Right atrial function index is an independent predictor of functional status in patients with pulmonary hypertension

doi:10.21203/rs.3.rs-1512100/v1

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Right atrial function index is an independent predictor of functional status in patients with pulmonary hypertension

https://doi.org/10.21203/rs.3.rs-1512100/v1

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Objectives: Right atrium (RA) plays an essential role in modulating right ventricular (RV) function. RA dysfunction is associated with poor survival in patients with pulmonary hypertension (PH). Right atrial function index (RAFI) which is defined as (RAEF×RVOT-VTI)/(RAVmax index) represents an easily obtainable echocardiographic variable of RA function assessment, synthesizing expressions of RA size, RA reservoir function and cardiac output. The purpose of our study was to evaluate RAFI and explore its association with functional status in PH subjects.

Methods: A total of 63 PH patients were retrospectively studied. Patients were classified into high RAFI group and low RAFI group based on the median of RAFI. Echocardiography parameters of right heart dimension, RV overload, RV function and RA strain were assessed. Patients’ data of clinical characteristics were documented.

Results: Elevated pulmonary arterial pressure, dilated RV dimension, RV overload and worsen cardiac function were observed in low RAFI group (P < 0.05). RAFI was significantly correlated with clinical and echocardiographic indices of pulmonary arterial pressure, pulmonary vascular resistance, RV dimension, RV overload and cardiac function (P < 0.05). In multivariable binary logistic regression analysis, RAFI independently predicted World Heart Organization functional class (WHO FC) III or IV (odds ratio = 0.847; 95% confidence interval, 0.722-0.994; P = 0.041). RAFI < 9.7 was the best cutoff to identify patients with WHO FC III or IV, with sensitivity of 70% and specificity of 79% (area under the curve = 0.777; 95% confidence interval, 0.660-0.894).

Conclusions: RAFI provided an easy and valid alternative approach to evaluating RA function. RAFI showed correlation with most clinical and echocardiographic indices of right heart. RAFI was the independent determinant of WHO FC III or IV implying clinical deterioration.

pulmonary hypertension

right atrium

echocardiography

Pulmonary hypertension (PH) encompasses multiple clinical conditions and is defined as an increase in mean pulmonary arterial pressure (mPAP) ≥ 25 mmHg at rest as assessed by right heart catheterization (RHC) [1]. PH is characterized by progressive increased pulmonary vascular resistance (PVR) and elevated pulmonary artery pressure, subsequently leads to right ventricular (RV) pressure overload and failure. RV function is a crucial determinant of symptoms and prognoses in patients with PH [2]. Generally, echocardiography is the most commonly used noninvasive modality for quantification of right heart. However, considering the complex anatomy of RV chamber, it is comparatively difficult to accurately evaluate the structure and function by current echocardiography methods.

In recent years, focus has been shifted to right atrium (RA) owing to its simpler geometric structure. A growing body of evidence suggested that RA played an essential role in modulating RV function and RA dysfunction was associated with poor survival in PH patients [3–6]. Cardiac atrial function index is an easily obtainable echocardiographic variable that incorporates information on atrial size, reservoir function and cardiac output. Thus, it might characterize atrial remodeling better than currently used echocardiographic volumetric and strain measures. [7] Thomas et al [8] first evaluated left atrial function index as a simple echocardiographic measure to quantify left atrial function in atrial fibrillation subjects. Subsequently, the clinical significance of the variable was further validated in coronary heart disease and heart failure patients [9, 10]. Based on previous studies, we hypothesize that right atrial function index (RAFI) applies equally to RA function assessment in patients with diseases relevant to right heart, especially PH. Therefore, the aim of the present study was to (1) evaluate RAFI and discuss its feasibility in RA function assessment in PH patients; (2) investigate the correlation of RAFI with other clinical and echocardiographic variables; (3) explore the impact of RAFI on patient functional status.

