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BAKERSFIELD, CALIFORNIA. Mitral regurgitation (MR) is defined as an abnormal reversal of
blood flow from the left ventricle to the left atrium. The most common causes of MR are
mitral valve prolapse (MVP), rheumatic heart disease, and ischemic heart disease. A group
of researchers from Bakersfield Heart Hospital now report that MR is significantly more
prevalent in patients with lone atrial fibrillation (LAF) than in patients without this condition.
Their study involved 57 patients with LAF who underwent transesophageal echocardiography
(TEE) prior to cardioversion and 100 patients without LAF who underwent TEE for various
other reasons. All of the study participants had structurally normal mitral valves.
LAF was defined as AF without concomitant heart disease, hypertension or diabetes, and
age less than 60 years.
The researchers found that LAF patients were far more likely to exhibit moderate MR than
were controls (66% vs 6%). Mild MR was found in 18% of LAF patients vs 31% in controls,
and absence of MR was noted in 16% of LAF patients vs 63% of controls. Left ventricular
ejection fraction and left atrial diameter did not differ between the two groups, but the
diameter of the mitral annulus was significantly greater in the LAF group.
The researchers conclude that moderate MR may be a risk factor for the development of LAF
primarily by causing mechanical stretch of the left atrium or conversely, that LAF may
predispose to the development of MR over time. They also suggest the possibility that
the observed MR may be a transient phenomenon that resolves once normal sinus rhythm is
restored.
Editor�s comment: The finding that mitral regurgitation and lone atrial fibrillation
are somehow connected is most interesting. It is not clear from the study which is
cause and which is effect, although the authors clearly lean toward the hypothesis
that moderate MR is the forerunner for LAF. Another possibility obviously has to be
that MR and LAF have the same origin. If this is indeed the case, then magnesium deficiency
is likely to be the common factor since both LAF and mitral valve prolapse have been found
to be associated with magnesium deficiency[1,2].
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