Respect or resect in Barlow disease.

Mitral regurgitation in Barlow disease may still be challenging to be repaired. Most often it involves the posterior leaflet. Many techniques and concepts are currently available; the main goal being to restore a good surface of coaptation. Basic principles such as thorough analysis is still required whatever the approach to assess excess tissue height, width, and prolapse. Nowadays it seems that two different ways of treating mitral prolapse coexist: the nonresection one and the resection one. Both will be discussed and analyzed. Similarly, the use of artificial chordae seems to have a preponderant role to support the free edge and correct a prolapse. Native secondary chord transfer are easy and reliable but seem abandoned by many. Anterior leaflet prolapse is also dealt with and fewer options are available to address this leaflet. Then commissural prolapse is mentioned. It is an important area of the valve which should deserve better treatment than commissuroplasty. Finally, a special entity will be described; mitro annular disjunction. The approach is not or no longer an issue as only good long-term results are important in an era where percutaneous therapy is the only noninvasive technique.

Description of the 'pronation manoeuvre' for the diagnosis of developmental hip dysplasia.

Introduction: Without a prompt diagnosis, developmental dysplasia of the hip (DDH) in infants can lead to severe sequelae. Current screening strategies emphasize the use of Ortolani and Barlow physical examination manoeuvres, yet they exhibit low sensitivity. The purpose of this study is to evaluate the performance of a new physical examination tool (the pronation manoeuvre) as a screening tool for DDH. Methods: To evaluate the new manoeuvre, a cross-sectional and analytic study was performed with a nonprobabilistic sampling method. Patients with either a positive Ortolani or Barlow manoeuver were evaluated with the new manoeuvre and hip ultrasound. Controls were infants with negative Ortolani, Barlow and pronation manoeuvres and also had ultrasound performed. Results: DDH was confirmed in 83 of 130 cases (64%) and 2 of 130 controls (2%). The new pronation manoeuvre had a sensitivity of 76% and a specificity of 94% as compared to the Ortolani and Barlow manoeuvres (sensitivity 31 to 32%, specificity 93 to 100%) (P<0.05). Conclusion: This new physical examination manoeuvre could serve as another clinical tool for the initial screening of DDH in newborns. Its promising results against traditional screening procedures might potentially impact diagnosis and prognosis for patients with DDH.

Stepwise mitral valve repair for Barlow's disease via a minimally invasive approach.

BACKGROUND AND AIM: Mitral regurgitation (MR) in Barlow's disease is complicated because of its mixed pathophysiology, leaflet billowing with or without organic prolapse, and abnormal annular dynamics that cause functional prolapse. Complex repair techniques, including aggressive leaflet resection and implantation of multiple artificial chordae, are conventionally performed; nevertheless, these are technically demanding, especially when performed using a minimally invasive approach. We aimed to standardize the repair technique for Barlow's disease and developed stepwise repair techniques. METHODS: Of 292 patients who underwent isolated minimally invasive mitral valve repair for MR, 29 patients (seven females, age 49 ± 10 years) were found to have Barlow's disease. Our repair technique consists of the following three steps: (a) stabilization of the mitral annulus by placing annuloplasty ring sutures; (b) distinction between organic and functional prolapse by a saline injection test; and (c) targeted repair for organic prolapse by leaflet resection or chordal replacement. RESULTS: Surgical techniques included leaflet resection in 22 patients, chordal replacement in 19 patients, and ring annuloplasty only in one patient. These procedures were applied to the anterior leaflet in one, posterior leaflet in eight, and both leaflets in 19 patients. The median annuloplasty ring size was 34 mm. The repair success rate was 100%. No patients developed moderate or greater MR during a mean follow-up period of 36 ± 21 months. CONCLUSIONS: A stepwise repair strategy facilitates mitral valve repair in patients with Barlow's disease and provides excellent outcomes even via a minimally invasive approach.

Degenerative Mitral Regurgitation: Assessment, Physical Examination, and Imaging.

