Mitral Regurgitation Augments Post-Myocardial Infarction Remodeling

In-hospital evolution of secondary mitral regurgitation in acutely decompensated heart failure

AIMS

Secondary mitral regurgitation (MR) negatively affects prognosis in acutely decompensated heart failure (ADHF), but can be rapidly sensitive to changes in volume status and medical interventions. We sought to assess the evolution of secondary MR in patients hospitalized for ADHF and its prognostic implications.

METHODS

We retrospectively enrolled 782 patients admitted for ADHF with at least two in-hospital echocardiographic evaluations of MR. We classified MR severity as none-mild or moderate-severe. Based on MR evolution, patients were divided into 'persistent moderate-severe MR', 'improved MR' (from moderate-severe to none-mild) and 'persistent none-mild MR'.

RESULTS

Four hundred and forty patients (56%) had moderate-severe MR at first evaluation, of whom 144 (33% of patients with baseline moderate-severe MR) had 'improved MR', while 296 (67%) had 'persistent moderate-severe MR'. Patients with improved MR had better clinical, laboratory and echocardiographic parameters of decongestion at discharge compared with those with persistent moderate-severe MR and showed a higher up-titration of recommended therapies. Left ventricular volume, ejection fraction and serum urea were the predictors of improved MR at multivariable analysis. After adjustment, no differences in 5-years survival (primary outcome) were observed according to baseline MR severity. When patients were stratified according to the in-hospital changes in MR severity, improved MR was associated with lower risk of 5-years mortality, compared with both persistent none-mild MR [hazard ratio (HR) = 0.505, P = 0.032] and persistent moderate-severe MR (HR = 0.556, P = 0.040).

CONCLUSIONS

The severity of MR frequently improved during hospitalization for ADHF; the extent and the changes in MR severity during the in-hospital stay identified distinct patient phenotypes, and seemed to portend different long-term outcomes, with higher 5-years survival associated with improvement in MR.

Impact of Functional Mitral Regurgitation on Left Ventricular Strain in Nonischemic Dilated Cardiomyopathy Patients with Type 2 Mellitus Diabetes: A Magnetic Resonance Feature Tracking Study

BACKGROUND

The impact of functional mitral regurgitation and type 2 mellitus diabetes (T2DM) on left ventricular (LV) strain in nonischemic dilated cardiomyopathy (NIDCM) patients remains unclear.

PURPOSE

To evaluate the impact of mitral regurgitation severity on LV strain, and explore additive effect of T2DM on LV function across varying mitral regurgitation severity levels in NIDCM patients.

STUDY TYPE

Retrospective.

POPULATION

352 NIDCM (T2DM-) patients (49.1 ± 14.6 years, 67% male) (207, 85, and 60 no/mild, moderate, and severe mitral regurgitation) and 96 NIDCM (T2DM+) patients (55.2 ± 12.4 years, 77% male) (47, 30, and 19 no/mild, moderate, and severe mitral regurgitation).

FIELD STRENGTH/SEQUENCE

3.0 T/balanced steady-state free precession sequence.

ASSESSMENT

LV geometric parameters and strain were measured and compared among groups. Determinants of LV strain were investigated.

STATISTICAL TEST

Student's t-test, Mann-Whitney U test, one-way ANOVA, Kruskal-Wallis test, univariable and multivariable linear regression. P < 0.05 was considered statistically significant.

RESULTS

LV GLPS and longitudinal PDSR decreased gradually with increasing mitral regurgitation severity in NIDCM patients with T2DM(GLPS: -5.7% ± 2.1% vs. -4.3% ± 1.6% vs. -2.6% ± 1.3%; longitudinal PDSR:0.5 ± 0.2 sec-1 vs. 0.4 ± 0.2 sec-1 vs. 0.3 ± 0.1 sec-1). NIDCM (T2DM+) demonstrated decreased GCPS and GLPS in the no/mild subgroup, reduced LV GCPS, GLPS, and longitudinal PDSR in the moderate subgroup, and reduced GRPS, GCPS, GLPS, and longitudinal PDSR in the severe subgroup compared with NIDCM (T2DM-) patients. Multivariable regression analysis identified that mitral regurgitation severity (β = -0.13, 0.15, and 0.25 for GRPS, GCPS, and GLPS) and the presence of T2DM (β = 0.14 and 0.13 for GCPS and GLPS) were independent determinants of LV strains in NIDCM patients.

DATA CONCLUSION

Increased mitral regurgitation severity is associated with reduced LV strains in NIDCM patients with T2DM. The presence of T2DM exacerbated the decline of LV function across various mitral regurgitation levels in NIDCM patients, resulting in reduced LV strains.

LEVEL OF EVIDENCE: 3

TECHNICAL EFFICACY

Stage 3.

Do False Tendons Prevent Adverse Left Ventricular Remodeling After Anterior Wall Myocardial Infarction? An Echocardiographic Strain Imaging Study

The role of muscular left ventricular (LV) false tendons (FTs) is poorly understood. To gain insight into their pathophysiologic significance, we adapted echocardiographic LV strain imaging software to measure LVFT longitudinal strain in subjects with normal left ventricles and in patients who sustained previous anterior wall myocardial infarction (AWMI). GE EchoPAC software was used to measure longitudinal strain in LVFTs ≥0.3 cm in diameter. Tendinous strain was measured in 11 patients with LVFTs confined to the left anterior descending artery territory (connecting the anteroseptum or anterior wall to the apex) ≥6 months after AWMI (myocardial infarction [MI]+FT+ group) and in 25 patients with normal hearts containing LVFTs (MI-FT+ group). We also compared the indexed LV end-diastolic volumes in the MI+FT+ group to that of 25 patients with previous AWMI without LVFTs (MI+FT- group). The mean LVFT strain in MI+FT+ group was 5.5 ± 6.2% and -28.9 ± 4.7% in the MI-FT+ group (p <0.0001). The indexed LV end-diastolic volume in the MI+FT+ group did not differ from the MI+FT- group (88.4 ± 17.8 vs 87.9 ± 17 ml/m2, p = 0.90). In conclusion, the negative strain (contraction) developed by LVFTs in the MI-FT+ group may help maintain normal LV size and shape by generating inward restraining forces. The development of positive strain (stretch) in LVFTs in patients in the MI+FT+ group suggests they become infarcted after AWMI. This implies that they are incapable of generating inward restraining forces that might otherwise mitigate adverse remodeling. Of note, LV volumes after AWMI do not differ whether or not LVFTs are present.