2.1 Study population

We retrospectively screened definite-diagnosed PH (mPAP ≥ 25 mmHg at rest assessed by RHC) subjects from our echocardiography database between May 2018 and July 2019 in a single center (Beijing Chaoyang Hospital, Capital Medical University, Beijing). Patients included in our study had to meet the following criteria: (1) age ≥ 18years; (2) performed RHC within 6 months; (3) were sinus rhythm and clinical stability at the time of enrollment; (4) absence of complex congenital heart disease; (5) with normal left ventricular function (left ventricular ejection fraction ≥ 50%); (6) with complete transthoracic echocardiography data; (7) with good images quality adequate for RA and RV analysis. Patients’ N-terminal pro-brain natriuretic peptide (NT-proBNP), World Heart Organization functional class (WHO FC) and RHC data including central venous pressure (CVP), mPAP, pulmonary arterial wedge pressure (PAWP), cardiac output (CO) and PVR were documented. Finally, a total of 63 patients were included in this study. The present study was approved by the institutional review board of Beijing Chaoyang Hospital Affiliated to Capital Medical University. Informed consent was waived owing to retrospective nature. Our study complied with the Declaration of Helsinki.

2.2 Conventional echocardiographic parameters

Standard transthoracic echocardiography was performed using a commercially available ultrasound machine (Philips EPIQ 7C; Philips Healthcare, Andover, MA, USA) equipped with an X5-1 probe. Patients were examined in the left lateral decubitus position. Images with three consecutive cardiac cycles were acquired based on the parasternal, apical, and subcostal views using two-dimensional, M-mode, color, pulsed-, and continuous-wave Doppler methods. Echocardiographic parameters were obtained in accordance with the current guideline [11, 12]. Quantification for cardiac chamber was made by a trained echocardiographic doctor blinded to the patients’ clinical status. All echocardiographic measurements were made in triplicate and averaged.

Left ventricular ejection fraction (LVEF) was measured using biplane Simpson’s method. Pulmonary artery systolic pressure (PASP) was estimated from the systolic transtricuspid pressure gradient plus right atrial pressure. Right atrial pressure was determined by diameter and inspiratory collapse of the inferior vena cava. Right heart dimension was assessed by RV basal diameter (RVD) in end-diastole and right atrial area (RAA) in end-systole. RV overload was assessed by left ventricular end diastolic eccentricity index (EI) and RV end diastolic area (RVEDA). Left ventricular end diastolic EI was measured on the parasternal short-axis view at the papillary muscle level and calculated as the ratio of axis of the left ventricle parallel to the septum and axis perpendicular to the septum at end-diastole. RV function was assessed using RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), RV index of myocardial performance (RIMP), and pulsed tissue Doppler-derived tricuspid lateral annular peak systolic velocity (S’).

2.3 Analysis of RA strain

RA strain analysis was performed offline on the QLAB software (version 13.0, Philips Andover, MA) in all participants. RA endocardial border was traced in the RV-focused apical four-chamber view. The software was then automatically generated a RA strain curve. RA strain was calculated as the average of the six RA segments.

2.4 Assessment of RAFI

The quantification of RA was from the apical view optimized for RA. XPlane technique with the sample line went through the tip of the tricuspid valve was used in order to analyze RA volume. Then, we obtained apical four-chamber and two-chamber view at the same cardiac cycle. Subsequently, endocardial border was traced manually in the two apical views. RA maximal volume (RAVmax) and RA minimal volume (RAVmin) were derived using the biplane area-length method before tricuspid valve opening and at tricuspid valve closure respectively (Fig. 1A and 1B). RA emptying fraction (RAEF) was calculated using the following formula: RAEF=(RAVmax−RAVmin)/RAVmax×100%. Distal right ventricular outflow tract velocity-time integral (RVOT-VTI) was acquired by the pulsed wave Doppler tracing (Fig. 1C).

According to previous derivation and validation of left atrial function index [7], RAFI was defined as: (RAEF×RVOT-VTI)/(RAVmax index).

