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

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 centers; 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 to controls (p<0.001); LV remodeling 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 versus 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 remodeling 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. CONCLUSIONS: BD patients without significant MR show early LV and LA remodeling, together with reduced LA strain. MR progression was associated with eccentric LV remodeling, MAD, and MR severity.

Factors influencing post-surgical survival in degenerative mitral regurgitation.

AIMS: Indications for surgery in patients with degenerative mitral regurgitation (DMR) are increasingly liberal in all clinical guidelines but the role of secondary outcome determinants (left atrial volume index ≥60 mL/m2, atrial fibrillation, pulmonary artery systolic pressure ≥50 mmHg and moderate to severe tricuspid regurgitation) and their impact on post-operative outcome remain disputed. Whether these secondary outcome markers are just reflective of the DMR severity or intrinsically affect survival after DMR surgery is uncertain and may have critical importance in the management of patients with DMR. To address these gaps of knowledge the present study gathered a large cohort of patients with quantified DMR, accounted for the number of secondary outcome markers and examined their independent impact on survival after surgical correction of the DMR. METHODS AND RESULTS: The Mitral Regurgitation International DAtabase-Quantitative registry includes patients with isolated DMR from centres across North America, Europe, and the Middle East. Patient enrolment extended from January 2003 to January 2020. All patients undergoing mitral valve surgery within 1 year of registry enrolment were selected. A total of 2276 patients [65 (55-73) years, 32% male] across five centres met study eligibility criteria. Over a median follow-up of 5.6 (3.6 to 8.7) years, 278 patients (12.2%) died. In a comprehensive multivariable Cox regression model adjusted for age, EuroSCORE II, symptoms, left ventricular ejection fraction (LVEF), left ventricular end-systolic diameter (LV ESD) and DMR severity, the number of secondary outcome determinants was independently associated with post-operative all-cause mortality, with adjusted hazard ratios of 1.56 [95% confidence interval (CI): 1.11-2.20, P = 0.011], 1.78 (95% CI: 1.23-2.58, P = 0.002) and 2.58 (95% CI: 1.73-3.83, P < 0.0001) for patients with one, two, and three or four secondary outcome determinants, respectively. A model incorporating the number of secondary outcome determinants demonstrated a higher C-index and was significantly more concordant with post-operative mortality than models incorporating traditional Class I indications alone [the presence of symptoms (P = 0.0003), or LVEF ≤60% (P = 0.006), or LV ESD ≥40 mm (P = 0.014)], while there was no significant difference in concordance observed compared with a model that incorporated the number of Class I indications for surgery combined (P = 0.71). CONCLUSION: In this large cohort of patients treated surgically for DMR, the presence and number of secondary outcome determinants was independently associated with post-surgical survival and demonstrated better outcome discrimination than traditional Class I indications for surgery. Randomised controlled trials are needed to determine if patients with severe DMR who demonstrate a cardiac phenotype with an increasing number of secondary outcome determinants would benefit from earlier surgery.

The MIDA-Q Mortality Risk Score: A Quantitative Prognostic Tool for the Mitral Valve Prolapse Spectrum.

