Primum non nocere: the case for watchful waiting in asymptomatic "severe" degenerative mitral regurgitation

Recovery of left ventricular function after surgery for aortic and mitral regurgitation with heart failure

Background

Severe aortic regurgitation (AR) and mitral regurgitation (MR) can lead to left ventricular (LV) systolic dysfunction; however, there are limited data about recovery of LV after surgery for AR or MR. Little is known to guide the management of combined AR and MR (mixed valvular heart disease [VHD]). This study is sought to investigate the predictors of postoperative LV function recovery in left-sided regurgitant VHD with reduced left ventricular ejection fraction (LVEF), especially for mixed VHD.

Methods

From 2010 to 2020, 2053 adult patients underwent aortic or mitral valve surgery at our center. The patients with valvular stenosis, infective endocarditis, concomitant revascularization, and preoperative LVEF ≥40 % were excluded. A total of 127 patients were included in this study: 22 patients with predominant AR (AR group), 64 with predominant MR (MR group), and 41 with combined AR and MR (AMR group).

Results

The mean preoperative LVEF was 32.4 %, 30.7 %, and 30.2 % (p = 0.44) in the AR, MR, and AMR groups, respectively. The AR group was more likely to have postoperative LVEF recovery. The cut-point of left ventricular end-systolic diameter (LVESD) for better recovery was 49 mm for the MR group and 58 mm for the AMR group.

Conclusion

LV dysfunction due to combined AR and MR has similar remodeling reserve as AR, and better recoverability than MR. Thus, double-valve surgery is recommended before the LVESD is > 58 mm.

Disparities in quantification of mitral valve regurgitation between cardiovascular magnetic resonance imaging and trans-thoracic echocardiography: a systematic review

Primary mitral regurgitation (MR) is a prevalent valvular heart disease. Therapy stratification for MR depends on accurate assessment of MR severity and left ventricular (LV) dimensions. While trans-thoracic echocardiography (TTE) has been the standard/preferred assessment method, cardiovascular magnetic resonance imaging (CMR) has gained recognition for its superior assessment of LV dimensions and MR severity. Both imaging modalities have their own advantages and limitation for therapy guidance. However, the differences between the two modalities for assessing/grade severity and clinical impact of MR remains unclear. This systematic review aims to evaluate the differences between TTE and CMR in quantifying MR severity and LV dimensions, providing insights for optimal clinical management. A literature search was performed from inception up to March 21st 2023. This resulted in 2,728 articles. After screening, 22 articles were deemed eligible for inclusion in the meta-analysis. The included study variables were, mitral valve regurgitation volume (MRVOL), regurgitation fraction (MRFRAC), LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV stroke volume (LVSV), and LV ejection fraction (LVEF). TTE showed a significant higher MRVOL (10.4 ml, I2 = 88%, p = 0.002) and MRFRAC (6.3%, I2 = 51%, p = 0.05) compared to CMR, while CMR demonstrated a higher LVEDV (21.9 ml, I2 = 66%, p =  < 0.001) and LVESV (16.8 ml, I2 = 0%, p =  < 0.001) compared to TTE. Our findings demonstrate substantial disparities in TTE and CMR derived measurements for parameters that play a pivotal role in the clinical stratification guidelines. This discrepancy prompts a critical question regarding the prognostic value of both imaging modalities, which warrants future research.

Degenerative Mitral Regurgitation Outcomes in Asian Compared With European-American Institutions

Background

Clinical outcome and interventional thresholds for degenerative mitral regurgitation (DMR) were developed in studies of patients at European and American institutions (EAIs), but little is known about patients at Asian institutions (AsIs).

Objectives

This study sought to contrast DMR presentation/management/outcomes of AsI patients vs EAI patients.

Methods

Patients with DMR due to flail leaflet from Hong Kong and Singapore (AsI cohort, n = 737) were compared with EAI patients (n = 682) enrolled in the MIDA (Mitral regurgitation International Database) registry with similar eligibility criteria.

