detected initially by characteristic nonejection clicks or a middle- to late-peaking crescendo systolic murmur on physical examination.

     

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  3. 3
    Prevalence

    MVP is the most common congenital cause of mitral regurgitation (MR) in adults and the most common indication for mitral valve surgery in the United States today. Previously, it was one of the most overdiagnosed conditions within cardiology, with suggested prevalence rates ranging from 5% to 15%. With the use of current diagnostic standards, rates are much lower; the overestimation was a consequence of diverse and nonuniformly accepted two-dimensional echocardiographic diagnostic criteria. Freed and colleagues, using the Framingham study population and applying consistent and more stringent echocardiographic diagnostic criteria, demonstrated a much lower prevalence of MVP (approximately 2.4%). The incidence appeared to be similar among men and women. Gender differences do exist, however. Women tend to have a more benign course, whereas men tend to have more advanced myxomatous disease resulting in a greater chance of more severe MR.

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  4. 4
    Classification

    Primary MVP is characterized by idiopathic myxomatous change of the mitral valve leaflets or the chordal structures or both. Secondary MVP is present when underlying conditions such as Marfan’s syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta, or other collagen vascular disorders are evident. Certain congenital cardiac abnormalities, including Ebstein anomaly, aortic coarctation, hypertrophic cardiomyopathy, and ostium secundum atrial septal defects, are also associated with MVP. Familial variants with an autosomal dominant pattern of inheritance have been identified, and work to identify the genes involved is under way. The reported prevalence of MVP in first-degree relatives is between 30% and 50%.

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  5. 5
    Pathology

    Macroscopic and microscopic changes can involve both the anterior and posterior leaflets as well as the chordal structures of the leaflet apparatus. Macroscopically, the surface area of the leaflet is increased, providing the accentuated, billowing appearance of the valve leaflets. Additional notable changes are thickening of the individual leaflets, increased leaflet length, thinning and stretching of the chordae, and increased circumference of the mitral valve annulus. At the microscopic level (Figure 1), normal mitral valves have three well- defined layers, each containing cells and a characteristic composition and configuration of the extracellular matrix: the fibrosa, composed predominantly of collagen fibers densely packed and arranged parallel to the free edge of the leaflet; the centrally located spongiosa, composed of loosely arranged collagen and proteoglycans; and the atrialis, composed of elastic fibers. In myxomatous mitral valves, the spongiosa layer is expanded by loose, amorphous extracellular matrix that has more proteoglycans but less collagen and more fragmented elastic fibers. What collagen is present appears to be disorganized and fragmented, giving the appearance of a haphazard layering of the spongiosa. It is this thickening that produces the classic macroscopic appearance of the myxomatous valve on two-dimensional echocardiography.

    FIGURE 1    Morphologic features of normal mitral valves (left)  and valves with myxomatous degeneration (right). Myxomatous valves have an abnormal layered architecture: loose collagen in fibrosa, expanded spongiosa strongly positive for proteoglycans, and disrupted elastin in atrialis (top). Movat pentachrome stain (collagen stains yellow, proteoglycans blue-green, and elastin black). (Modified from Rabkin E,

    Aikawa M, Stone JR, et al: Activated interstitial myofibroblasts express catabolic enzymes and mediate matrix remodeling in myxomatous heart valves. Circulation 2001;104:2525.)

     

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  6. 6
    Clinical Presentation

