Discussion
Similar to previously reported data, our study showed that nearly 12%
of echocardiographic studies resulted in a classification of IndtDFx
[15]. The writing committee of the
latest American Society of Echocardiography endorse the reporting of LV
filling status as follows: “normal, elevated or cannot be determined”
especially in cases referred with symptoms of dyspnea and HF, in view of
their prognostic information [6].
In this study we have demonstrated that patients with indtDFx by Doppler
echocardiography criteria exhibit a similar clinical profile to patients
with definite diastolic dysfunction. It was associated with established
major cardiovascular disease risk factors and a two-fold relative risk
of presenting HF symptoms compared to patients with normal diastolic
function as assessed by echocardiography. IndtDFx may not be a benign
condition and needs to be clinically defined.
All conventional classifiying parameters were responsible for the
inability to determine diastolic function in the indtDFx groop, showing
large variability and values overlapping with either groups. The fact
that the indtDFx group exhibit similar clinical profile and intermediate
parameters compared to DDFx may suggest that most of these patients were
at an early stage of DDFx, with an already impaired diastolic function.
Furthermore, LA phasic function analysis patients (subgroups)
demonstated a similar pattern of clinical and conventional
echocardiographic characterstics as our global database cohort and thus
were representative of our population.
We found that LA phasic function parmaters like phasic LA minimal volume
(LA geometry) and LA resevoir strain (LA function) in IndtDFX and DDFx
were significantly different than in NDFx, and thus could be helpful in
re- classification of IndtDFX as actual DDFx. Both parameters were
probably related to the various aspects of LA remodeling following
changes in relaxation and stiffening of the LV resulting in LA
enlargement and reduced LA relaxation and contractility. Phasic LA
minimal volume index was the only parameter that remained a significant
correlates of HF symptoms by multivariate analysis. Interestingly, LA
maximal volume, which is the mostly commonly measured parameter and
generally associated with prognosis – was not found to be predictive of
symptoms when tested along with LA strain and minimal volume. LA minimal
volume was previously shown to have a better correlation with LA total
ejection fraction compared to the maximal volume. We found LA maximal
volume not helpful in redefining diastolic function. This is probably
because the minimal volume holds both size and functional information of
LA [16].. In a recent study looking
at the correlation between LA function and risk of de novo HF
admissions, LA function was a stronger predictor than LVEF, LV global
strain, or even LA volume index, highlighting the importance of the LA
in the evolution and progression of symptoms
[17]. Future studies are requested to
determine whether LA functional analysis may help re-defining the
IndtDFx group [18] and more prospective studies are required to
confirm LA minimal volume as a better predictor of outcome.