2.2. Echocardiographic Analysis

An advanced echocargiographic assessment was prospectively conducted in all participants on the first day of admission using Vivid E95 or Vivid S70 ultrasound systems (GE Healthcare, Chicago, IL, USA). The echocardiographic data were analyzed offline using an EchoPac112.0.1 workstation (GE Medical Systems, Horten, Norway). All analyses were undertaken by a cardiologist with expertise in cardiovascular imaging, who was blinded to the laboratory and clinical characteristics of the participants.

Updated recommendations were followed to acquire and analyze all relevant echocardiographic data, including dimensions and Doppler data [15,16,17]. In particular, Simpson’s biplane method was used to estimate the LV ejection fraction. The biplane method was employed to measure left atrial maximum volume at an end-systolic apical four- and two-chamber frame [15]. Stroke volume was derived from left ventricular outflow tract diameter and velocity time integral, and by multiplying for heart rate, thecardiac output was derived. The relevant guidelines for the assessment of valvular heart disease were used to estimate left-sided valvular disease severity [17].

An RV-focused view was used to measure metrics of the RV size and function. All recommended metrics of RV function were calculated, including fractional area change, tricuspid annular peak systolic excursion, and systolic movement of the RV free wall by tissue Doppler imaging (S’) [18]. For the fractional area change frames for the RV, end-diastole and end-systole were used [18]. M-mode and tissue Doppler imaging were employed to calculate tricuspid annular peak systolic excursionand S’ [18]. Dimensions of the RV were measured at end-diastole frame at three levels tricuspid annulus, RV base, and RV mid-diameter [18]. Transtricuspid measurements of the RV E wave were taken using pulse-wave Doppler [18]. Right atrial (RA) volume was evaluatedat an end-systolic frame [18]. Grading of tricuspid regurgitation severity was performed as suggested in updated recommendations [16,17]. The simplified Bernoulli equation was used for pulmonary artery systolic pressure assessment, and the diameter and inspiratory variationof the inferior vena cava were assessed to evaluate the RA pressure [18].

Speckle-tracking data are reported in absolute numbers (i.e., positive). LV global longitudinal strain was measured using four-, three-, and two-chamber views [19]. A 16segment model was used by the software to divide the myocardium, and their average number was reported as LV global longitudinal strain.

RV global longitudinal strain values were calculated from the basal, mid, and apical segments of the RV free wall and the septum [20]. For the RV free wall longitudinal strain, the average of the 3 free-wall segments was used, and septal segments were excluded [20].

Left atrial strain analysis was undertaken using loops from the apical four-chamber and apical two-chamber view, and subsequently, a six-segment model was automatically generated. Peak left atrial strain values were calculated by averaging these 6 segments. In a similar manner, for the RA strain, the RA was traced in an RV-focused view, and the left atrial strain software was applied. Given the high prevalence of atrial fibrillation in this study, values for reservoir strain were assessed and presented.