[Application effect of a dual release system of androgen and its antagonist in the repair of full-thickness burn wounds in mice]

Objective: To explore the optimal ratio of dihydrotestosterone and hydroxyflutamide (hereinafter referred to as DH), construct a dual release system of androgen and its antagonist, and analyze the application effect of this system in the repair of full-thickness burn wounds in mice. Methods: This study was an experimental study. The HaCaT cells were divided into blank group (without drug culture), low baseline group, medium baseline group, and high baseline group according to the random number table (the same grouping method below), and the last three groups of cells were cultured by adding three different ratios of DH. Under a medium ratio, the mass of dihydrotestosterone in the three baseline groups from low to high was 1.4, 2.8, and 4.0 µg, respectively, and the mass of hydroxyflutamide was 1.2, 1.6, and 2.0 µg, respectively. On this basis, under a small ratio, the mass of dihydrotestosterone was reduced by half and the mass of hydroxyflutamide was increased by half; under a large ratio, the mass of dihydrotestosterone was increased by half and the mass of hydroxyflutamide was reduced by half. After culture of 2 days, the cell proliferation level was detected by cell counting kit 8 (n=4). Sixteen 6-8-week-old male BALB/c mice were used to establish a full-thickness burn wound on the back and divided into blank group, small ratio group, medium ratio group, and large ratio group, with 4 mice in each group. On post injury day (PID) 7, normal saline containing different ratios of DH was locally dropped to the wounds of mice in the last three groups of mice (the total mass of DH in the three ratio groups from small to large was 127.5, 165.0, and 202.5 µg, respectively, and the mass ratios of dihydrotestosterone to hydroxyflutamide (hereinafter referred to as drug mass ratio) were 8∶9, 8∶3, and 8∶1, respectively), afterwards, the administration was repeated every 48 hours until PID 27; normal saline was dropped to the wound of mice in blank group at the aforementioned time points. The wound healing status on PID 0 (immediately), 7, 14, 21, and 28 was observed, and the wound healing rates on PID 7, 14, 21, and 28 were calculated (n=4). On PID 28, the wound tissue was taken, which was stained with hematoxylin and eosin for observing re-epithelialization and with Masson for observing collagen fibers, and the proportion of collagen fibers was analyzed (n=3). Twenty 6-8-week-old male BALB/c mice were used to establish a full-thickness burn wound on the back and divided into ordinary scaffold group, small proportion scaffold group, medium proportion scaffold group, and large proportion scaffold group (with 5 mice in each group). On PID 7, the wound was continuously dressed with a polycaprolactone scaffold without drug and a polycaprolactone scaffold containing DH with a drug mass ratio of 1∶3, 1∶1, or 3∶1 (i.e. the dual release system of androgen and its antagonist, with total mass of DH being about 1.7 mg) prepared by using electrospinning technology until the end of the experiment. Histopathological analyses of tissue (n=3) at the same time points as those in the previous animal experiment were performed. On PID 7 and 14, the wound exudates were collected and the relative abundance of bacterial communities was analyzed using 16S ribosomal RNA high-throughput sequencing (n=3). Results: After culture of 2 days, under a small ratio, the proliferation levels of HaCaT cells in low baseline group and high baseline group were significantly higher than the level in blank group (P<0.05). As the time after injury prolonged, the wounds of all four groups of mice continued to shrink. On PID 14, the wound healing rate of mice in large ratio group was 72.5% (61.7%, 75.1%), which was close to 53.3% (49.5%, 64.4%) in blank group (P>0.05); the wound healing rates of mice in small and medium ratio groups were 74.2% (71.0%, 84.2%) and 70.4% (65.1%, 74.4%), respectively, which were significantly higher than the rate in blank group (with both Z values being -2.31, P<0.05). On PID 21, the wound healing rate of mice in small ratio group was significantly higher than that in blank group (Z=-2.31, P<0.05). On PID 28, the wounds of mice in the three ratio groups were completely re-epithelialized and the epidermis was thicker than that in blank group; compared with that in blank group, the collagen fiber content in the wound tissue of mice in the three ratio groups was higher and arranged more orderly, and the proportions of collagen fibers in the wound tissue of mice in small and large ratio groups were significantly increased (P<0.05). On PID 28, the wounds of mice in ordinary scaffold group were partially epithelialized, while the wounds of mice in the three proportion scaffold groups were almost completely epithelialized. Among them, the wounds of mice in small proportion scaffold group had the thickest epidermis. The proportion of collagen fibers in the wound tissue of mice in small proportion scaffold group was significantly increased compared with that in ordinary scaffold group (P<0.05). On PID 7, the bacterial communities with high relative abundance in the wound exudation of mice in the four groups included bacteria of Corynebacterium, Staphylococcus, and Rhodococcus. On PID 14, the bacterial communities with high relative abundance in the wound exudation of mice in the four groups included bacteria of Stenotrophomonas, Rhodococcus, and Staphylococcus, and the number of bacterial species in the wound exudation of mice in the three proportion scaffold groups was more than that in ordinary scaffold group. Conclusions: When the drug mass ratio is relatively small, DH has the effect of promoting the proliferation of HaCaT cells. The ratio of 8∶9 is the optimal mass ratio of dihydrotestosterone to hydroxyflutamide, and DH with this mass ratio can promote re-epithelialization and collagen deposition of full-thickness burn wounds in mice, and promote wound healing. The constructed dual release system of androgen and its antagonist with DH in a 1∶3 drug mass ratio contributes to the re-epithelialization and collagen deposition of the full-thickness burn wounds in mice, and can improve the diversity of wound microbiota.