Results

AsI patients presented similar DMR lesion/consequences vs EAI patients, but they were younger, with fewer symptoms (74% vs 44% Class I), more sinus rhythm (83% vs 69%), and lower EuroSCORE II (European System for Cardiac Operative Risk Evaluation II) (0.9 ± 0.5 vs 1.4 ± 1.5; all P < 0.0001). Imaging showed smaller absolute left atrial/ventricular dimensions in AsI patients, belying cardiac dilatation with larger body surface area-indexed diameters (all P < 0.01). Surgical/interventional mitral repair was similarly predominant (90% vs 91%; P = 0.47), and early repair was similarly beneficial (for AsI patients, adjusted HR: 0.28; 95% CI: 0.16-0.49; for EAI patients, HR: 0.32; 95% CI: 0.20-0.49; both P < 0.0001). However, AsI patients underwent fewer interventions (55% ± 2% vs 77% ± 2% at 1 year; P < 0.0001) and incurred excess mortality (adjusted HR: 1.60 [95% CI: 1.13-2.27] vs EAI patients; P = 0.008) at long-term postdiagnosis. Propensity score matching (434 patient pairs), which balanced all clinical characteristics, confirmed that there was undertreatment and excess mortality in the long term in AsI patients with DMR (P < 0.0001).

Conclusions

Imaging may underestimate volume overload in AsI patients due to smaller cardiac cavities related to smaller body size compared with EAI patients with similar mitral lesions and DMR severity. AsI patients enjoy similar mitral repair predominance and early intervention benefits but undergo fewer mitral interventions than EAI patients and incur subsequent excess mortality, suggesting the need to account for imaging and cultural specificity to improve DMR outcomes worldwide.

Navigating Asymptomatic Mitral Regurgitation: Diagnostic Dilemmas and Treatment Strategies

This case report explores the complexities involved in the diagnosis and management of asymptomatic mitral regurgitation (MR) in a 64-year-old male presenting with an incidental systolic murmur. Torrential MR with flail mitral valve (MV) segments was identified through comprehensive imaging and clinical evaluation, including echocardiography and catheterization. The discussion highlights the nuances of surgical timing, emphasizing the importance of tailored approaches based on left ventricular (LV) function and dilation. This report sheds light on the evolving landscape of managing asymptomatic MR, underscoring the need for balancing surveillance with proactive intervention to optimize patient outcomes.

Mitral Regurgitation: Advanced Imaging Parameters and Changing Treatment Landscape

Mitral regurgitation is a common valvular heart disease with increasing prevalence due to the aging population. In degenerative (primary) mitral regurgitation, medical therapies are limited and the mainstay of treatment is mitral valve surgery. Patients are referred for mitral valve surgery based on the American College of Cardiology/American Heart Association guidelines, which recommend surgery in patients with severe mitral regurgitation. Echocardiography uses multiple parameters that lack reproducibility and accuracy. Studies comparing cardiovascular magnetic resonance (CMR) and echocardiography have shown that CMR is a better predictor of clinical outcome and postsurgical left ventricular remodeling than echocardiography.

The relationship between mitral regurgitant severity, symptoms, and exercise capacity in primary degenerative mitral regurgitation

Although it is assumed that more severe MR is associated with a greater burden of symptoms and lower exercise capacity, the relationship between symptoms, exercise capacity, and mitral regurgitant severity has not been well studied. We prospectively studied 67 (63 ± 11 years, 72% male) patients with at least mild degenerative MR and left ventricular ejection fraction ≥ 50% who underwent stress echocardiography, CMR, and evaluation with the Kansas City Cardiomyopathy questionnaire (KCCQ). Symptoms and exercise capacity were evaluated in the context of MR severity. Patients reporting dyspnea had lower KCCQ symptom scores (79 ± 23 vs. 96 ± 9, p = 0.01) and achieved lower percentage of age and gender predicted METs (114 ± 37 vs. 152 ± 43%, p < 0.001) compared to those without dyspnea. There was no significant difference in MR volume between those with vs. without dyspnea by CMR (43 ± 26 ml vs. 51 ± 28 ml, p = 0.3) or echocardiography (64 ± 28 vs. 73 ± 41ml, p = 0.4). Those with severe MR by CMR had similar KCCQ symptom scores (96 ± 10 vs. 89 ± 17, p = 0.04) and percentage of age and gender predicted METs (148 ± 42 vs. 133 ± 47%, p = 0.2) to those without severe MR. Those with severe MR by echocardiography had similar KCCQ symptom score (93 ± 15 vs. 89 ± 16, p = 0.3) and percentage of age and gender predicted METs (138 ± 43 vs. 153 ± 46%, p = 0.2) to those without severe MR. Patients with degenerative MR assessed by CMR and stress echocardiography, there was no relationship between MR severity and either symptoms or exercise capacity. These findings highlight the disconnect between symptoms and the severity of MR and challenge the assumption that correcting MR can be counted on to improve symptom status in patients with degenerative MR.

