Case report
An otherwise well 59-year-old male was admitted to hospital with
undifferentiated migratory polyarthralgia, fevers, raised inflammatory
markers and a new pansystolic murmur. Transthoracic echocardiogram was
performed to investigate for infective endocarditis and showed localised
thickening of the anterior mitral valve leaflet with mild prolapse with
moderate mitral regurgitation (see Figure 1). The findings were
suspicious for endocarditis. Left ventricular cavity size and systolic
function were normal. A transoesophageal echocardiogram revealed a left
atrial mitral valve chordae. This was attached from the left atrial
wall, near the ostium of the left atrial appendage, to the anterior
leaflet near the junction of A1 and A2 (see Figures 2 and 3).
Mild-moderate mitral regurgitation was present with multiple jets. The
patient was discharged home with a plan for repeat echocardiography in 2
years to reassess the severity of his mitral regurgitation and left
ventricular function.
Left atrial mitral valve chordae is a rare congenital abnormality of
which is the prevalence is largely unknown. There have been few case
reports worldwide and the clinical significance remains uncertain,
ranging from incidental findings with mild-moderate mitral valve
pathology managed conservatively(1-4) to severe mitral regurgitation
requiring surgical intervention(5-13). There has been an isolated report
of left atrial mitral valve chordae causing complex endocarditis(14). In
our patient, recognition of this congenital abnormality was imperative
to avoid over diagnosis and unnecessary surgical intervention,
particularly given the differential diagnosis of infective endocarditis.
The origin of left atrial mitral valve chordae is proposed to be a
result of a developmental defect during embryogenesis between the
14th and 17th weeks of gestation as
the papillary muscles and chordae develop(4). Left atrial mitral valve
chordae have been identified in children as young as 8-years-old(12),
while one case was only diagnosed at the age of 85-years-old(6). At
59-years-old, our patient was asymptomatic from his valvular pathology
and his finding was incidental. It has been hypothesised that symptoms
may be delayed by progressive growth and dilatation of the left atrium,
resulting in gradual traction of the aberrant chord eventually resulting
in leaflet prolapse(6). Other suggested mechanisms include the chord
holding the free edge of the leaflet in a scallop during diastole with
the atrial kicking motion resulting in the development of mitral
regurgitation(7) and traumatic injury to the free edge of the leaflet
resulting in tethering and restricted mobility(10). Most cases in the
literature describe involvement of the A2 leaflet of the mitral valve(3,
4, 8, 10-13), with one case involving the A3 leaflet(7) and one case
involving P2 leaflet(6). We describe the first case which involves the
junction of A1 and A2.