Project description:Ischaemic mitral regurgitation (IMR), a frequent complication following myocardial infarction (MI), leads to higher mortality and poor clinical prognosis if untreated. Accumulating evidence suggests that mitral valve (MV) leaflets actively remodel post MI, and this remodelling increases both the severity of IMR and the occurrence of MV repair failures. However, the mechanisms of extracellular matrix maintenance and modulation by MV interstitial cells (MVICs) and their impact on MV leaflet tissue integrity and repair failure remain largely unknown. Herein, we sought to elucidate the multiscale behaviour of IMR-induced MV remodelling using an established ovine model. Leaflet tissue at eight weeks post MI exhibited significant permanent plastic radial deformation, eliminating mechanical anisotropy, accompanied by altered leaflet composition. Interestingly, no changes in effective collagen fibre modulus were observed, with MVICs slightly rounder, at eight weeks post MI. RNA sequencing indicated that YAP-induced genes were elevated at four weeks post MI, indicating elevated mechanotransduction. Genes related to extracellular matrix organization were downregulated at four weeks post MI when IMR occurred. Transcriptomic changes returned to baseline by eight weeks post MI. This multiscale study suggests that IMR induces plastic deformation of the MV with no functional damage to the collagen fibres, providing crucial information for computational simulations of the MV in IMR.
Project description:AimRandomized controlled trials comparing the use of the MitraClip device in addition to guideline directed medical therapy (GDMT) to GDMT alone in patients with secondary mitral regurgitation (MR) have shown conflicting results. However, if these differences could be due to the underlying MR aetiology is still unknown. Therefore, we aimed to evaluate if the effects of percutaneous edge-to-edge repair with MitraClip implantation could differ in patients with ischaemic (I-MR) and non-ischaemic mitral regurgitation (NI-MR).Methods and resultsPubMed, Embase, BioMed Central, and the Cochrane Central Register of Controlled Trials were searched for all studies including patients with secondary MR treated with the MitraClip device. Data were pooled using a random-effects model. Primary endpoint was the composite of all-cause death and heart failure-related hospitalization. Secondary endpoints were the single components of the primary endpoint, New York Heart Association functional Classes III and IV, and mitral valve re-intervention. Seven studies enrolling 2501 patients were included. Patients with I-MR compared with patients with NI-MR had a similar risk of the primary endpoint (odds ratio: 1.17; 95% confidence interval: 0.93 to 1.46; I2 : 0%). The risk of all-cause death was increased in patients with I-MR (odds ratio: 1.31; 95% confidence interval: 1.07 to 1.62; I2 : 0%), while no differences were observed between the two groups in terms of the other secondary endpoints.ConclusionsThe risk of mortality after MitraClip implantation is lower in patients with NI-MR than in those with I-MR. No absolute differences in the risk of heart failure related hospitalization were observed between groups.
Project description:AimsSex differences in prognosis of functional mitral regurgitation (FMR) associated with ischaemic cardiomyopathy (ICM) demonstrate the need to identify sex differences in cardiac remodelling. This study aimed to characterize sex differences in cardiac remodelling associated with FMR in the setting of ICM, sex interactions with cardiac remodelling and FMR severity, and predictors of all-cause mortality or heart transplantation using cardiac magnetic resonance (CMR) imaging.Methods and resultsConsecutive patients with ICM referred to CMR between 2002 and 2017 were reviewed. Eligible 790 patients [mean age: 62.0 (standard deviation = 11.2] years and 24.7% females] were evaluated over a median follow-up of 5.8 years. There were 773 subjects with complete data for survival analysis, with 449 primary events. Coronary artery disease risk factors, medications, and previous coronary revascularization were similar in females and males (all P > 0.05). Indexed left ventricular and right ventricular (LV and RV) volumes were larger in males (P < or =0.005 for all comparisons) with similar slope of increasing LV and RV volumes in the setting of increasing FMR (all P > 0.05, for interactions). However, indexed left atrial volume was similar in males and females (P = 0.696), after adjusting for FMR severity. After adjusting for medical risk factors and post-CMR procedural interventions, females demonstrated increased risk of primary clinical composite point with enlarging LV volumes [hazard ratio: 1.04 (95% confidence interval: 1.01-1.06), P = 0.034].ConclusionBecause females with increasing LV size and FMR severity demonstrated significantly increased risk of adverse outcomes, our findings suggest the importance of deriving sex-specific CMR selection criteria for therapeutic management of FMR in the setting of ICM.
