Is subvalvular repair worthwhile in severe ischemic mitral regurgitation? Subanalysis of the Papillary Muscle Approximation trial

Best treatment option for secondary mitral regurgitation surgery: a network meta-analysis of randomized and non-randomized controlled studies

The objective of this study is to ascertain whether subvalvular papillary muscle repair in conjunction with restrictive mitral valve annuloplasty represents the most efficacious treatment for patients presenting with secondary ischemic mitral regurgitation, as compared to restrictive mitral valve annuloplasty alone and to mitral valve replacement. A network meta-analysis was conducted to investigate outcomes of randomized controlled trials, propensity-matched studies, and observational studies, comparing various treatments for secondary ischemic mitral regurgitation. The average follow-up duration for late mortality was 4.4 years. Coronary artery bypass grafting (CABG) without mitral valve surgery had a late mortality incidence of 3.7%. Restrictive mitral annuloplasty demonstrated a rate of 6.5%, while restrictive mitral annuloplasty + CABG resulted in a rate of 4.1%. Subvalvular papillary muscle repair plus restrictive mitral annuloplasty ± CABG and mitral valve replacement + CABG had rates of 4.4% and 5.1%. SUCRA analysis showed that CABG was the most effective treatment for reducing late mortality (70.0%). This was followed by subvalvular papillary muscle repair plus restrictive mitral annuloplasty with or without CABG (62.4%). The top strategy for decreasing early death, reoperation, and readmission to the hospital for heart failure is subvalvular papillary muscle repair plus restrictive mitral annuloplasty with or without CABG, based on SUCRA probabilities (84.6%, 85.54%, and 86.3%, respectively). Subvalvular papillary muscle repair plus restrictive mitral annuloplasty ± CABG has potential to reduce the risks associated with early mortality, reoperation, and re-hospitalization for heart failure. However, further research is required to substantiate these findings.

Interpapillary muscle distance independently predicts recurrent mitral regurgitation

OBJECTIVE

Ischaemic secondary mitral regurgitation (ISMR) after surgery is due to the displacement of papillary muscles resulting from progressive enlargement of the left ventricle end-diastolic diameter (LVEDD). Our aim was to prove that if the interpapillary muscle distance (IPMD) is surgically stabilized, an increase in LVEDD will not lead to a recurrence of ischaemic mitral regurgitation (MR).

METHODS

Ninety-six patients with ISMR, who underwent surgical revascularisation and annuloplasty, were randomly assigned in a 1:1 ratio to undergo papillary muscle approximation (PMA). At the 5-year follow-up, we assessed the correlation between PMA and echocardiographic improvements, the effect size of PMA on echocardiographic improvements, and a prediction model for recurrent MR using inferential tree analysis.

RESULTS

There was a significant correlation between PMA and enhancements in both the α and β angles (Spearman's rho > 0.7, p < 0.01). The α angle represents the angle between the annular plane and either the A2 annular-coaptation line or the P2 annular-coaptation line. The β angle indicates the angle between the annular plane and either the A2 annular-leaflet tip line or the P2 annular-leaflet tip line. PMA led to substantial improvements in LVEDD, tenting area, α and β angles, with a large effect size (Hedge's g ≥ 8, 95% CI ORs ≠ 1). The most reliable predictor of recurrent MR grade was the interpapillary distance, as only patients with an interpapillary distance greater than 40 mm developed ≥ 3 + grade MR. For patients with an IPMD of 40 mm or less, the best predictor of recurrent MR grade was LVEDD. Among the patients, only those with LVEDD greater than 62 mm showed moderate (2+) MR, while only those with LVEDD less than or equal to 62 mm had absent to mild (1+) MR.

CONCLUSION

Prediction of recurrent ischaemic MR is not independent of progressive LVEDD increase. PMA-based surgical procedure stabilises IPMD.

Impact of Mitral Regurgitation Recurrence on Mitral Valve Repair for Secondary Ischemic Mitral Regurgitation

OBJECTIVES

The current guidelines still do not include specific recommendations on the use of subvalvular repair (SV-r) for treatment of ischemic mitral regurgitation (IMR). Therefore, the objective of our study was to evaluate the clinical impact of mitral regurgitation (MR) recurrence and ventricular remodeling on long-term outcomes after SV-r combined with restrictive annuloplasty (RA-r).

METHODS

We performed a subanalysis of the papillary muscle approximation trial, studying 96 patients with severe IMR and coronary artery disease undergoing restrictive annuloplasty alongside subvalvular repair (SV-r + RA-r group) or restrictive annuloplasty alone (RA-r group). We analyzed treatment failure differences, the influence of residual MR, left ventricular remodeling, and clinical outcomes. The primary endpoint was treatment failure (composite of death; reoperation; or recurrence of moderate, moderate-to-severe, or severe MR) within 5 years of follow-up after the procedure.

