Arrhythmic mitral valve prolapse

Arrhythmic or arrhythmogenic mitral valve prolapse is an entity that describes the presence of frequent or complex ventricular arrhythmias and mitral valve prolapse, possibly associated with mitral annular disjunction^1-3.

The following two major phenotypic subtypes are recognised ¹:

• degenerative mitral valve prolapse with severe mitral regurgitation

• severe myxomatous mitral valve prolapse irrespective of the degree of mitral regurgitation

Epidemiology

Arrhythmogenic mitral valve prolapse seems to be more common in young females ².

Diagnosis

According to an expert consensus statement, the diagnosis can be established if the following findings are present ¹:

• mitral valve prolapse possibly associated with mitral annular disjunction

• frequent or complex ventricular arrhythmias

• absence of any other well-known arrhythmic substrates

Clinical presentation

Common symptoms include palpitations, chest pain and dyspnoea but patients might also be completely asymptomatic or show mild symptoms such as atypical chest discomfort or anxiety.

Syncope is a more alarming sign and should be investigated further ¹.

The presence of either frequent premature ventricular contractions (≥5% total burden) or complex ventricular arrhythmias such as nonsustained ventricular tachycardia (NSVT), ventricular tachycardia or ventricular fibrillation (VS) are required as a criterion for the diagnosis ¹.

Some ECG features associated with arrhythmias are T-wave abnormalities such as T-wave inversion and biphasic T-waves, especially in inferior and lateral leads ^1,2.

Complications

Complications of arrhythmogenic mitral valve prolapse include cardiac arrest and sudden cardiac death ^1-3.

Radiographic features

Main imaging features include the demonstration of mitral valve prolapse defined as displacement of the mitral leaflets >2 mm above the mitral annular plane³.

Echocardiography

Echocardiography displays mitral valve prolapse often associated with mitral annular disjunction involving the insertion of the posterior leaflet on the mitral annulus possibly leading to mechanical dispersion and postsystolic shortening of the inferobasal segments of the left ventricle.

MRI

In addition to mitral valve prolapse and mitral annular disjunction MRI might show myocardial fibrosis of the papillary muscles and the inferobasal segments and the periannular region ^1-4, demonstrated as non-ischaemic pattern of late gadolinium enhancement suggesting replacement fibrosis or increased T1 mapping values ^1,3.

Radiology report

The radiology report should include a description of the following features ^1-4:

• mitral valve prolapse

  • affected leaflets

  • prolapse depth, leaflet length

  • myxomatous valve, leaflet thickness

• mitral regurgitation with degree

• mitral annular disjunction (if present)

  • extent and severity

  • mitral annulus systolic enlargement (ap and commissural diameter in end-systole and end-diastole)

  • the ratio of basal to midventricular wall thickness

• left ventricular remodelling

• myocardial fibrosis (focal or diffuse)

  • papillary muscles

  • periannular region

Treatment and prognosis

Treatment options are aimed at alleviating symptoms and improving survival and include medical therapy, ICD implantation, catheter ablation and mitral valve surgery, the latter being controversial as a stand-alone treatment ¹.