Early Repair of Moderate Ischemic Mitral Regurgitation Reverses Left Ventricular Remodeling: A Functional and Molecular Study

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.

Effect of early versus late onset mitral regurgitation on left ventricular remodeling in ischemic cardiomyopathy in an animal model

BACKGROUND

Patients who survive a myocardial infarction have progressive cardiac dysfunction and ventricular remodeling. Mitral regurgitation is often diagnosed in these patients, and is a risk factor that portends poor prognosis. Whether such postinfarction mitral regurgitation magnifies adverse left ventricular remodeling is unclear, which was studied in an animal model.

METHODS

Forty-one adult rats were induced with myocardial infarction using left coronary artery ligation and assigned to 3 groups: group 1, myocardial infarction only; group 2, myocardial infarction with severe mitral regurgitation introduced after 4 weeks; and group 3, myocardial infarction with severe mitral regurgitation introduced after 10 weeks. Valve regurgitation was introduced by advancing a transapical ultrasound-guided needle into the mitral valve anterior leaflet. Animals were survived to 20 weeks from the index procedure, with biweekly cardiac ultrasound, and invasive hemodynamics and histology at termination.

RESULTS

At 20 weeks, end diastolic volume was largest in the groups with mitral regurgitation, compared with the group without the valve lesion (group 1, 760.9 ± 124.6 μL; group 2, 958.0 ± 115.1 μL; group 3, 968.3 ± 214.9 μL). Similarly, end systolic volume was larger in groups with regurgitation (group 1, 431.2 ± 152.6 μL; group 2, 533.2 ± 130.8 μL; group 3, 533.1 ± 177.5 μL). In the infarction-only group, left ventricular remodeling was maximal until 6 weeks and plateaued thereafter. In groups with mitral regurgitation, left ventricular remodeling was significantly elevated at the onset of regurgitation and persisted.

CONCLUSIONS

Mitral regurgitation is a potent driver of adverse cardiac remodeling after a myocardial infarction, irrespective of the timing of its onset.

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.

Proportionate or disproportionate secondary mitral regurgitation: how to untangle the Gordian knot?

Recent randomised percutaneous mitral intervention trials in patients with heart failure with secondary mitral regurgitation (SMR) have yielded contrasting results. A 'relative load' or 'proportionality' conceptual framework for SMR has been proposed to partly explain the disparate results. The rationale behind the framework is that SMR depends on the left ventricular dimension and not vice versa. In this review, we provide an in-depth analysis of the proportionality parameters used in this framework and also discuss the regurgitant fraction. We also consider haemodynamic observations in SMR that may affect the interpretation and comparisons among proportionality parameters. The conclusion is that the proportionality concept remains hypothetical and requires prospective validation before envisaging its use at individual patient level for risk stratification or therapeutic decision-making.

Phenotyping progression of secondary mitral regurgitation in chronic systolic heart failure

BACKGROUND

Secondary mitral regurgitation (sMR) drives adverse cardiac remodelling in patients with heart failure with reduced ejection fraction (HFrEF). Progression in severity over time contributes to a transition towards more advanced HF stages. Early identification of patients at risk for sMR progression remains challenging. We therefore sought to assess a broad spectrum of neurohumoral biomarkers in patients with HFrEF to explore their ability to predict progression of sMR.

METHODS

A total of 249 HFrEF patients were enrolled. Biomarkers encompassing key neurohumoral pathways in heart failure were sampled at baseline, and sMR progression was assessed over 3 years of follow-up.

RESULTS

Of 191 patients with nonsevere sMR at baseline, 18% showed progressive sMR within three years after study enrolment. Progression of sMR was associated with higher levels of MR-proADM (adj.OR 2.25, 95% CI 1.29-3.93; P = .004), MR-proANP (adj.OR 1.84, 95% CI 1.14-3.00; P = .012), copeptin (adj.OR 1.66, 95% CI 1.04-2.67; P = .035) and CT-pro-ET1 (adj.OR 1.68, 95% CI 1.06-2.68; P = .027) but not with NT-proBNP (P = .54).

CONCLUSION

Increased plasma levels of neurohumoral cardiac biomarkers are predictors of sMR progression in patients with HFrEF and add easily available incremental prognostic information for risk stratification. Importantly, NT-proBNP was not useful to predict progressive sMR in the present analysis. On the contrary, MR-proANP, primarily produced in the atria, copeptin partly triggered by intra-cardiac and intra-arterial pressures and MR-proADM, a marker of forward failure and peripheral released vasoactive CT-proET1, increase based on a progressive loading burden by sMR and may thus serve as better predictors of sMR progression.