Fecal calprotectin: A novel predictor of ulcerated esophageal injury after atrial fibrillation catheter ablation

BACKGROUND

Atrial esophageal fistula (AEF) is a lethal complication that can occur post atrial fibrillation (AF) ablation. Esophageal injury (EI) is likely to be the initial lesion leading to AEF. Endoscopic examination is the gold standard for a diagnosis of EI but extensive endoscopic screening is invasive and costly. This study was conducted to determine whether fecal calprotectin (Fcal), a marker of inflammation throughout the intestinal tract, may be associated with the existence of esophageal injury.

METHODS

This diagnostic study was conducted in a cohort of 166 patients with symptomatic AF undergoing radiofrequency catheter ablation from May 2020 to June 2021. Fcal tests were performed 1-7 days after ablation. All patients underwent endoscopic ultrasonography 1 or 2 days after ablation.

RESULTS

The levels of Fcal were significantly different between the EI and non-EI groups (404.9 µg/g (IQR 129.6-723.6) vs. 40.4 µg/g (IQR 15.0-246.2), p < .001). Analysis of ROC curves revealed that a Fcal level of 125 µg/g might be the optimal cut-off value for a diagnosis of EI, giving a 78.8% sensitivity and a 65.4% specificity. The negative predictive value of Fcal was 100% for ulcerated EI.

CONCLUSIONS

The level of Fcal is associated with EI post AF catheter ablation. 125 µg/g might be the optimal cut-off value for a diagnosis of EI. Negative Fcal could predict the absence of ulcerated EI, which could be considered a precursor to AEF.

Left atrial appendage mechanical dispersion assessed by speckle-tracking echocardiography as a determinant of left atrial appendage stasis in patients with non-valvular atrial fibrillation

Background

We sought to investigate the relationship of left atrial appendage (LAA) mechanical dispersion (MD) with LAA dense spontaneous echo contrast (SEC) or thrombus, and to compare its usefulness in the identification of thrombogenesis with left atrial (LA) MD or LA/LAA strain parameters in patients with nonvalvular atrial fibrillation (AF).

Methods

We conducted a cross-sectional study of 493 consecutive patients with AF (median age 65, male 66.9%) who underwent echocardiography prior to catheter ablation. We measured the LAA and LA global longitudinal strain (GLS) using speckle-tracking echocardiography (STE). LAA MD and LA MD was defined as the standard deviation (SD) of time to peak positive strain corrected by the R-R interval.

Results

Patients with LAA dense SEC/thrombus (n=70) had significantly higher LAA MD than controls (n=423) (median 14.20% vs 9.35%). Areas under the receiver-operating curve for CHA2DS2-VASc score plus LAA MD, LAA GLS or LA GLS were comparable (0.830, 0.843 and 0.809) and superior to that combined with LA MD (0.762, all p&lt;0.01). Multivariable analysis showed that LAA MD was an independent determinant of LAA dense SEC/thrombus in four different models (Odds ratio, 1.23–1.24; P&lt;0.001), and provided additional diagnostic value over clinical and standard echocardiographic parameters. Whereas LA MD was not independently associated with LAA dense SEC/thrombus and had no incremental predictive value.

Conclusion

LAA mechanical dispersion provided incremental information over conventional risk factors in the identification of LAA dense SEC or thrombus in AF patients and is superior to LA mechanical dispersion.

Funding Acknowledgement

Type of funding sources: None.

