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.