Mitral regurgitation worsens cardiac remodeling in ischemic cardiomyopathy in an experimental model

OBJECTIVE

Mitral regurgitation (MR) developing concomitant with ischemic cardiomyopathy is a frequently diagnosed valvular lesion, for which an optimal therapeutic strategy is unknown. The contribution of MR to the ongoing cardiac remodeling from myocardial infarction (MI) remains controversial. We have developed a novel experimental model in which MI and severe MR can be independently introduced, to study the role of MR in chronic remodeling of the ischemic heart.

METHODS

A total of 98 rats were induced with MI+MR (group 1), MI (group 2), MR (group 3), or sham surgery (group 4). MR was induced by inserting a needle into the anterior mitral leaflet via the ventricular apex in a beating heart. MI was induced by ligating the left coronary artery. Biweekly ultrasound examinations were performed after surgery, and invasive hemodynamic assessments were performed in some rats at 2, 10, and 20 weeks.

RESULTS

At 2 weeks postsurgery, the mean end-diastolic volume was 432 ± 103 μL in ischemic hearts with MR, compared with 390 ± 76.3 μL in ischemic hearts without MR (a 10.76% difference). By 20 weeks, the mean volume was significantly greater in the former group (767 ± 246 μL vs 580 ± 85 μL; a 32.24% difference). At 2 weeks, mean end-systolic volume was 147 ± 46.8 μL in the ischemic hearts with MR and 147 ± 45.7 μL in those without MR. By 20 weeks, the mean volumes had increased to 357 ± 136.4 μL and 271 ± 82.3 μL, respectively (a 31.73% difference).

CONCLUSIONS

MR in ischemic hearts significantly increased end-diastolic and end-systolic volumes of the left ventricle, indicating adverse cardiac remodeling and worse systolic function.

"RFEF" and mitral regurgitation jet direction: surrogate markers for likelihood of left ventricle reverse remodeling in patients with moderate chronic ischemic mitral regurgitation

Purpose

Surgical management of moderate chronic ischemic mitral regurgitation (CIMR) is controversial. We propose a simplified classification of moderate CIMR based on regurgitant fraction (RF), ejection fraction (EF), and jet direction (central/eccentric) to predict left ventricle (LV) remodeling and identify patient subsets which need mitral valve (MV) repair along with coronary artery bypass grafting (CABG).

Methods

In this prospective controlled study (n = 210), patients with moderate CIMR were randomized. Group I (n = 106) underwent off-pump CABG alone while group II (n = 104) underwent CABG + MV repair. The product of regurgitation fraction and ejection fraction ("RFEF") was taken as a surrogate for myocardial reserve. The cut-off defined was 0.12; patients with RFEF ≤ 0.12 were categorized as the "bad" and those with RFEF > 0.12 as the "good" subset. The patients were further subdivided on the basis of their mitral regurgitation (MR) jet direction (central/eccentric). The percentage improvement in left ventricular end-systolic volume index (LVESVI) and MR grade were recorded 6 monthly.

Results

Analysis of the continuous variable "RFEF" in conjunction with jet direction was performed. At 12 months, the patient in good subset with central direction of jet showed improvement in LVESVI % in both groups (p = 0.428), while the patients in bad subset with eccentric direction of jet showed significantly higher improvement in LVESVI %, group II as compared to group I (p = 0.004).

Conclusion

This study thus identifies "RFEF" as a surrogate for reverse remodeling capacity. In association with MR jet direction, predicts the subset of moderate CIMR patients most likely to have maximum LVESVI and MR grade reduction.

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.

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.