BACKGROUND: Mitral valve prolapse (MVP) is responsible for a considerable disease burden but is widely heterogeneous. The lack of a comprehensive prognostic instrument covering the entire MVP spectrum, encompassing the quantified consequent degenerative mitral regurgitation (DMR), hinders clinical management and therapeutic trials. METHODS: The new Mitral Regurgitation International Database Quantitative (MIDA-Q) registry enrolled 8187 consecutive patients (ages 63±16 years, 47% women, follow-up 5.5±3.3 years) first diagnosed with isolated MVP, without or with DMR quantified prospectively (measuring effective regurgitant orifice [ERO] and regurgitant volume) in routine practice of 5 tertiary care centers from North America, Europe, and the Middle East. The MIDA-Q score ranges from 0 to 15 by accumulating guideline-based risk factors and DMR severity. Long-term survival under medical management was the primary outcome end point. RESULTS: MVP was associated with DMR absent/mild (ERO <20 mm2) in 50%, moderate (ERO 20-40 mm2) in 25%, and severe or higher (ERO ≥40 mm2) in 25%, with mean ERO 24±24 mm2, regurgitant volume 37±35 mL. Median MIDA-Q score was 4 with a wide distribution (10%-90% range, 0-9). MIDA-Q score was higher in patients with EuroScore II ≥1% versus <1% (median, 7 versus 3; P < 0.0001) but with wide overlap (10%-90% range, 4-11 versus 0-7) and mediocre correlation (R2 0.18). Five-year survival under medical management was strongly associated with MIDA-Q score, 97±1% with score 0, 95±1% with score 1 to 2, 82±1% with score 3 to 4, 67±1% with score 5 to 6, 60±1% with score 7 to 8, 44±1% with score 9 to 10, 35±1% with score 11 to 12, and 5±4% with MIDA-Q score ≥13, with hazard ratio 1.31 [1.29-1.33] per 1-point increment. Excess mortality with higher MIDA-Q scores persisted after adjustment for age, sex, and EuroScore II (adjusted hazard ratio, 1.13 [1.11-1.15] per 1-point increment). Subgroup analysis showed persistent association of MIDA-Q score with mortality in all possible subsets, in particular, with EuroScore II<1% (hazard ratio, 1.08 [1.02-1.14]) or ≥1% (hazard ratio, 1.11 [1.08-1.13]) and with no/mild DMR (hazard ratio, 1.14 [1.10-1.19]) or moderate/severe DMR (hazard ratio, 1.13 [1.10-1.16], all per 1-point increment with P<0.0001). Nested-model and bootstrapping analyses demonstrated incremental prognostic power of MIDA-Q score (all P<0.0001). CONCLUSIONS: This large, international cohort of isolated MVP, with prospective DMR quantification in routine practice, demonstrates the wide range of risk factor accumulation and considerable heterogeneity of outcomes after MVP diagnosis. The MIDA-Q score is strongly, independently, and incrementally associated with long-term survival after MVP diagnosis, irrespective of presentation, and is therefore a crucial prognostic instrument for risk stratification, clinical trials, and management of patients diagnosed with all forms of MVP.

Left Atrial Remodeling after Mitral Valve Repair for Primary Mitral Regurgitation: Evolution over Time and Prognostic Significance.

Left atrial (LA) dilatation is associated with worse outcomes in primary mitral regurgitation (MR). However, the effects of mitral valve repair on LA size and its prognostic implications are not well known. In the current study, LA volume index (LAVi) and LA reservoir strain (LASr) were evaluated immediately before and after surgery, and during long-term follow-up in 226 patients undergoing mitral valve repair for primary MR (age 62 ± 13 years, 66% male). Mean LAVi was reduced significantly after surgery and at long-term follow-up (from 56 ± 28 to 38 ± 21 to 32 ± 17 mL/m2; p < 0.001). LASr reduced significantly after surgery but increased again during the long-term (from 23.6 ± 9.4 to 11.5 ± 5.0 to 17.3 ± 7.5%; p < 0.001). Age, pre-operative LAVi, MR severity, and postoperative transmitral pressure gradient were associated with LA reverse remodeling by the long-term check-up. During a median follow-up of 72 (40−114) months, 43 (19%) patients died. Patients with LAVi ≥ 42 mL/m2 at long-term follow-up showed significant higher mortality rates compared to patients with LAVI < 42 mL/m2 (p < 0.001), even after adjusting for clinical covariates. In conclusion, significant LA reverse remodeling was observed both immediately and at long-term follow-up after mitral valve repair. LA dilatation at long term follow-up after surgery was still associated with all-cause mortality.

Prognostic value of left atrial reservoir function in patients with severe primary mitral regurgitation undergoing mitral valve repair.