2.4 Statistical analysis

Continuous variables with normal distribution are expressed as mean ± standard deviation, and those with non-normally distribution are expressed as median and interquartile range (IQR). Categorical variables are expressed as frequency and percentages. According to the median value of RAFI, the cohort was divided into two groups: high RAFI group (RAFI ≥ 11.9) and low RAFI group (RAFI < 11.9). Continuous variables between high RAFI group and low RAFI group were compared using independent-samples t tests (for normally distributed variables) and Mann-Whitney U tests (for skewed distribution). Chi-square tests were used for the comparison of categorical variables between the two groups.

Correlation of RAFI with pulmonary invasive hemodynamic parameters, NT-proBNP and echocardiographic parameters including right heart dimension, RV overload and RV function was investigated using univariate linear correlation analysis. A binary logistic regression analysis was evaluated to identify independent predictors of WHO FC III or IV in PH patients. Parameters of right heart function (NT-proBNP, CO, RVFAC, TAPSE, RIMP, S’, RA strain and RAFI) were identified initially by univariable analyses. Then variables with a P value < 0.10 in univariate analysis were included in a multivariate model. Receiver operating characteristic (ROC) analysis was performed to determine the optimal cut-off values of RAFI for classifying WHO FC III or IV in PH patients.

We constructed Bland-Altman plots to evaluate interobserver and intraobserver variability of RAFI in 10 randomly selected PH patients. Interobserver and intraobserver variability was expressed in terms of bias with its limits of agreement. Interobserver variability was evaluated by a second experienced observer blinded for the initial analysis. For intraobserver variability, the second measurements were performed at a different time point.

A two-sided P value < 0.05 was considered to indicate statistical significance. Statistical analyses were performed by computer programs SPSS version 23.0 (IBM Corp., Armonk, New York) and GraphPad version 5.00 (San Diego, California, USA).

3.1 Clinical characteristics between groups

Overall, the present study consisted of 63 PH patients with mean age of 55 ± 12 years, mean body surface area of 1.68 ± 0.14 m², 70% of whom were women, 22 with pulmonary arterial hypertension (PAH) and 41 with chronic thromboembolic pulmonary hypertension (CTEPH). 32 patients were stratified into high RAFI group and 31 patients into low RAFI group. Clinical characteristics of the study population according to RAFI were summarized in Table 1. The two groups showed no significant difference in age, sex, body surface area and pulmonary hypertension etiology. Patients in low RAFI group presented with higher values of NT-proBNP, mPAP, PVR, lower values of CO and advanced WHO FC compared with those in high RAFI group (all P < 0.05).

Table 1

Clinical characteristics of the study population according to RAFI
	high RAFI group (n = 32)	low RAFI group (n = 31)	P value
Age, y	56 ± 11	54 ± 13	0.634
Female (%)	25(78)	19(61)	0.146
Height, cm	160(158–168)	170(162–172)	0.005
Weight, kg	64(60–67)	60(55–70)	0.345
Body surface area, m²	1.68 ± 0.16	1.69 ± 0.11	0.786
Pulmonary hypertension etiology (%)			0.663
PAH	12(37)	10(32)
CTEPH	20(63)	21(68)
World Heart Organization functional class (%)			0.011
I	1(3)	0(0)
II	22(69)	10(32)
III	8(25)	15(48)
IV	1(3)	6(20)
NT-proBNP, pg/mL	274(151–678)	2337 ± 1616	< 0.001
Right heart catheterization
CVP, cmH₂O	7 ± 3	6(5–11)	0.948
mPAP, mmHg	43(36–55)	48(45–52)	0.045
PAWP, mmHg	11 ± 3	9(6–12)	0.096
CO, L/min	4.24 ± 1.31	3.43 ± 1.11	0.031
PVR, dyn·sec/cm⁵	787 ± 360	995(815–1153)	0.016
RAFI, right atrial function index; PAH, pulmonary arterial hypertension; CTEPH, chronic thromboembolic pulmonary hypertension; NT-proBNP, N-terminal pro-brain natriuretic peptide; CVP, central venous pressure; mPAP, mean pulmonary arterial pressure; PAWP, pulmonary arterial wedge pressure; CO, cardiac output; PVR, pulmonary vascular resistance.