Left Ventricular Remodeling Shortly after Open Mitral Valve Replacement for Rheumatic Mitral Stenosis

Introduction

Left ventricular dysfunction after surgical treatment of mitral stenosis is uncommon. We intend to determine the pattern of left ventricular remodeling, shortly after open mitral valve replacement for rheumatic mitral stenosis, with in-hospital postoperative outcomes and the determinants of postoperative worsening of left ventricular ejection fraction.

Methods

From January 2008 to January 2015, 107 adult patients with rheumatic mitral stenosis were submitted to open mitral valve replacement. Their mean age was 45±11 years and 93 (86.9%) were women. Left ventricular morphology and function were studied longitudinally with echocardiography. The end point was postoperative worsening of left ventricular ejection fraction, defined by a decrease of 10% compared to preoperative basal assessment. Determinants of worsening left ventricular ejection fraction were determined by multivariable logistic regression analysis.

Results

The end point occurred in 18 patients (16.8%). We tested clinical and echocardiographic parameters to verify independent variables related to the decrease in postoperative ejection fraction. Lower body weight (P=0.005; odds ratio [OR]=0.89) and smaller preoperative mitral valve area (P=0.02; OR=0.02) were independent predictors of left ventricular dysfunction. These patients presented higher mortality and morbidity rates.

Conclusion

Left ventricular remodeling patterns differed among patients with predominant rheumatic mitral stenosis undergoing open mitral valve replacement. Lower preoperative body weight and mitral valve area were independent determinants of deteriorating ejection fraction with increased end-systolic volumes, indicating that this specific problem may occur in anthropometric smaller patients with more extensive rheumatic disease.

A review of the pivotal role of cardiac MRI in mitral valve regurgitation

Cardiac imaging is the cornerstone of defining the etiology, quantification, and management of mitral regurgitation (MR). This continues to be even more so the case with emerging transcatheter techniques to manage MR. Transthoracic echocardiography remains the first-line imaging modality to assess MR but has limitations. Cardiac MRI(CMR) provides the advantages of quantitative nonvisual estimation, 3D volumetric data, late gadolinium, T1, and extracellular volume measurements to comprehensively assess mitral valvular pathology, cardiac remodeling, and the prognostic impact of therapies. This review describes the superiority, technical aspects and growing evidence behind CMR, and lays the roadmap for the future of CMR in MR.

Clinical Situations Associated with Inappropriately Large Regurgitant Volumes in the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method in Patients with Chordae Rupture

BACKGROUND

Regurgitant volume (RVol) calculated using the proximal flow convergence method (proximal isovelocity surface area [PISA]) has been accepted as a key quantitative parameter for the diagnosis of and clinical decision-making with regard to severe mitral regurgitation (MR). However, a recent prospective study showed a significant overestimation of RVol by the echocardiographic PISA method compared with the MR volume measured using magnetic resonance imaging. We aimed to evaluate the frequency of overestimation of RVol by the PISA method and the clinical conditions that require a different quantitative method to correct the overestimation.

METHODS

We retrospectively enrolled 166 consecutive patients with degenerative MR and chordae rupture, in whom RVol was measured using both the PISA and two-dimensional Doppler volumetric methods. The volumetric method was used to measure total stroke volume using the two-dimensional Simpson biplane method, and forward stroke volume was measured using pulsed Doppler tracing at the left ventricular (LV) outflow tract. RVol by the volumetric method was calculated using total stroke volume - forward stroke volume. Severe MR was defined as an RVol >60 mL.