Angiogenic stem cell delivery platform to augment post-infarction neovasculature and reverse ventricular remodeling

Many cell-based therapies are challenged by the poor localization of introduced cells and the use of biomaterial scaffolds with questionable biocompatibility or bio-functionality. Endothelial progenitor cells (EPCs), a popular cell type used in cell-based therapies due to their robust angiogenic potential, are limited in their therapeutic capacity to develop into mature vasculature. Here, we demonstrate a joint delivery of human-derived endothelial progenitor cells (EPC) and smooth muscle cells (SMC) as a scaffold-free, bi-level cell sheet platform to improve ventricular remodeling and function in an athymic rat model of myocardial infarction. The transplanted bi-level cell sheet on the ischemic heart provides a biomimetic microenvironment and improved cell-cell communication, enhancing cell engraftment and angiogenesis, thereby improving ventricular remodeling. Notably, the increased density of vessel-like structures and upregulation of biological adhesion and vasculature developmental genes, such as Cxcl12 and Notch3, particularly in the ischemic border zone myocardium, were observed following cell sheet transplantation. We provide compelling evidence that this SMC-EPC bi-level cell sheet construct can be a promising therapy to repair ischemic cardiomyopathy.

Metabolomics implicate eicosanoids in severe functional mitral regurgitation

AIMS

Secondary, or functional, mitral regurgitation (FMR) was recently recognized as a separate clinical entity, complicating heart failure with reduced ejection fraction (HFrEF) and entailing particularly poor outcome. Currently, there is a lack of targeted therapies for FMR due to the fact that pathomechanisms leading to FMR progression are incompletely understood. In this study, we sought to perform metabolomic profiling of HFrEF patients with severe FMR, comparing results to patients with no or mild FMR.

METHODS AND RESULTS

Targeted plasma metabolomics and untargeted eicosanoid analyses were performed in samples drawn from HFrEF patients (n = 80) on optimal guideline-directed medical therapy. Specifically, 17 eicosanoids and 188 metabolites were analysed. Forty-seven patients (58.8%) had severe FMR, and 33 patients (41.2%) had no or non-severe FMR. Comparison of eicosanoid levels between groups, accounting for age, body mass index, and sex, revealed significant up-regulation of six eicosanoids (11,12-EET, 13(R)-HODE, 12(S)-HETE, 8,9-DiHETrE, metPGJ2, and 20-HDoHE) in severe FMR patients. Metabolites did not differ significantly. In patients with severe FMR, but not in those without severe FMR, levels of 8,9-DiHETrE above a cut-off specified by receiver-operating characteristic analysis independently predicted all-cause mortality after a median follow-up of 43 [interquartile range 38, 48] months [hazard ratio 12.488 (95% confidence interval 3.835-40.666), P < 0.0001].

CONCLUSIONS

We report the up-regulation of various eicosanoids in patients with severe FMR, with 8,9-DiHETrE appearing to predict mortality. Our observations may serve as a nucleus for further investigations into the causes and consequences of metabolic derangements in this important valvular abnormality.

Edge-to-edge percutaneous mitral repair for functional ischaemic and non-ischaemic mitral regurgitation: a systematic review and meta-analysis

AIM

Randomized 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 RESULTS

PubMed, 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.

CONCLUSIONS

The 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.

Loss of left ventricular rotation is a significant determinant of functional mitral regurgitation

AIM

To evaluate insufficient rotational movement of the left ventricle (LV) as a potential novel mechanism for functional regurgitation of the mitral valve (FMR).

METHODS AND RESULTS

We compared reference subjects and patients with LV dysfunction (LVD, ejection fraction EF < 50%) with and without FMR (regurgitant volume RVol>10 ml). Subjects without structural mitral valve pathology undergoing cardiac MRI were evaluated. Delayed enhancement, global LV remodeling parameters, systolic twist and torsion were measured (using manual and novel automated cardiac MRI tissue-tracking). The study included 117 subjects with mean ± SD age 50.4 ± 17.8 years, of which 30.8% were female. Compared to subjects with LVD without FMR (n = 31), those with FMR (n = 37) had similar clinical characteristics, diagnoses, delayed enhancement, EF, and longitudinal strain. Subjects with FMR had significantly larger left ventricles (EDVi:136.6 ± 41.8 vs 97.5 ± 26.2 ml/m, p < 0.0001) with wider separation between papillary muscles (21.1 ± 7.6 vs 17.2 ± 5.7 mm, p = 0.023). Notably, they had lower apical (p < 0.0001) but not basal rotation and lower peak systolic twist (3.1 ± 2.4° vs 5.5 ± 2.5°, p < 0.0001) and torsion (0.56 ± 0.38°/cm vs 0.88 ± 0.52°/cm, p = 0.004). In a multivariate model for RVol including age, gender, twist, LV end-diastolic volume, sphericity index and separation between papillary muscles, only gender, volume and twist were significant. Twist was the most powerful correlate (beta -2.23, CI -3.26 to -1.23 p < 0.001). In patients with FMR, peak systolic twist negatively correlates with RVol (r = -0.73, p < 0.0001).

CONCLUSION

Reduced rotational systolic LV motion is significantly and independently associated with RVol among patients with FMR, suggesting a novel pathophysiological mechanism and a potential therapeutic target.

Reduction of tethering distance by papillary muscle tugging approximation with mitral valve replacement for non-ischemic functional mitral regurgitation induces left ventricular reverse remodeling

BACKGROUND

Functional mitral regurgitation (FMR) is caused by left ventricular (LV) remodeling and subsequent tethering of the mitral valve (MV). If LV remodeling is irreversibly advanced, it could not be attenuated by the MV procedure alone, although the additional subvalvular procedure could induce LV reverse remodeling by forcibly reducing MV tethering. This study aimed to assess the anti-tethering effect of papillary muscle tugging approximation (PMTA) on LV reverse remodeling after mitral valve replacement (MVR) for non-ischemic FMR.