3.2. Echocardiographic characteristics between groups

Echocardiographic characteristics stratified by RAFI were displayed in Table 2. Low RAFI patients showed significantly increased PASP, EI, RVD, RVEDA, RVESA, RIMP, RAA, RAVmax, RAVmin and reduced RVFAC, TAPSE, S’, RAEF, RA strain when compared with high RAFI patients (all P < 0.05). Left ventricular ejection fraction did not differ between groups.

Table 2

Echocardiographic characteristics of the study population according to RAFI
	high RAFI group (n = 32)	low RAFI group (n = 31)	P value
PASP, mmHg	78 ± 25	96 ± 21	0.004
Left ventricular
LVEF, %	66 ± 5	66 ± 6	0.931
EI	1.17(1.11–1.27)	1.43 ± 0.22	< 0.001
Right ventricular
RVD, mm	39(37–43)	51 ± 9	< 0.001
RVEDA, m²	21 ± 7	30 ± 8	< 0.001
RVESA, m²	14 ± 6	23 ± 7	< 0.001
RVFAC, %	36.2 ± 9.9	24.4(19.2–26.5)	< 0.001
TAPSE, mm	17.9 ± 2.8	13.4 ± 3.3	< 0.001
RIMP	0.59 ± 0.19	0.86 ± 0.32	0.001
S’, cm/s	11.0 ± 2.4	8.2(7.0-10.8)	< 0.001
Right atrial
RAA, m²	17(15–21)	28 ± 8	< 0.001
RAVmax, mL	61 ± 22	117 ± 49	< 0.001
RAVmin, mL	31 ± 12	83 ± 42	< 0.001
RA strain, %	34.0(28.625–39.75)	15.3(11.8–26.4)	< 0.001
RAEF, %	49.0 ± 11.5	30.0 ± 9.7	< 0.001
RAFI, right atrial function index; PASP, pulmonary arterial systolic pressure; LVEF, left ventricular ejection fraction; EI, eccentricity index; RVD, right ventricular basal diameter; RVEDA, right ventricular end diastolic area; RVESA, right ventricular end systolic area; RVFAC, right ventricular fractional area change; TAPSE, tricuspid annular plane systolic excursion; RIMP, right ventricular index of myocardial performance; S’, pulsed tissue Doppler-derived tricuspid lateral annular peak systolic velocity; RAA, right atrial area; RAVmax, right atrial maximal volume; RAVmin, right atrial minimal volume; RAEF, right atrial emptying fraction.

3.3. Right atrial function index and its association with other variables

Interobserver and intraobserver variability of RAFI was depicted in Fig. 2. There was no significant interobserver and intraobserver variation for RAFI.

Table 3 showed the correlation of RAFI with NT-proBNP and pulmonary invasive hemodynamic parameters. RAFI was significantly associated with NT-proBNP, mPAP, CO and PVR (r = -0.676, -0.402, 0.468 and − 0.509, all P < 0.05). However, no relevance was observed between RAFI with CVP and PAWP. Additionally, correlation of RAFI with echocardiographic variables was illustrated in Fig. 3. RAFI was negatively associated with measures of right heart dimension (RVD and RAA) and RV overload (EI and RVEDA) (r = -0.731, -0.801, -0.628 and − 0.714, all P < 0.05). In terms of RV function parameters, RAFI showed remarkable correlation with RVFAC, TAPSE, RIMP and S’ (r = 0.615, 0.649, -0.439 and 0.486, all P < 0.05).

