Regression of Left Ventricular Hypertrophy in Patients Combined with Peritoneal Dialysis and Hemodialysis

Methods This retrospective study enrolled 58 patients at The Second Affiliated Hospital of Soochow University who switched from PD to PHD. Clinical data and echocardiographic examination results were collected. Data from the two groups with a normal distribution were compared with the paired t-test. A pvalue <0.05 (two-tailed) was considered statistically significant. Results A total of 58 subjects were enrolled, including 46 males and 12 females, with a median age of 50.2 ± 11.1 (47–68) years. The mean duration of peritoneal dialysis was 67.2 ± 33.6 months. Before and after PHD, the ultrafiltration volume (p = 0.021) and hemoglobin (p = 0.001) were increased, while SBP (p = 0.002), DBP (p = 0.002), phosphorus (p < 0.001), and ESA dosage (p < 0.001) were decreased. Before and after combined dialysis (PHD), the incidence of LVH was 76.4% and 61.8%, respectively (p = 0.013), and LVMI decreased from 173.8 ± 86.2 g/m2 to 160.6 ± 78.5 g/m2 (p < 0.001). Conclusion Compared with PD alone, the combination of PD and HD resulted in regression of LVH and reduced LVMI.


Introduction
Peritoneal dialysis is an efective treatment for uremia patients [1,2]. In long-term PD patients, peritonitis recurrence, loss of residual renal function, and deterioration of peritoneal membrane function may cause ultrafltration failure, fuid overload, and toxin accumulation, which may fnally lead to technology failure and death [3][4][5]. Combining PD with hemodialysis (PHD) may be an efective solution for these patients [6,7]. Several studies have already confrmed the benefts of PHD, including maintaining fuid balance, achieving dialysis adequacy, and prolonged life expectancy [8,9].
It is well-established that cardiovascular disease is the primary cause of death in ESRD patients [10,11]. Our previous studies have confrmed a high prevalence of left ventricular systolic and diastolic dysfunction, LVH, and valvular calcifcation in PD patients [12][13][14]. Many studies reported that hypertension, fuid overload, and phosphorus are risk factors for LVH in dialysis patients [15][16][17]. Tese risk factors can be alleviated after PHD, which may lead to the remission of LVH. We conducted this study to research cardiac structure change and function in patients before and after PHD.

Patients and Methods
PHD was defned as patients receiving combined therapy of peritoneal dialysis and hemodialysis [8]. In this retrospective study, there were 75 patients enrolled at Te Second Afliated Hospital of Soochow University who switched from PD alone to combination therapy with PD and HD between Jan 1, 2015, and Dec 30, 2021. Reasons for the switch to PDH include dialysis inadequacy (n � 38), ultrafltration failure (n � 25), and fuid overload (n � 12). Seventeen patients were excluded because of missing data (n � 8), transfer to HD (n � 4), peritonitis within three months (n � 3), and congenital heart disease (n � 2). Tus, only 58 patients participated in this study ( Figure 1).

Indication of Combination Terapy with PD and HD.
Tirty-eight patients received six days of PD and one session of HD per week. Kt/V of HD was targeted from 1.0 to 1.2. Other 20 patients received four days of PD and two sessions of HD per week.
Peritoneal dialysis was not conducted on the day of the HD session, defned as the day of peritoneal rest. For the HD prescription, no patient used a high-fux membrane dialyzer. Twelve patients received hemofltration every two weeks, and nine received hemoperfusion once a month.

Physical and Laboratory
Examinations. Blood pressure (BP) and body weight (BW) were measured before echocardiographic studies in these patients. Te dose of erythropoietin stimulating agent (ESA) for one week was also analyzed. Clinical data, including age, gender, body mass index (BMI), dialysis vintage, history of diabetes, statins, ca channel blockers, renin-angiotensin system blockers, and α β-receptor blockers, as well as combination preparations, were collected from all patients. Te blood test was performed just before the HD session on the dialysis day. We collected fasting biochemical blood indices from all patients, including serum creatinine, urea nitrogen, albumin (Alb), prealbumin (PA), PTH, serum Ca, serum P, CRP, triglyceride (TG), TC, high-density lipoprotein, and lowdensity lipoprotein levels.