    Most patients with MVP are asymptomatic and will remain so, testifying to the often benign nature of this disease. Previously, various nonspecific symptoms, including fatigue, dyspnea, palpitations, postural orthostasis, anxiety, and panic attacks, were described as an MVP syndrome when present in association with the characteristic nonejection systolic click or middle- to late-peaking crescendo systolic murmur. Other symptoms, including chest discomfort, near-syncope, and syncope, have also been described by patients with MVP. However, in a community-based study, the prevalence of various clinical complaints including chest pain, dyspnea, and syncope was no higher in patients with MVP than in those without evidence of MVP, making such findings nonspecific. In a controlled study that compared symptomatic MVP patients with first-degree relatives with and without echocardiographic evidence of MVP, there also was no association of MVP with atypical chest pain, dyspnea, panic attacks, or anxiety. There was, however, a significant association of MVP with physical findings of systolic clicks, systolic murmurs, thoracic bony abnormalities, low body weight, and low blood pressure. Congestive heart failure, atrial fibrillation, stroke or transient ischemic attack, hypertension, diabetes, and hypercholesterolemia are no more likely in patients with MVP than in those without MVP. However, previous retrospective studies suggested a higher incidence of cerebral embolic events, infectious endocarditis, severe MR, and need for mitral valve replacement in patients with classic (complicated) versus nonclassic MVP. Symptoms of poor cardiac reserve, such as reduced exercise tolerance, dyspnea on exertion, and fatigue, may reflect the presence of significant MR and warrant clinical concern.

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  7. 7
    Diagnosis

    Symptoms are not predictive of the presence or absence of MVP. Certain physical and auscultatory characteristics on examination do support the diagnosis of MVP. Patients with MVP more often have a lower body mass index, have a lower waist-to-hip ratio, and are taller. Findings of scoliosis, pectus excavatum, and hyperextensibility are also prevalent among patients with MVP. The classic auscultatory findings include a midsystolic click and a middle- to late-peaking crescendo systolic murmur heard best at the apex. The auscultatory findings are best elicited with the diaphragm of the stethoscope, and they change in relation to the first and second heart sounds (S1 and S2) in response to changes in left ventricular (LV) volume. Therefore, the patient should be examined in several positions: supine (including lateral decubitus), sitting, standing, and, if possible, squatting.

    Changes in LV filling and volume affect the degree of prolapse.

    The most important and most specific finding on auscultation is the presence of a nonejection midsystolic click or clicks caused by snapping of the valve apparatus as parts of the valve leaflets billow into the atrium during systole. Although these clicks can be heard over the entire precordium, they are best heard at the apex. The click can be misinterpreted as a split S1, a true S1  with an S4, or a true S1 with an early ejection click from a bicuspid valve. It can be differentiated from an ejection click heard in bicuspid aortic valves by its timing relative to the beginning of the carotid upstroke. Ejection clicks occur as the aortic valve opens and therefore precede the carotid upstroke, whereas the nonejection clicks of MVP occur afterward.

    Clicks from atrial septal aneurysms are uncommon but can be difficult to distinguish from those of MVP. Ejection clicks and clicks from atrial septal aneurysms are not altered by changes in loading characteristics, allowing them to be differentiated from clicks of MVP. Often, but not always, a middle- to late-peaking crescendo systolic murmur can be appreciated by itself or after a click. The murmur terminates with closure of the aortic valve (A2). This represents MR, and, in general, the duration of the murmur correlates with the severity of the MR.

    The earlier in systole the murmur is detected, the more severe the MR. Eventually, with more severe MR, the murmur becomes holosystolic. MVP manifestations on examination vary, and they may not always be reproducible, even in the same patient.

    Certain maneuvers can aid in more accurately diagnosing MVP on examination (Figure 2). MVP is very sensitive to LV filling, and subtle changes in auscultatory findings elicited by careful examination maneuvers can be instrumental in separating MVP from other valvular abnormalities. Generally, measures that decrease LV volume or increase contractility produce earlier and more prominent systolic prolapse of the mitral leaflets, causing the systolic click and murmur to move closer to S1. For example, in the transition from squatting to standing, LV volume is reduced, and the onset of the click and murmur is moved closer to S1. Conversely, anything that increases LV volume, such as leg-raising, squatting, or slowing the heart rate (increased diastolic filling), delays the onset of the click or murmur and usually diminishes its duration and intensity.

