Mitral valve repair in asymptomatic patients with severe mitral regurgitation: pushing past the tipping point

Transcatheter mitral valve therapies: State of the art

Mitral regurgitation (MR) is one of the most prevalent valvular pathologies in the developed world. There continues to be a growing population of aging patients with MR who may be too high risk for surgical management. The rapid adoption and remarkable success of transcatheter aortic valve replacement (TAVR) generated enthusiasm for transcatheter mitral valve therapies; however, the complex anatomy and pathophysiology of the mitral valve confers several unique challenges for a fully percutaneous approach. Nevertheless, several devices are under development and in various phases of preclinical or clinical testing, both for transcatheter mitral valve replacement and repair. MitraClip (Abbott Vascular), which has received FDA approval, is the most established percutaneous repair strategy and has been performed in over 80,000 patients as of 2019. The following article serves as a review of the available and upcoming devices for the various etiologies of mitral valvular disease, as well as the unique challenges and potential complications of transcatheter mitral valve intervention.

Robotic Mitral Valve Repair: Indication for Surgery Does Not Influence Early Outcomes

OBJECTIVE

To evaluate the outcomes of robotic mitral valve repair (MVr) by primary indication per American Heart Association guidelines for surgery: class I vs class IIa.

PATIENTS AND METHODS

From January 1, 2008, through September 30, 2016, 603 patients underwent robotic MVr for severe primary mitral regurgitation. Medical records of 576 consenting patients were retrospectively reviewed to determine the primary indication for surgery. Patients were stratified into class I or class IIa, and preoperative, intraoperative, and postoperative variables were compared.

RESULTS

Of 516 patients, 428 (83%) had class I indication and 88 (17%) had class IIa indication for surgery. Preoperatively, no significant differences were observed between both cohorts. Importantly, a significantly higher number of patients with class I indication underwent MVr for bileaflet prolapse (172 of 428 [40%] vs 21 of 88 [25%]; P=.03). Early MVr outcomes indicated recurrent mitral regurgitation (moderate or greater) in only 12 of 576 (2%), and no significant differences were observed between classes (P=.23). Apart from parameters for ventricular size, all other intraoperative and postoperative variables were comparable between both cohorts.

CONCLUSION

Comparable outcomes were indicated across all classes of indications for MVr surgery. These results continue to support the use of this surgical technique, even in less sick patients. Early referral along with more extensive robotic MVr experience will likely result in further improvements in long-term outcomes.

Transcatheter Mitral Valve Therapy: Defining the Patient Who Will Benefit

PURPOSE OF REVIEW

This report aims to define the clinical and anatomic variables key in determining patient suitability for transcatheter mitral valve therapies.

RECENT FINDINGS

Candidacy for transcatheter mitral valve repair requires weighing the clinical variables that may impact the ability to improve patient symptoms and prolong survival that include left ventricular ejection fraction, symptom severity, pulmonary hypertension, and magnitude of residual regurgitation or stenosis. Individualized selection of transcatheter repair or replacement based on patho-anatomy is being explored. The primary goal is achieving significant reduction in mitral regurgitation. Transcatheter mitral valve replacement requires rigorous anatomic screening using computed tomography and candidates should be able to take oral anticoagulation. Selection of patients for transcatheter mitral valve repair is complex and requires intimate knowledge of clinical variables and specific device limitations.

Timing of invasive septal reduction therapies and outcome of patients with obstructive hypertrophic cardiomyopathy

BACKGROUND

Whether early vs. delayed referral to septal reduction therapies (SRT, alcohol septal ablation or surgical myectomy) bears prognostic relevance in hypertrophic obstructive cardiomyopathy (HOCM) is unresolved. We analyzed the impact of SRT timing on the outcome of HOCM patients.

METHODS

We followed 126 patients for 5 ± 4 years after SRT (mean age 53 ± 15 years; 55 post-ASA and 71 post-SM). Based on time-to-treatment (TTT; from HOCM diagnosis to SRT), patients were divided into three groups: "<3" years, N = 50; "3-5" years, N = 25; ">5" years, N = 51.

RESULTS

Patients with TTT > 5 years were younger at diagnosis and more often had atrial fibrillation (AF). Left ventricular outflow tract (LVOT) gradients were comparable in the 3 TTT groups. Two patients died peri-operatively, all with TTT > 5. Long-term, 8 patients died (3 suddenly and 5 due to heart failure). Mortality increased progressively with TTT (2% vs. 4% vs. 12% for TTT "<3", "3-5", and ">5" years, p for trend = 0.039). Independent predictors of disease progression (new-onset AF, worsening to NYHA III/IV symptoms, re-intervention or death) were TTT ("3-5" vs. "<3" years: HR: 4.988, 95%CI: 1.394-17.843; ">5" vs. "<3" years: HR: 3.420, 95%CI: 1.258-9.293, overall p-value = 0.025), AF at baseline (HR: 1.896, 95%CI: 1.002-3.589, p = 0.036) and LVOT gradient (HR per mm Hg increase: 1.022, 95%CI: 1.007-1.024, p = 0.023).