RESULTS

A total of 45 patients showed failure of the treatment within 5 years, of which 16 patients underwent SV-r + RA-r (35.6%) and 29 underwent RA-r (64.4%, p = 0.006). Patients with significant residual MR presented with a higher rate of all-cause mortality at 5 years compared with trivial MR (HR 9.09, 95% CI 2.08-33.33, p = 0.003). MR progression occurred earlier in the RA-r group, as 20 patients in the RA-r group vs. 6 in SV-r + RA-r group had a significant MR 2 years after surgery (p = 0.002).

CONCLUSIONS

RA-r remains a surgical mitral repair technique with an increased risk of failure and mortality at 5 years compared with SV-r. The rates of recurrent MR are higher, and recurrence occurs earlier, with RA-r alone compared to SV-r. The addition of the subvalvular repair increases the durability of the repair, thus extending all of the benefits of preventing MR recurrence.

Description, Feasibility, and Histological Assessment of the Vsling, a Novel Transcatheter Ventricular Repair Device

Background

Reshaping the dilated left ventricle using a surgically implanted papillary muscle sling has been shown to provide long-term improvement in cardiac function compared to annuloplasty alone in patients with systolic heart failure. A papillary muscle sling which can be implanted via a transcatheter approach has the potential to make this treatment more widely available to patients.

Methods

The Vsling transcatheter papillary muscle sling device was evaluated in a chronic animal model (sacrificed at 30 and 90 days), in a simulator, and in a human cadaver.

Results

The Vsling device was successfully implanted in 10 pigs, 6 simulator procedures, and 1 human cadaver. Procedure complexity and device usability were rated as reasonable or better by 6 interventional cardiologists. Gross and histological analysis in chronic pigs through 90 days demonstrated near-complete endothelial coverage with mild inflammation and small hematoma formation but without adverse tissue reactions, thrombi, or embolization.

Conclusions

Preliminary feasibility and safety of the Vsling implant and implantation procedure have been demonstrated. Human trials are planned to begin in the summer of 2022.

Surgical mitral valve repair technique considerations based on the available evidence

Mitral valve regurgitation is the second most common valve disease in the western world. Surgery is currently the best tool for generating a long-lasting elimination of mitral valve regurgitation. However, the mitral valve apparatus is a complex anatomical and functional structure, and repair results and durability show substantial heterogeneity. This is not only due to differences in the underlying mitral valve regurgitation pathophysiology but also due to differences in repair techniques. Repair philosophies differ substantially from one surgeon to the other, and consensus for the technically best repair strategy has not been reached yet. We had previously addressed this topic by suggesting that ring sizing is "voodoo". We now review the available evidence regarding the various repair techniques described for structural and functional mitral valve regurgitation. Herein, we illustrate that for structural mitral valve regurgitation, resuspension of prolapsing valve segments or torn chordae with polytetrafluoroethylene sutures and annuloplasty can generate the most durable results paired with the best achievable hemodynamics. For functional mitral valve regurgitation, the evidence suggests that annuloplasty alone is insufficient in most cases to generate durable results, and additional subvalvular strategies are associated with improved durability and possibly improved clinical outcomes. This review addresses current strategies but also implausibilities in mitral valve repair and informs the mitral valve surgeon about the current evidence. We believe that this information may help improve outcomes in mitral valve repair as the heterogeneity of mitral valve regurgitation pathophysiology does not allow a one-size-fits-all concept.

Update on surgical repair in functional mitral regurgitation

BACKGROUND

Functional mitral regurgitation (FMR) is common in patients with myocardial infarction or dilated cardiomyopathy, and portends a poor prognosis despite guideline-directed medical therapy (GDMT). Surgical or transcatheter mitral repair for FMR from recent randomized clinical trials showed disappointing or conflicting results.

AIMS

To provide an update on the role of surgical repair in the management of FMR.

MATERIALS AND METHODS

A literature search was conducted utilizing PubMed, Ovid, Web of Science, Embase, and Cochrane Library. The search terms included secondary/FMR, ischemic mitral regurgitation, mitral repair, mitral replacement, mitral annuloplasty, transcatheter mitral repair, and percutaneous mitral repair. Randomized clinical trials over the past decade were the particular focus of the current review.

RESULTS

Recent data underlined the complexity and poor prognosis of FMR. GDMT and cardiac resynchronization, when indicated, should always be applied. Accurate assessment of the interplay between ventricular geometry and mitral valve function is essential to differentiate proportionate FMR from the disproportionate subgroup, which could be helpful in selecting appropriate transcatheter intervention strategies. Surgical repair, most commonly performed with an undersized ring annuloplasty, remains controversial. Adjunctive valvular or subvalvular repair techniques are evolving and may produce improved results in selected FMR patients.

CONCLUSION

FMR resulted from complex valve-ventricular interaction and remodeling. Distinguishing proportionate FMR from disproportionate FMR is important in exploring their underlying mechanisms and to guide medical treatment with surgical or transcatheter interventions. Further studies are warranted to confirm the clinical benefit of appropriate surgical repair in selected FMR patients.