    FIGURE 2 Auscultative findings with changes in position in patients with mitral valve prolapse (MVP). Abbreviations: C = click of MVP; S1, mitral valve closure; S2, aortic valve closure. (Modified from Devereux RB, Perloff JK, Reichek N, et al: Mitral valve prolapse. Circulation 1976;54[1]:3–14.)

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  8. 8
    Use of Echocardiography

    Two-dimensional echocardiography has proved to be the most accurate noninvasive tool for the diagnosis, assessment, and follow-up of clinically suspected MVP. In fact, physical signs of MVP in an asymptomatic patient are an American College of Cardiology/American Heart Association (ACC/AHA) class I indication for use of echocardiography to make the diagnosis of MVP and assess the severity of MR, leaflet morphology, and ventricular size and function. Once the diagnosis is made, follow-up is determined by the severity of MVP. Routine echocardiographic follow-up of asymptomatic patients with MVP is not recommended unless there are significant findings of MR or LV structural changes. Frequency of follow-up in patients with prolapse and MR is determined by the severity of MR and should be at least annual in patients with severe MR.

    Diagnostic criteria for MVP on two-dimensional echocardiography are

    •   Billowing of one or both mitral valve leaflets or their prolapse superiorly across the mitral annular plane in the parasternal long- axis view by greater than 2 mm during systole

    •   The degree of thickening of the leaflets

    Combined leaflet prolapse of greater than 2 mm and leaflet thickness greater than 5 mm are supportive of classic MVP, whereas prolapse in the absence of increased thickness is considered nonclassic MVP. In addition to more often being associated with the auscultative findings of the click and murmur, the classic form is more commonly associated with increased risk of endocarditis, stroke, progressive MR, and need for mitral valve repair or replacement.

    Because the mitral apparatus is saddle-shaped, certain echocardiographic views are more specific than others for determining leaflet prolapse. Most practitioners agree that the parasternal long-axis and apical two-chamber or apical long-axis views are the most accurate for determining prolapse. A finding of prolapse as determined on other views, particularly the apical four- chamber view, is much less specific and frequently leads to a false- positive diagnosis.

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  9. 9
    Medical Management

    Most patients with MVP remain asymptomatic and require no additional management aside from careful observation over time. It is appropriate to provide reassurance that uncomplicated (nonclassic) MVP is a non–life-threatening condition and is unlikely to affect longevity. Periodic clinical evaluation every 3 to 5 years is reasonable. Patients who develop palpitations, lightheadedness, dizziness, or syncope should undergo Holter or event monitoring for detection of arrhythmias. Palpitations are frequently controlled with β-blockers or calcium channel blockers, although the presence of specific arrhythmias may mandate additional therapy. Endocarditis prophylaxis is no longer recommended for patients with MVP unless they have a history of endocarditis or valve replacement. Prophylaxis is recommended for patients who have undergone repair if prosthetic material was used (e.g., in ring repairs). Aspirin or warfarin (Coumadin) therapy may be recommended for certain symptomatic patients with neurologic events who have atrial fibrillation, significant MR, hypertension, or heart failure (Table 1).

    Table 1

    ACC/AHA Recommendations for Oral Anticoagulation in Patients with Mitral Valve Prolapse

     

    Class Recommendation
    I ASA therapy (75–325 mg/d) for cerebral TIAs
    Warfarin (Coumadin) therapy for patients ≥65 years in atrial fibrillation with hypertension, MR, or history of congestive heart failure
    ASA therapy (75–325 mg/d) for patients <65 years in atrial fibrillation with no history of MR, hypertension, or congestive heart failure
    Warfarin therapy after stroke for patients with MR, atrial fibrillation, or left atrial thrombus
    IIa ASA therapy is reasonable in patients after stroke who do not have MR, atrial fibrillation, left atrial thrombus, or echocardiographic evidence of thickening >5 mm or redundancy of leaflets
    Warfarin therapy is reasonable after stroke for patients without MR, atrial fibrillation, or left atrial thrombus who have echocardiographic evidence of thickening >5 mm or redundancy of leaflets
    Warfarin therapy is reasonable for TIAs that occur despite ASA therapy
    ASA therapy (75–325 mg/d) can be beneficial for patients with a history of stroke who have contraindications to anticoagulants
    IIb ASA therapy (75–325 mg/d) may be considered for patients in sinus rhythm with echocardiographic evidence of complicated mitral valve prolapse