RESULTS

All patients had severe MR based on RVol by the PISA method, but 68 (41.1%) showed RVol by the volumetric method values of <60 mL, resulting in discordant results. The patients with discordant results were characterized by a higher prevalence of female sex, lower body surface area, smaller LV diastolic and systolic dimensions and volumes, smaller left atrial volume, smaller PISA angle, and lower frequency of flail leaflets (39.7% vs 62.2%, P = .004). Multivariate analysis revealed that LV end-diastolic volume (LVEDV) and PISA angle were independent factors, with the best cutoff LVEDV and PISA angle being 173 mL and 103°, respectively. During follow-up (median, 3.4 years; interquartile range, 2.0-4.8 years), mitral valve repair and replacement were performed in 103 and six patients, respectively. The 2-year mitral valve surgery-free survival rate was higher in the discordant group (51.8% ± 0.06% vs 31.2% ± 0.05%, P < .001).

CONCLUSIONS

Even in the patients with documented chordae rupture, the PISA method alone resulted in inappropriate overestimation of MR severity in a significant proportion of patients. Thus, an additive quantitative method is absolutely necessary in patients with a small LVEDV or narrow PISA angle.

Benefits of Early Surgery on Clinical Outcomes After Degenerative Mitral Valve Repair

BACKGROUND

This study aimed to evaluate the clinical trends of mitral valve repair for degenerative mitral regurgitation and the benefit of early surgical intervention on repair durability in a high-volume center.

METHODS

From January 2003 to December 2015, 1,903 consecutive patients with severe degenerative mitral regurgitation underwent mitral valve repair at our institution. The timing of surgical intervention was evaluated by guideline-related indications including symptoms, atrial fibrillation, left ventricular dysfunction, and pulmonary hypertension. Clinical outcomes and risk factors for recurrent mitral regurgitation were analyzed.

RESULTS

Over 13 years from 2003 to 2015, trends of preoperative characteristics demonstrated that the proportion of asymptomatic patients substantially increased. The 8-year overall survival, freedom from reoperation for mitral valve, and freedom from recurrent mitral regurgitation were 96%, 96%, and 85%, respectively. Ejection fraction less than 60%, left ventricular end-diastolic dimension greater than 60 mm, isolated anterior leaflet lesion, and intraoperative mild residual mitral regurgitation were independent predictive factors for recurrent mitral regurgitation. The incidence of recurrent mitral regurgitation was significantly lower in the early intervention group (3% versus 18%, p < 0.01). In subgroup analysis of asymptomatic patients, the incidence of recurrent mitral regurgitation was significantly lower in patients without guideline-related indications (3% versus 31%, p < 0.0001).

CONCLUSIONS

Early surgical intervention for severe degenerative mitral regurgitation before symptoms, atrial fibrillation, and ventricular dysfunction are associated with excellent clinical outcomes. Besides complexity of leaflet lesion and repair quality, surgical timing also significantly affects repair durability. Early surgical intervention should therefore be recommended to reduce recurrent mitral regurgitation.

Prognostic Implications of Magnetic Resonance-Derived Quantification in Asymptomatic Patients With Organic Mitral Regurgitation: Comparison With Doppler Echocardiography-Derived Integrative Approach

BACKGROUND

Magnetic resonance imaging (MRI) is an accurate method for the quantitative assessment of organic mitral regurgitation (OMR). The aim of the present study was to compare the discriminative power of MRI quantification and the recommended Doppler echocardiography (ECHO)-derived integrative approach to identify asymptomatic patients with OMR and adverse outcome.

METHODS

The study population consisted of 258 asymptomatic patients (63±14 years, 60% men) with preserved left ventricular ejection fraction (>60%) and chronic moderate and severe OMR (flail 25%, prolapse 75%) defined by using the ECHO-derived integrative approach. All patients underwent MRI to quantify regurgitant volume (RV) of OMR by subtracting the aortic forward flow volume from the total left ventricular stroke volume. Severe OMR was defined as RV≥60 mL.

RESULTS

Mean ECHO-derived RV was on average 17.1 mL larger than the MRI-derived RV (P<0.05). Concordant grading of OMR severity with both techniques was observed in 197 (76%) individuals with 62 (31%) patients having severe OMR (MRI SEV-ECHO SEV) and 135 (69%) patients having moderate OMR (MRI MOD-ECHO MOD). The remaining 61 (24%) individuals had discordant findings (MRI SEV-ECHO MOD or MRI MOD-ECHO SEV) between the 2 techniques. The majority of these differences in OMR classification were observed in patients with late systolic or multiple jets (both κ<0.2). Patients with eccentric jets showed moderate agreement (κ=0.53; 95% confidence interval, 0.41-0.64). In contrast, a very good agreement (κ=0.90; 95% confidence interval, 0.82-0.98) was observed in a combination of holosystolic, central, and single jet. During a median follow-up of 5.0 years (interquartile range, 3.5-6.0 years), 38 (15%) patients died and 106 (41%) either died or developed indication for mitral valve surgery. In separate Cox regression analyses, the MRI-derived left ventricular end-systolic volume index, RV, and OMR category (severe versus moderate), and the ECHO-derived OMR category were independent predictors of all-cause mortality (all P<0.05). The MRI-derived RV showed the largest area under the curve to predict mortality (0.72) or its combination with the development of indication for mitral valve surgery (0.83).