Project description:ObjectivesThe Cardiothoracic Surgical Trials Network recently reported no difference in the primary end point of left ventricular end-systolic volume index at 1 year postsurgery in patients randomized to repair (n = 126) or replacement (n = 125) for severe ischemic mitral regurgitation. However, patients undergoing repair experienced significantly more recurrent mitral regurgitation than patients undergoing replacement (32.6% vs 2.3%). We examined whether baseline echocardiographic and clinical characteristics could identify those who will develop moderate/severe recurrent mitral regurgitation or die.MethodsOur analysis includes 116 patients who were randomized to and received mitral valve repair. Logistic regression was used to estimate a model-based probability of recurrence or death from baseline factors. Receiver operating characteristic curves were constructed from these estimated probabilities to determine classification cut-points maximizing accuracy of prediction based on sensitivity and specificity.ResultsOf the 116 patients, 6 received a replacement before leaving the operating room; all other patients had mild or less mitral regurgitation on intraoperative echocardiogram after repair. During the 2-year follow-up period, 76 patients developed moderate/severe mitral regurgitation or died (53 mitral regurgitation recurrences, 13 mitral regurgitation recurrences and death, and 10 deaths). The mechanism for recurrent mitral regurgitation was largely mitral valve leaflet tethering. Our model (including age, body mass index, sex, race, effective regurgitant orifice area, basal aneurysm/dyskinesis, New York Heart Association class, history of coronary artery bypass grafting, percutaneous coronary intervention, or ventricular arrhythmias) yielded an area under the receiver operating characteristic curve of 0.82.ConclusionsThe model demonstrated good discrimination in identifying patients who will survive 2 years without recurrent mitral regurgitation after mitral valve repair. Although our results require validation, they offer a clinically relevant risk score for selection of surgical candidates for this procedure.
Project description:ObjectivesThe current guidelines still do not include specific recommendations on the use of subvalvular repair (SV-r) for treatment of ischemic mitral regurgitation (IMR). Therefore, the objective of our study was to evaluate the clinical impact of mitral regurgitation (MR) recurrence and ventricular remodeling on long-term outcomes after SV-r combined with restrictive annuloplasty (RA-r).MethodsWe performed a subanalysis of the papillary muscle approximation trial, studying 96 patients with severe IMR and coronary artery disease undergoing restrictive annuloplasty alongside subvalvular repair (SV-r + RA-r group) or restrictive annuloplasty alone (RA-r group). We analyzed treatment failure differences, the influence of residual MR, left ventricular remodeling, and clinical outcomes. The primary endpoint was treatment failure (composite of death; reoperation; or recurrence of moderate, moderate-to-severe, or severe MR) within 5 years of follow-up after the procedure.ResultsA total of 45 patients showed failure of the treatment within 5 years, of which 16 patients underwent SV-r + RA-r (35.6%) and 29 underwent RA-r (64.4%, p = 0.006). Patients with significant residual MR presented with a higher rate of all-cause mortality at 5 years compared with trivial MR (HR 9.09, 95% CI 2.08-33.33, p = 0.003). MR progression occurred earlier in the RA-r group, as 20 patients in the RA-r group vs. 6 in SV-r + RA-r group had a significant MR 2 years after surgery (p = 0.002).ConclusionsRA-r remains a surgical mitral repair technique with an increased risk of failure and mortality at 5 years compared with SV-r. The rates of recurrent MR are higher, and recurrence occurs earlier, with RA-r alone compared to SV-r. The addition of the subvalvular repair increases the durability of the repair, thus extending all of the benefits of preventing MR recurrence.
