In the past, left atrium was thought of as a chamber that
passively transports blood from the pulmonary circulation to the left
ventricle. But it is not so. During the later half of the last century,
multiple studies were conducted to obtain normal values for left atrium.
S o far several echocardiographic variables have been developed
for the evaluation of the function of left atrium. The size of the left atrium
in M mode, trans mitral flow velocities, (E & A ) tissue Doppler
estimation of myocardial relaxation ( e’ & a’) are the ones useful in the
evaluation of the left atrial function. Another important parameter, Left
atrial funtional index1,3 (LAFI) is a ratio that involves the analogues of
left ventricular stroke volume, reservoir function of left atrium and the
size of the left atrium. LAFI adjusts for extremes of body weight and
extremes of heart rate. In otherwords it is rhythm independent3 . In
patients with AF and normal sized left atrium ( good emptying during
diastole) the LAFI should be normal.
AIMS AND OBJECTIVES:
To evaluate Left Atrial Functional Index (LAFI) using Transthoracic
Echocardiogram in persons suffering from atrial fibrillation and also in
patients with diastolic dysfunction and the comparison of this left atrial
functional index to the conventional echocardiogrophic parameters of
left atrial function.
CONCLUSION:
For the evaluation of left atrium no single parameter is sufficient.
Several traditional parameters like LAOT A wave peak velocity, LAOT
A VTI and fraction of atrial contribution to ventricular filling, are
dependent on the rhythm as well as the Systolic function of the LV.
L e ft atrial volume indexed to body surface area was higher in
persons with abnormal transmitral filling patterns as well as in patients
with chronic atrial fibrillation. Left atrial volume is increased in patients
with left atrial dysfunction. Several studies have confirmed that
measurement of left atrial volume is an independent predictor of
cardiovascular events in patients with HFpEF. Our study demonstrates
clear association between left atrial volume and left atrial dysfunction.
W e found that the Left Atrial Functional Index as measured by
echocardiogram, is decreased in patients with abnormal myocardial
relaxation and also in persons with chronic atrial fibrillation. Since this
parameter incorporates cardiac output and body surface area in addition
to left atrial end systolic volume, it is rhythm independent marker for left
atrial function.
T he predictors of the left atrial functional index are the baseline
left atrial dimension by M mode Echo and the rhythm at the time of evaluation. These factors remain independent predictors of LAFI even
after correction for other parameters. Thus baseline LA dimension has
got negative association with LAFI and sinus rhythm has got positive
association with LAFI.
LAFI can be used in the prognostication of heart failure with
normal ejection fraction group of patients. The prognostic value of LAFI
can be increased, when it is used in association with Other clinical risk
factors and NT-proBNP. Because LAFI is a rhythm independent marker
of left atrial function, it can be used as a marker of left atrial dysfunction
in patients with atrial fibrillation. In the future, the LAFI may be used as
a potential target for therapeutic maneuvers