CONCLUSIONS

The findings of the present study suggest that the MRI-derived assessment of OMR can better identify patients with severe OMR and adverse outcome than ECHO-derived integrative approach warranting close follow-up and perhaps, early mitral valve surgery.

A prospective study examining the role of myocardial Fibrosis in outcome following mitral valve repair IN DEgenerative mitral Regurgitation: rationale and design of the mitral FINDER study

Background

The optimal management of chronic severe primary degenerative mitral regurgitation (MR) is to repair the valve but identification of the optimal timing of surgery remains challenging. Current guidelines suggest ‘watchful waiting’ until the onset of symptoms or left ventricular (LV) dysfunction but these have been challenged as promoting ‘rescue surgery’. Better predictors are required to inform decision-making in relation to the necessity and timing of surgery. Chronic volume overload is a stimulus for adverse adaptive LV remodelling. Subclinical reduction in LV strain before mitral repair predicts a fall in LV ejection fraction following surgery and is thought to reflect the development of myocardial fibrosis in response to chronic volume overload. Myocardial fibrosis can be detected non-invasively using cardiac magnetic resonance (CMR) imaging techniques as an expansion of the extracellular volume (ECV).

Methods/design

This study investigates whether: 1) patients with above median ECV will have smaller reduction in end-systolic volume index (as a measure of the degree of reverse LV remodelling) on CMR following mitral valve repair, compared to those with below median ECV; and 2) higher ECV on CMR, validated through histology, adversely impacts upon post-operative complications and symptomatic improvement following surgery.

This is a multi-centre, prospective, cross-sectional comparison of patients prior to and 9 months following surgery for chronic severe primary degenerative MR. To establish the natural history of ECV in MR, an additional cohort of patients with asymptomatic MR who do not wish to consider early repair will be followed. Investigations include CMR, cardiopulmonary exercise test, stress echocardiography, signal-averaged electrocardiogram, 24-h electrocardiogram monitoring, laboratory tests and patient-reported outcome measures. Patients undergoing surgery will have cardiac biopsies performed at the time of mitral valve repair for histological quantification of fibrosis.

Discussion

This study will advance our understanding of ventricular remodelling in MR, its impact on patient symptoms and ventricular response following surgery. Establishing the link between myocardial fibrosis (measured on CMR and validated through histology), with early ventricular dysfunction, will offer physicians a novel non-invasive biomarker that can further inform the timing of surgery.

Trial registration

This trial was registered at ClinicalTrials.gov (NCT02355418) on 30th November 2015.

Baseline mitral regurgitation predicts outcome in patients referred for dobutamine stress echocardiography

A number of parameters recorded during dobutamine stress echocardiography (DSE) are associated with worse outcome. However, the relative importance of baseline mitral regurgitation (MR) is unknown. The aim of this study was to assess the prevalence and associated implications of functional MR with long-term mortality in a large cohort of patients referred for DSE. 6745 patients (mean age 64.9 ± 12.2 years) were studied. Demographic, baseline and peak DSE data were collected. All-cause mortality was retrospectively analyzed. DSE was successfully completed in all patients with no adverse outcomes. MR was present in 1019 (15.1%) patients. During a mean follow up of 5.1 ± 1.8 years, 1642 (24.3%) patients died and MR was significantly associated with increased all-cause mortality (p < 0.001). With Kaplan-Meier analysis, survival was significantly worse for patients with moderate and severe MR (p < 0.001). With multivariate Cox regression analysis, moderate and severe MR (HR 2.78; 95% CI 2.17-3.57 and HR 3.62; 95% CI 2.89-4.53, respectively) were independently associated with all-cause mortality. The addition of MR to C statistic models significantly improved discrimination. MR is associated with all-cause mortality and adds incremental prognostic information among patients referred for DSE. The presence of MR should be taken into account when evaluating the prognostic significance of DSE results.