    Adapted from Bonow RO, Carabello BA, Chatterjee K, et al: ACC/AHA 2006 guidelines for   the management of patients with valvular heart disease. J Am Coll Cardiol 2006;48(3):e1–e148. [Erratum in J Am Coll Cardiol  2007;49(9):1014.]

    Abbreviations: ACC/AHA = American College of Cardiology/American Heart Association;   ASA = aspirin; MR = mitral regurgitation; TIA = transient ischemic  attack.

    Patients with classic (complicated) MVP deserve regular clinical follow-up, particularly if MR is present. These patients are more likely to develop moderate or severe MR over time. Patients with mild to moderate MR and normal LV function should be clinically evaluated at least annually and should undergo echocardiography every second or third year if stable. Patients with severe MR should have an annual echocardiogram and closer clinical follow-up. Those who have severe MR and develop symptoms or impaired LV systolic function require cardiac catheterization and evaluation for mitral valve surgery. Often the valve can be repaired rather than replaced, with a low operative mortality rate and excellent short- and long-term results when performed at experienced centers. Preservation of the native valve allows for lower risks of thrombosis and endocarditis than does prosthetic valve replacement.

     

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  10. 10
    Surgical Management

    MVP is the most common cause of adult MR requiring mitral valve surgery. Symptoms of heart failure, severity of MR, presence or absence of atrial fibrillation, LV systolic function, LV end-diastolic and end-systolic volumes, and pulmonary artery pressure (at rest and with exercise) influence the decision to recommend mitral valve surgery.

    Indications for surgery in patients with MVP and MR mirror those with other forms of nonischemic severe MR. Patient outcomes after mitral valve repair are typically very good, and the surgical risk is lower than for many other forms of cardiac surgery, including mitral valve replacement.

    Based on a Cleveland Clinic review of 1072 patients who underwent primary isolated mitral valve repair for MR due to myxomatous disease, the in-hospital mortality rate was 0.3%. The Mayo Clinic reviewed 1173 patients who underwent mitral valve repair for MVP from 1980 to 1999, observing mortality rates of 0.7%, 11.3%, and 29.4% at 30 days, 5 years, and 10 years, respectively.

    Because of the remarkably low mortality rates associated with MVP repair, some experts advocate earlier rather than later repair of MVP in asymptomatic patients with severe MR and no evidence of LV dysfunction, pulmonary hypertension, or atrial fibrillation. AHA/ACC recommendations for surgery in patients with chronic primary mitral valve regurgitation are shown in Table 2.

    Table 2

    ACC/AHA Recommendations for Surgery in Patients with Chronic Primary Mitral Valve Regurgitation

     