Table 3

Correlation of RAFI with NT-proBNP and pulmonary invasive hemodynamic parameters
	RAFI
Variable	r	P value
NT-proBNP	-0.676	0.000
Right heart catheterization
CVP, cmH₂O	-0.179	0.264
mPAP, mmHg	-0.402	0.002
PAWP, mmHg	0.028	0.857
CO, L/min	0.468	0.001
PVR, dyn·sec/cm⁵	-0.509	0.000
RAFI, right atrial function index; NT-proBNP, N-terminal pro-brain natriuretic peptide; CVP, central venous pressure; mPAP, mean pulmonary arterial pressure; PAWP, pulmonary arterial wedge pressure; CO, cardiac output; PVR, pulmonary vascular resistance.

3.4. RAFI and WHO functional class

A binary logistic regression analysis was performed for each right heart functional parameter separately to assess predictors of WHO FC III or IV (Table 4). In univariable analysis, NT-proBNP, TAPSE, RA strain and RAFI were significant predictors of WHO FC III or IV. However, multivariable analysis showed that only RAFI was the independent determinant of WHO FC III or IV (odds ratio = 0.847; 95% confidence interval, 0.722–0.994; P = 0.041).

Table 4

Univariate and multivariate binary logistic regression analysis to identify independent predictors of World Heart Organization functional class III or IV in the cohort
Variable	odds ratio (95% confidence interval)	P Value	β-Coefficient	odds ratio (95% confidence interval)	P Value
Age	0.981(0.941–1.023)	0.366
Sex	1.375(0.464–4.072)	0.565
Body surface area	0.106(0.002–4.734)	0.247
Pulmonary hypertension etiology	0.652(0.230–1.848)	0.421
NT-proBNP	1.000(1.000-1.001)	0.028	0.000	1.000(0.999-1.000)	0.333
CO	0.594(0.339–1.041)	0.069	-0.422	0.656(0.305–1.410)	0.280
RVFAC	0.968(0.925–1.014)	0.173
TAPSE	0.859(0.743–0.993)	0.040	0.085	1.089(0.789–1.503)	0.604
RIMP	6.382(0.943–43.195)	0.057	2.240	9.389(0.279-316.448)	0.212
S’	0.977(0.812–1.175)	0.801
RA strain	0.929(0.882–0.978)	0.005	0.004	1.004(0.892–1.130)	0.953
RAFI	0.889(0.827–0.956)	0.001	-0.166	0.847(0.722–0.994)	0.041
NT-proBNP, N-terminal pro-brain natriuretic peptide; CO, cardiac output; RVFAC, right ventricular fractional area change; TAPSE, tricuspid annular plane systolic excursion; RIMP, right ventricular index of myocardial performance; S’, pulsed tissue Doppler-derived tricuspid lateral annular peak systolic velocity; RAFI, right atrial function index.

On the basis of the ROC analysis, RAFI < 9.7 was the best cutoff to identify patients with WHO FC III or IV, with sensitivity of 70% and specificity of 79% (area under the curve = 0.777; 95% confidence interval, 0.660–0.894) (Fig. 4).

The present study introduced a new variable to assess RA function and added new implications into evaluation of functional status in PH subjects. The main findings were summarized as follow: (1) RAFI represented an easily accessible method of RA function assessment with good repeatability; (2) RAFI had remarkable correlation with indices of pulmonary arterial pressure, RV dimension, RV overload and cardiac function; (3) RAFI emerged as an independent factor in predicting WHO FC III or IV which indicated clinical deterioration. RAFI < 9.7 was the best cutoff to identify patients with WHO FC III or IV.

RA seems to play multiple roles (reservoir, conduit and contraction function) in regulating RV function. To date, there is now growing concern on RA function in patients suffering from PH. With the development of speckle-tracking echocardiography and three-dimensional echocardiography, it is feasible for investigating RA deformation and phasic function and the prognostic value of the mentioned variables has been well studied in PH [13–16]. However, analysis of RA deformation and phasic function requires special software which is not conducive to popularization. In contrast, RAFI is an easily obtainable echocardiographic variable of RA function assessment with good repeatability according to the present study. Moreover, compensatory changes in RA function might occur with abnormal RA size and/or RV systolic function. Compared with other indices of RA function, RAFI synthesizes the information on RA size (expressed by RA volumes), RA reservoir function (expressed by RAEF) and cardiac output (expressed by RVOT-VTI). These characteristics make RAFI promising for use in PH patients.