Forward Left Ventricular Ejection Fraction: A Simple Risk Marker in Patients With Primary Mitral Regurgitation

Background

The timing of mitral valve surgery in asymptomatic patients with primary mitral regurgitation (MR) is controversial. We hypothesized that the forward left ventricular (LV) ejection fraction (LVEF; ie, LV outflow tract stroke volume divided by LV end‐diastolic volume) is superior to the total LVEF to predict outcomes in MR. The objective of this study was to examine the association between echocardiographic parameters of MR severity and LV function and outcomes in patients with MR.

Methods and Results

The clinical and Doppler‐echocardiographic data of 278 patients with ≥mild MR and no class I indication of mitral valve surgery at baseline were retrospectively analyzed. The primary study end point was the composite of mitral valve surgery or death. During a mean follow‐up of 5.4±3.2 years, there were 147 (53%) events: 96 (35%) MV surgeries and 66 (24%) deaths. Total LVEF and global longitudinal strain were not associated with the occurrence of events, whereas forward LVEF (P<0.0001) and LV end‐systolic diameter (P=0.0003) were. After adjustment for age, sex, MR severity, Charlson probability, coronary artery disease, and atrial fibrillation, forward LVEF remained independently associated with the occurrence of events (adjusted hazard ratio: 1.09, [95% confidence interval]: 1.02–1.17 per 5% decrease; P=0.01), whereas LV end‐systolic diameter was not (P=0.48).

Conclusions

The results of this study suggest that the forward LVEF may be superior to the total LVEF and LV end‐systolic diameter to predict outcomes in patients with primary MR. This simple and easily measurable parameter may be useful to improve risk stratification and select the best timing for intervention in patients with primary MR.

Trials Testing the Value of Imaging Use in Valve Disease and in Transcatheter Valvular Interventions

The role of imaging in the diagnosis of valvular heart disease is well established through years of investigation and validation. However, the role of imaging in guiding the treatment decision-making for valvular heart disease is less well established, and there is a striking paucity of randomized trial data to help inform these decisions. Given this relative absence of randomized trial data, the present article highlights some of the most important knowledge gaps and defines meaningful opportunities for the field to help advance the care of patients with valvular heart disease in a cost-effective fashion. (The PARTNER 3-Trial: The Safety and Effectiveness of the SAPIEN 3 Transcatheter Heart Valve in Low Risk Patients With Aortic Stenosis [P3]; NCT02675114; Medtronic Transcatheter Aortic Valve Replacement in Low Risk Patients; NCT02701283).

[Structure and function of the mitral valve. Eligibility criteria for surgical and interventional approaches]

Mitral valve disease, especially severe mitral valve insufficiency, is an increasing issue in our population. Older patients with multiple comorbidities in particular are often denied surgery due to an increased perioperative risk. Because conservative medical treatment of mitral valve disease is often unsatisfactory, interventional techniques to treat mitral valve disease have emerged in recent years as serious alternatives to surgical treatment. Innovative developments in cardiovascular imaging have opened up new ways of looking at the mitral valve for improved diagnostic and therapeutic management of patients with mitral valve disease. These advantages of imaging are important for correct patient selection with either surgical or interventional strategies. This review describes the diagnostic capabilities of echocardiographic techniques for a precise diagnosis of the mitral valve structure and function for planning and performing interventional or surgical procedures.

Cardiomyocyte mitochondrial oxidative stress and cytoskeletal breakdown in the heart with a primary volume overload