PURPOSE OF REVIEW: In this review, we provide a comprehensive approach to assess degenerative mitral regurgitation. RECENT FINDINGS: In the evaluation of MR, it is important to differentiate between primary (degenerative/organic) MR in which an intrinsic mitral valve lesion(s) is responsible for the occurrence of MR and secondary (functional) MR where the mitral valve is structurally normal, but alterations of the left ventricular geometry cause deterioration of the MV apparatus. Advanced imaging modalities, foremost two-dimensional and three-dimensional echocardiography, are essential for this determination. In the evaluation of degenerative MR, the exact mechanism, the extent of the disease, associated valve lesions, the grade of mitral regurgitation severity, and hemodynamic consequences require careful assessment in order to provide patients with appropriate monitoring and treatment.

Repair of bileaflet prolapse in Barlow syndrome: The 4-chord technique.

Barlow syndrome is a form of degenerative mitral valve (MV) disease found in a subset of patients with bileaflet prolapse. The hallmark of Barlow's disease includes excessive and billowing leaflet tissue caused by myxomatous tissue proliferation, elongated chordae, and pronounced annular dilatation. Surgical repair of patients with Barlow's disease is challenging due to the extent of the leaflet and annular abnormalities. Several techniques have been described to repair Barlow's MV including currently popular "non-resectional" approaches. Repair with neochordae has been associated with excellent results and includes the advantage of preserved leaflet mobility and a large surface of coaptation. We describe a simple approach to the use of neochordae to repair bileaflet prolapse in patients with Barlow syndrome and avoid systolic anterior motion.

Streptococcus gordonii-associated infective endocarditis in a girl with Barlow's mitral valve disease.

We present a case of infective endocarditis caused by Streptococcus gordonii in an 11-year-old girl with Barlow's mitral valve disease. The differential diagnosis of rheumatic carditis and infective endocarditis was difficult as the patient fulfilled the Jones criteria. Vegetation on the mitral valve which became evident later in course of the disease and positive blood culture allowed diagnosing "definite" infective endocarditis.

Three-dimensional echocardiography of mitral Barlow's disease with infective endocarditis: Perforations or cleft-like indentations?

Barlow's disease is a complicated form of degenerative mitral valve (MV) disease. Infective endocarditis (IE) often occurs on the basis of primary heart diseases and may be combined with valve perforations. Cleft-like indentations (CLIs) were suggested by Ring et al. in 2013. They are located at the inter-scallop position and involve at least one-half of the valve. Herein, we report a case of Barlow's disease combined with IE and CLIs, which was confirmed intra-operatively and by histopathological examination. The CLIs were misdiagnosed by two-dimensional transthoracic echocardiography as perforations, but rightly interpreted by preoperative three-dimensional echocardiography. The possibility of CLIs should be considered in the evaluation of mitral regurgitation caused by myxomatous MV diseases.

Genomic analysis in patients with myxomatous mitral valve prolapse: current state of knowledge.

BACKGROUND: Myxomatous mitral valve prolapse is a common cardiac abnormality. Morbus Barlow is characterized by excess myxomatous leaflet tissue, bileaflet prolapse or billowing, chordae elongation and annular dilatation with or without calcification. Extensive myxoid degeneration with destruction of the normal three-layered leaflet tissue architecture is observed histologically in such patients. Autosomal dominant inheritance with an age and sex-dependent expression has long been recognised. This review explores the current understanding of the genetics of bileaflet prolapse, with a focus on genetic analysis and the role for echocardiographical screening of the first degree relatives of affected patients. METHODS: Systematic literature searches were performed using PubMed and Embase up to September 2017. In Disse et al.'s study (study one) first degree relatives of 25 patients with Morbus Barlow who underwent mitral valve repair were screened for bileaflet valve prolapse. In Nesta et al.'s study one family with three living generations of 43 individuals with 9 confirmed cases of MVP was screened. Genotyping was performed in four families for 344 microsatellite markers from Chromosome 1 to 16. RESULTS: In study one, autosomal dominant inheritance was shown in four pedigrees. Genome-wide linkage analysis of the most informative pedigree (24 individuals, three generations) showed a significant linkage for markers mapping to chromosome 16p. Linkage to this locus was confirmed in a second family within the same study, but was excluded in the remaining two pedigrees. In study two an autosomal dominant locus was mapped to chromosome 13. 8 of the 9 individuals affected were found to suffer from bileaflet prolapse. CONCLUSIONS: Barlow's disease is a heritable trait but the genetic causes remain largely elusive. Ch16p11.2-p12.1 is the only locus proven to be associated with bileaflet prolapse. Locus 13.q31.3-q32.1 was shown to cause bileaflet as well as posterior leaflet prolapse. This review intends to make physicians aware of genetic causes of myxomatous mitral valve prolapse, thereby emphasising the importance of cardiological examination of first-degree relatives of patients with Morbus Barlow. Integrated and more comprehensive studies are needed for identification of genes involved in this heterogenic disease. Further genomic studies may facilitate more individualised and accurate risk assessment and may help to develop possible preventive stategies for patients in the future.