METHODS

The study subjects were 19 patients who underwent MVR with and without PMTA [MVR + PMTA (n = 11) and MVR alone (n = 8), respectively] for non-ischemic FMR. The tethering distance (TD) and LV end-systolic volume (ESV) at the preoperative, postoperative, and follow-up periods were assessed in terms of their correlation and time-dependent changes. The intra-LV energy efficiency was also evaluated through vector flow mapping analysis.

RESULTS

TD and ESV were comparable between both procedures preoperatively and did not change after MVR alone. In MVR + PMTA, however, a significant decrease was identified in TD and ESV at the early postoperative and follow-up periods, respectively [TD = 48, 30, and 31 mm (p < 0.001) and ESV = 159, 133, and 82 mL (p < 0.001) at the preoperative, postoperative, and follow-up periods, respectively]. Finally, at follow-up, the extent of change from the preoperative value in ESV significantly correlated with that in TD (ρ = 0.81, p < 0.001 for overall; ρ = 0.93, p < 0.001 for MVR + PMTA; ρ = 0.86, p = 0.011 for MVR alone). The ratio of TD to ESV was also significantly correlated with systolic energy loss to LV stroke work after MVR + PMTA (ρ = 0.81, p = 0.015).

CONCLUSIONS

PMTA for non-ischemic FMR could induce LV reverse remodeling depending on the extent of postoperative TD reduction. A smaller TD to ESV was associated with a higher intra-LV energy efficiency after PMTA + MVR.

Pathophysiology, Diagnosis, and New Therapeutic Approaches for Ischemic Mitral Regurgitation

Ischemic mitral regurgitation (MR) is a valvular complication frequently seen in patients with coronary artery disease and is associated with increased mortality and morbidity. Ischemic mitral regurgitation has a complex, heterogeneous, and still incompletely understood pathophysiology involving both the mitral valve and the left ventricle. The occurrence of valve regurgitation in patients with ischemic cardiomyopathy in return accelerates left ventricular remodelling and dysfunction, ultimately leading to irreversible heart failure. Diagnostic evaluation of ischemic MR is unique and different from the other causes of MR. The severity thresholds associated with outcomes are different from primary MR, and specific imaging characteristics are potentially useful to guide therapy. The use of imaging modalities such as 3-dimensional echocardiography and cardiac magnetic resonance imaging can refine the diagnostic evaluation and help in choosing the correct management. Although multiple treatments are available to improve ischemic MR, each therapeutic option is associated with limitations and incomplete success. Therapy has therefore to be individualised for each patient. Current options include optimal medical therapy, cardiac resynchronisation therapy, percutaneous or surgical revascularisation, surgical mitral repair or replacement, and new percutaneous interventions. This review aims to discuss the latest insights regarding the pathophysiology, diagnosis, and treatment of ischemic MR.

Natural history of bivalvular functional regurgitation

AIMS

Bivalvular functional regurgitation (BVFR) defined as concomitant mitral and tricuspid insufficiency has not been described or systematically assessed before. Therefore, this study sought to define incidence, impact and natural history of BVFR in heart failure with reduced ejection fraction (HFrEF) to provide the foundation for risk assessment and directions for potential treatment strategies.

METHODS AND RESULTS

We enrolled 1021 consecutive patients with HFrEF under guideline-directed medical therapy and performed comprehensive echocardiographic and neurohumoral profiling. All-cause mortality during a 5 years of follow-up served as the primary endpoint. Thirty percent of patients suffered from moderate or severe BVFR. Long-term mortality increased with the presence and severity of functional regurgitation (FR) with severe BVFR representing the highest risk-subset (P < 0.001). Severe BVFR patients were more symptomatic and displayed an adverse remodelling and neurohumoral activation pattern (all P < 0.05). Severe BVFR was associated with excess mortality independently of clinical [adjusted hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.39-1.84; P < 0.001] and echocardiographic (adjusted HR 1.31, 95% CI 1.11-1.54; P = 0.001) confounders, guideline-directed medical therapy (adjusted HR 1.55, 95% CI 1.35-1.79; P < 0.001) and neurohumoral activation (adjusted HR 1.31, 95% CI 1.07-1.59; P = 0.009). Moderate BVFR (n = 99) comprised equal baseline characteristics and similar risk as isolated severe FR (HR 0.95, 95% CI 0.69-1.30; P = 0.73).

CONCLUSION

This long-term outcome study shows the multi-faceted nature of FR and defines BVFR as an important clinical entity associated with impaired functional class, adverse cardiac remodelling, and excess risk of mortality. Moderate BVFR conveys similar risk as isolated severe FR reflecting the deleterious impact of the global regurgitant load on the failing heart and the need of an integrated understanding for risk-assessment.

Beneficial Effects of Mineralocorticoid Receptor Antagonism on Myocardial Fibrosis in an Experimental Model of the Myxomatous Degeneration of the Mitral Valve

Mitral valve prolapse (MVP) patients develop myocardial fibrosis that is not solely explained by volume overload, but the pathophysiology has not been defined. Mineralocorticoid receptor antagonists (MRAs) improve cardiac function by decreasing cardiac fibrosis in other heart diseases. We examined the role of MRA in myocardial fibrosis associated with myxomatous degeneration of the mitral valve. Myocardial fibrosis has been analyzed in a mouse model of mitral valve myxomatous degeneration generated by pharmacological treatment with Nordexfenfluramine (NDF) in the presence of the MRA spironolactone. In vitro, adult human cardiac fibroblasts were treated with NDF and spironolactone. In an experimental mouse, MRA treatment reduced interstitial/perivascular fibrosis and collagen type I deposition. MRA administration blunted NDF-induced cardiac expression of vimentin and the profibrotic molecules galectin-3/cardiotrophin-1. In parallel, MRA blocked the increase in cardiac non-fibrillar proteins such as fibronectin, aggrecan, decorin, lumican and syndecan-4. The following effects are blocked by MRA: in vitro, in adult human cardiac fibroblasts, NDF-treatment-induced myofibroblast activation, collagen type I and proteoglycans secretion. Our findings demonstrate, for the first time, the contribution of the mineralocorticoid receptor (MR) to the development of myocardial fibrosis associated with mitral valve myxomatous degeneration. MRA could be a therapeutic approach to reduce myocardial fibrosis associated with MVP.