AIMS: Mitral regurgitation (MR) has a significant haemodynamic impact on the left atrium. Assessment of left atrial reservoir strain (LARS) may have important prognostic implications, incremental to left atrial (LA) volume, and conventional parameters of left ventricular (LV) structure and function. This study investigated whether preoperative assessment of LARS by speckle tracking echocardiography is associated with long-term outcomes in patients undergoing mitral valve repair for severe primary MR. METHODS AND RESULTS: Echocardiography was performed prior to mitral valve surgery in 566 patients (age 64 ± 12years, 66% men) with severe primary MR. The study population was subdivided based on a LARS value of 22%, using a spline curve analysis. The primary endpoint was all-cause mortality. During a median follow-up of 7 (4-12) years, 129 (22.8%) patients died. Patients with LARS ≤22% showed significantly higher mortality rates at 1-, 3-, and 5-year follow-up (6%, 12%, and 15%, respectively) when compared with patients with LARS >22% (2%, 3% and 5%, respectively, P < 0.001). Age [hazard ratio (HR): 1.06; 95% confidence interval (CI): 1.03-1.09; P < 0.001], LV global longitudinal strain (HR: 0.92; 95% CI: 0.87-0.98; P = 0.014), and LARS (HR: 0.96; 95% CI: 0.93-0.99; P = 0.014) were independently associated with all-cause mortality. CONCLUSION: Preoperative LARS is independently associated with all-cause mortality in patients undergoing mitral valve repair for primary MR and provides incremental prognostic value over LA volume. LARS might be helpful to guide timing of mitral valve surgery in patients with severe primary MR.

Long-Term Impact of Preventive Tricuspid Valve Annuloplasty on Right Ventricular Remodeling.

In patients with primary mitral regurgitation (MR), concomitant tricuspid valve (TV) annuloplasty at the time of left-sided valve surgery is indicated in case of a dilated TV annulus ≥40 mm independent of the presence or severity of tricuspid regurgitation (TR). However, the long-term impact on right ventricular (RV) adverse remodeling is less well established and the benefit of preventive TV annuloplasty remains controversial. The aim of the study was to assess differences in long-term RV adverse remodeling and the development of significant TR in those patients. In total, 98 patients (mean age 65 ± 11 years, 85% men) with significant primary MR and TV annulus dilatation ≥40 mm without significant TR who underwent mitral valve (MV) repair with or without concomitant TV annuloplasty were included. Of the 98 patients, 28 patients underwent isolated MV repair without TV annuloplasty and 70 patients received concomitant TV annuloplasty at the time of MV surgery. The RV basal diameter (p = 0.03), RV long-axis diameter (p = 0.04), RV end-diastolic area (p <0.01), and RV end-systolic area (p = 0.03) showed less adverse remodeling at follow-up in patients with concomitant TV annuloplasty compared with patients without TV annuloplasty. Additionally, 4 patients (14%) in the subgroup without TV annuloplasty developed significant TR during follow-up in contrast to zero patients in the subgroup with TV annuloplasty (p = 0.001). In conclusion, concomitant preventive TV annuloplasty during MV surgery in patients with primary MR, no significant TR and a tricuspid annulus (≥40 mm) prevented RV adverse remodeling and the development of significant TR at long-term follow-up.

Prognostic Impact of Extra-Mitral Valve Cardiac Involvement in Patients With Primary Mitral Regurgitation.