Exploring the Operative Strategy for Secondary Mitral Regurgitation: A Systematic Review

Background

Mitral valve disease surgery is an evolving field with multiple possible interventions. There is an increasing body of evidence regarding the optimal strategy in secondary mitral regurgitation where the pathology lies within the ventricle. We conducted a systematic review to identify the benefits and limitations of each surgical option.

Methods

A systematic review of the literature was performed to identify pertinent randomized controlled trials (RCTs), propensity-matched observational series, and meta-analyses which were considered initially and followed by unmatched observational series using the MEDLINE, Ovid EMBASE, and Cochrane Library.

Results

We identified 6 different strategies for treating secondary mitral valve regurgitation: mitral valve replacement, restrictive mitral annuloplasty, surgical revascularization (with and without mitral annuloplasty), subvalvular procedures (papillary muscle approximation, papillary muscle relocation, ring and string procedure), and procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement) alongside transcatheter heart valve therapy. We also highlighted the role of left ventricular assist devices in the management of this condition. The benefits and limitations of each intervention are highlighted.

Conclusion

There is currently no unanimous and shared strategy for the optimal treatment of patients with secondary IMR. The management of patients with secondary mitral regurgitation must be entrusted to a multidisciplinary Heart Team to ensure ideal intervention and patient matching for the best outcomes.

The Role of Surgical Treatment of Severe Functional Mitral Regurgitation in Heart Failure

Patient selection is mandatory to successful mitral valve repair in functional mitral valve regurgitation. Preoperative echo evaluation is critical to better evaluate the anatomic modification of the mitral apparatus. In light of recent randomized trials, several patients could benefit from transcatheter mitral therapy. Mitral annuloplasty is not effective in all patients with functional mitral valve regurgitation; meanwhile, adding surgical techniques should be performed to improve the repair durability.

Surgical repair of ischemic mitral regurgitation: one ring does not fit all

PURPOSE OF REVIEW

The review summarizes the key parameters that can aid in determining the optimal treatment of ischemic mitral regurgitation (IMR).

RECENT FINDINGS

Left ventricular (LV) and mitral valve (MV) parameters are important for surgical planning and risk stratification in IMR. Although LV dimensions is one of the main parameters used in the guidelines, volumes more accurately depict LV remodelling. Furthermore, wall motion abnormalities and wall motion score index can also be useful for surgical planning in treatment of IMR. Viability is best measured with cardiac magnetic resonance, but it is not feasible in certain centres. In contrast, measurement of strain with echocardiography is an emerging and feasible tool for estimating viability. MV leaflet tethering and pattern measured with echocardiography are also useful for MV surgery. Anterior leaflet excursion angle can identify patients in whom undersized ring annuloplasty is potentially unsuitable.

SUMMARY

Treatment of IMR relies on accurate parameters that can determine the optimal surgical approach. In some patients, lack of viable myocardium suggests inadequacy of revascularization and thus, an adjunctive left ventricular reconstruction may be necessary. Degree and pattern of MV leaflet tethering can indicate whether ring annuloplasty, which is the most common repair technique, is sufficient or an adjunctive sub-valvular intervention is beneficial.

The Use of Radial Artery for CABG: An Update

We used the radial artery as a second target conduit for coronary artery bypass grafting since 1971. However, randomized clinical studies have demonstrated differences in clinical outcomes between the radial artery and other grafts because these trials are underpowered. As we proceed toward 50 years of experience with radial artery grafting, we examined the literature to define the best second-best target vessel for coronary artery bypass grafting. The literature was reviewed with emphasis, and a large number of randomized controlled trials, propensity-matched observational series, and meta-analyses were identified with a large patient population who received arterial conduit and saphenous vein grafts. The radial artery has been shown to be effective and safe when used as a second target conduit for coronary artery bypass grafting. Results and patency rates were superior to those for saphenous vein grafting. It has also been shown that the radial artery is a safe and effective graft as a third conduit into the territory of the artery right coronary artery. However, there is little evidence based on a few comparable series limiting the use of the gastroepiploic artery. In its fifth decade of use, we can finally deduced that the aorto-to-coronary radial bypass graft is the conduit of choice for coronary operations after the left internal thoracic artery to the left anterior descending artery.

Quantitating Mitral Regurgitation in Clinical Trials: The Need for a Uniform Approach

BACKGROUND

There is an established relationship between the degree of mitral regurgitation (MR) and prognosis. Quantitation of MR severity guides therapeutic approaches. Inconsistent definitions and categorization of MR severity in clinical studies limit meaningful comparisons between trials and compromise development of an effective evidence base. The purpose of this study was to quantify heterogeneity in grading systems for MR severity in the contemporary literature.

METHODS

We performed a systematic review of randomized (RCT) and propensity score (PS) adjusted clinical studies of MV interventions (surgical or percutaneous). A total of 35 articles from 2015-2020 were included (15 RCT, 20 PS).