Mitral valve leaflet response to ischaemic mitral regurgitation: from gene expression to tissue remodelling

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.

Experimental models of cardiac physiology and pathology

Experimental models of cardiac disease play a key role in understanding the pathophysiology of the disease and developing new therapies. The features of the experimental models should reflect the clinical phenotype, which can have a wide spectrum of underlying mechanisms. We review characteristics of commonly used experimental models of cardiac physiology and pathophysiology in all translational steps including in vitro, small animal, and large animal models. Understanding their characteristics and relevance to clinical disease is the key for successful translation to effective therapies.

Secondary mitral regurgitation: pathophysiology, proportionality and prognosis

Secondary mitral regurgitation (SMR) occurs as a result of multifactorial left atrioventricular dysfunction and maleficent remodelling. It is the most common and undertreated form of mitral regurgitation (MR) and is associated with a very poor prognosis. Whether SMR is a bystander reflecting the severity of the cardiomyopathy disease process has long been the subject of debate. Studies suggest that SMR is an independent driver of prognosis in patients with an intermediate heart failure (HF) phenotype and not those with advanced HF. There is also no universal agreement regarding the quantitative thresholds defining severe SMR and indeed there are challenges with echocardiographic quantification. Until recently, no surgical or transcatheter intervention for SMR had demonstrated prognostic benefit, in contrast with HF medical therapy and cardiac resynchronisation therapy. In 2018, the first two randomised controlled trials (RCTs) of edge-to-edge transcatheter mitral valve repair versus guideline-directed medical therapy in HF (Percutaneous Repair with the MitraClip Device for Severe (MITRA-FR), Transcather mitral valve repair in patients with heart failure (COAPT)) reported contrasting yet complimentary results. Unlike in MITRA-FR, COAPT demonstrated significant prognostic benefit, largely attributed to the selection of patients with disproportionately severe MR relative to their HF phenotype. Consequently, quantifying the degree of SMR in relation to left ventricular volume may be a useful discriminator in predicting the success of transcatheter intervention. The challenge going forward is the identification and validation of such parameters while in parallel maintaining a heart-team guided holistic approach.

Impact of posteromedial papillary muscle infarction on mitral regurgitation during ST-segment elevation myocardial infarction

The exact role of papillary muscle infarction (PMI) during the acute phase of acute ST-segment elevation myocardial infarction (STEMI) is not well understood, as existing data on the impact of PMI location is conflicting. We hypothesized that infarction of the posteromedial papillary muscle (PM-PMI) as determined by cardiac magnetic resonance imaging might be associated with an increased incidence of mitral valve regurgitation in the first week after STEMI. 242 patients with first STEMI underwent a late-enhancement (LGE-) cardiac magnetic resonance imaging within a median of 2 (IQR 2-5) days and echocardiography within 3 (IQR 2-5) days after primary angioplasty for the index event. PMI was scored based on short axis slices (AL-PMI: anterolateral PMI, PM-PMI, AL/PM-PMI: AL- and PM-PMI). Patients with PM-PMI had significantly higher odds (OR 2.62, p < 0.01) for the occurrence of mitral regurgitation than patients with no-PMI, AL-PMI or AL/PM-PMI. Furthermore, advanced age, non-anterior infarct location and longer pain-to-balloon time were identified as risk factors for the occurrence of mitral regurgitation. Binary logistic regression analysis revealed that PM-PMI is a predictor of mitral regurgitation independent of infarct location and age (OR 2.229, CI 1.078-4.903, p = 0.031). PM-PMI as determined by cardiac magnetic resonance imaging is an independent predictor of mitral regurgitation in the setting of acute STEMI. Our data might improve our understanding of the dynamic nature of functional mitral regurgitation.

Refining the prognostic impact of functional mitral regurgitation in chronic heart failure

Aims

Significant efforts are currently undertaken to reduce functional mitral regurgitation (FMR) in patients with chronic heart failure in the hope to improve prognosis. We aimed to assess the prognostic impact of FMR in heart failure with reduced ejection fraction (HFrEF) under optimal medical therapy (OMT) and various conditions of HFrEF. We further intended to identify a heart failure phenotype, where FMR is most likely a driving force and not a mere bystander of the disease.

Methods and results

We prospectively included 576 consecutive HFrEF patients into our long-term observational study. Functional [i.e. New York Heart Association (NYHA) class], echocardiographic, invasive haemodynamic, and biochemical (i.e. NT-proBNP, MR-proANP, MR-proADM, CT-proET-1, copeptin) measurements were performed at baseline. During a median follow-up of 62 months (interquartile range 52-76), 47% of patients died. Severe FMR was a significant predictor of mortality [hazard ratio (HR) 1.76, 95% confidence interval (CI) 1.34-2.30; P < 0.001], independent of clinical (adjusted HR 1.61, 95% CI 1.22-2.12; P = 0.001), and echocardiographic (adjusted HR 1.46, 95% CI 1.09-1.94; P = 0.01) confounders, OMT (adjusted HR 1.81, 95% CI 1.25-2.63; P = 0.002), and neurohumoral activation (adjusted HR 1.38, 95% CI 1.03-1.84; P = 0.03). Subanalysis revealed that severe FMR was associated with poor outcome in an intermediate-failure phenotype of HFrEF i.e. patients with NYHA class II (adjusted HR 2.17, 95% CI 1.07-4.44; P = 0.03) and III (adjusted HR 1.80, 95% CI 1.17-2.77; P = 0.008), moderately reduced left ventricular function (adjusted HR 2.37, 95% CI 1.36-4.12; P = 0.002), and within the second quartile (871-2360 pg/mL) of NT-proBNP (adjusted HR 2.16, 95% CI 1.22-3.86; P = 0.009).

Conclusion

In a patient cohort under OMT, the adverse prognostic impact of FMR is given predominantly in a sub-cohort of a specific intermediate-failure phenotype-well-defined functionally, haemodynamically, biochemically, and morphologically.