Utility of cardiac magnetic resonance for evaluation of mitral regurgitation prior to mitral valve surgery

Mitral regurgitation (MR) is a common cause of morbidity worldwide and an accepted indication for interventional therapies which aim to reduce or resolve adverse clinical outcomes associated with MR. Cardiac magnetic resonance (CMR) provides highly accurate means of assessing MR, including a variety of approaches that can measure MR based on quantitative flow. Additionally, CMR is widely accepted as a reference standard for cardiac chamber quantification, enabling reliable detection of subtle changes in cardiac chamber size and function so as to guide decision-making regarding timing of mitral valve directed therapies. Beyond geometric imaging, CMR enables tissue characterization of ischemia and infarction in the left ventricular (LV) myocardium as well as within the mitral valve apparatus, thus enabling identification of structural substrates for MR. This review provides an overview of established and emerging CMR approaches to measure valvular regurgitation, including relative utility of different approaches for patients with primary or secondary MR. Clinical outcomes studies are discussed with focus on data demonstrating advantages of CMR for guiding diagnosis, risk stratification, and management of patients with known or suspected MR. Comparative data is reviewed with focus on diagnostic performance of CMR in comparison to conventional assessment via echocardiography (echo). Emerging literature is reviewed concerning potential new approaches that utilize CMR tissue characterization to guide clinical decision-making in order to improve therapeutic outcomes and clinical prognosis for patients with MR.

The Electrophysiologic Effects of Acute Mitral Regurgitation in a Canine Model

BACKGROUND

Atrial fibrillation (AF) occurs in 30% of patients with mitral regurgitation referred for surgical intervention. However, the underlying mechanisms in this population are poorly understood. This study examined the effects of acute left atrial volume overload on atrial electrophysiology and the inducibility of AF.

METHODS

Ten canines underwent insertion of an atrioventricular shunt between the left ventricle and left atrium. Shunt and aortic flows were calculated, and the shunt was titrated to a shunt fraction to 40% to 50% of cardiac output. An epicardial plaque with 250 bipolar electrodes was used to determine activation and refractory periods. Biatrial pressures and volumes, conduction times, and atrial fibrillation inducibility were recorded. Data were collected at baseline and 20 minutes after shunt opening and closure.

RESULTS

Mean shunt flow was 1.3 ± 0.5 L/min with a shunt fraction of 43% ± 6% simulating moderate to severe mitral regurgitation. Compared with baseline, left atrial volumes and maximum pressures increased by 27% and 29%, respectively, after shunt opening. Biatrial effective refractory periods did not change significantly after shunt opening or closure. Conduction times increased by 9% with shunt opening and returned to baseline after closure. AF duration or inducibility did not change with shunt opening.

CONCLUSIONS

This canine model of mitral regurgitation demonstrated that acute left atrial volume overload did not increase the inducibility of atrial arrhythmias in contrast with experimental and clinical findings of chronic left atrial volume overload. This suggests that the substrates for AF in patients with mitral regurgitation are a result of chronic remodeling.

Percutaneous coronary intervention for acute myocardial infarction with mitral regurgitation

Ischemic mitral regurgitation (IMR) is a common complication of acute myocardial infarction (AMI). Current evidences suggest that revascularization of the culprit vessels with percutaneous coronary artery intervention (PCI) or coronary artery bypass grafting can be beneficial for relieving IMR. A 2.5-year follow-up data of a 61-year-old male patient with ST-segment elevation AMI complicated with IMR showed that mitral regurgitation area increased five days after PCI, and decreased to lower steady level three months after PCI. This finding suggest that three months after PCI might be a suitable time point for evaluating the possibility of IMR recovery and the necessity of surgical intervention of the mitral valve for AMI patient.

Mitral valve repair for ischemic moderate mitral regurgitation in patients undergoing coronary artery bypass grafting

Objectives:

To investigate whether mitral valve repair (MVR) at the time of coronary artery bypass grafting (CABG) in patients with ischemic moderate mitral regurgitation (MR) and coronary artery disease could improve short- and mid-term postoperative outcomes.

Methods:

Between March 2013 and December 2015, 90 patients with moderate ischemic MR underwent first-time CABG in Bursa Yuksek Ihtisas Training and Research Hospital, Bursa, Turkey. Out of 90 patients, 44 (48.9%) underwent combined CABG+MVR. The remaining 46 (51.1%) underwent CABG alone. Ventricular functions and effort capacities of patients in both groups were evaluated echocardiographically and clinically in the preoperative period, and in the first postoperative year.