CONCLUSIONS

Delay in SRT referral has significant impact on long-term outcome of patients with HOCM, particularly when >5 years from first detection of gradient, even when successful relief of symptoms and gradient is achieved. Earlier interventions are associated with lower complication rates and better prognosis, suggesting the importance of timely SRT to maximize treatment benefit and prevent late HOCM-related complications.

Simple versus complex degenerative mitral valve disease

OBJECTIVES

At a center where surgeons favor mitral valve (MV) repair for all subsets of leaflet prolapse, we compared results of patients undergoing repair for simple versus complex degenerative MV disease.

METHODS

From January 1985 to January 2016, 6153 patients underwent primary isolated MV repair for degenerative disease, 3101 patients underwent primary isolated MV repair for simple disease (posterior prolapse), and 3052 patients underwent primary isolated MV repair for complex disease (anterior or bileaflet prolapse), based on preoperative echocardiographic images. Logistic regression analysis was used to generate propensity scores for risk-adjusted comparisons (n = 2065 matched pairs). Durability was assessed by longitudinal recurrence of mitral regurgitation and reoperation.

RESULTS

Compared with patients with simple disease, those undergoing repair of complex pathology were more likely to be younger and female (both P values < .0001) but with similar symptoms (P = .3). The most common repair technique was ring/band annuloplasty (3055/99% simple vs 3000/98% complex; P = .5), followed by leaflet resection (2802/90% simple vs 2249/74% complex; P < .0001). Among propensity-matched patients, recurrence of severe mitral regurgitation 10 years after repair was 6.2% for simple pathology versus 11% for complex pathology (P = .007), reoperation at 18 years was 6.3% for simple pathology versus 11% for complex pathology, and 20-year survival was 62% for simple pathology versus 61% for complex pathology (P = .6).

CONCLUSIONS

Early surgical intervention has become more common in patients with degenerative MV disease, regardless of valve prolapse complexity or symptom status. Valve repair was associated with similarly low operative risk and time-related survival but less durability in complex disease. Lifelong annual echocardiographic surveillance after MV repair is recommended, particularly in patients with complex disease.

Outcome and undertreatment of mitral regurgitation: a community cohort study

BACKGROUND

Mitral regurgitation is the most common valve disease worldwide but whether the community-wide prevalence, poor patient outcomes, and low rates of surgical treatment justify costly development of new therapeutic interventions remains uncertain. Therefore, we did an observational cohort study to assess the clinical characteristics, outcomes, and degree of undertreatment of mitral regurgitation in a community setting.

METHODS

We used data from Mayo Clinic electronic health records and the Rochester Epidemiology Project to identify all cases of moderate or severe isolated single-valvular mitral regurgitation (with no other severe left-sided valvular disease or previous mitral surgery) diagnosed during a 10-year period in the community setting in Olmsted County (MN, USA). We assessed clinical characteristics, mortality, heart failure incidence, and results of cardiac surgery post-diagnosis.

FINDINGS

Between Jan 1, 2000, and Dec 31, 2010, 1294 community residents (median age at diagnosis 77 years [IQR 66-84]) were diagnosed with moderate or severe mitral regurgitation by Doppler echocardiography (prevalence 0·46% [95% CI 0·42-0·49] overall; 0·59% [0·54-0·64] in adults). Left-ventricular ejection fraction below 50% was frequent (recorded in 538 [42%] patients), and these patients had a slightly lower regurgitant volume than those with an ejection fraction of 50% or higher (mean 39 mL [SD 16] vs 45 mL [21], p<0·0001). Post-diagnosis mortality was mainly cardiovascular in nature (in 420 [51%] of 824 patients for whom the cause of death was available) and higher than expected for residents of the county for age or sex (risk ratio [RR] 2·23 [95% CI 2·06-2·41], p<0·0001). This excess mortality affected all subsets of patients, whether they had a left-ventricular ejection fraction lower than 50% (RR 3·17 [95% CI 2·84-3·53], p<0·0001) or of 50% or higher (1·71 [1·53 -1·91], p<0·0001) and with primary mitral regurgitation (RR 1·73 [95% CI 1·53-1·96], p<0·0001) or secondary mitral regurgitation (2·72 [2·48-3·01], p<0·0001). Even patients with a low comorbidity burden combined with favourable characteristics such as left-ventricular ejection fraction of 50% or higher (RR 1·28 [95% CI 1·10-1·50], p<0·0017) or primary mitral regurgitation (1·29 [1·09-1·52], p=0·0030) incurred excess mortality. Heart failure was frequent (mean 64% [SE 1] at 5 years postdiagnosis), even in patients with left-ventricular ejection fraction of 50% or higher (49% [2] at 5 years postdiagnosis) or in those with primary mitral regurgitation (48% [2]). Mitral surgery was ultimately done in only 198 (15%) of 1294 patients, of which the predominant type of surgery was valve repair (in 149 [75%] patients). Mitral surgery was done in 28 (5%) of 538 patients with left-ventricular ejection fraction below 50% and in 170 (22%) of 756 patients with ejection fraction of 50% or higher, and in 34 (5%) of 723 with secondary mitral regurgitation versus 164 (29%) of 571 with primary regurgitation. All other types of cardiac surgery combined were performed in only 3% more patients (237 [18%] patients) than the number who underwent mitral surgery.