Use of speckle-tracking echocardiography to stratify risk of atrial fibrillation-related stroke: comparison of left atrial and atrial appendage mechanics

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): the National Natural Science Foundation of China

onbehalf

Sir Run Run Shaw Hospital,Zhejiang University,School of Medicine

Background

Left atrial (LA) and appendage (LAA) dysfunction were associated with increased risk of stroke in atrial fibrillation. However, usefulness of LA and LAA mechanics has not been fully compared. Methods:201 AF patients were prospectively enrolled. 42(20.8%) had previous stroke/TIA.  Speckle tracking was used to measure LA and LAA peak postive strain. LA and LAA MD was defined as the SD of time to peak positive strain corrected by the R-R interval. Results:LA MD and LAA MD were independently associated with stroke/TIA. The model based on CHA2DS2-VASc score for discrimination of stroke was significantly improved by adding LA MD or LAA MD (P &lt; 0.01). Diagnostic value of LA MD was better than LAA MD in patients with normal LA volumes, while LAA MD was more useful in patients with LA enlargement.Conclusion:Both LA and LAA mechanics had incremental value over CHA2DS2VASc score. However, priorities of strain assessment depend on patients’ LA volume.

Variables Univariate analysis Multivariate analysis Model 1 Model 2 Model 3 OR (95% CI) P value OR (95% CI) P value OR (95% CI) p value OR (95% CI) P value Clinical parameters Age 1.09(1.04-1.14) &lt;0.001 1.11(1.04-1.17) 0.001 1.11(1.05-1.17) 0.001 1.11(1.04-1.17) 0.001 BMI 0.988(0.89-1.10) 0.84 1.07(0.92-1.25) 0.40 1.07(0.91-1.25) 0.40 CHA2DS2-VASc score 1.52(1.15-2.00) 0.003 1.08(0.67-1.74) 0.76 1.08(0.65-1.80) 0.77 1.10(0.69-1.76) 0.69 Persistent AF 1.88(0.94-3.74) 0.07 0.75(0.23-2.40) 0.63 0.87(0.27-2.81) 0.82 Therapeutic anticoagulation 0.56(0.28-1.11) 0.10 0.22(0.09-0.57) 0.002 0.23(0.09-0.59) 0.002 0.22(0.09-0.57) 0.002 LA parameters LAEF 0.96(0.94-0.99) 0.002 0.982(0.953-1.01) 0.26 iLAVmin 1.03(1.01-1.05) 0.006 0.98(0.94-1.02) 0.27 LA MD 1.22(1.10-1.36) &lt;0.001 1.16(1.02-1.32) 0.02 1.18(1.03-1.34) 0.02 1.16(1.02-1.32) 0.02 LA GLS 0.935(0.893-0.98) 0.005 1.0(0.953-1.14) 0.36 1.02(0.94-1.12) 0.59 1.02(0.94-1.10) 0.72 LAA parameters LAAEV 0.12(0.02-0.74) 0.02 3.34(0.31-36.06) 0.32 LAA EF 0.98(0.96-1.00) 0.06 1.01(0.98-1.04) 0.65 LAA GLS 0.85(0.77-0.94) 0.001 0.96(0.86-1.07) 0.46 0.97(0.87-1.08) 0.59 0.96(0.87-1.06) 0.44 LAA dense SEC/thrombus 3.12(1.39-6.99) 0.006 2.02(0.75-5.45) 0.167 LAA MD 1.19(1.09-1.29) &lt;0.001 1.19(1.08-1.31) 0.001 1.19(1.08-1.31) 0.001 1.19(1.08-1.31) 0.001 Univariable and multivariable logistic regression analyses of associations between clinical and echocardiographic covariates with stroke Abstract Figure.

Risk of esophageal thermal injury during catheter ablation for atrial fibrillation guided by different ablation index

BACKGROUND

During ablation for atrial fibrillation (AF), energy delivery toward the left atrial posterior wall may cause esophageal injury (EI). Ablation index (AI) was introduced to estimate ablation lesion size, however, the impact of AI technology on the risk of EI has not been explored.

METHOD

From March 2019 to December 2019, 60 patients with paroxysmal AF undergoing first-time ablation were prospectively enrolled. The first 30 consecutive patients were ablated with the AI target value of 400 (AI-400 group), and the later 30 consecutive patients were ablated with the AI target value of 350 at the posterior wall (AI-350 group). Endoscopic ultrasonography was used to evaluate EI postablation. EI was classified as a category 1 (erythema or erosion) or a category 2 (hematoma or ulceration).