Myocardial reconstruction in ischaemic cardiomyopathy

An increase in left ventricular volume after a myocardial infarction is a key component of the adverse remodelling process leading to chamber dysfunction, heart failure and an unfavourable outcome. Hence, the therapeutic strategies have been designed to reverse the remodelling process by medical therapy, devices or surgical strategies. Surgical ventricular reconstruction primarily combined with myocardial revascularization has been introduced as an optional intervention aimed to reduce the left ventricle through resection of the scar tissue and is recommended in selected patients with predominant heart failure symptoms, and with myocardial scarring and moderate left ventricular remodelling. This review outlines the rationale and the technique for reconstructing the left ventricle and the possible indications for using that technique, based on experiences from the centre with the largest international experience. The major contributions in the literature are briefly discussed.

Overview of complications of acute and chronic myocardial infarctions: revisiting pathogenesis and cross-sectional imaging

Myocardial infarction (MI) remains one of the leading contributors to overall mortality and morbidity in the modern world, even with recent advances in medicine. Various complications can arise following an MI, particularly with delayed or inadequate treatment. Even though many of these complications are uncommon, they can have a significant impact on patient outcomes. Some of these complications can be diagnosed based on clinical, laboratory and echocardiographic evaluation. Other times, however, cardiac MR and multidetector CT are necessary in their diagnosis and proper evaluation. Accurate detection of these complications is an important aspect of optimising prompt and effective patient care, leading to better clinical outcomes. It is the goal of this article to review the role of cross-sectional imaging in patients with post-MI as well as the characteristic imaging findings and differential diagnosis of common and uncommon complications of MI.

Evolution of secondary mitral regurgitation

Aims

Secondary mitral regurgitation (MR) drives adverse remodelling towards late heart failure stages. Little is known about the evolution of MR under guideline-directed therapy (GDT) and its relation to cardiac remodelling and outcome. We therefore aimed to assess incidence, impact, and predictors of progressive secondary MR in patients under GDT.

Methods and results

We prospectively enrolled 249 patients with chronic heart failure and reduced ejection fraction receiving GDT in this long-term observational study. Of patients with non-severe MR at baseline 81% remained stable whereas 19% had progressive MR. Those patients were more symptomatic (P < 0.001), had higher neurohumoral activation (encompassing various neurohumoral pathways in heart failure, all P < 0.05), larger left atrial size (P = 0.004) and more tricuspid regurgitation (TR, P = 0.02). During a median follow-up of 61 months (IQR 50-72), 61 patients died. Progression of MR conveyed an increased risk of mortality-univariately (HR 2.33; 95% CI 1.34-4.08; P = 0.003), that persisted after multivariate adjustment using a bootstrap-selected confounder model (adjusted HR 2.48; 95% CI 1.40-4.39; P = 0.002). In contrast, regression of MR was not associated with a beneficiary effect on outcome (crude HR 0.84; 95% CI 0.30-2.30; P = 0.73).

Conclusions

Every fifth patient with chronic heart failure suffers from MR progression. This entity is associated with a more than two-fold increased risk of death even after careful multivariable adjustment. Symptomatic status, left atrial size, TR, and neurohumoral pathways help to identify patients at risk for progressive secondary MR in an early disease process and open the possibility for closer follow-up and timely intervention.

Mitral Leaflet Changes Following Myocardial Infarction: Clinical Evidence for Maladaptive Valvular Remodeling

BACKGROUND

Ischemic mitral regurgitation (MR) is classically ascribed to functional restriction of normal leaflets, but recent studies have suggested post-myocardial infarction (MI) mitral valve (MV) leaflet fibrosis and thickening, challenging valve normality. Progression of leaflet thickness post-MI has not been studied. We hypothesized that excessive MV remodeling post-MI contributes to MR. Our objectives are to characterize MV changes after MI and relate them to MR.

METHODS AND RESULTS

Three groups of 40 patients with serial echocardiograms over a mean of 23.4 months were identified from an echocardiography database: patients first studied early (6±12 days) and late (12±7 years) after an inferior MI and normal controls. MV thickness was correlated with MR. We studied the mechanisms for MV changes in a sheep model (6 apical MI versus 6 controls) followed for 8 weeks, with MV cellular and histopathologic analyses. Early post-MI, leaflet thickness was found to be similar to controls (2.6±0.5 vs 2.5±0.4 mm; P=0.23) but significantly increased over time (2.5±0.4 to 2.9±0.4 mm; P<0.01). In this group, patients tolerating maximal doses of renin-angiotensin blocking agents had less thickening (25% of patients; P<0.01). The late-MI group had increased thickness (3.2±0.5 vs 2.5±0.4 mm; P<0.01) without progression. At follow-up, 48% of post-MI patients had more than mild MR. Increased thickness was independently associated with MR. Experimentally, 8 weeks post-MI, MVs were 2-fold thicker than controls, with increased collagen, profibrotic transforming growth factor-β, and endothelial-to-mesenchymal transformation, confirmed by flow cytometry.

CONCLUSIONS

MV thickness increases post-MI and correlates with MR, suggesting an organic component to ischemic MR. MV fibrotic remodeling can indicate directions for future therapy.

Multiplanar strain quantification for assessment of right ventricular dysfunction and non-ischemic fibrosis among patients with ischemic mitral regurgitation

Background

Ischemic mitral regurgitation (iMR) predisposes to right ventricular (RV) pressure and volume overload, providing a nidus for RV dysfunction (RV_DYS) and non-ischemic fibrosis (NIF). Echocardiography (echo) is widely used to assess iMR, but performance of different indices as markers of RV_DYS and NIF is unknown.

Methods

iMR patients prospectively underwent echo and cardiac magnetic resonance (CMR) within 72 hours. Echo quantified iMR, assessed conventional RV indices (TAPSE, RV-S’, fractional area change [FAC]), and strain via speckle tracking in apical 4-chamber (global longitudinal strain [RV-GLS]) and parasternal long axis orientation (transverse strain). CMR volumetrically quantified RVEF, and assessed ischemic pattern myocardial infarction (MI) and septal NIF.