Results:

Postoperative regurgitant volume changes according to preoperative values were -24.76±19 ml/beat in the combined CABG+MVR group, and -8.70±7.2 ml/beat in the CABG alone group (p=0.001). The change of vena contracta width was -3.40±0.2 mm in the combined CABG+MVR group whereas in the CABG alone -1.45±0.7 mm (p=0.019). The changes of left ventricular end-systolic volume index were -30.77±25.9 ml/m² in the combined CABG+MVR group and -15.6±9.4 ml/m² in the CABG alone group (p=0.096). Ejection fraction changes in the combined CABG+MVR group was +1.51±5.3% and in the CABG alone group was +1.15±4.3%. No statistically significant difference was found between both groups (p=0.604). Preoperative New York Heart Association class values in the combined CABG+MVR group was 2.18±0.45, and in the CABG alone group was 2.13±0.54.

Conclusions:

Moderate MR in patients undergoing CABG affects the outcome adversely and it does not reliably improve after CABG alone. Therefore, patients with ischemic moderate MR should undergo simultaneous MVR at the time of CABG.

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.

Beneficial effects of a cardiac support device on left ventricular remodeling after posterior myocardial infarction: an evaluation by echocardiography, pressure-volume curves and ventricular histology

PURPOSE

Posterior myocardial infarction (MI) can induce LV remodeling and ischemic mitral regurgitation (IMR). The protective effects of a cardiac support device (CSD) against LV remodeling and IMR after posterior MI have been poorly documented.

METHODS

Posterior MI was induced by ligation of the left circumflex coronary artery in beagle dogs. After 7 days, the dogs were randomized to a CSD placement (CSD group, n = 8) or no treatment (CTL group, n = 8).

RESULTS

At 3 months after MI, the LV remodeling was less marked and the LV and RV systolic functions were better in the CSD group than in the CTL group. Neither the RV nor LV diastolic function (min dP/dt, Tau and EDPVR) was disturbed by the CSD. IMR was consistently prevented in our canine model.

CONCLUSION

Early application of a CSD after posterior MI can attenuate LV remodeling without causing any deterioration of the biventricular diastolic function.

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.

Dynamic alterations of connexin43, matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2 during ventricular fibrillation in canine

The aim of this study is to investigate the dynamic alterations of cardiac connexin 43 (Cx43), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in the setting of different ventricular fibrillation (VF) duration. In this study, thirty-two dogs were randomly divided into sham control group, 8-min VF group, 12-min VF group, and 30-min VF group. Cx43 and phosphorylated Cx43 (p-Cx43) in tissues were detected by western blot and immunofluorescence analysis. MMP-2 and TIMP-2 were detected by western blot and immunohistochemistry analysis. The results showed that Cx43 levels in three VF groups were significantly decreased compared with sham control group. p-Cx43 levels in 12-min and 30-min VF groups were significantly reduced compared with sham control group. The ratio of p-Cx43/Cx43 was also decreased in VF groups. Compared with sham controls, no significant difference was observed between the sham control group and 8-min VF group in MMP-2 level, but MMP-2 level increased in 12-min and 30-min VF groups. The ratios of MMP-2/TIMP-2 were higher in VF groups, and were correlated with the duration of VF. A remarkable correlation was observed between the ratio of p-Cx43/Cx43 and MMP-2/TIMP-2 (r = -0.93, P < 0.01). In conclusion, the alteration of Cx43 and/or p-Cx43 levels and the imbalance of MMP-2 and TIMP-2 may contribute to the initiation and/or persistence of VF. Maneuvers managed to modulate Cx43 level or normalize the balance of MMP-2/TIMP-2 are promising to ameliorate prognosis of VF.

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.

Right ventricular myocardial performance index is decreased with severe pressure-overload cardiac hypertrophy in young rats

Although the right ventricular (RV) myocardial performance index (MPI) usually is increased in the presence of RV dysfunction and pressure overload, debate continues over the correlation between the RV MPI and functional derangement in patients with RV pressure-overload congenital heart disease (CHD). To address this controversy, this study took serial measurements of the RV MPI in addition to invasive RV hemodynamic measurements during the acute stage of mild to severe pressure overload. Right ventricle pressure overload was induced by partial pulmonary arterial banding (PAB) in 3-week-old rats. The rats were divided into two groups: mild pulmonary stenosis (PS) group (20-40 % stenosis; n = 20) and severe PS group (40-70 % stenosis; n = 28). Sham-treated animals (sham group; n = 30) underwent the same surgical procedure without PAB. Pressure-overload RV hypertrophy was documented by weighing the heart, by evaluating echocardiograms, and by evaluating cardiac hypertrophy-associated gene expression. The RV MPI was checked 1, 2, 3, 5, and 8 weeks after PAB. The MPI was calculated as the sum of the isovolumic contraction time and the isovolumic relaxation time (IRT) divided by the ejection time. The RV MPI of the mild PS group did not differ significantly from that of the sham group. The RV MPI of the severe PS group, however, was lower than that of the sham group (0.27 ± 0.01 vs 0.29 ± 0.01) 2 to 8 weeks after PAB: 0.19 ± 0.01 at 2 weeks (P < 0.001), 0.16 ± 0.01 at 3 weeks (P < 0.001), 0.20 ± 0.01 at 5 weeks (P = 0.021), and 0.18 ± 0.01 at 8 weeks (P < 0.001) after PAB. The decreased RV MPI was associated with decreased IRT and increased ejection time. RV hypertrophy contributes to the decrease in the RV MPI in the severe pressure-overload condition.