Previous studies have demonstrated the respective role of these 3 properties (RA size, RA reservoir function and cardiac output) on PH progression. A study with speckle tracking echocardiography showed that RA volume and reservoir function significantly correlated with functional status and exercise capacity in PH patients [17]. According to Sato et al [5], RA volume and reservoir function are predictors of clinical worsening in patients with pre-capillary PH during a mean follow-up period of 24 months. Alenezi et al [4] emphasized that RA reservoir function is an independent predictor of death and hospitalizations in PAH after adjusting for age, sex, and RA area. However, comprehensive analysis of RA function based on RAFI in patients with PH has not been well described. Our study revealed that patients with lower RAFI exhibited increased NT-proBNP, decreased CO and worsen echocardiographic indices of cardiac function such as TAPSE, RVFAC, RIMP, S’ and RA strain. RAFI was also markedly related to pulmonary arterial pressure, PVR, RV dimension and RV overload in our study. Mouratoglou et al [18] also confirmed the correlation of RAFI with 6-minute walk distance, NT-proBNP and echocardiographic RV function. In addition, RAFI carried incremental prognostic value beyond that of established risk factors. Nevertheless, a single-plane algorithm in their study led to underestimation of RA volumes since it assumed RA enlargement was symmetrical. In the present study, standard orthogonal views at the same cardiac cycle of RA were available by using the XPlane function. Quantification of RA volumes with biplane area-length method was likely to be more robust and accurate for determination.

The mechanism of impaired RAFI and correlation of RAFI with other indices in PH patients may be explained as follows: Initially, RV hypertrophy develops to compensate for the increased RV afterload which may lead to RV diastolic dysfunction and RV filling pressure abnormal. As PH progression, RV chamber dilation accompanied with RV contractile dysfunction contributes to insufficient cardiac output, RV volume overload and RV filling abnormality. On the other hand, the dilation of tricuspid annular contributing to tricuspid regurgitation aggravates the RV volume overload and subsequently adds to an extra increase in RV filling pressure. Finally, right atrial pressure (RAP) elevates, RA enlarged and RA dysfunction existed.

WHO FC remains the most frequently used variable for prognostic evaluation and risk classification at diagnosis as well as during follow-up in PH centers [19, 20]. Generally, a worsening WHO FC is the principle indicator of disease progression and poor prognosis, which should trigger further diagnostic studies to identify the causes of clinical deterioration [19, 21, 22]. According to the recent guideline, patients with WHO FC III or IV were categorized as intermediate or high risk with an estimated 1-year mortality > 5% [1]. Studies have been conducted to investigate the impact of RA function on WHO FC. RA reservoir function reduced gradually in PH patients with worsening WHO-FC [3, 17, 23, 24]. Moreover, RA reservoir function exhibited a better correlation with WHO FC than RV strain and RAA, suggesting that RA function might be a more sensitive indicator to identify clinical deterioration [17, 24]. However, no correlation of RAFI with WHO FC was observed according to Mouratoglou [18]. The lack of correlation was mainly due to a high proportion of patients with congenital heart disease associated PH who were known to subjectively underestimate their functional capacity. Similar to most prior studies, our findings revealed that RAFI was associated with disease severity determined based on WHO FC. We also found that among the clinical and echocardiographic variables of right heart function including RA strain, RAFI emerged as an independent factor in predicting WHO FC III or IV which indicated an intermediate or high risk for clinical worsening or death. These results demonstrated the crucial implications of RAFI evaluation in revealing functional status and disease severity over other cardiac functional variables.