Results

73 iMR patients were studied; 36% had RV_DYS (EF<50%) on CMR among whom LVEF was lower, PA systolic pressure higher, and MI size larger (all p<0.05). CMR RVEF was paralleled by echo results; correlations were highest for RV-GLS (r = 0.73) and lowest for RV-S’ (r = 0.43; all p<0.001). RV_DYS patients more often had CMR-evidenced NIF (54% vs. 7%; p<0.001). Whereas all RV indices were lower among NIF-affected patients (all p≤0.006), percent change was largest for transverse strain (48.3%). CMR RVEF was independently associated with RV-GLS (partial r = 0.57, p<0.001) and transverse strain (r = 0.38, p = 0.002) (R = 0.78, p<0.001). Overall diagnostic performance of RV-GLS and transverse strain were similar (AUC = 0.93[0.87–0.99]|0.91[0.84–0.99], both p<0.001), and yielded near equivalent sensitivity and specificity (85%|83% and 80%|79% respectively).

Conclusion

Compared to conventional echo indices, RV strain parameters yield stronger correlation with CMR-defined RVEF and potentially constitute better markers of CMR-evidenced NIF in iMR.

A Swine Model of Percutaneous Intracoronary Ethanol Induced Acute Myocardial Infarction and Ischemic Mitral Regurgitation

Ischemic mitral regurgitation (IMR) is a frequent complication after a myocardial infarction (MI), which doubles mortality. Transcatheter mitral repairs are emerging as alternative treatment options to open heart surgery for IMR, but animal models to test them are lacking. We report a percutaneous swine model of IMR. Seventeen swine were randomized to (group 1, n = 12) MI causing IMR, and (group 2, n = 5) controls. In group 1, MI was induced via percutaneous ethanol injection into the obtuse marginal branches of the left circumflex artery, resulting in ST elevating myocardial infarction. Nine animals were survived to 8-10 weeks with weekly echocardiograms and three swine were survived to 16-20 weeks with MRI at termination. In group 1 animals, average IMR fraction at termination was 26.6 ± 2.3% in the echo group, and 24.51 ± 0.41% in the MRI group. None of the animals in group 2 had IMR. Left ventricular dysfunction and significant dilatation were evident in group 1 animals, compared to the controls. In conclusion, a reproducible model of IMR is reported for use in pre-clinical testing of new mitral technologies.

Basal Left Ventricular Dilatation and Reduced Contraction in Patients With Mitral Valve Prolapse Can Be Secondary to Annular Dilatation

Background—

Prominent mitral valve (MV) annular dilatation with only modest left ventricular (LV) dilatation in patients with MV prolapse (MVP) suggests predominant dilatation in adjacent basal LV, which may augment regional wall tension and attenuate contraction by Laplace’s law. We hypothesized that MV annular dilatation in patients with MVP is associated with the basal predominance of LV dilatation and attenuated contraction, which can be altered by surgical MV plasty with annulus reduction.

Methods and Results—

Echocardiography with speckle-tracking analysis to assess regional cross-sectional short-axis area and longitudinal contraction (strain) of basal, middle, and apical LV was performed in 30 controls and 130 patients with MVP. The basal value/averaged middle and apical values (B/M·A ratio) of LV cross-sectional area and strain were obtained. Patients with MVP showed significantly greater MV annular area (6.4±1.6 versus 3.7±0.6 cm 2 /m 2 ), increased B/M·A LV area ratio (2.4±0.5 versus 1.8±0.2), and reduced B/M·A LV strain ratio (0.83±0.14 versus 0.96±0.09) than controls ( P <0.001). Multivariable analyses identified that MV annular dilatation was independently associated with increased B/M·A LV area ratio (β=0.60, P <0.001), which was associated with reduced B/M·A LV strain ratio (β=−0.32, P <0.001). In 35 patients with MVP, B/M·A LV area and strain ratio significantly altered after surgical MV plasty with annulus reduction (2.5±0.5–1.8±0.3 and 0.73±0.10–0.89±0.17, P <0.001, respectively).

Conclusions—

In patients with MVP, MV annular dilatation was associated with the basal predominance of LV dilatation and reduced contraction, which can be altered by surgical MV plasty with annulus reduction, suggesting unfavorable influence from MV annular dilatation on basal LV.

Moderate Ischemic Mitral Regurgitation After Posterolateral Myocardial Infarction in Sheep Alters Left Ventricular Shear but Not Normal Strain in the Infarct and Infarct Borderzone

BACKGROUND

Chronic ischemic mitral regurgitation (CIMR) is associated with poor outcome. Left ventricular (LV) strain after posterolateral myocardial infarction (MI) may drive LV remodeling. Although moderate CIMR has been previously shown to affect LV remodeling, the effect of CIMR on LV strain after posterolateral MI remains unknown. We tested the hypothesis that moderate CIMR alters LV strain after posterolateral MI.

METHODS

Posterolateral MI was created in 10 sheep. Cardiac magnetic resonance imaging with tags was performed 2 weeks before and 2, 8, and 16 weeks after MI. The left and right ventricular volumes were measured, and regurgitant volume indexed to body surface area (regurgitant volume index) was calculated as the difference between left ventricle and right ventricle stroke volumes divided by body surface area. Three-dimensional strain was calculated.

RESULTS

Circumferential strain (Ecc) and longitudinal strain (Ell) were reduced in the infarct proper, MI borderzone, and remote myocardium 16 weeks after MI. In addition, radial circumferential (Erc) and radial longitudinal (Erl) shear strains were reduced in remote myocardium but increased in the infarct and borderzone 16 weeks after MI. Of all strain components, however, only Erc was affected by regurgitant volume index (p = 0.0005). There was no statistically significant effect of regurgitant volume index on Ecc, Ell, Erl, or circumferential longitudinal shear strain (Ecl).

CONCLUSIONS

Moderate CIMR alters radial circumferential shear strain after posterolateral MI in sheep. Further studies are needed to determine the effect of shear strain on myocyte hypertrophy and the effect of mitral repair on myocardial strain.

Mitral valve disease--morphology and mechanisms

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

Efficacy of polymer injection for ischemic mitral regurgitation: persistent reduction of mitral regurgitation and attenuation of left ventricular remodeling

OBJECTIVES

The aim of this study was to examine the chronic effects of polyvinyl-alcohol (PVA) injection on mitral regurgitation (MR) reduction, mitral valve geometry, and left ventricular (LV) remodeling in a chronic ischemic MR sheep model.