Impact of bileaflet mitral valve prolapse on quantification of mitral regurgitation with cardiac magnetic resonance: a single-center study.

BACKGROUND: To quantify mitral regurgitation (MR) with CMR, the regurgitant volume can be calculated as the difference between the left ventricular (LV) stroke volume (SV) measured with the Simpson's method and the reference SV, i.e. the right ventricular SV (RVSV) in patients without tricuspid regurgitation. However, for patients with prominent mitral valve prolapse (MVP), the Simpson's method may underestimate the LV end-systolic volume (LVESV) as it only considers the volume located between the apex and the mitral annulus, and neglects the ventricular volume that is displaced into the left atrium but contained within the prolapsed mitral leaflets at end systole. This may lead to an underestimation of LVESV, and resulting an over-estimation of LVSV, and an over-estimation of mitral regurgitation. The aim of the present study was to assess the impact of prominent MVP on MR quantification by CMR. METHODS: In patients with MVP (and no more than trace tricuspid regurgitation) MR was quantified by calculating the regurgitant volume as the difference between LVSV and RVSV. LVSVuncorr was calculated conventionally as LV end-diastolic (LVEDV) minus LVESV. A corrected LVESVcorr was calculated as the LVESV plus the prolapsed volume, i.e. the volume between the mitral annulus and the prolapsing mitral leaflets. The 2 methods were compared with respect to the MR grading. MR grades were defined as absent or trace, mild (5-29% regurgitant fraction (RF)), moderate (30-49% RF), or severe (≥50% RF). RESULTS: In 35 patients (44.0 ± 23.0y, 14 males, 20 patients with MR) the prolapsed volume was 16.5 ± 8.7 ml. The 2 methods were concordant in only 12 (34%) patients, as the uncorrected method indicated a 1-grade higher MR severity in 23 (66%) patients. For the uncorrected/corrected method, the distribution of the MR grades as absent-trace (0 vs 11, respectively), mild (20 vs 18, respectively), moderate (11 vs 5, respectively), and severe (4 vs 1, respectively) was significantly different (p < 0.001). In the subgroup without MR, LVSVcorr was not significantly different from RVSV (difference: 2.5 ± 4.7 ml, p = 0.11 vs 0) while a systematic overestimation was observed with LVSVuncorr (difference: 16.9 ± 9.1 ml, p = 0.0007 vs 0). Also, RVSV was highly correlated with aortic forward flow (n = 24, R 2 = 0.97, p < 0.001). CONCLUSION: For patients with severe bileaflet prolapse, the correction of the LVSV for the prolapse volume is suggested as it modified the assessment of MR severity by one grade in a large portion of patients.

[Atypical scurvy associated with anorexia nervosa]. / Scorbut atypique associé à une anorexie mentale.

INTRODUCTION: Scurvy, or "Barlow's disease", is a widely described disease involving cutaneous and mucosal lesions resulting from vitamin C deficiency. Herein, we report a case of scurvy in a 48-year-old woman that was unusual in its atypical cutaneous-mucosal presentation as well as its association with anorexia nervosa. PATIENTS AND METHODS: A 48-year-old woman treated for depression for several years was admitted to hospital for her impaired general state of health. Over the last year, she had presented palmoplantar rash and episodes of perimalleolar oedema. The clinical examination showed the patient to have wasting syndrome, with a BMI of 11.9kg/m2, lower-limb oedema, palmoplantar fissures, geographic tongue, telogen effluvium and purpuric petechiae on her right knee. However, no gingival bleeding was noted and there was no loss of tooth enamel. The remainder of the clinical examination was normal. Blood tests revealed extremely low vitamin C levels without any other associated deficiencies, as well as laboratory signs of cytolysis and anicteric cholestasis without inflammatory syndrome. The diagnosis of anorexia nervosa was made by psychiatrists, despite the unusual age of onset. Favorable clinical outcome was rapidly achieved via a one-month course of vitamin C supplements at a daily dose of 1g. DISCUSSION: The absence of classical buccal-dental symptoms and the presence of keratotic dermatosis with fissures and ulcers on the hands and feet are atypical in scurvy; however, this diagnosis was confirmed by the existence of purpura evoking capillary fragility, the patient's drastically low vitamin C level and the rapid subsidence of symptoms following treatment with oral vitamin C alone. Anorexia nervosa was doubtless the cause of deficiency. This situation is rare and a systematic review of the literature in Medline via PubMed showed that only three reports of scurvy associated with mental anorexia have been published since 1975.