RESULTS

There were 22 studies that reported MR severity in numerical categories, either values from the historical "plus" system or numerical MR grades, while 9 studies reported MR severity using text-only descriptive categories. Among the studies that used numerical categories, 2+ MR was defined as moderate in 64% of studies, mild in 27%, and mild-moderate in 9% and 3+ MR was defined as moderate in 14%, moderate-severe in 52%, and severe in 14%.

CONCLUSIONS

There was substantial variability in MR severity definition and reporting in contemporary clinical studies of MV interventions. We recommend the historical "plus" numerical grading system be abandoned and that inclusion and outcome criteria in MR clinical trials be based on American and European guideline-recommended categories as none/trace, mild, moderate, and severe. Adoption of these simple recommendations will improve the consistency and quality of MR clinical trial design and reporting.

Ischemic functional mitral regurgitation: from pathophysiological concepts to current treatment options. A systemic review for optimal strategy

OBJECTIVE

The current treatment of ischemic functional mitral regurgitation (FMR) remains debated due to differences in inclusion criteria of randomized studies and baseline characteristics. Also, the role of left ventricular pathophysiology and the role of subvalvular apparatus have not been thoroughly investigated in recent literature.

METHODS

A literature search was performed from PubMed inception to June 2020.

RESULTS

Novel concepts of pathophysiology, such as the proportionate/disproportionate conceptual framework, the role of papillary muscles and left ventricular dysfunction, the impact of myocardial ischemia and revascularization, left ventricular remodeling, and the effect of restrictive annuloplasty or subvalvular procedures have been reviewed.

CONCLUSIONS

The clinical benefits associated with the use of MitraClip is more evident in patients with disproportionate FMR with greater and sustained left ventricular reverse remodeling. Importantly, in the absence of myocardial revascularization, expansion of myocardial scar tissue and non-perfused areas of ischemic myocardium occur with time, and this impact on outcomes with a longer follow-up period cannot be quantified. In advanced phases of FMR, neither mitral ring annuloplasty nor percutaneous therapies could significantly modify the established pathoanatomic alterations.

Treatment options for ischemic mitral regurgitation: A meta-analysis

BACKGROUND

Treatment of ischemic mitral regurgitation (IMR) is in evolution, as percutaneous procedures and complex surgical repair have been recently investigated in randomized clinical trials and matched studies. This study aims to review and compare the current treatment options for IMR.

METHODS

A comprehensive literature search was conducted using electronic databases. The primary outcome was all-cause long-term mortality. The secondary outcomes were perioperative mortality, unplanned rehospitalization, reoperation, and composite end points as defined in the original articles.

RESULTS

A total of 12 articles met the inclusion criteria and were included in the final meta-analysis. The MitraClip procedure did not confer a significant benefit in mortality and repeated hospitalization compared with medical therapy alone. In patients with moderate IMR, the adjunct of mitral procedure over coronary artery bypass graft is not associated with clinical improvements. When evaluating mitral valve (MV) replacement versus repair, hospital mortality was greater among patients undergoing replacement (odds ratio [OR], 1.91; P = .009), but both reoperation and readmission rates were lower (OR, 0.60, P = .05; and OR, 0.45, P < .02, respectively). Comparing restrictive annuloplasty alone with adjunctive subvalvular repair, subvalvular procedures resulted in fewer readmissions (OR, 0.50; P = .06) and adverse composite end points (P = .009).

CONCLUSIONS

MitraClip procedure is not associated with improved outcomes compared with medical therapy. MV replacement is associated with increased early mortality but reduced reoperation rate and readmission rate compared with MV repair using annuloplasty in moderate-to-severe IMR. Despite no significant benefit in isolated outcomes comparing annular and adjunct subvalvular procedures, the adjunct of subvalvular procedures reduces the risk of major postoperative adverse events.

Mitral regurgitation: lessons learned from COAPT and MITRA-Fr

Recent studies about percutaneous treatment of secondary mitral regurgitation (MR) underlined the importance of left ventricular geometry and features of mitral valve as determinants of procedural and long-term success. Guideline-directed medical therapy (GDMT), transcatheter mitral valve treatment (TMVT) and surgical procedures (mitral valve replacement, mitral valve repair at level of the annulus or subvalvular apparatus) have been extensively evaluated but not adequately compared in current clinical studies. A detailed analysis of the results of the study about transcatheter mitral valve repair would allow to evaluate the safety and effectiveness of such procedure and would provide potential indications for improving the quality of percutaneous and surgical repair in patients with moderate-to-severe secondary MR. Patients with proportionate MR (i.e., MR severity is proportional to the amount of left ventricular dilatation) are prone to respond to the optimization of medical therapy, while patients with disproportionate MR (i.e., MR severity is disproportionately higher than predicted by left ventricular dilatation, with high EROA and small left ventricle) are likely to benefit from additional repair. The identification of specific subpopulation of "high responders", based on the anatomic characteristics of the mitral valve and the relative dimensions of the annulus, the regurgitation and the left ventricle, can also apply to medical therapy. However, some pivotal component of MR (such as the symmetry of tethering and the differences in biomechanical features of leaflets) are not adequately investigated in current studies and warrant further evaluation.

