Mitral Valve Prolapse in Emergency Medicine Workup

Updated: Aug 03, 2016
  • Author: Michael C Plewa, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Workup

Laboratory Studies

Specific lab studies are not necessary to confirm mitral valve prolapse (MVP), although some may be indicated to exclude other diagnoses, such as the following.

  • Arterial blood gas (ABG) analysis may be obtained to exclude the diagnosis of hyperventilation, hypoxemia, and metabolic acidosis in patients with tachypnea or dyspnea.

  • Serum electrolytes may be obtained to exclude the diagnosis of hypokalemia and acidosis in patients with dysrhythmias or palpitations.

  • Serum hemoglobin may be obtained to exclude the diagnosis of anemia in patients with fatigue or near-syncope.

  • Serum glucose may be obtained to exclude the diagnosis of hypoglycemia in patients with fatigue or near-syncope.

  • Cardiac enzymes may be obtained to exclude the diagnosis of an acute myocardial event in patients with chest pain.

  • A urine toxin screen may be obtained to exclude the diagnosis of an exposure to amphetamines, cocaine, or phencyclidine in patients with agitation, chest pain, dyspnea, and tachydysrhythmia.

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Other Tests

Tilt table testing

Tilt table tests may be more likely to be positive in patients with mitral valve prolapse than in control patients; however, this finding is nonspecific. [38]

Holter monitoring

Outpatient Holter monitoring or transtelephonic event recording should be considered in patients with palpitations that are associated with syncope or near-syncope.

Supraventricular tachydysrhythmias occur in 30% of patients with MVP, but the incidence of ventricular dysrhythmias is similar to that of the general population.

Electrophysiologic testing

Electrophysiologic testing is indicated for those with near-sudden death, symptomatic complex ventricular ectopy, Wolff-Parkinson-White syndrome, and recurrent unexplained syncope.

Stress testing

Contrary to earlier studies that report a false-positive result 50% of the time on exercise stress ECGs and thallium imaging studies, more recent reports have found stress test abnormalities no more likely in patients with MVP than in the general population.

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Chest Radiography

Chest radiography is not specifically indicated except to exclude other causes of chest pain and dyspnea.

The chest radiograph may reveal an increased left atrial or pulmonary artery size, which is indicative of MR. A lateral chest radiograph may reveal dorsal spine straightening and a narrow anteroposterior diameter.

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Echocardiography

Outpatient echocardiography (echo) is indicated for those with a murmur.

Although screening subjects who are at a low risk for complications (ie, those without MR) is not indicated, 2-dimensional echocardiography can detect the patients with more severe or unusual forms of MVP (eg, patients with significant MR, annular and leaflet thickening, chordal lengthening, atrial septal defect [ie, secundum], hypertrophic cardiomyopathy).

Two-dimensional echocardiography is less sensitive than M-mode echo, detecting only 50% of patients with M-mode echo and auscultatory findings, but it is more specific for MVP than M-mode echo.

Diagnostic criteria include systolic billowing of one or both mitral leaflets by more than 2 mm into the left atrium. This systolic billowing occurs on the left atrial side, above the visualized annular plane, in the long-axis parasternal view. Additionally, parasternal long-axis views demonstrate 5 mm or more of leaflet thickness.

An M-mode echocardiogram gives many false-negative and false-positive results, but it can identify MVP with at least 2 mm of midsystolic prolapse or 3 mm of holosystolic or late-systolic movement of the leaflets, which are posterior to the line connecting the valve's opening and the closure points.

Doppler echocardiography is recommended every 2-3 years for patients with mild MR, and it is recommended yearly for those with significant MR.

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Electrocardiography

Electrocardiographic (ECG) findings include the following:

  • Results usually are normal.

  • Minor QTc prolongation (0.42 ± 0.05) may occur.

  • More commonly QTc intervals are normal, yet QT dispersion is elevated. [38, 39]  QT dispersion may differentiate between primary MVP and rheumatic MVP. [40]   

  • Prolonged Tp- interval and Tp-e/QT ratios are higher in patients with MVP, increasing their risk for ventricular arrhythmias. [39]

  • Nonspecific ST- and T-wave changes were previously noted, but they may not be more frequent than in the general population.

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Computed Tomography Scanning

Cardiac multidetector computed tomography (MDCT) scanning, more commonly used for the assessment of coronary artery anatomy, also has useful accuracy in assessing MVP. [41]

Although not commonly used clinically, single-photon emission CT myocardial perfusion imaging has excluded myocardial ischemia in patients with MVP and exercise-induced chest pain. [37]

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Other Imaging Studies

Other imaging modalities, including cardiovascular magnetic resonance (MRI) [42] and 3-dimensional echocardiography, [43, 44]  are under investigation. These imaging modalities are highly sensitive and specific for MVP, yet they are not widely available or accepted in clinical practice.

Cardiac CT angiography also has good sensitivity and specificity in detecting MVP, defined as a 2-mm displacement of the mitral leaflet below the annulus plane. [45]

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