BACKGROUND

Previous studies have demonstrated acute efficacy of PVA hydrogel polymer injection into infarcted myocardium underlying the papillary muscle to relieve MR by papillary muscle repositioning. However, the chronic efficacy of PVA injection in the chronic infarction setting remains unclear.

METHODS

Sixteen sheep developed chronic MR 8 weeks after induced inferoposterior myocardial infarction. Ten consecutive sheep underwent PVA injection (PVA group) and 6 sheep served as control subjects with saline injection. Epicardial 2-/3-dimensional echocardiography was performed at the baseline, chronic MR (pre-injection), and sacrifice (8 weeks after injection) stages.

RESULTS

Both groups were comparable at the baseline and chronic MR stages. At sacrifice, MR decreased from moderate to trace or mild (vena contracta: 0.17 ± 0.08 cm vs. 0.56 ± 0.10 cm, p < 0.001) in the PVA group but progressed to moderate to severe in the control group. End-systolic and -diastolic volumes remained stable in the PVA group but increased significantly in the control group (both p < 0.05). At sacrifice, compared with the control group, the PVA group had significantly less left ventricular remodeling (end-systolic volume: 41.1 ± 10.4 ml vs. 55.9 ± 12.4 ml, p < 0.05), lower MR severity (vena contracta: 0.17 ± 0.08 cm vs. 0.60 ± 0.14 cm, p < 0.01), and favorable changes in mitral valve geometry.

CONCLUSIONS

Polymer injection in a chronic ischemic MR model results in persistent reduction of MR and attenuation of continued left ventricular remodeling over 8 weeks of follow-up.

Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis

BACKGROUND

The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function.

METHODS

Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated.

RESULTS

PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function.

CONCLUSIONS

PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function.

Repair or prosthesis insertion in ischemic mitral regurgitation: Two faces of the same medal

Objective

The proper treatment of chronic ischemic mitral regurgitation (CIMR) is still under evaluation. The different role of mitral valve repair (MVr) or mitral valve prosthesis insertion (MVPI) is still not defined.

Methods

From May 2009 to December 2011 167 patients with ejection fraction (EF) ≤ 40% had MV surgery for CIMR, MVr in 135 (80.8%) and MVPI in 32 (19.2%). Indication to MVPI was a MV coaptation depth > 10 mm. EF was lower (26 ± 7 vs 32 ± 6, p = 0.0000) in MVPI, whereas MR grade (3.6 ± 0.8 vs 2.7 ± 0.9, p = 0.0000), left ventricle dimensions (end diastolic, LVEDD, 62 ± 7 vs 57 ± 6 mm, p = 0.0001; end systolic, LVESD, 49 ± 8 vs 44 ± 8 mm, p = 0.0018), systolic pulmonary artery pressure (51 ± 22 vs 41 ± 16 mm Hg, p = 0.0037) and NYHA Class (3.6 ± 0.5 vs 2.8 ± 0.6, p = 0.0000) were higher.

Results

In-hospital mortality was similar (3.1 vs 3.7%) as well as 3-year survival (86 ± 6 vs 88 ± 4) and survival in NYHA Class I/II (80 ± 5 vs 83 ± 4). One hundred thirty nine patients had an echocardiographic evaluation after a minimum of 4 months (13 ± 8). EF rose significantly in both groups (from 26 ± 7% to 30 ± 4%, p = 0.0122, and from 32 ± 6% to 35 ± 8%, p = 0.0018). LVESD reduced significantly in both groups (from 49 ± 8 to 43 ± 9 mm, p = 0.0109, and from 44 ± 8 to 41 ± 7 mm, p = 0.0033). MR grade was significantly lower in patients who had MVPI (0.1 ± 0.2 vs 0.3 ± 0.3, p = 0.0011).

Conclusions

With appropriate indications, MVPI is a safe procedure which provides similar results to MVr with lower MR return, even if addressed to patients with worse preoperative parameters.

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Time-delayed feedback control is used to control system chaos.

Late repair of ischemic mitral regurgitation does not prevent left ventricular remodeling: importance of timing for beneficial repair

BACKGROUND

Ischemic mitral regurgitation (MR) is a frequent complication of myocardial infarction associated with left ventricular (LV) dilatation and dysfunction, which doubles mortality. At the molecular level, moderate ischemic MR is characterized by a biphasic response, with initial compensatory rise in prohypertrophic and antiapoptotic signals, followed by their exhaustion. We have shown that early MR repair 30 days after myocardial infarction is associated with LV reverse remodeling. It is not known whether MR repair performed after the exhaustion of compensatory mechanisms is also beneficial. We hypothesized that late repair will not result in LV reverse remodeling.

METHODS AND RESULTS

Twelve sheep underwent distal left anterior descending coronary artery ligation to create apical myocardial infarction and implantation of an LV-to-left atrium shunt to create standardized moderate volume overload. At 90 days, animals were randomized to shunt closure (late repair) versus sham (no repair). LV remodeling was assessed by 3-dimensional echocardiography, dP/dt, preload-recruitable stroke work, and myocardial biopsies. At 90 days, animals had moderate volume overload, LV dilatation, and reduced ejection fraction (all P<0.01 versus baseline, P=NS between groups). Shunt closure at 90 days corrected the volume overload (regurgitant fraction 6 ± 5% versus 27 ± 16% for late repair versus sham, P<0.01) but was not associated with changes in LV volumes (end-diastolic volume 106 ± 15 versus 110 ± 22 mL; end-systolic volume 35 ± 6 versus 36 ± 6 mL) or increases in preload-recruitable stroke work (41 ± 7 versus 39 ± 13 mL mm Hg) or dP/dt (803 ± 210 versus 732 ± 194 mm Hg/s) at 135 days (all P=NS). Activated Akt, central in the hypertrophic process, and signal transducer and activator of transcription 3 (STAT3), a critical node in the hypertrophic stimulus by cytokines, were equally depressed in both groups.

CONCLUSIONS

Late correction of moderate volume overload after myocardial infarction did not improve LV volume or contractility. Upregulation of prohypertrophic intracellular pathways was not observed. This contrasts with previously reported study in which early repair (30 days) reversed LV remodeling. This suggests a window of opportunity to repair ischemic MR after which no beneficial effect on LV is observed, despite successful repair.