The Choice of Treatment in Ischemic Mitral Regurgitation With Reduced Left Ventricular Function

BACKGROUND

Ischemic mitral regurgitation is a condition characterized by mitral insufficiency secondary to an ischemic left ventricle. Primarily, the pathology is the result of perturbation of normal regional left ventricular geometry combined with adverse remodeling. We present a comprehensive review of contemporary surgical, medical, and percutaneous treatment options for ischemic mitral regurgitation, rigorously examined by current guidelines and literature.

METHODS

We conducted a literature search of the PubMed database, Embase, and the Cochrane Library (through November 2018) for studies reporting perioperative or late mortality and echocardiographic outcomes after surgical and nonsurgical intervention for ischemic mitral regurgitation.

RESULTS

Treatment of this condition is challenging and often requires a multimodality approach. These patients usually have multiple comorbidities that may preclude surgery as a viable option. A multidisciplinary team discussion is crucial in optimizing outcomes. There are several options for treatment and management of ischemic mitral regurgitation with differing benefits and risks. Guideline-directed medical therapy for heart failure is the treatment choice for moderate and severe ischemic mitral regurgitation, with consideration of coronary revascularization, mitral valve surgery, cardiac resynchronization therapy, or a combination of these, in appropriate candidates. The use of transcatheter mitral valve therapy is considered appropriate in high-risk patients with severe ischemic mitral regurgitation, heart failure, and reduced left ventricular ejection fraction, especially in those with hemodynamic instability.

CONCLUSIONS

The role of mitral valve surgery and transcatheter mitral valve therapy continues to evolve.

Euler's Elastica-Based Biomechanics of the Papillary Muscle Approximation in Ischemic Mitral Valve Regurgitation: A Simple 2D Analytical Model

Ischemic mitral regurgitation (IMR) occurs as an adverse consequence of left ventricle remodeling post-myocardial infarction. A change in mitral valve configuration with an imbalance between closing and tethering forces underlie this pathological condition. These abnormalities lead to impaired leaflet coaptation and a variable degree of mitral regurgitation, which can in turn influence the ventricular filling status, the heart rhythm and the afterload regardless of the residual ischemic insult. The IMR correction can be pursued through under-sizing mitral annuloplasty and papillary muscle approximation to restore the mitral valve and left ventricle physiological geometry to, consequently, achieve normalization of the engaged physical forces. Because the structures involved undergo extremely large deformations, a biomechanics model based on the Euler's Elastica -the mitral leaflet- interlaced with nonlinear chordae tendineae anchored on papillary muscles has been constructed to elucidate the interactions between closing and tethering forces. The model takes into account the actual updated geometrical and mechanical features of the valvular and subvalvular apparatuses in physiological and IMR conditions, as well as in case of papillary muscle approximation, finally furnishing ad hoc geometry-based mathematical relations that could be utilised to support-and optimize-the relevant choices in cardiac surgery.

Can We Predict Failure of Mitral Valve Repair?

Objective: To identify echocardiographic and surgical risk factors for failure after mitral valve repair. Methods: We identified a total of 77 consecutive patients from our institutional mitral valve surgery database who required redo mitral valve surgery due to recurrence of mitral regurgitation after primary mitral valve repair. A control group of 138 patients who had a stable echocardiographic long-term result was included based on propensity score matching. Systematic analysis of echocardiographic parameters was performed before primary surgery; after mitral valve repair and prior to redo surgery. Risk factor analysis was performed using multivariate Cox regression model. Results: Redo surgery was associated with the presence of pulmonary hypertension ≥ 50 mmHg (p = 0.02), a mean transmitral gradient > 5 mmHg (p = 0.001), left ventricular ejection fraction ≤ 45% (p = 0.05) before surgery and mitral regurgitation ≥moderate at time of discharge (p = 0.002) in the whole cohort. Patients with functional mitral valve regurgitation had a higher tendency to undergo redo surgery if preoperative left ventricular end-diastolic diameter exceeded 65 mm (p = 0.043) and if postoperative tenting height exceeded 6 mm (p = 0.018). Low ejection fraction was not significantly associated with the need for redo mitral valve surgery in the functional subgroup. Conclusions: Recurrent mitral regurgitation is still a valuable problem and is associated with relevant perioperative mortality. Patients with severe mitral regurgitation should undergo early mitral valve repair surgery as long as systolic pulmonary artery pressure is low, left ventricular ejection fraction is preserved, and LVEED is deceeds 65 mm.

