Mitral Prolapse on the Electrocardiogram

Etiology of Mitral Valve Prolapse

Two main etiologies of mitral valve prolapse are described:^2 3 4

• Myxomatous mitral prolapse: also known as Barlow's disease. It is characterized by excess tissue including chordal thickening/elongation, annular dilatation and calcification with low probability of chordal rupture.
• Fibroelastic deficiency: This is the most common etiology. It is characterized by chordal thinning, elongation and/or high probability of rupture, with classic findings of mitral prolapse and mitral regurgitation of variable severity.

Signs and Symptoms of of Mitral Valve Prolapse

Physical examination and echocardiography are the gold standard tests for the diagnosis of mitral valve prolapse.

Patients with mitral valve prolapse are usually asymptomatic, although some may present with palpitations and atypical chest pain.^5 6

The classic auscultatory finding of mitral valve prolapse is a mesosystolic snap that may be accompanied by an end-systolic murmur if mitral regurgitation is present. Echocardiographic prolapse may be present without significant auscultatory findings.⁷

EKG changes caused by mitral prolapse

T wave alterations:

The most common finding in patients with mitral valve prolapse is flattening and inversion of the T waves in the inferior leads with or without ST-segment depression.^6 8

T wave changes in the right precordial leads are associated with prolapse of both leaflets.⁶

T wave abnormalities occur frequently also in patients with mitral insufficiency caused by a mitral valve in Marfan syndrome.⁵

Q waves

Pathological Q waves have been described in some patients with mitral valve prolapse simulating inferior or anterior myocardial infarction, with normal coronary angiography.⁶

ST-segment abnormalities

In patients with mitral valve prolapse, ST-segment depression may be observed, which may accompany negative T waves in leads II, III and aVF.⁶

In addition, horizontal ST-segment depression may occur during exercise in patients with mitral valve prolapse and normal coronary angiograms.⁶

Arrhythmias

Cardiac arrhythmias, both ventricular and supraventricular, are common in patients with mitral valve prolapse, and may occasionally lead to sudden death.⁶

Premature ventricular complexes are the most common arrhythmia in patients with mitral valve prolapse. They have been observed in approximately one third of routine EKGs in these patients.⁶

Arrhythmic mitral valve prolapse and sudden cardiac death

Although mitral valve prolapse is usually considered a benign condition, cases of ventricular arrhythmias and sudden cardiac death have been reported. ^4 9

The patient with mitral valve prolapse and ventricular arrhythmias at risk of sudden cardiac death is usually a young adult female with a mesosystolic click on auscultation and involvement of the posterior leaflet of the mitral valve.

EKG in these patients shows T-wave abnormalities in inferior leads and polymorphic or left bundle branch block type ventricular arrhythmias.⁹

Summary

Mitral prolapse is a congenital condition characterized by abnormal displacement of one or both leaflets of the mitral valve into the left atrium during systole.^1 2

Although electrocardiographic changes are not pathognomonic of mitral prolapse, it is possible to observe several manifestations that may suggest the presence of this alteration.

Patients are usually asymptomatic; physical examination and echocardiography are the gold standard tests for the diagnosis of mitral valve prolapse..

The main electrocardiographic findings seen in patients with mitral valve prolapse are usually T wave abnormalities, ST-segment abnormalities, arrhythmias and the presence of a Q waves.

Although mitral valve prolapse is usually considered a benign disease, cases of ventricular arrhythmias and sudden cardiac death have been described.