Differential patterns of replacement and reactive fibrosis in pressure and volume overload are related to the propensity for ischaemia and involve resistin

Pathological left ventricle (LV) hypertrophy (LVH) results in reactive and replacement fibrosis. Volume overload LVH (VOH) is less profibrotic than pressure overload LVH (POH). Studies attribute subendocardial fibrosis in POH to ischaemia, and reduced fibrosis in VOH to collagen degradation favouring dilatation. However, the mechanical origin of the relative lack of fibrosis in VOH is incompletely understood. We hypothesized that reduced ischaemia propensity in VOH compared to POH accounted for the reduced replacement fibrosis, along with reduced reactive fibrosis. Rats with POH (ascending aortic banding) evolved into either compensated-concentric POH (POH-CLVH) or dilated cardiomyopathy (POH-DCM); they were compared to VOH (aorta-caval fistula). We quantified LV fibrosis, structural and haemodynamic factors of ischaemia propensity, and the activation of profibrotic pathways. Fibrosis in POH-DCM was severe, subendocardial and subepicardial, in contrast with subendocardial fibrosis in POH-CLVH and nearly no fibrosis in VOH. The propensity for ischaemia was more important in POH versus VOH, explaining different patterns of replacement fibrosis. LV collagen synthesis and maturation, and matrix metalloproteinase-2 expression, were more important in POH. The angiotensin II-transforming growth-factor β axis was enhanced in POH, and connective tissue growth factor (CTGF) was overexpressed in all types of LVH. LV resistin expression was markedly elevated in POH, mildly elevated in VOH and independently reflected chronic ischaemic injury after myocardial infarction. In vitro, resistin is induced by angiotensin II and induces CTGF in cardiomyocytes. Based on these findings, we conclude that a reduced ischaemia propensity and attenuated upstream reactive fibrotic pathways account for the attenuated fibrosis in VOH versus POH.

Mitral apparatus assessment by delayed enhancement CMR: relative impact of infarct distribution on mitral regurgitation

OBJECTIVES

This study sought to assess patterns and functional consequences of mitral apparatus infarction after acute myocardial infarction (AMI).

BACKGROUND

The mitral apparatus contains 2 myocardial components: papillary muscles and the adjacent left ventricular (LV) wall. Delayed-enhancement cardiac magnetic resonance (DE-CMR) enables in vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR).

METHODS

Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography was used to measure MR. Imaging occurred 27 ± 8 days after AMI (CMR, echocardiography within 1 day).

RESULTS

A total of 153 patients with first AMI were studied; PMI was present in 30% (n = 46 [72% posteromedial, 39% anterolateral]). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p <0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p <0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p <0.001). Prevalence of lateral wall infarction was 3-fold higher among patients with PMI compared to patients without PMI (65% vs. 22%, p <0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p = 0.002). Conversely, MR severity did not differ on the basis of presence (p = 0.19) or extent (p = 0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (odds ratio 1.20/% LV myocardium [95% confidence interval: 1.05 to 1.39], p = 0.01) was independently associated with substantial (moderate or greater) MR even after controlling for mitral annular (odds ratio 1.22/mm [1.04 to 1.43], p = 0.01), and LV end-diastolic diameter (odds ratio 1.11/mm [0.99 to 1.23], p = 0.056).

CONCLUSIONS

Papillary muscle infarction is common after AMI, affecting nearly one-third of patients. Extent of PMI parallels adjacent LV wall injury, with lateral infarction-rather than PMI-associated with increased severity of post-AMI MR.

Percutaneous coronary intervention of the left main artery before MitraClip implantation

Functional mitral regurgitation (MR) is common in patients with ischemic cardiomyopathy. We present a case of an 83-year-old patient with ischemic heart disease and ischemic cardiomyopathy, who was repeatedly admitted for pulmonary edema and underwent a percutaneous trans-septal MitraClip procedure. During coronary angiography, a severe left main stenosis was demonstrated. Treatment included both percutaneous coronary intervention and the implantation of two MitraClip devices, with very good results. We believe that this case illustrates the need for comprehensive assessment of ischemia in patients with functional MR.

Comprehensive annular and subvalvular repair of chronic ischemic mitral regurgitation improves long-term results with the least ventricular remodeling

BACKGROUND

Undersized ring annuloplasty for ischemic mitral regurgitation (MR) is associated with variable results and >30% MR recurrence. We tested whether subvalvular repair by severing second-order mitral chordae can improve annuloplasty by reducing papillary muscle tethering.

METHODS AND RESULTS

Posterolateral myocardial infarction known to produce chronic remodeling and MR was created in 28 sheep. At 3 months, sheep were randomized to sham surgery versus isolated undersized annuloplasty versus isolated bileaflet chordal cutting versus the combined therapy (n=7 each). At baseline, chronic myocardial infarction (3 months), and euthanasia (6.6 months), we measured left ventricular (LV) volumes and ejection fraction, wall motion score index, MR regurgitation fraction and vena contracta, mitral annulus area, and posterior leaflet restriction angle (posterior leaflet to mitral annulus area) by 2-dimensional and 3-dimensional echocardiography. All groups were comparable at baseline and chronic myocardial infarction, with mild to moderate MR (MR vena contracta, 4.6±0.1 mm; MR regurgitation fraction, 24.2±2.9%) and mitral annulus dilatation (P<0.01). At euthanasia, MR progressed to moderate to severe in controls but decreased to trace with ring plus chordal cutting versus trace to mild with chordal cutting alone versus mild to moderate with ring alone (MR vena contracta, 5.9±1.1 mm in controls, 0.5±0.08 with both, 1.0±0.3 with chordal cutting alone, 2.0±0.4 with ring alone; P<0.01). In addition, LV end-systolic volume increased by 108% in controls versus 28% with ring plus chordal cutting, less than with each intervention alone (P<0.01). In multivariate analysis, LV end-systolic volume and mitral annulus area most strongly predicted MR (r(2)=0.82, P<0.01).

CONCLUSIONS

Comprehensive annular and subvalvular repair improves long-term reduction of both chronic ischemic MR and LV remodeling without decreasing global or segmental LV function at follow-up.