Introduction
The left atrium (LA) serves as a dynamic station between the arterial
and pulmonary circulation. In addition to its mechanical functions, it
has reflex-mediated regulatory functions and endocrine functions via
atrial baroreceptors and atrial natriuretic peptides. Left ventricular
(LV) filling optimization is provided by modification of LA mechanical
functions via these mechanisms. The mechanical functions of LA have the
following three phases: the reservoir phase, which is during stage of LV
systole when blood flows from the pulmonary veins into the LA; the
conduit phase, which occurs because LV relaxation, and blood flows from
the LA to the LV in early diastole phase; and the contraction phase in
which blood passage is promoted from the LA to the LV by the pressure
gradient created by the LA contraction (1).
Heart failure patients with reduced ejection fraction (HFrEF) have
chronic exposure to increased LV filling pressures, and postcapillary
pulmonary hypertension is followed by the progression of the
precapillary pulmonary hypertension resulting from chronic changes in
the pulmonary vascular system. The chronic increase in the right
ventricular (RV) afterload would result as the RV systolic dysfunction,
which has adverse prognostic implications in HFrEF patients (2,3).
Grading of the LV diastolic dysfunction (LVDD) helps clinicians to
determine which patients will have increased left ventricular filling
pressure and guides for the treatment both in preserved ejection
fraction heart failure (HFpEF) and HFrEF patients. Exposure of the
pulmonary vascular bed to increased LV filling pressure results in
pulmonary arterial hypertension because of vascular remodeling (4,5).
The LA functional failure in HFpEF patients along with the increased
LVDD were documented in many previous reports. In summary, the atrial
reservoir and conduit functions progressively decrease with the
increased LVDD grades, but the contractile function is initially
augmented in the early stages, which is followed by a reduction in
patients with grade II LVDD (6,7).
The correlation between the LA functions and the RV functions were
previously reported, along with the increased LVDD grades of the RV
systolic function that is reduced in HFpEF patients (8).
In HFrEF, the contractile atrial functions were found to be lower
compared with HFpEF patients (9). Additionally, in HFrEF patients, along
with the reduced LA reservoir function, there was a reduction in RV
systolic function and an increase in pulmonary pressure (10).
However, the exact correlation between the LA functions and the RV
systolic functions were not completely assessed, and the role of
estimated pulmonary vascular resistance (PVR) in grading LVDD was not
evaluated in previous studies.
In this study, we aimed to determine the correlation of the
two-dimensional (2D) speckle tracking echocardiography (2DSTE)-derived
LA functional parameters, echocardiographic RV systolic functions, and
PVR estimates in HFrEF. We also examined patients according to their
LVDD grade.