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.

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.

Coronary artery bypass surgery with or without mitral valve annuloplasty in moderate functional ischemic mitral regurgitation: final results of the Randomized Ischemic Mitral Evaluation (RIME) trial

BACKGROUND

The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.

METHODS AND RESULTS

Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.

CONCLUSIONS

Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.

Imbalance between tissue inhibitor of metalloproteinase 1 and matrix metalloproteinase 9 after cardiopulmonary resuscitation

AIMS

This study aimed to determine whether (a) there was an imbalance between matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) after cardiopulmonary resuscitation (CPR) in a canine model of prolonged ventricular fibrillation (VF); (b) with the duration of VF, the degree of the imbalance would be greater; and (c) there was a relationship between the level of MMP-9 or TIMP-1 and the cardiac function.

METHODS AND RESULTS

Ventricular fibrillation was electrically induced in 24 dogs. The animals were randomly divided into 3 groups (sham control, n = 8; 8-minute VF, n = 8; 12-minute VF, n = 8). Echocardiographic measurement and hemodynamic variables were recorded before VF and after return of spontaneous circulation. Tissue inhibitor of metalloproteinase 1 (TIMP-1) and MMP-9 were analyzed by Western blot and immunohistochemistry. Compared with sham controls, dogs under VF and CPR showed significantly decreased level of TIMP-1 (P < .001), and with the duration of VF, the level of TIMP-1 declined (P < .01). The level of MMP-9 did not achieve statistical significance in the 3 groups (P > .05); however, they were higher in VF and longer duration VF groups. The ratios of TIMP-1/MMP-9 were lower in VF groups (P < .05). There was a negative correlation between TIMP-1 and left atrium dimension and left ventricular diastolic dimensions (r = -0.83 and r = -0.96, respectively; P < .01) and a positive correlation between TIMP-1 and left ventricular ejection fraction (r = 0.85; P < .01).

CONCLUSIONS

There was an imbalance between TIMP-1 and MMP-9 after CPR. It may partly contribute to the postresuscitation cardiac dysfunction.

Moderate mitral regurgitation accelerates left ventricular remodeling after posterolateral myocardial infarction

BACKGROUND

Chronic ischemic mitral regurgitation (MR) is associated with poor outcome. However, the effect of chronic ischemic MR on left ventricular (LV) remodeling after posterolateral myocardial infarction (MI) remains controversial. We tested the hypothesis that moderate MR accelerates LV remodeling after posterolateral MI.

METHODS

Posterolateral MI was created in 10 sheep. Cardiac magnetic resonance imaging was performed 2 weeks before and 2, 8, and 16 weeks after MI. Left ventricular and right ventricular volumes were measured, and regurgitant volume was calculated as the difference between LV and right ventricle stroke volumes.

RESULTS

Multivariate mixed effects regression showed that LV volumes at end diastole and end systole and LV sphericity were strongly correlated with both regurgitant volume (p < 0.0001, p = 0.0086, and p = 0.0007, respectively) and percent infarct area (p = 0.0156, p = 0.0307, and p < 0.0001, respectively). Conversely, whereas LV hypertrophy (LV wall volume) increased from 2 weeks to 16 weeks after MI, there was no effect of either regurgitant volume or percent infarct.

CONCLUSIONS

Moderate MR accelerates LV remodeling after posterolateral MI. Further studies are needed to determine whether mitral valve repair is able to slow or reverse MI remodeling after posterolateral MI.