BACKGROUND: In patients with severe primary mitral regurgitation (MR), the indication for surgery is currently based on the presence of symptoms, left ventricular dilatation and dysfunction, atrial fibrillation, and pulmonary hypertension. OBJECTIVES: The aim of this study was to evaluate the prognostic impact of the presence of extra-mitral valve cardiac involvement (including known risk factors but also severe left atrial [LA] dilatation and right ventricular [RV] dysfunction) in a large multicenter study of patients with primary MR. METHODS: Patients with severe primary MR undergoing surgery were included and categorized according to the extent (highest) of cardiac involvement: group 0, no cardiac involvement; group 1, left ventricular involvement; group 2, LA involvement; group 3, pulmonary vasculature or tricuspid valve involvement; or group 4, RV involvement. The outcome was all-cause mortality. RESULTS: A total of 1,106 patients were included (mean age 63 ± 12 years, 68% male). In total, 377 patients (34%) were classified in group 0, 239 (22%) in group 1, 213 (19%) in group 2, 180 (16%) in group 3, and 97 (9%) in group 4. Kaplan-Meier curve analysis revealed significantly worse survival (log-rank chi-square = 43.4; P < 0.001) with higher group. On multivariable analysis, age, male sex, chronic obstructive pulmonary disease, kidney function, and group of cardiac involvement were independently associated with all-cause mortality. For each increase in group, a 17% higher risk for all-cause mortality was observed (95% CI: 1.051-1.313; P = 0.005) during a median follow-up time of 88 months. CONCLUSIONS: In patients with severe primary MR, a novel classification system based on extra-mitral valve cardiac involvement may help refine risk stratification and timing of surgery, particularly including severe LA dilatation and RV dysfunction in the assessment.

Extramitral Valvular Cardiac Involvement in Patients With Significant Secondary Mitral Regurgitation.

Patients with secondary mitral regurgitation (SMR) often have extramitral valve cardiac involvement, which can influence the prognosis. SMR can be defined according to groups of extramitral valve cardiac involvement. The prognostic implications of such groups in patients with moderate and severe SMR (significant SMR) are unknown. A total of 325 patients with significant SMR were classified according to the extent of cardiac involvement on echocardiography: left ventricular involvement (group 1), left atrial involvement (group 2), tricuspid valve and pulmonary artery vasculature involvement (group 3), or right ventricular involvement (group 4). The primary end point was all-cause mortality. The prevalence of each cardiac involvement group was 17% in group 1, 12% in group 2, 23% in group 3%, and 48% in group 4. Group 3 and group 4 were independently associated with all-cause mortality (hazard ratio 1.794, 95% confidence interval 1.067 to 3.015, p = 0.027 and hazard ratio 1.857, 95% confidence interval 1.145 to 3.012, p = 0.012, respectively). In conclusion, progressive extramitral valve cardiac involvement (group 3 and group 4) was independently associated with all-cause mortality in patients with significant SMR.

Mitral valve repair for isolated posterior mitral valve leaflet prolapse: The effect of respect and resect techniques on left ventricular function.

OBJECTIVE: Posterior mitral valve leaflet prolapse repair can be performed by leaflet resection or chordal replacement techniques. The impact of these techniques on left ventricular function remains a topic of debate, considering the presumed better preservation of mitral-ventricular continuity when leaflet resection is avoided. We explored the effect of different posterior mitral valve leaflet repair techniques on postoperative left ventricular function. METHODS: In total, 125 patients were included and divided into 2 groups: leaflet resection (n = 82) and isolated chordal replacement (n = 43). Standard and advanced echocardiographic assessments were performed preoperatively, directly postoperatively, and at late follow-up. In addition, left ventricular global longitudinal strain was measured and corrected for left ventricular end-diastolic volume to adjust for the significant changes in left ventricular volumes. RESULTS: At baseline, no significant intergroup difference in left ventricular function was observed measured with the corrected left ventricular global longitudinal strain (resect: 1.76% ± 0.58%/10 mL vs respect: 1.70% ± 0.57%/10 mL, P = .560). Postoperatively, corrected left ventricular global longitudinal strain worsened in both groups but improved significantly during late follow-up, returning to preoperative values (resect: 1.39% ± 0.49% to 1.71% ± 0.56%/10 mL, P < .001 and respect: 1.30% ± 0.45% to 1.70% ± 0.54%/10 mL, P < .001). Mixed model analysis showed no significant effect on the corrected left ventricular global longitudinal strain when comparing the 2 different surgical repair techniques over time (P = .943). CONCLUSIONS: Our study showed that both leaflet resection and chordal replacement repair techniques are effective at preserving postoperative left ventricular function in patients with posterior mitral valve leaflet prolapse and significant regurgitation.