Project description:BackgroundMitral regurgitation (MR) in the context of left ventricular systolic dysfunction is often designated as functional, with emphasis on the underlying cardiomyopathy leading to malcoaptation of the 'otherwise normal valve'.Case summaryA 63-year-old male with ischaemic cardiomyopathy (left ventricular ejection fraction 20%) presented with intractable heart failure in need of inotropic support and could not be stepped down from an ICU hospital setting. Functional MR, graded as moderate on transthoracic echocardiography, was initially not considered as pertinent to the clinical condition and options discussed included initiation of dialysis for volume management, chronic inotropic support, and palliative measures. However, a re-examination of the mitral valve by transoesophageal echo revealed severe regurgitation from annular dilatation and restricted mobility during systole. Transcatheter edge to edge repair utilizing the PASCAL device resulted in marked reduction of MR followed by an abrupt clinical improvement, weaning off inotropes and discharge home 4 days later. At four-year follow-up, the patient is stable on optimal heart failure therapy.DiscussionFor many patients with heart failure and underlying cardiomyopathy, the presence of significant functional MR, instead of a 'bystander' disease, actually becomes the dominant driver of symptoms and compounds the low cardiac output state. In these patients, the term 'functional' MR becomes a misnomer, as in fact the so called 'otherwise normal' mitral valve is actually a severely dysfunctional valve with a wide malcoaptation zone. Transcatheter edge to edge repair is an effective bailout procedure for patients with low cardiac output and disproportionate severe functional MR.
Project description:Rationale: Ischemic mitral regurgitation (IMR) is frequently observed following myocardial infarction (MI) and is associated with higher mortality and poor clinical prognosis if left untreated. Accumulating evidence suggests that mitral valve (MV) leaflets actively remodel post-MI, yet the cellular mechanisms underlying these responses and how this affects tissue function remain largely unknown. Objective: We sought to elucidate MV remodeling post-MI at the tissue, cellular, and transcriptomic levels. Methods and Results: The mechanical behavior of ovine MV leaflets pre-MI and 8 weeks post-MI reveal a significant decrease in radial direction extensibility, which essentially eliminated the mechanical anisotropy typically observed in healthy MVs. Quantitative histology and ultrastructural assessment by transmission electron microscopy revealed altered leaflet composition and architecture at 8 weeks post-MI. Assessment of the MV interstitial cell (MVIC) nuclear aspect ratio, a metric of cellular deformation, revealed that MVICs were on average rounder following MI. RNA sequencing (RNA-seq) indicated that YAP-induced genes were elevated at 4 weeks post-MI and genes related to extracellular matrix organization were some of the most downregulated in sheep with IMR compared to sheep without IMR at 4 weeks post-MI. Additionally, RNA-seq revealed the possible recruitment of immune cells in this remodeling process due to the drastic elevation of CXCL9 and CLEC10A. Conclusions: This multiscale assessment revealed significant mechanical and microstructural changes due to MI. RNA-seq provided a baseline for global gene expression changes in response to MI with and without IMR and suggests YAP-induced mechanotransduction, altered expression of ECM-related genes, and recruitment of immune cells as mechanisms contributing to altered MV biomechanics post-MI. Conclusions: This multiscale assessment revealed significant mechanical and microstructural changes due to MI. RNA-seq provided a baseline for global gene expression changes in response to MI with and without IMR and suggests YAP-induced mechanotransduction, altered expression of ECM-related genes, and recruitment of immune cells as mechanisms contributing to altered MV biomechanics post-MI.
Project description:This review outlines the first trial experience with transcatheter therapy for mitral regurgitation (MR), developed from the EVEREST II MitraClip trial in a trial population comprised predominantly of patients with degenerative mitral regurgitation (DMR). Subsequent experience with MitraClip and several other devices has been mostly in functional MR patients. At the same time, there has been ongoing experience with MitraClip in DMR, and a variety of other devices have been developed for catheter-based treatment of MR. Annuloplasty devices have been indicated for DMR, and the potential for transcatheter annuloplasty to be used, in conjunction with other catheter techniques, such as chordal replacement, as it is in standard mitral repair, is developing. Transcatheter mitral valve replacement will clearly have some role for MR of both functional and degenerative etiologies, when repair is not feasible or fails. This review will discuss the evidence base and future development of these mitral repair and replacement approaches for DMR.