    Class Recommendation
    I Mitral valve (MV) surgery is recommended for symptomatic patients with chronic severe primary MR (stage D) and left ventricular ejection fraction (LVEF) >30%
    MV surgery is recommended for asymptomatic patients with chronic severe primary MR and left ventricular (LV) dysfunction (LVEF 30%-60% and/or left ventricular end-systolic dimension [LVESD] _40 mm, stage C2)
    MV repair is recommended in preference to mitral valve replacement (MVR) when surgical treatment is indicated for patients with chronic severe primary MR limited to the posterior leaflet
    MV repair is recommended in preference to MVR when surgical treatment is indicated for patients with chronic severe primary MR involving the anterior leaflet or both leaflets when a successful and durable repair can be accomplished
    Concomitant MV repair or replacement is indicated in patients with chronic severe primary MR undergoing cardiac surgery for other indications
    IIa MV repair is reasonable in asymptomatic patients with chronic severe primary MR (stage C1) with preserved LV function (LVEF >60% and LVESD <40 mm) in whom the likelihood of a successful and durable repair without residual MR is >95% with an expected mortality rate of <1% when performed at a Heart Valve Center of Excellence
    MV repair is reasonable for asymptomatic patients with chronic severe nonrheumatic primary MR (stage C1) and preserved LV function in whom there is a high likelihood of a successful and durable repair with 1) new onset of atrial fibrillation or 2) resting pulmonary hypertension (pulmonary artery systolic arterial pressure >50 mm Hg)
    Concomitant MV repair is reasonable in patients with chronic moderate primary MR (stage B) undergoing cardiac surgery for other indications
    IIb MV surgery may be considered in symptomatic patients with chronic severe primary MR and LVEF _30% (stage D)
    MV repair may be considered in patients with rheumatic mitral valve disease when surgical treatment is indicated if a durable and successful repair is likely or if the reliability of long-term anticoagulation management is questionable
    Transcatheter MV repair may be considered for severely symptomatic patients (New York Heart Association class III/IV) with chronic severe primary MR (stage D) who have a reasonable life expectancy but a prohibitive surgical risk because of severe comorbidities
    III

    Harm

    MVR should not be performed for treatment of isolated severe primary MR limited to less than one half of the posterior leaflet unless MV repair has been attempted and was unsuccessful

    Adapted from ACC/AHA 2014 guidelines for the management of patients with valvular heart disease. J Am Coll Cardiol 2014;63(22),  e103.

     

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  11. 11
    References

    Bonow R.O., Carabello B.A., Chatterjee K., et al. 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) developed in collaboration with the Society of Cardiovascular Anesthesiologists endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons. J Am Coll Cardiol. 2006;48(3):e1– 148 (Erratium in J Am Coll Cardiol 2007;49(9):1014).

    Devereux R.B., Kramer-Fox R., Brown W.T., et al. Relation between clinical features of the mitral prolapse syndrome and echocardiographically documented mitral valve prolapse. J Am Coll Cardiol. 1986;8:763–772.

    Flack J.M., Kvasnicka J.H., Gardin J.M., et al. Anthropometric and physiologic correlates of mitral valve prolapse in a biethnic cohort of young adults: The CARDIA study. Am Heart J. 1999;138:486.

    Freed L.A., Benjamin E.J., Levy D., et al. Mitral valve prolapse in the general population: The benign nature of echocardiographic features in the Framingham Heart Study. J Am Coll Cardiol. 2002;40:1298–1304.

    Freed L.A., Levy D., Levine R.A., et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med. 1999;341:1–7.

    Gillinov A.M., Cosgrove D.M., Blackstone E.H., et al. Durability of mitral valve repair for degenerative disease. J Thorac Cardiovasc Surg. 1998;116(5):734–743.

    Levy D., Savage D. Prevalence and clinical features of mitral valve prolapse. Am Heart J. 1987;113:1281–1290.

    Marks A.R., Choong C.Y., Sanfilippo A.J., et al. Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse. N Engl J Med. 1989;320:1031–1036.

    Rabkin E., Aikawa M., Stone J.R., et al. Activated interstitial myofibroblasts express catabolic enzymes and mediate matrix remodeling in myxomatous heart valves. Circulation.

    2001;104:2525–2532.

    Savage D.D., Devereux R.B., Garrison R.J., et al. Mitral valve prolapse in the general population: 2. Clinical features: The Framingham Study. Am Heart J. 1983;106:577–581.

    Savage D.D., Garrison R.J., Devereux R.B., et al. Mitral valve prolapse in the general population: 1. Epidemiologic features: The Framingham Study. Am Heart J. 1983;106:571–576.

    Suri R.M., Schaff H.V., Dearani J.A., et al. Survival advantage and improved durability of mitral repair for leaflet prolapse subsets in the current era. Ann Thorac Surg. 2006;82(3):819–826.

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