RESULTS

Compared with the AI-400 group (59.9 ± 8.4 years; male, 60%), the AI-350 group (59.1 ± 9.9 years; male, 50%) had a lower incidence of EI (3.3% vs 26.7%, P = .03). There was no significant difference in the percentage of first-pass PVI between the AI-400 group and the AI-350 group (left PVI: 80% vs 73.4%, P = .54; right PVI: 80% vs 60%, P = .1). Neither ablation time nor fluoroscopy time was significantly different between the AI-400 group and the AI-350 group.

CONCLUSIONS

AF ablation guide by AI target value of 350 may reduce esophageal thermal injury and has a similar efficiency on the acute success rate of first-pass PVI compared with an AI target value of 400 at the posterior wall.

Characteristics of Atrial Fibrillation Patients Suffering Esophageal Injury Caused by Ablation for Atrial Fibrillation

The close proximity of esophagus to the left atrial posterior wall predisposes esophagus to thermal injury during catheter ablation for atrial fibrillation (AF). In this retrospective study, we aimed to investigate risk factors of esophageal injury (EI) caused by catheter ablation for AF. Patients who underwent first-time AF ablation from July 2013 to June 2018 were included. The esophagus was visualized by oral soluble contrast during ablation for all patients and a subset of patients were selected to undergo endoscopic ultrasonography (EUS) to estimate EI post ablation. Degree of EI was categorized as Kansas City classification: type 1: erythema; type 2: ulcers (2a: superficial ulcers; 2b: deep ulcers); type 3: perforation (3a: perforation without communication with the atria; 3b: atrioesophageal fistula [AEF]). Of 3,852 patients, 236 patients (61.5 ± 9.7 years; male, 69%) received EUS (EUS group) and 3616 (63.2 ± 10.9 years; male, 61.1%) without EUS (No-EUS group). In EUS group, EI occurred in 63 patients (type 1 EI in 35 and type 2 EI in 28), and no type 3 EI was observed during follow up. In a multivariable logistic regression analysis, an overlap between the ablation lesion and esophagus was an independent predictor of EI (odds ratio, 21.2; 95% CI: 6.23–72.0; P < 0.001). In No-EUS group, esophagopericardial fistula (EPF; n = 3,0.08%) or AEF (n = 2,0.06%) was diagnosed 4–37 days after ablation. In 3 EPF patients, 2 completely recovered with conservative management and 1 died. Two AEF patients died. Ablation at the vicinity of the esophagus predicts risk of EI. EUS post ablation may prevent the progression of EI and should be considered in management of EI. It remains challenging to identify patients with high risk of EI.

PV isolation guided by esophageal visualization with a tailored ablation strategy for the avoidance of esophageal thermal injury: a randomized trial

PURPOSE

Radiofrequency ablation along the posterior wall of the left atrium may lead to atrioesophageal fistula due to esophageal thermal injury. The purpose of our study was to prospectively investigate whether ablation guided by soluble contrast esophageal visualization (SCEV) reduces injury during atrial fibrillation (AF) ablation.

METHODS

Seventy-eight patients with paroxysmal AF undergoing circumferential pulmonary vein isolation (PVI) were randomized to a SCEV group (n = 39) and control group without visualization (n = 39). Cine imaging of the esophagus was performed during soluble contrast swallowing at the beginning of ablation, after adjacent ipsilateral PVI and at the end of the procedure. The ablation lesion set was modified to avoid radiofrequency delivery within the contrast esophagram boundaries. In the control group, a single final ingestion was performed at the end of the procedure. Esophageal injury was assessed by esophagogastroscopy within 24 h in all patients.

RESULTS

In the control group, the ablation lesion crossed over the esophagus in 46.2% of patients, whereas in SCEV group, the ablation line violated the boundaries of the esophagus unavoidably in 15.4% of patients (confidence interval (CI); 1.61-13.98, p = 0.003). The incidence of esophageal injury was significantly lower in patients that underwent ablation with SCEV (5.1% vs. 20.5%, CI; 0.04-1.06, p = 0.042). Regardless of randomization group, patients who received ablation which overlapped the esophagus had a higher incidence of esophageal injury compared with those without overlap (37.5 vs. 1.9%, CI; 3.73-271.37, p = 0.000).

CONCLUSIONS

Esophageal contrast visualization helps to reduce the potential for esophageal injury during paroxysmal AF ablation. This simple procedural adjunct has important implications to improve safety of paroxysmal AF ablation procedures globally.