INTERPRETATION

In the community, isolated mitral regurgitation is common and is associated with excess mortality and frequent heart failure postdiagnosis in all patient subsets, even in those with normal left-ventricular ejection fraction and low comorbidity. Despite these poor outcomes, only a minority of affected patients undergo mitral (or any type of cardiac) surgery even in a community with all means of diagnosis and treatment readily available and accessible. This suggests that in a wider population there might be a substantial unmet need for treatment for this disorder.

FUNDING

Mayo Clinic Foundation.

Robotic surgery is the optimal approach for mitral surgery

This report presented an overview of the patient selection, technical considerations and clinical evidence for robotic mitral valve surgery. A review of comparative outcomes to medical therapy, sternotomy approach, and the MitraClip device suggested that robotic mitral valve surgery is safe and effective in specialized centres. Potential benefits include a reliable and durable repair, with reduced perioperative morbidity and improved quality of life. Future studies should aim to delineate mid- and long-term clinical and echocardiographic outcomes following robotic mitral valve repair compared to the conventional sternotomy approach.

Minimally invasive mitral valve surgery through a right mini-thoracotomy

Since its introduction in the mid-1990s, minimally invasive mitral valve surgery (MIMVS) has been shown to be a feasible alternative to a conventional full-sternotomy approach, and several studies have reported excellent clinical outcomes with low perioperative morbidity and mortality. As a result, MIMVS is being increasingly employed as a routine procedure worldwide. On the other hand, several issues have been raised, including complications specific to this technique and its steep learning curve, while there are also concerns regarding the durability of a mitral valve repair through a limited access. In this study, the current status and future perspectives of MIMVS were examined.

Year in review: mitral valve surgery

PURPOSE OF REVIEW

In the past year, there has been progress on several fronts in the field of mitral valve surgery and intervention. Here, we review key publications regarding the surgical and transcatheter management of mitral valve disease.

RECENT FINDINGS

This past year heralded the publication of the 2014 American Heart Association (AHA)/American College of Cardiology (ACC) Guidelines for the Management of Patients With Valvular Heart Disease. Regarding degenerative mitral regurgitation, low risk of operative mortality and data demonstrating clinical benefit for early surgery are prompting renewed calls for early intervention before guideline-based triggers. For functional mitral regurgitation, the precise roles of chordal-sparing replacement versus repair and the optimal management of moderate disease at the time of surgical revascularization are unclear. Sternal-sparing minimally invasive mitral valve surgery has become a mature procedure in experienced centers and offers comparable surgical morbidity and mortality with superior cosmesis and faster return to baseline function. Transcatheter interventions for mitral regurgitation continue to undergo development and testing. Mounting experience and ongoing clinical trials with the MitraClip endovascular edge-to-edge repair device will provide important data on the optimal target population for this device.

SUMMARY

This past year has seen important advances in the surgical treatment of degenerative and functional mitral regurgitation as well as continued refinement of transcatheter interventions.

Early surgical intervention or watchful waiting for the management of asymptomatic mitral regurgitation: a systematic review and meta-analysis

BACKGROUND

Discordance between studies drives continued debate regarding the best management of asymptomatic severe mitral regurgitation (MR). The aim of the present study was to conduct a systematic review and meta-analysis of management plans for asymptomatic severe MR, and compare the effectiveness of a strategy of early surgery to watchful waiting.

METHODS

A systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies were excluded if they: (I) lacked a watchful waiting cohort; (II) included symptomatic patients; or (III) included etiologies other than degenerative mitral valve disease. The primary outcome of the study was all-cause mortality at 10 years. Secondary outcomes included operative mortality, repair rate, repeat mitral valve surgery, and development of new atrial fibrillation.

RESULTS

Five observational studies were eligible for review and three were included in the pooled analysis. In asymptomatic patients without class I triggers (symptoms or ventricular dysfunction), pooled analysis revealed a significant reduction in long-term mortality with an early surgery approach [hazard ratio (HR) =0.38; 95% confidence interval (CI): 0.21-0.71]. This survival benefit persisted in a sub-group analysis limited to patients without class II triggers (atrial fibrillation or pulmonary hypertension) [relative risk (RR) =0.85; 95% CI: 0.75-0.98]. Aggregate rates of operative mortality did not differ between treatment arms (0.7% vs. 0.7% for early surgery vs. watchful waiting). However, significantly higher repair rates were achieved in the early surgery cohorts (RR =1.10; 95% CI: 1.02-1.18).

CONCLUSIONS

Despite disagreement between individual studies, the present meta-analysis demonstrates that a strategy of early surgery may improve survival and increase the likelihood of mitral valve repair compared with watchful waiting. Early surgery may also benefit patients when instituted prior to the development of class II triggers.