Superimposed Tissue Formation in Human Aortic Valve Disease: Differences between Regurgitant and Stenotic Valves.

The formation of superimposed tissue (SIT), a layer on top of the original valve leaflet, has been described in patients with mitral regurgitation as a major contributor to valve thickening and possibly as a result of increased mechanical stresses. However, little is known whether SIT formation also occurs in aortic valve disease. We therefore performed histological analyses to assess SIT formation in aortic valve leaflets (n = 31) from patients with aortic stenosis (n = 17) or aortic regurgitation due to aortic dilatation (n = 14). SIT was observed in both stenotic and regurgitant aortic valves, both on the ventricular and aortic sides, but with significant differences in distribution and composition. Regurgitant aortic valves showed more SIT formation in the free edge, leading to a thicker leaflet at that level, while stenotic aortic valves showed relatively more SIT formation on the aortic side of the body part of the leaflet. SIT appeared to be a highly active area, as determined by large populations of myofibroblasts, with varied extracellular matrix composition (higher collagen content in stenotic valves). Further, the identification of the SIT revealed the presence of foldings of the free edge in the diseased aortic valves. Insights into SIT regulation may further help in understanding the pathophysiology of aortic valve disease and potentially lead to the development of new therapeutic treatments.

Characterization of Degenerative Mitral Valve Disease: Differences between Fibroelastic Deficiency and Barlow's Disease.

Degenerative mitral valve disease causing mitral valve prolapse is the most common cause of primary mitral regurgitation, with two distinct phenotypes generally recognized with some major differences, i.e., fibroelastic deficiency (FED) and Barlow's disease. The aim of this review was to describe the main histological, clinical and echocardiographic features of patients with FED and Barlow's disease, highlighting the differences in diagnosis, risk stratification and patient management, but also the still significant gaps in understanding the exact pathophysiology of these two phenotypes.

Evolution from mitral annular dysfunction to severe mitral regurgitation in Barlow's disease.

OBJECTIVES: Barlow's disease (BD) is characterized by thick, redundant mitral valve (MV) leaflets, which can lead to prolapse and significant mitral regurgitation (MR). MV annular abnormalities are also commonly observed and increasingly recognized as possible primary pathology, with leaflet thickening being secondary to increased stress on the MV apparatus. To provide more insights into this hypothesis, the evolution of MV abnormalities over time in patients with BD was assessed. METHODS: A total of 64 patients (54 ± 12 years, 72% male) with BD who underwent MV surgery and had multiple transthoracic echocardiograms (TTE) before surgery were included. In total, 186 TTE were analysed (median time interval 4.2, interquartile range 2.2-6.5 years) including specific MV characteristics. RESULTS: At baseline, MV leaflet length, thickness, billowing height and annular diameter were larger in patients with BD compared to 59 healthy subjects. Systolic outward motion (curling) of the annulus was observed in 77% and severe mitral annular disjunction (≥5 mm) in 38% of patients with BD. Forty (63%) patients had MR grade I-II and 24 (37%) MR grade III-IV; at baseline, the 2 groups only differed in left atrial volume and in thickness and billowing height of the posterior leaflet, showing comparable MV annular abnormalities and dilatation despite different grades of MR. Over time, MV annulus diameter, leaflet length and billowing height increased significantly along with MR grade. CONCLUSIONS: In patients with BD, MV annulus abnormalities are present at an early stage and precede the development of significant MR, suggesting their substantial role in the pathophysiology of this disease and as an important target for surgical treatment.

Parameters associated with ventricular arrhythmias in mitral valve prolapse with significant regurgitation.