Defnition of Ultrafltration Volume.
We calculated the daily UF volume by averaging the total weekly UF volume. Weekly UF volume includes ultrafltration volume of peritoneal dialysis and hemodialysis.

Echocardiographic Examination.
Cardiac sonography was examined before the HD session. We calculate the LV mass according to the following equation: LVH was defned as the LV mass/height 2.7 (LV mass divided by height in meters in the power of 2.7) >52 g/m 2 . 7 in men and >47 g/m 2 . 7 in women as suggested by the 2013 ESH/ESC guidelines [10]. LV systolic function was assessed by ejection fraction (EF) measurement, and systolic dysfunction was defned as an EF <50%. Results of two echocardiographic data were collected at the initiation of PHD and during the following time. All echocardiographic measurements were performed by experienced technicians blinded to the clinical conditions.

Statistical
Analysis. Data were expressed as mean ± SD or median (interquartile range) based on the distribution type. Te statistical analysis was performed using SPSS 24.0 (IBM SPSS, Somers, N.Y., USA). Two groups of data with a normal distribution were compared with the paired t-test, skewed data were compared with the Mann-Whitney U test, and categorical data were compared with the χ2 test. Univariate logistic regression analysis was performed to estimate the relationship with LVMI improvement. Factors enrolled in the multivariate regression analysis were based on the clinical signifcance or univariate logistic regression results (factors with p < 0.1). Tus, dialysis vintage, SBP, DBP, HGB, and ultrafltration volume were enrolled in multivariate regression analysis. A p value <0.05 (two-tailed) was considered statistically signifcant.

Discussion
Te efectiveness of PD in the Chinese population has already been proved by the "PD frst policy" in Hong Kong [2]. However, in long-term PD patients, deterioration of peritoneal membrane function, dialysis inadequacy, and fuid overload are signifcant causes of technique failure and death [3,4]. Te lack of biocompatible dialyzate in mainland China and the limited use of automated peritoneal dialysis (APD) due to medical insurance policies may worsen these problems. In recent years, several studies have confrmed the efectiveness of PHD in these subjects. Based on the evidence above, patients who cannot continue PD alone switch to PHD in our center.
Tere were more male patients than female patients receiving PHD. Tis may cause more dialysis insufciency in male than female PD patients. Tis result is also found in research conducted in Taiwan [18]. Primary nephritis is the most common cause in this study. However, a higher proportion (18.9%) of ESRD caused by hypertension was observed. One signifcant reason may be hypertensive nephropathy combined with paralleled cardiac disease, causing more strict volume control in long-term dialysis patients.
In this study, compared to PD alone, patients who received PHD showed better blood pressure control, increased ultrafltration volume, decreased phosphorus, and elevated HGB with lower ESA usage. Tese fndings are consistent with previous studies [19][20][21].
Tis study also reveals the amelioration of left ventricular hypertrophy and left ventricular diastolic function after receiving PHD treatment. Tere may be several reasons for the regression of LVH and reduced LVMI observed after PHD. Firstly, reduced   International Journal of Clinical Practice fuid overload and better blood pressure control are the primary factors for this phenomenon [22]. Ozkahya et al. report that the volume decrease in dialysis patients can achieve reasonable longterm BP control and decreased LVMI [23]. Secondly, elevated HGB also afects reducing LVMI [24]. Furthermore, better phosphorus control is also a beneft for the decreased prevalence of LVH [16].
Te present study's limitations include a lack of controls, a small number of patients, and a short follow-up period. Some factors, such as residual renal function, combined obstructive sleep apnea dosage, and CKD-MBD disorders, that may afect LVMI were lacking in this study. Further studies are needed to focus on these issues. We look forward to multicenter and large-scale prospective research in the future. In conclusion, the present study demonstrates that, compared with PD alone, PD and HD's combination resulted in regression of LVH and reduced LVMI.

Data Availability
Available upon request.

Ethical Approval
Te Ethics Committee of Te Second Afliated Hospital of Soochow University approved this study. Te study protocol was developed in line with the Declaration of Helsinki. Informed consent was obtained from all participants.

Disclosure
Luyan Gao and Haixia Zhang contributed equally to this article. Zhi Wang and Huaying Shen were the corresponding authors.  International Journal of Clinical Practice 5