4.1 Study limitations

There were several potential limitations in our study. First, the present study was a retrospective analysis in a single-center. Second, the small sample remained as a limitation towards further subgroup analysis. Future prospective studies in a larger patient population are necessary to validate the application of RAFI in PH. Third, we included PH patients with diverse etiologies in this study. However, patients included in our study were mainly PAH and CTEPH which had similar pathophysiologic features. Therefore, the impact of etiology on the results was greatly minimized. Forth, we used biplane method rather than three-dimensional echocardiography to assess RA volumes when calculated RAFI. Although three-dimensional echocardiography has advantages over two-dimensional method in quantifying right heart volumes, biplane method using XPlane technique is easier to performed and less affected by image quality, which is easy for promotion and application.

In conclusion, RAFI represented an easy and valid alternative approach to evaluating RA function. RAFI showed correlation with most clinical and echocardiographic indices of right heart. RAFI was the independent determinant of WHO FC III or IV implying clinical deterioration. Further studies are necessary to investigate clinical utility and prognostic value of RAFI in a larger cohort of patients.

PH = pulmonary hypertension

mPAP = mean pulmonary arterial pressure

RHC = right heart catheterization

PVR = pulmonary vascular resistance

RV = right ventricular

RA = right atrium

RAFI = right atrial function index

NT-proBNP = N-terminal pro-brain natriuretic peptide

WHO FC = World Heart Organization functional class

CVP = central venous pressure

PAWP = pulmonary arterial wedge pressure

CO = cardiac output

LVEF = left ventricular ejection fraction

PASP = pulmonary arterial systolic pressure

RVD = right ventricular basal diameter

RAA = right atrial area

EI = eccentricity index

RVEDA = right ventricular end diastolic area

RVFAC = right ventricular fractional area change

TAPSE = tricuspid annular plane systolic excursion

RIMP = right ventricular index of myocardial performance

S’ = pulsed tissue Doppler-derived tricuspid lateral annular peak systolic velocity

RAVmax = right atrial maximal volume

RAVmin = right atrial minimal volume

RAEF = right atrial emptying fraction

RVOT-VTI = right ventricular outflow tract velocity-time integral

IQR = interquartile range

ROC = receiver operating characteristic

PAH = pulmonary arterial hypertension

CTEPH = chronic thromboembolic pulmonary hypertension

RAP = right atrial pressure

Ethical approval and consent to participants

The present study was approved by the institutional review board of Beijing Chaoyang Hospital Affiliated to Capital Medical University. Ethics Committee of Beijing Chaoyang Hospital Affiliated to Capital Medical University waived the need of informed consent since it was a retrospective study. Our study complied with the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

There are no conflicts of interest.

Acknowledgments

We thank all subjects for their participation and other colleagues for their support.

Authors’ contributions

Di-chen Guo conducted the research and wrote the paper; Di-chen Guo and Hui-min Hu analysed the data; Hui-min Hu and Xin-yuan Zhang collected echocardiographic data; Yuan-hua Yang and Juan-ni Gong recruited PH patients and collected clinical data; Yi-dan Li and Xiu-zhang Lu designed the reseach and had primary responsibility for final content. All authors read and approved the final manuscript.

Funding

This study was supported by the National Natural Science Foundation of China (No. 81871356), the fund of Beijing Municipal Administration of Hospitals Incubating Program (No. PX2019013).

Availability of data and materials

All data supporting the findings of this study are available within the manuscript. The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

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No competing interests reported.

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Right atrial function index is an independent predictor of functional status in patients with pulmonary hypertension

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Abstract

Figures

1. Introduction

2. Methods

2.1 Study population

2.2 Conventional echocardiographic parameters

2.3 Analysis of RA strain

2.4 Assessment of RAFI

2.4 Statistical analysis

3. Results

3.1 Clinical characteristics between groups

3.2. Echocardiographic characteristics between groups

3.3. Right atrial function index and its association with other variables

3.4. RAFI and WHO functional class

4. Discussion

4.1 Study limitations

5. Conclusion

Abbreviations

Declarations

References

Additional Declarations

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