Risk of Ischemic Mitral Regurgitation Recurrence After Combined Valvular and Subvalvular Repair

BACKGROUND

Mitral valve repair (MVr) combined with papillary muscle approximation (PMA) may improve repair durability in severe ischemic mitral regurgitation (MR), when compared with MVr alone. We sought to identify preoperative transthoracic echocardiographic markers associated with MR recurrence after MVr with PMA.

METHODS

A post-hoc analysis was performed on patients with severe ischemic MR who underwent coronary artery bypass graft surgery with MVr with PMA in the papillary muscle approximation randomized trial. The PMA was performed utilizing a 4-mm polytetrafluoroethylene graft placed around the papillary muscles. Linear regression analyses and receiver-operating characteristic curves were used to identify echocardiographic variables and diagnostic models associated with recurrent MR.

RESULTS

There were 48 patients with a mean age of 63 ± 7 years, a left ventricular ejection fraction of 35% ± 5%, and a left ventricular end-diastolic diameter of 63 ± 3 mm. Of these, 37 patients had baseline and 5-year follow-up echocardiograms, with moderate-to-severe MR recurring in 27%. Linear regression analyses revealed associations between preoperative pulmonary artery systolic pressure (standardized beta coefficient, β = 0.49/mm Hg, p = 0.002), MV tenting area (β = 0.47/cm², p = 0.004), a symmetric MV tethering pattern (β = 0.44, p = 0.007), and left ventricular end-diastolic diameter (β = 0.37/mm, p = 0.02) with follow-up MR grade. The presence of both MV tenting area 3.1 cm² or greater (area under the curve 0.822) and left ventricular end-diastolic diameter of 64 mm or greater (area under the curve 0.801) was the most robust discriminative model for moderate-to-severe MR recurrence (specificity 92%, sensitivity 69%, area under the curve 0.804, p = 0.003).

CONCLUSIONS

In patients undergoing coronary artery bypass graft surgery with MVr plus PMA, the extent of baseline MV apparatus and left ventricle geometric remodeling identifies patients at increased risk for MR recurrence.

Do annuloplasty rings designed to treat ischemic/functional mitral regurgitation alter left-ventricular dimensions in the acutely ischemic ovine heart?

OBJECTIVE

To quantify the effects of annuloplasty rings designed to treat ischemic/functional mitral regurgitation on left ventricular septal-lateral (S-L) and commissure-commissure (C-C) dimensions.

METHODS

Radiopaque markers were placed as opposing pairs on the S-L and C-C aspects of the mitral annulus and the basal, equatorial, and apical level of the left ventricle (LV) in 30 sheep. Ten true-sized Carpentier-Edwards Physio (PHY), Edwards IMR ETlogix (ETL), and GeoForm (GEO; all from Edwards Lifesciences, Irvine, Calif) annuloplasty rings were inserted in a releasable fashion. After 90 seconds of left circumflex artery occlusion with the ring implanted (RING), 4-dimensional marker coordinates were obtained using biplane videofluoroscopy. After ring release, another data set was acquired after another 90 seconds of left circumflex artery occlusion (NO RING). S-L and C-C diameters were computed as the distances between the respective marker pairs at end-diastole. Percent change in diameters was calculated between RING versus NO RING as 100 × (diameter in centimeters [RING] - diameter in centimeters [NO RING])/diameter in centimeters [NO RING]).

RESULTS

Compared with NO RING, all ring types (PHY, ETL, and GEO) reduced mitral annular S-L dimensions by -20.7 ± 5.6%, -26.8 ± 3.9%, and -34.5 ± 3.8%, respectively. GEO reduced the S-L dimensions of the LV at the basal level only by -2.3 ± 2.4%, whereas all other S-L dimensions of the LV remained unchanged with all 3 rings implanted. PHY, ETL, and GEO reduced mitral annular C-C dimensions by -17.5 ± 4.8%, -19.6 ± 2.5, and -8.3 ± 4.9%, respectively, but none of the rings altered the C-C dimensions of the LV.

CONCLUSIONS

Despite radical reduction of mitral annular size, disease-specific ischemic/functional mitral regurgitation annuloplasty rings do not induce relevant changes of left ventricular dimensions in the acutely ischemic ovine heart.

Characterization of 3-dimensional papillary muscle displacement in in vivo ovine models of ischemic/functional mitral regurgitation

OBJECTIVE

Papillary muscle (PM) displacement contributes to ischemic/functional mitral regurgitation (IMR/FMR). The displaced PMs pull the mitral leaflets into the left ventricle (ie, toward the apex) thus hampering leaflet coaptation. Intuitively apical leaflet tethering results from apical PM displacement. The 3-dimensional directions of PM displacement are, however, incompletely characterized.

METHODS

Data from in vivo ovine models of IMR (6-8 weeks of posterolateral infarction, n = 12) and FMR (9-21 days of rapid left ventricular pacing, n = 11) were analyzed. All sheep had radiopaque markers implanted on the anterior and posterior PM (PPM) tips, around the mitral annulus, and on the left ventricular apex. To explore 3-dimensional PM displacement directions, differences in marker coordinates were calculated at end-systole before and during IMR/FMR using a right-handed coordinate system centered on the mitral annular "saddle horn" with the y-axis passing through the apical marker.