Current Discoveries and Interventions for Barlow's Disease.

Mitral valve prolapse is a common valve pathology. One particular type of mitral valve prolapse that can be difficult to treat is Barlow's disease. This review serves to give insight on the current discoveries and therapeutic interventions of Barlow's disease.

[Infantile scurvy: Two cases]. / Scorbut chez l'enfant: deux cas.

BACKGROUND: Scurvy is the classic and most severe form of vitamin C deficiency. This condition has become extremely rare among children in the industrialized countries. PATIENTS AND METHODS: We report the case of two boys presenting bone pain associated with haemorrhagic gingivitis, with perifollicular purpura of the lower limbs in one boy. The children had an unbalanced diet. Scurvy was associated with vitamin D and iron deficiency. The dermatological and radiological abnormalities seen were characteristic and a favourable outcome was rapidly obtained following supplementation. DISCUSSION: The possibility of this forgotten historical illness should not be overlooked in the presence of these dermatological and rheumatologic signs, since this can help avoid unnecessary or excessively aggressive investigations.

A balanced mitral leaflet and large ring strategy avoids systolic anterior motion in Barlow's disease.

OBJECTIVES: Mitral valve repair for Barlow's disease offers good outcomes but excessive and myxomatous valvular tissue is associated with systolic anterior motion. Although valvular disease might progress after repair and cause long-term systolic anterior motion, few reports focus on this aspect. Herein, we will review our 16-year experience with mitral valve repair for Barlow's disease and systolic anterior motion incidence. METHODS: We retrospectively reviewed surgical outcomes of 92 cases of mitral valve repair using a balanced leaflet/large ring strategy plus median sternotomy for Barlow's disease (median age 45.1 ± 12.7 years old [19-72], 37 females) from 2004 to 2019. Concomitant surgeries, except for tricuspid valve or anti-arrhythmic surgeries, were excluded. RESULTS: The follow-up period was 5.8 ± 4.4 years with no deaths. Patients had mitral regurgitation of grade 3/4 (15 cases) or 4/4 (77 cases) due to anterior leaflet (3 cases), posterior leaflet (75 cases), or bileaflet (14 cases) prolapse, with chord elongation (39 cases), chord rupture (22 cases), or a combination of both (14 cases). All cases required ring annuloplasty (median size of 33.0 ± 5.4 mm) combined with leaflet resection (91 cases), chord intervention (12 cases), or indentation closure (2 cases). No case had short- or long-term SAM. The freedom-from-mitral-regurgitation (of greater than grade 2/4) rate was 94.1% over 5 years and 76.0% over 10 years without reoperation. CONCLUSIONS: Our two-pronged strategy for mitral valve repair in Barlow's disease avoids systolic anterior motion over the long-term, with good outcomes.

Mid-term clinical outcomes of totally endoscopic repair for mitral regurgitation in Barlow's disease.

OBJECTIVE: This study aimed to confirm the safety and feasibility of totally endoscopic repair for mitral regurgitation (MR) in Barlow's disease. METHODS: From June 2018 to December 2022, 21 consecutive Barlow's disease patients (aged 33 ± 12 years; 57.1% male) underwent totally endoscopic mitral valve (MV) repair with leaflets folding, multiple artificial chordae implantation and ring annuloplasty. The safety and feasibility of this technique was evaluated by its mid-term clinical outcomes. RESULTS: There was no operative death or complications. The mean cardiopulmonary bypass (CPB) time was 190 ± 41 (128-267) min, and the aortic cross-clamp time was 145 ± 32 (66-200) min. The average number of artificial chordae implantation was 2.9 ± 0.7 (1-4) pairs. The mean MV coaptation length was 1.4 ± 0.3 (0.8-1.8) cm, and the median transvalvular gradient was 1 [interquartile range (IQR), 1-2] mmHg. During a median follow-up time of 24 (IQR, 10-38) months, all patients showed persistent effective valve function with no significant MR or systolic anterior motion. CONCLUSIONS: Totally endoscopic repair was a safe, effective, and reproducible procedure with satisfied mid-term clinical outcomes for MR in Barlow's disease. However, further randomized and long-term follow-up studies were warranted to determine its clinical effects.

