DISCUSSION.
In this population of asymptomatic patients with sAR and normal LV
systolic function, baseline diastolic parameters were prognostic markers
of cardiovascular events; among them, LASr played a strong independent
predictor role. In addition, our results also showed that LV volumes had
greater prognostic value that LV diameters in patients with asymptomatic
sAR.
In accordance with current clinical practice guidelines (1), aortic
valve replacement in patients with sAR should be limited to symptomatic
patients or those with LV dysfunction. However, there are possible
advantages of an early surgery in valvular heart disease in order to
prevent sudden cardiac death, persistent LV systolic dysfunction or
worse perioperative and postoperative outcomes. In addition, considering
the development of new percutaneous treatments less aggressive than
cardiac surgery, identifying those conditions associated with a worse
prognosis and who may benefit from an early intervention, seems
important.
Previous studies have analyzed the role of the diastolic function in sAR
undergoing aortic valve replacement. Ma et al described that LV
diastolic disfunction, analyzed by the integration of 2
echocardiographic parameters (LA volume index and E/e’ ratio) is highly
prevalent in patients undergoing aortic valve replacement and might
improve after surgery (11). In a similar way, Cayli et al (12)
reported that diastolic function is a reliable parameter in predicting
outcomes in patients with sAR and LV dysfunction. They found that
preoperative diastolic disfunction had an adverse impact on the recovery
of the cardiac function after surgery and justify this finding due to
the correlation of the myocardial fibrosis and worse diastolic function.
Kim et al , also found that preoperative E/e’ ratio was correlated
with postoperative improvement of LVEF (13).
To the best of our knowledge, this study is the first to evaluate the
clinical relevance of baseline diastolic function parameters in patients
with asymptomatic sAR. In our sample, E wave, E/e´ratio, SPAP and LA
size and function, have significant prognostic value in these patients.
Among the analyzed diastolic function parameters, we found that LASr
played a strong independent predictor role in outcomes, stronger than LA
diameter and LA volume. In patients with sAR, the volume and pressure
overload promote LV dilatation and eccentric hypertrophy; in this
context, LA function estimated by strain can be reduced even in the
absence of LA dilatation, mainly due to interstitial fibrosis, and
reflects LV filling pressure. In fact, LA volume has been shown to have
low sensitivity in the early detection of LA dysfunction in the setting
of LV diastolic dysfunction (14).
There are few data available on AR and LA function and its prognosis
implications. Salas Pacheco et al (15) demonstrated that in
patients with severe aortic disease (AR and aortic stenosis) LASr was
the main variable associated with pulmonary hypertension, they
considered that the maintenance of LASr function may be one explanation
for the absence of pulmonary hypertension in some patients with severe
aortic disease. In isolated aortic stenosis, LA enlargement is
recognized as a marker of aortic stenosis severity as well as predictor
of postoperative clinical outcomes independently of mean transaortic
gradient and LV mass (16). Even more, LASr has been shown as an
independent predictor of prognosis in patients with aortic stenosis
(17).
We used automated quantification technique for the LA strain assessment,
which has the potential advantages of time saving and greater accuracy
and reproducibility of the measurements (18). Its implementation could
lead to simplify these measurements, making it possible to obtain the
deformation parameters in the daily clinical practice.
Finally, although the objective of the study was to analyze diastolic
function in patients with sAR, an interesting finding has been that LV
volumes have more prognostic value than LV diameters. This finding is in
accordance with current guidelines (8) that considered the LV size
should be routinely assessed by calculating volumes and the biplane
method as the currently recommended 2D method to assess LVEF, however
the indications for valve replacement in sAR are still based on LV
diameters (1). Previous studies described that LV long axis diameter is
closely related with LV systolic and diastolic function in patients with
chronic severe AR and that LV long axis function is impaired prior to
deterioration of LV global systolic function in these patients, which
might indicate subclinical LV dysfunction (19). Therefore, a global
assessment of the LV size and function seems necessary, beyond that
provided by the determination of isolated diameters.
Although further studies, with large sample size, are required to
stablish cut off points, we believe that careful assessment of diastolic
function including LA strain, could be useful to identify high risk
patients who could benefit from shortening follow up periods and early
aortic surgery.