Left ventricular (LV) volume overload (VO) results in cardiomyocyte oxidative stress and mitochondrial dysfunction. Because mitochondria are both a source and target of ROS, we hypothesized that the mitochondrially targeted antioxidant mitoubiquinone (MitoQ) will improve cardiomyocyte damage and LV dysfunction in VO. Isolated cardiomyocytes from Sprague-Dawley rats were exposed to stretch in vitro and VO of aortocaval fistula (ACF) in vivo. ACF rats were treated with and without MitoQ. Isolated cardiomyocytes were analyzed after 3 h of cyclical stretch or 8 wk of ACF with MitoSox red or 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate to measure ROS and with tetramethylrhodamine to measure mitochondrial membrane potential. Transmission electron microscopy and immunohistochemistry were used for cardiomyocyte structural assessment. In vitro cyclical stretch and 8-wk ACF resulted in increased cardiomyocyte mitochondrial ROS production and decreased mitochondrial membrane potential, which were significantly improved by MitoQ. ACF had extensive loss of desmin and β₂-tubulin that was paralleled by mitochondrial disorganization, loss of cristae, swelling, and clustering identified by mitochondria complex IV staining and transmission electron microscopy. MitoQ improved mitochondrial structural damage and attenuated desmin loss/degradation evidenced by immunohistochemistry and protein expression. However, LV dilatation and fractional shortening were unaffected by MitoQ treatment in 8-wk ACF. In conclusion, although MitoQ did not affect LV dilatation or function in ACF, these experiments suggest a connection of cardiomyocyte mitochondria-derived ROS production with cytoskeletal disruption and mitochondrial damage in the VO of ACF.

Current status of stress echocardiography: is it a required procedure for every sonographer?

BACKGROUND

Stress echocardiography is a versatile modality in the clinical cardiology. In its earlier days, its sole indication was restricted to diagnosing coronary artery disease. However, in response to the rapid development of ultrasound technology and analysis software, the indications have now evolved with expansion to several fields of cardiovascular disease.

METHODS

I reviewed previous stress echocardiography publications, and discussed the current status of stress echocardiography in routine clinical setting.

RESULTS

Although its portability and online assessment make possible for immediate diagnosis even at the bedside, establishment of an appropriate procedure and an accurate assessment require some experience. Other imaging competitors, such as multidetector computed tomography and cardiac magnetic resonance are gradually replacing the role of stress echocardiography in some fields. However, stress echocardiography has a potential for other new fields, including valvular heart disease and congestive heart failure.

CONCLUSION

Although primary indication of stress echocardiography for coronary artery disease seems to be not relevant especially in Japan, novel indication of stress echocardiography in other field of cardiovascular disease is rapidly expanding in conjunction with the advent of new technology. Stress echocardiography is not a tool for limited researchers, but rather a fundamental routine method of choice for every sonographer.

Quantification of Left Ventricular Interstitial Fibrosis in Asymptomatic Chronic Primary Degenerative Mitral Regurgitation

Background—

The optimum timing of surgery in asymptomatic patients with chronic severe primary degenerative mitral regurgitation (MR) remains controversial, and further markers are needed to improve decision-making. There are limited data that wall stress is increased in MR and may result in ventricular fibrosis. We investigated the hypothesis that chronic volume overload in MR is a stimulus for myocardial fibrosis using T1-mapping cardiac MRI.

Methods and Results—

A cross-sectional study of 35 patients (age 60±14 years) with asymptomatic moderate and severe primary degenerative MR (mean effective regurgitant orifice area, 0.45±0.25 cm) 2 with no class I indication for surgery were compared with age and sex controls. Subjects were studied with cardiopulmonary exercise testing, echocardiography, and cardiac MRI.

Longitudinal and circumferential myocardial deformation was reduced with MR when left ventricular ejection fraction (67%±10%) and N-terminal pro B Natriuretic peptide (126 [76–428] ng/L) were within the normal range. Myocardial extracellular volume was increased (0.32±0.07 versus 0.25±0.02, P <0.01) and was associated with increased left ventricular end-systolic volume index ( r =0.62, P <0.01), left atrial volume index ( r =0.41, P <0.05) but lower left ventricular ejection fraction ( r =−0.60, P <0.01), longitudinal function (mitral annular plane systolic excursion, r =−0.46, P <0.01), and peak V O 2 max ( r =−0.51, P <0.05). In a multivariable regression model, left ventricular end-systolic volume index and left atrial volume index were independent predictors of extracellular volume ( r 2 =0.42, P <0.01).

Conclusions—

Patients with asymptomatic MR demonstrate a spectrum of myocardial fibrosis associated with reduced myocardial deformation and reduced exercise capacity. Future work is warranted to investigate whether left ventricle fibrosis affects clinical outcomes.