Metabolic benefits of rivaroxaban in non-valvular atrial fibrillation patients after radiofrequency catheter ablation

BACKGROUND AND OBJECTIVE

Rivaroxaban is a new oral anticoagulant for stroke prevention in patients with non-valvular atrial fibrillation (NVAF), which has less drug-food interaction than warfarin. We conducted this prospective randomized study to evaluate the metabolic benefits as well as the safety and efficacy with rivaroxaban versus warfarin in patients with NVAF following radiofrequency catheter ablation (RFCA).

METHODS

From April to July 2014, 60 patients with NVAF undergoing RFCA were prospectively enrolled in our study. Following RFCA, all patients were randomly assigned to receive rivaroxaban (Group R, n=30) or warfarin (Group W, n=30). Metabolic indices including serum total protein, albumin, globulin, and high-density lipoprotein (HDL) as well as bleeding, stroke, and systemic thromboembolism events were evaluated and compared during follow-up after 15, 30, 60, and 90 d of RFCA procedure.

RESULTS

Serum total protein, albumin, globulin, and HDL levels were all significantly elevated at each follow-up stage in Group R when compared to the baseline (P<0.05 respectively). In Group W, the metabolic indices decreased at first and then had an increasing trend. There were no deaths or thromboembolic complications in each group. The prevalence of total bleeding complications was similar between Group R and Group W (11/30, 36.7% vs. 10/30, 33.3%, P=0.79).

CONCLUSIONS

Patients with NVAF receiving rivaroxaban after RFCA procedures appear to benefit from a metabolic perspective compared with warfarin, providing practical clinical reference for the choice of the anticoagulant. Rivaroxaban seems to be as safe and effective in preventing thromboembolic events as warfarin for these patients.

Impact of Anatomically Guided Ganglionated Plexus Ablation on Electrical Firing from Isolated Pulmonary Veins

BACKGROUND

The mechanisms underlying atrial fibrillation (AF) initiation and pulmonary vein isolation (PVI) effectiveness remain unclear. Ganglionated plexus (GPs) have been implicated in AF initiation and maintenance. In this study, we evaluated the impact of GP ablation in patients with pulmonary vein (PV) firing after PVI.

METHODS

Patients with drug-refractory paroxysmal AF undergoing radiofrequency catheter ablation therapy with PVI were screened. Among 840 cases over a 3.75-year period, 12 cases were identified with persistent PV firing (left = 4 and right = 8) after PVI was achieved and left atrial sinus rhythm restored. Adjacent GP ablation was performed anatomically and followed if necessary by additional PV ablation.

RESULTS

In eight patients, PV firing was terminated during GP ablation outside of the circumferential ablation line. In one patient, additional PV ablation resulted in cessation of PV firing and in the remaining three patients, firing could not be terminated by GP ablation or additional PVI.

CONCLUSION

GP ablation outside of wide antral circumferential line frequently results in the cessation of rapid firing from electrically isolated PVs. These observations suggest that interactions between left atrium and PV beyond electrical conduction warrant consideration in AF mechanisms.

Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal atrial fibrillation: mechanistic implications

BACKGROUND

Pulmonary vein (PV) isolation has become the mainstay acute procedural end point for paroxysmal atrial fibrillation (AF) ablation.

OBJECTIVE

To examine the incidence of conduction recovery in the PVs in patients without clinical recurrence of AF after paroxysmal AF ablation.

METHODS

From August 2008 to March 2011, 392 patients with drug-refractory PAF underwent catheter ablation in our center, a wide area circumferential ablation approach guided with a circular mapping catheter was performed with the intended endpoint of entrance block in all PVs. 276 (70.4%) of them were free from recurrence at one year follow-up, and 32 of them were enrolled to assess the incidence of PV reconnection. Forty-three patients with clinical recurrence after ablation were analyzed for comparison. The regions of gap were mapped and characterized in all of the reconnected PVs.

RESULTS

Among patients without recurrence, recovery of PV conduction was observed in 29 of 32 (90.6%) patients: 10/32 (31.2%) reconnection in 4 veins, 7/32 (21.9%) in 3 veins, 10/32 (31.2%) in 2 veins, and 2/32 (6.2%) in 1 vein. No anatomic propensity was seen because reconnection was evenly distributed throughout all veins (left superior pulmonary vein 21, left inferior pulmonary vein 20, right superior pulmonary vein 19, and right inferior pulmonary vein 23). When compared to patients with recurrence, no significant differences were seen in the proportion of patients with reconnection (P = 1.0) or in left atrium-PV intervals (73.4 ± 43.3 ms vs 61.9 ± 31.8 ms; P > .05).