Relief of mitral leaflet tethering following chronic myocardial infarction by chordal cutting diminishes left ventricular remodeling

BACKGROUND

one of the key targets in treating mitral regurgitation (MR) is reducing the otherwise progressive left ventricular (LV) remodeling that exacerbates MR and conveys adverse prognosis. We have previously demonstrated that severing 2 second-order chordae to the anterior mitral leaflet relieves tethering and ischemic MR acutely. The purpose of this study was to test whether this technique reduces the progression of LV remodeling in the chronic ischemic MR setting.

METHODS AND RESULTS

a posterolateral MI was created in 18 sheep by obtuse marginal branch ligation. After chronic remodeling and MR development at 3 months, 6 sheep were randomized to sham surgery (control group) and 12 to second-order chordal cutting (6 each to anterior leaflet [AntL] and bileaflet [BiL] chordal cutting, techniques that are in clinical application). At baseline, chronic infarction (3 months), and follow-up at a mean of 6.6 months post-myocardial infarction (MI) (euthanasia), we measured LV end-diastolic (EDV) and end-systolic volume (ESV), ejection fraction, wall motion score index, and posterior leaflet (PL) restriction angle relative to the annulus by 2D and 3D echocardiography. All measurements were comparable among groups at baseline and chronic MI. At euthanasia, AntL and BiL chordal cutting limited the progressive remodeling seen in controls. LVESV increased relative to chronic MI by 109±8.7% in controls versus 30.5±6.1% with chordal cutting (P<0.01) (LVESV in controls, 82.5±2.6 mL; in AntL, 60.6±5.1 mL; in BiL, 61.8±4.1 mL). LVEDV increased by 63±2.0% in controls versus 26±5.5% and 22±3.4% with chordal cutting (P<0.01). LV ejection fraction and wall motion score index were not significantly different at follow-up among the chordal cutting and control groups. MR progressively increased to moderate in controls but decreased to trace-mild with AntL and BiL chordal cutting (MR vena contracta in controls, 5.9±1.1 mm; in AntL, 2.6±0.1 mm; in BiL, 1.7±0.1 mm; P<0.01). BiL chordal cutting provided greater PL mobility (decreased PL restriction angle to 54.2±5.0° versus 83±3.2° with AntL chordal cutting; P<0.01).

CONCLUSIONS

reduced leaflet tethering by chordal cutting in the chronic post-MI setting substantially decreases the progression of LV remodeling with sustained reduction of MR over a chronic follow-up. These benefits have the potential to improve clinical outcomes.

Gene delivery of sarcoplasmic reticulum calcium ATPase inhibits ventricular remodeling in ischemic mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) doubles mortality after myocardial infarction (MI). We have demonstrated that MR worsens remodeling after MI and that early correction reverses remodeling. Sarcoplasmic reticulum Ca(+2)-ATPase (SERCA2a) is downregulated in this process. We hypothesized that upregulating SERCA2a might inhibit remodeling in a surgical model of apical MI (no intrinsic MR) with independent MR-type flow.

METHODS AND RESULTS

In 12 sheep, percutaneous gene delivery was performed by using a validated protocol to perfuse both the left anterior descending and circumflex coronary arteries with occlusion of venous drainage. We administered adeno-associated virus 6 (AAV6) carrying SERCA2a under a Cytomegalovirus promoter control in 6 sheep and a reporter gene in 6 controls. After 2 weeks, a standardized apical MI was created, and a shunt was implanted between the left ventricle and left atrium, producing regurgitant fractions of ≈30%. Animals were compared at baseline and 1 and 3 months by 3D echocardiography, Millar hemodynamics, and biopsies. The SERCA2a group had a well-maintained preload-recruitable stroke work at 3 months (decrease by 8±10% vs 42±12% with reporter gene controls; P<0.001). Left ventricular dP/dt followed the same pattern (no change vs 55% decrease; P<0.001). Left ventricular end-systolic volume was lower with SERCA2a (82.6±9.6 vs 99.4±9.7 mL; P=0.03); left ventricular end-diastolic volume, reflecting volume overload, was not significantly different (127.8±6.2 vs 134.3±9.4 mL). SERCA2a sheep showed a 15% rise in antiapoptotic pAkt versus a 30% reduction with the reporter gene (P<0.001). Prohypertrophic activated STAT3 was also 41% higher with SERCA2a than in controls (P<0.001). Proapoptotic activated caspase-3 rose >5-fold during 1 month in both SERCA2a and control animals (P=NS) and decreased by 19% at 3 months, remaining elevated in both groups.