Quantified planar collagen distribution in healthy and degenerative mitral valve: biomechanical and clinical implications.

Degenerative mitral valve disease is a common valvular disease with two arguably distinct phenotypes: fibroelastic deficiency and Barlow's disease. These phenotypes significantly alter the microstructures of the leaflets, particularly the collagen fibers, which are the main mechanical load carriers. The predominant method of investigation is histological sections. However, the sections are cut transmurally and provide a lateral view of the microstructure of the leaflet, while the mechanics and function are determined by the planar arrangement of the collagen fibers. This study, for the first time, quantitatively examined planar collagen distribution quantitatively in health and disease using second harmonic generation microscopy throughout the thickness of the mitral valve leaflets. Twenty diseased samples from eighteen patients and six control samples were included in this study. Healthy tissue had highly aligned collagen fibers. In fibroelastic deficiency they are less aligned and in Barlow's disease they are completely dispersed. In both diseases, collagen fibers have two preferred orientations, which, in contrast to the almost constant one orientation in healthy tissues, also vary across the thickness. The results indicate altered in vivo mechanical stresses and strains on the mitral valve leaflets as a result of disease-related collagen remodeling, which in turn triggers further remodeling.

Mitral valve repair with resection and non-resection techniques in Barlow's disease: A multi-center study.

BACKGROUND: Various mitral valve (MV) repair techniques are nowadays in use. Non-resection techniques, that rely exclusively on Gore-Tex® neochords and annuloplasty, have been popularized; however, their efficacy in Barlow's disease, characterized by large myxomatous leaflets, is yet unclear. METHODS: Consecutive patients undergoing MV repair for Barlow's disease between 2011 and 2019 were selected on the basis of being eligible for resection and non-resection techniques. Study endpoints included overall survival, freedom from MV reintervention and recurrent regurgitation. RESULTS: Of 209 patients meeting the inclusion criteria, 135 (65%) underwent MV repair with and 74 (35%) without resection. There was one early reoperation due to residual regurgitation (resection group). Mean clinical follow-up duration was 6.1 (IQR 3.9-8.5) years. At 6 years after surgery, there was no difference in overall survival or freedom from MV reintervention. Mean echocardiographic follow-up (95% complete) duration was 3.5 (IQR 2.3-5.8) years. At 6 years, there was no difference in freedom from recurrent regurgitation rate (86.1%, 95% CI 78.5-93.7% vs. 83.0%, 95% CI 71.6-94.4%, P = 0.20) between the groups. Inverse probability-of-treatment weighting adjusted analysis demonstrated no significant difference between groups (HR 0.535, 95% CI 0.212-1.349, P = 0.20). Uni- and multivariable Cox proportional regression analysis did not demonstrate an effect of valve repair technique on the occurrence of recurrent regurgitation. CONCLUSIONS: At mid-term, the clinical and echocardiographic results of valve repair for Barlow's disease were very good and MV reintervention was rarely needed. At this time point, the results of non-resection techniques were comparable to the "gold standard" resection techniques.

Mitral valve early systolic billowing induces following annular expansion and leaflet augmentation in Barlow's disease: sequential analysis using 3D echocardiography.