CONCLUSION

A high incidence of PV reconnection was similarly observed in patients with and without recurrence of AF, suggesting that sustained PV isolation may not be required for freedom from clinical recurrence of AF.

Early detection of pulmonary vein reconnection after isolation in patients with paroxysmal atrial fibrillation: a comparison of ATP-induction and reassessment at 30 minutes postisolation

INTRODUCTION

Catheter ablation for paroxysmal AF (PAF) is limited by an unacceptable recurrence rate, mainly due to pulmonary vein (PV) reconnection. Strategies to minimize reconnection include adenosine infusion and also a waiting period of 30 minutes after PV isolation. The aim of the present study was to assess whether these two strategies revealed the same conduction gap.

METHODS AND RESULTS

In total, 88 consecutive patients (54 males, mean age of 60 years) with drug refractory PAF underwent circumferential PV isolation (CPVI). After isolation of ipsilateral PVs, with entry and exit block checked using a circular mapping catheter, 20 mg ATP was injected during isoproterenol infusion to reveal dormant conduction gap(s). Unless the reconnection revealed by ATP persisted, PVs were further remapped with the circular mapping catheter at 30 minutes postisolation. Totally, PV reconnection was observed in 56 (64%) patients. 24.3% veins (80/329) were found reconnected. Reassessment at 30 minutes postablation was more efficient as compared to ATP induction (19.8% vs 14.6% for ATP). The agreement between these 2 methods is moderate (kappa value = 0.50). In veins that transiently reconnected after ATP administration and later observed at 30 minutes postablation, 94% (17 of 19) of them were found being reconnected with the same gap.

CONCLUSION

Acute PV reconnection is common, occurring in 64% of patients, as detected by adenosine infusion and waiting time. Each shows a unique quality as compared to one another. The combined use of these 2 methods may reduce the AF recurrence rate after CPVI.

ATP revealed extra pulmonary vein source of atrial fibrillation after circumferential pulmonary vein isolation

Noninducibility of atrial fibrillation (AF) by additional electrograms-guided ablation may benefit the clinical outcome. This report illustrates the effect of adenosine triphosphate (ATP) injection on AF inducibility after pulmonary vein (PV) isolation. AF was triggered twice by ATP without PV reconnection. Meanwhile, complex fractionated atrial electrograms (CFAEs) were observed, and ablation targets on these sites appeared to be essential to the AF elimination. It suggests that CFAEs may contribute to the initiation of some AF. ATP may be useful to induce AF after proven PV isolation, and further ablation might be necessary to ensure efficacy after circumferential PV isolation.

Skewed X-chromosome inactivation is associated with trisomy in women ascertained on the basis of recurrent spontaneous abortion or chromosomally abnormal pregnancies

An increase in extremely skewed X-chromosome inactivation (XCI) (> or = 90%) among women who experienced recurrent spontaneous abortion (RSA) has been previously reported. To further delineate the etiology of this association, we have evaluated XCI status in 207 women who experience RSA. A significant excess of trisomic losses was observed among the women who had RSA with skewed XCI versus those without skewed XCI (P=.02). There was also a significant excess of boys among live births in this group (P=.04), which is contrary to expectations if the cause of skewed XCI was only that these women carried X-linked lethal mutations. To confirm the association between skewed XCI and the risk of trisomy, an independent group of 53 women, ascertained on the basis of a prenatal diagnosis of trisomy mosaicism, were investigated. Only cases for which the trisomy was shown to be of maternal meiotic origin were included. The results show a significantly higher level of extreme skewing (> or = 90%) in women whose pregnancies involved placental trisomy mosaicism (17%) than in either of two separate control populations (n=102 and 99) (P=.02 compared with total control subjects). An additional 11 cases were ascertained on the basis of one or more trisomic-pregnancy losses. When all women in the present study with a trisomic pregnancy (n=103) were considered together, skewed XCI was identified in 18%, as compared with 7% in all controls (n=201) (P=.005). This difference was more pronounced when a cutoff of extreme skewing of 95% was used (10% vs. 1.5% skewed; P=.002). Maternal age was not associated with skewing in either the patient or control populations and therefore cannot account for the association with trisomy. Previous studies have shown that a reduced ovarian reserve is associated with increased risk of trisomic pregnancies. We hypothesize that the association between skewed XCI and trisomic pregnancies is produced by a common mechanism that underlies both and that involves a reduction of the size of the follicular pool.