OBJECTIVE: Mitral valve prolapse (MVP) has been associated with ventricular arrhythmias (VA), but little is known about VA in patients with significant primary mitral regurgitation (MR). Our aim was to describe the prevalence of symptomatic VA in patients with MVP (fibro-elastic deficiency or Barlow's disease) referred for mitral valve (MV) surgery because of moderate-to-severe MR, and to identify clinical, electrocardiographic, standard and advanced echocardiographic parameters associated with VA. METHODS: 610 consecutive patients (64±12 years, 36% female) were included. Symptomatic VA was defined as symptomatic and frequent premature ventricular contractions (PVC, Lown grade ≥2), non-sustained or sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) without ischaemic aetiology. RESULTS: A total of 67 (11%) patients showed symptomatic VA, of which 3 (4%) had VF, 3 (4%) sustained VT, 27 (40%) non-sustained VT and 34 (51%) frequent PVCs. Patients with VA were significantly younger, more often female and showed T-wave inversions; furthermore, they showed significant MV morphofunctional abnormalities, such as mitral annular disjunction (39% vs 20%, p<0.001), and dilatation (annular diameter 37±5 mm vs 33±6 mm, p<0.001), lower global longitudinal strain (GLS 20.9±3.1% vs 22.0±3.6%, p=0.032) and prolonged mechanical dispersion (45±12 ms vs 38±14 ms, p=0.003) as compared with patients without VA. Female sex, increased MV annular diameter, lower GLS and prolonged mechanical dispersion were identified as independent associates of symptomatic VA. CONCLUSION: In patients with MVP with moderate-to-severe MR, symptomatic VA are relatively frequent and associated with significant MV annular abnormalities, subtle left ventricular function impairment and heterogeneous contraction. Assessment of these parameters might help decision-making over further diagnostic analyses and improve risk-stratification.

Identification of known and unknown genes associated with mitral valve prolapse using an exome slice methodology.

PURPOSE: Although a familial distribution has been documented, the genetic aetiology of mitral valve prolapse (MVP) is largely unknown, with only four genes identified so far: FLNA, DCHS1, DZIP1 and PLD1. The aim of this study was to evaluate the genetic yield in known causative genes and to identify possible novel genes associated with MVP using a heart gene panel based on exome sequencing. METHODS: Patients with MVP were referred for genetic counselling when a positive family history for MVP was reported and/or Barlow's disease was diagnosed. In total, 101 probands were included to identify potentially pathogenic variants in a set of 522 genes associated with cardiac development and/or diseases. RESULTS: 97 (96%) probands were classified as Barlow's disease and 4 (4%) as fibroelastic deficiency. Only one patient (1%) had a likely pathogenic variant in the known causative genes (DCHS1). However, an interesting finding was that 10 probands (11%) had a variant that was classified as likely pathogenic in six different, mostly cardiomyopathy genes: DSP (1×), HCN4 (1×), MYH6 (1×), TMEM67 (1×), TRPS1 (1×) and TTN (5×). CONCLUSION: Exome slice sequencing analysis performed in MVP probands reveals a low genetic yield in known causative genes but may expand the cardiac phenotype of other genes. This study suggests for the first time that also genes related to cardiomyopathy may be associated with MVP. This highlights the importance to screen these patients and their family for the presence of arrhythmias and of 'disproportionate' LV remodelling as compared with the severity of mitral regurgitation, unravelling a possible coexistent cardiomyopathy.

Malignant Arrhythmic Mitral Valve Prolapse: A Continuum of Clinical Challenges from Diagnosis to Risk Stratification and Patient Management.

Mitral valve prolapse (MVP) is a common valvular disease, which may remain a benign condition for a long period of time. However, some patients experience malignant ventricular arrhythmias and sudden cardiac death (SCD). It is still largely unknown how to risk-stratify these patients, and no specific recommendations have been proposed to help the clinical decision-making. We present the case of a young man whose first clinical presentation was an out-of-hospital cardiac arrest and was subsequently diagnosed with MVP. We highlighted the possible risk factors for SCD and the challenges in the clinical management of these patients.