AIMS: Although systolic expansion of the annulus has been recognized in Barlow's disease, the mechanisms of the unique pathological movement of the annulus and its relation to the leaflet augmentation have not yet been clarified. We aimed to investigate the detailed mechanisms of the characteristic mitral apparatus dynamics in Barlow's disease by frame-by-frame sequential geometric analysis using real-time 3D transoesophageal echocardiography. METHODS AND RESULTS: Fifty-three patients with Barlow's disease and severe mitral regurgitation without torn chordae, as well as 10 controls, were included. We evaluated geometric changes in the mitral complex using 3D transoesophageal echocardiography at five points during systole. To identify early systolic billowing of leaflets, the annulo-leaflet angle was measured. We also performed a more detailed analysis in four consecutive frames just before and after leaflet free-edge prolapse above the annulus plane. The median annulo-leaflet angle of both leaflets in early systole was >0° (above annulus plane) in patients with Barlow's disease, and billowing of the leaflet body was observed from early systole. The prolapse volume of both leaflets increased markedly from early to mid-systole [1.60 (0.85-2.80) to 4.00 (2.10-6.45) mL; analysis of variance (ANOVA), P < 0.001; post hoc, P < 0.05]. With frame-by-frame analysis, dynamic augmentation of the annulus and leaflets developed between frames just before and just after leaflet free-edge prolapse (ANOVA, P < 0.01; post hoc, P < 0.05). CONCLUSION: In Barlow's disease, early systolic billowing of the mitral leaflet induces systolic annulus expansion followed by leaflet augmentation and leaflet free-edge prolapse.

Five-year outcomes of different techniques for minimally invasive mitral valve repair in Barlow's disease.

OBJECTIVES: Barlow's disease is a specific sub-form of mitral valve (MV) disease, characterized by diffuse excessive tissue and multi segment prolapse. The anterolateral mini-thoracotomy represents the standard access for MV regurgitation in many centres. It still remains unclear which surgical technique provides the best results. Therefore, the aim of this study was to compare operative safety and mid-term outcomes after (i) isolated annuloplasty, (ii) use of additional artificial chordae or (iii) leaflet resection in patients suffering from Barlow's disease undergoing minimally invasive MV repair. METHODS: A consecutive series of patients suffering from Barlow's disease undergoing minimally invasive MV surgery between 2001 and 2020 were analysed (n = 246). Patients were grouped and analysed according to the used surgical technique. The primary outcome was a modified Mitral Valve Academic Research Consortium combined end-point of mortality, reoperation due to repair failure or reoccurrence of severe mitral regurgitation within 5 years. The secondary outcome included operative success and safety up to 30 days. RESULTS: No significant difference was found between the 3 surgical techniques with regard to operative safety (P = 0.774). The primary outcome did not differ between groups (P = 0.244). Operative success was achieved in 93.5% and was lowest in the isolated annuloplasty group (77.1%). Conversion to MV replacement was increased in patients undergoing isolated annuloplasty (P < 0.001). CONCLUSIONS: Isolated annuloplasty, use of additional artificial chordae and leaflet resection represent feasible techniques in Barlow patients undergoing minimally invasive MV surgery with comparable 5-year results. In view of the increased conversion rate in the annuloplasty group, the pathology should not be oversimplified.

Structural and functional abnormalities of left-sided cardiac chambers in Barlow's disease without significant mitral regurgitation.

AIMS: This study aims to explore the presence of left ventricular (LV) and left atrial (LA) morphological and functional abnormalities in patients with Barlow's disease (BD) without significant mitral regurgitation (MR) and to investigate whether these abnormalities may predict MR progression. METHODS AND RESULTS: Consecutive patients with BD were retrospectively identified from two tertiary centres; those with MR graded from trivial to mild-to-moderate were selected and matched with healthy controls in a 1:1 ratio. Conventional and speckle-tracking echocardiographic data were collected. The development of moderate-to-severe or greater MR was evaluated on follow-up echocardiograms. Patients with BD (n = 231) showed increased LV dimensions and indexed LV mass (LVMi) in comparison with controls (P < 0.001); LV remodelling worsened with higher MR severity and was accompanied by an increased prevalence of eccentric LV hypertrophy (eLVH). Moreover, BD patients had larger LA volumes and more impaired LA reservoir strain vs. controls (P < 0.001), while LV strain was similar between the two groups. Multivariable linear regression analyses in the overall population identified BD and MR grade as independent predictors of remodelling markers (LV dimensions, LVMi, and LA volume) and BD as independent correlate of LA strain. MR progression was observed in 51 BD subjects (out of 170 patients with available follow-up). On Cox regression analysis, age, eLVH, mild-to-moderate MR, and mitral annular disjunction (MAD) emerged as independent predictors of MR progression. CONCLUSION: BD patients without significant MR show early LV and LA remodelling, together with reduced LA strain. MR progression was associated with eccentric LV remodelling, MAD, and MR severity.