RESULTS

No apical PM displacement was observed during either IMR or FMR. The anterior PM displaced laterally during FMR. Posterolateral PPM displacement was observed during IMR and FMR.

CONCLUSIONS

Experimental in vivo ovine models suggest posterolateral PPM displacement as a predominant pathomechanism leading to apical leaflet tethering during IMR/FMR.

Mitral Valve and Subvalvular Repair for Secondary Mitral Regurgitation: Rationale and Clinical Outcomes of the Papillary Muscle Sling

Secondary mitral regurgitation (MR) is a common finding in patients with dilated cardiomyopathy, and it is associated with poor outcomes. It is the result of incomplete systolic closure of the mitral valve (MV) as a consequence of left ventricular dilatation, papillary muscle displacement with impaired systolic shortening, and mitral leaflet tethering. MV surgery may be performed in cases of significant secondary MR despite guideline-directed medical therapy. However, MV repair, which is most commonly performed with an undersized ring annuloplasty, is associated with a 30-60% recurrence of moderate or greater MR at mid-term follow-up. To improve MV repair durability, several adjunctive subvalvular procedures have been proposed, one of which is the addition of papillary muscle approximation utilizing a papillary muscle sling. Recent studies comparing the outcomes of a conventional undersized ring annuloplasty with a MV repair utilizing a papillary muscle sling have reported a significant reduction in recurrent moderate or severe MR, greater left ventricular reverse remodeling, and improved MV apparatus geometry with the addition of the papillary muscle sling. We present a comprehensive review of the pathophysiology of secondary MR, and the rationale and clinical outcomes of MV repair with papillary muscle sling placement for the treatment of secondary MR.

Functional mitral regurgitation: an overview for surgical management framework

Functional mitral regurgitation (FMR) is one the most common complications of myocardial infarction (MI) in adults carrying a significant clinical and economic burden. Despite specific randomized controlled studies to address its treatment have been performed, there are still a number of questions remained unanswered. Outcomes of surgical repair of FMR are still hampered by a significant rate of recurrence of regurgitation and need for reoperation. Mechanisms underlying failure of repairs still need to be completely clarified and questions regarding the indications and optimal timing for intervention as well as the best suitable operative technique to be applied are still debated. This work will review the current knowledge on FMR including its pathogenic mechanisms, the available treatment strategies, the evidences from trials and observational studies and the potential future directions to address the issues related to its treatment.

Analysing the reasons of failure of surgical mitral repair approaches-do we need to better think in biomechanics?

The failure of mitral valve repair procedures revealed in the outcomes of the recent randomized studies is suggesting the necessity for a better understanding of the biomechanical mechanisms underlying the failure of the surgical approaches. Use of biomechanical modelling and finite element analysis (FEA) in cardiovascular research is an important aid in this context. In our group we developed a biomechanical model taking into account all the component of the mitral valve functional unit including the valve leaflets, the annulus, the papillary muscles, the chordae tendinea and the ventricular geometry. The two-dimensional mathematical model was capable to predict some of the actual geometrical and mechanical features of the valvular and subvalvular apparatuses in physiological and pathological conditions providing the engineering quantitative relations between closing and tethering forces and the mechanisms governing the mitral valve unit function. This model might further become patient-specific by means of 3D reconstruction of clinical imaging. Images are first converted in a standard vector format (DICOM, etc.), then automatically translated in a "structural" finite element model and finally implemented in a finite element code. This allows for in silico simulations to virtually explore the effects of different surgical approaches at an early stage after the procedure, to help the operative decision processes, or to optimize the design of surgical implants.

Mitral valve repair and subvalvular intervention for secondary mitral regurgitation: a systematic review and meta-analysis of randomized controlled and propensity matched studies

BACKGROUND

Combining a ring annuloplasty (Ring) with a mitral subvalvular intervention (Ring + subvalvular) in patients with secondary mitral regurgitation (MR) may improve mitral valve (MV) repair durability. However, the outcomes of this strategy compared with a Ring only, have not been clearly defined.

METHODS

A systematic review and meta-analysis was performed utilizing randomized controlled and propensity matched studies which compared a Ring + subvalvular versus Ring MV repair for the treatment of secondary MR. Risk ratio (RR), weighted mean difference (MD), and the 95% confidence interval (CI) were calculated by the Mantel-Haenszel and inverse-variance methods, for clinical outcomes and echocardiographic measures of follow-up MR, left ventricular (LV) reverse remodeling, and MV apparatus geometry.