CONCLUSIONS

In this controlled model, upregulating SERCA2a induced better function and lesser remodeling, with improved contractility, smaller volume, and activation of prohypertrophic/antiapoptotic pathways. Although caspase-3 remained activated in both groups, SERCA2a sheep had increased molecular antiremodeling "tone." We therefore conclude that upregulating SERCA2a inhibits MR-induced post-MI remodeling in this model and thus may constitute a useful approach to reduce the vicious circle of remodeling in ischemic MR.

Moderate ischemic mitral regurgitation: Is there a case for early intervention?

Ischemic mitral regurgitation (IMR) results from left ventricular remodelling after myocardial infarction and severely affects cardiovascular mortality and morbidity. Ischemic mitral valve regurgitation also represents a negative prognostic factor for long-term survival in patients undergoing surgical myocardial revascularization. While severe mitral regurgitation should always be corrected during a coronary artery bypass operation, the decision making is more difficult in patients with a moderate degree of regurgitation. In this review, we wish to highlight the negative impact of IMR on long-term survival and discuss the available evidence for surgical correction of IMR at the time of coronary revascularization.

Ischemic mitral regurgitation: recent advances

This article reviews recent developments in the pathophysiology and management of ischemic mitral regurgitation. Recent imaging studies using three-dimensional echocardiography have added clarity to the mechanism responsible for this condition. This article also discusses recent studies on outcomes of surgical repair, including current results and potential risks of restrictive annuloplasty. Because of the limitations imposed by restrictive annuloplasty, adjunctive surgical methods focusing on the left ventricle or papillary muscles are being investigated to address this disease. In the interim, a downsized complete rigid or semirigid annuloplasty repair appears to offer good midterm outcomes.

Mitral cerclage annuloplasty, a novel transcatheter treatment for secondary mitral valve regurgitation: initial results in swine

OBJECTIVES

We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy.

BACKGROUND

Catheter-based annuloplasty for secondary mitral regurgitation exploits the proximity of the coronary sinus to the mitral annulus, but is limited by anatomic variants and coronary artery entrapment.

METHODS

The procedure, "cerclage annuloplasty," is guided by magnetic resonance imaging (MRI) roadmaps fused with live X-ray. A coronary sinus guidewire traverses a short segment of the basal septal myocardium to re-enter the right heart where it is exchanged for a suture. Tension is applied interactively during imaging and secured with a locking device.

RESULTS

We found 2 feasible suture pathways from the great cardiac vein across the interventricular septum to create cerclage. Right ventricular septal re-entry required shorter fluoroscopy times than right atrial re-entry, which entailed a longer intramyocardial traversal but did not cross the tricuspid valve. Graded tension progressively reduced septal-lateral annular diameter, but not end-systolic elastance or regional myocardial function. A simple arch-like device protected entrapped coronary arteries from compression even during supratherapeutic tension. Cerclage reduced mitral regurgitation fraction (from 22.8 +/- 12.7% to 7.2 +/- 4.4%, p = 0.04) by slice tracking velocity-encoded MRI. Flexible cerclage reduced annular size but preserved annular motion. Cerclage also displaced the posterior annulus toward the papillary muscles. Cerclage introduced reciprocal constraint to the left ventricular outflow tract and mitral annulus that enhanced leaflet coaptation. A sample of human coronary venograms and computed tomography angiograms suggested that most have suitable venous anatomy for cerclage.

CONCLUSIONS

Transcatheter mitral cerclage annuloplasty acutely reduces mitral regurgitation in porcine ischemic cardiomyopathy. Entrapped coronary arteries can be protected. MRI provided insight into the mechanism of cerclage action.

Trans-Coronary-Venous Interventions

The coronary venous system is routinely targeted during electrophysiological measurements or cardiac resynchronization therapy. However, several novel interventional techniques require coronary venous catheterization and visualization as well as transvenous delivery of devices and/or therapeutic agents. Recent reports suggest the possibility of a transvenous approach for the interventional treatment of refractory angina and mitral valve regurgitation. In addition, the coronary venous system has been used as a route for the delivery of stem cells in patients with left ventricular dysfunction due to ischemic heart disease. We review the potential value of using a coronary venous approach in association with recent therapeutic developments in the interventional treatment of structural and ischemic heart disease. We will also discuss techniques related to coronary venous catheterization.