RESULTS

Five studies were identified, with a total of 397 patients. Baseline characteristics were similar between groups, and all patients had moderate to severe secondary MR, with the vast majority in the setting of ischemic cardiomyopathy. A Ring + subvalvular repair consisted of papillary muscle approximation (n=2), papillary muscle relocation (n=2), or secondary chordal cutting (n=1). Follow-up ranged from 10.1 (mean range =0.25-42) to 69 [interquartile range (IQR) =23-82] months. When compared with Ring only at last follow-up, a Ring + subvalvular MV repair was associated with: (I) a smaller MR grade (MD =-0.44, 95% CI -0.69 to -0.19; P=0.0005); (II) a reduced risk of moderate or greater recurrent MR (RR =0.43, 95% CI, 0.27-0.66; P=0.0002); (III) a smaller mean LV end-diastolic diameter (MD =-3.56 mm, 95% CI -5.40 to -1.73; P=0.0001) and a greater ejection fraction (MD =2.64%, 95% CI, 0.13-5.15; P=0.04); and, (IV) an improved MV apparatus geometry. There were no differences in operative mortality, post-operative morbidity, or follow-up survival between surgical approaches.

CONCLUSIONS

When compared with Ring only, a Ring + subvalvular MV repair is associated with greater LV reverse remodeling and systolic function, less recurrence of moderate or greater MR, and an improved geometry of the MV apparatus at short and mid-term follow-up.

Papillary muscle approximation in mitral valve repair for secondary MR

Ischemic mitral regurgitation (IMR) is a complex disorder occurring after a myocardial infarction and affecting both the mitral valvular and subvalvular apparati. Several abnormalities can be detected in IMR as annular dilatation, leaflet tethering with impaired coaptation and papillary muscle (PM) displacement along a posterior, apical or lateral vectors. Treatments available include, beside myocardial revascularization, mitral-valve repair or chordal-sparing replacement. Repair is normally achieved downsizing the mitral valve annulus with a rigid or semirigid ring. However, considering the involvement of the subvalvular apparatus, techniques addressing the PM have been developed. The rationale at the basis of this strategy relies in the possibility to reduce the interpapillary muscle distance restoring the geometry of the left ventricle (LV) and ultimately resolving the leaflet tethering at the basis of IMR. Subvalvular apparatus surgical approaches include the papillary muscle approximation (PMA), surgical relocation and PM sling. Improved outcomes in terms of postoperative positive left ventricular remodeling and recurrence of mitral regurgitation have been reported, but more investigations are required to confirm the efficacy of subvalvular apparatus surgery. Application of finite element analysis to improve preoperative and intraoperative planning and achieve a correct and durable repair by means of subvalvular surgery is an exciting new avenue in IMR research.

Biomechanics raises solution to avoid geometric mitral valve configuration abnormalities in ischemic mitral regurgitation

Ischemic mitral regurgitation (IMR) is a form of mitral insufficiency that is characterized by papillary muscle (PM) displacement, leaflet tethering, reduced closing forces, and different degree of annular dilatation. Treatment of this condition includes mitral valve replacement or mitral valve repair with restrictive annuloplasty. Recent evidences in mitral valve repair showed that addressing only the annulus and neglecting the subvalvular apparatus provides a suboptimal operation with poor long-term results. However, the complexity of the geometrical aberrances occurring in IMR demands for more accurate analysis also involving the biomechanics underlying the failing mitral valve and subvalvular apparatus. Finite element analysis (FEA) is a powerful tool in this context and we developed a biomechanical model of mitral valve and subvalvular unit using 3D geometry of the leaflets, annulus, chordae and PM. After the application of structural properties of materials to these elements and simulation of systemic pressure loading, FEA could be used to directly determine biomechanical changes and geometry variations. We believe this approach can provide valuable information to better address the surgical treatment of IMR and answer some of the questions still pending in IMR management.

Cardiac surgery 2016 reviewed

For the year 2016, more than 20,000 published references can be found in Pubmed when entering the search term "cardiac surgery". Publications last year have helped to more clearly delineate the fields where classic surgery and modern interventional techniques overlap. The field of coronary bypass surgery (partially compared to percutaneous coronary intervention) was enriched by five large prospective randomized trials. The value of CABG for complex coronary disease was reconfirmed and for less complex main stem lesions, PCI was found potentially equal. For aortic valve treatment, more evidence was presented for the superiority of transcatheter aortic valve implantation for patients with intermediate risk. However, the 2016 evidence argued against the liberal expansion to the low-risk field, where conventional aortic valve replacement still appears superior. For the mitral valve, many publications emphasized the significant impact of mitral valve reconstruction on survival in structural mitral regurgitation. In addition, there were many relevant and other interesting contributions from the purely operative arena in the fields of coronary revascularization, surgical treatment of valve disease, terminal heart failure (i.e., transplantation and ventricular assist devices), and aortic surgery. While this article attempts to summarize the most pertinent publications it does not have the expectation of being complete and cannot be free of individual interpretation. As in recent years, it provides a condensed summary that is intended to give the reader "solid ground" for up-to-date decision-making in cardiac surgery.