Impact of exercise pulmonary hypertension on postoperative outcome in primary mitral regurgitation

AIMS

The management of asymptomatic patients with mitral regurgitation (MR) remains controversial. Exercise-induced pulmonary hypertension (ExPHT) was recently reported as a strong predictor of rapid onset of symptoms. We hypothesised that ExPHT is a predictor of postoperative cardiovascular events in patients with primary MR.

METHODS AND RESULTS

One hundred and two patients with primary MR, no or mild symptoms (New York heart association (NYHA) ≤2), and no LV dysfunction/dilatation, were prospectively recruited in 3 centres and underwent exercise-stress echocardiography. The presence of ExPHT was defined as an exercise systolic pulmonary arterial pressure >60 mm Hg. All patients were closely followed up and operated on when indication for surgery was reached. Postoperative events were defined as the occurrence of atrial fibrillation (AF), stroke, cardiac-related hospitalisation or death. Among the 102 patients included, 59 developed ExPHT (58%). These patients were significantly older than those without ExPHT (p=0.01). During a mean postoperative follow-up of 50±23 months, 28 patients (26%) experienced a predefined cardiovascular event. Patients with ExPHT had significantly higher rate of postoperative events (39% vs 12%, p=0.005); the rate of events was still higher in these patients (32% vs 9%, p=0.013), even when excluding early postoperative AF (ie, within 48 h). Event-free survival was significantly lower in the ExPHT group (all events: 5-year: 60±8% vs 88±5%, p=0.007, events without early AF: 5-year: 67±7% vs 90±4%, p=0.02). Using Cox multivariable analysis, ExPHT remained independently associated with higher risk of postoperative events in all models (all p≤0.04).

CONCLUSIONS

ExPHT is associated with increased risk of adverse cardiac events following mitral valve surgery in patients with primary MR.

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

Degenerative mitral valve regurgitation (MR) is the one of the most frequent valvular heart conditions in the Western world and is increasingly recognized as an important preventable cause of chronic heart failure. This condition also represents the most common indication for mitral surgery and is of particular interest because the mitral valve can be repaired in most patients with very low surgical risk. Historical single-center studies have supported the performance of "early mitral valve repair" in asymptomatic patients with severe degenerative MR to normalize survival and improve late outcomes. Emerging recent evidence further indicates for the first time that the prompt surgical correction of severe MR due to flail mitral leaflets within 3 months following diagnosis in asymptomatic patients without classical Class I indications (symptoms or left ventricular dysfunction) conveys a 40% decrease in the risk of late death and a 60% diminution in heart failure incidence. A 10-point rationale based on the weight of rapidly accumulating clinical data, supports the performance of early mitral valve repair even in the absence of symptoms, left ventricular dysfunction, or guideline-based triggers; when effective operations can be provided using conventional or minimally invasive techniques at very low surgical risk.

Timing of surgery in valvular heart disease: prophylactic surgery vs watchful waiting in the asymptomatic patient

In the absence of randomized controlled trial data, the management of patients with severe valvular heart disease without symptoms, ventricular dysfunction, or other identified triggers for surgery is controversial. In this review, we frame the debate between prophylactic surgery vs close follow-up until triggers occur (watchful waiting) for severe aortic stenosis and degenerative mitral regurgitation (MR), the 2 conditions for which the pros and cons of these approaches are best articulated. Classic high-gradient severe aortic stenosis is generally accurately diagnosed. In asymptomatic patients, stress testing can be used to confirm asymptomatic status and identify high-risk features including reduced exercise tolerance, exercise-induced symptoms, and absolute or relative hypotension. Resting echocardiographic predictors of disease progression and/or adverse events include very high gradients, rapid progression, and extensive calcification. Surgical risk calculators can help estimate perioperative morbidity/mortality with the ultimate choice of a medical vs a prophylactic surgical approach to be made after discussion with the patient. With degenerative MR, severity can be inaccurately estimated. Stress testing might clarify whether the patient is truly asymptomatic and identify features associated with worse prognosis and symptom onset. Selecting patients with high probability of repair can be challenging. Perioperative risk and postoperative risks including those of unanticipated valve replacement and recurrent MR after repair are also considerations. In aggregate, management of patients with valvular disease who are asymptomatic and who have no clear trigger for surgery is complex, requires individualization, and should be carried out by or in collaboration with a heart valve centre of excellence.

Mitral valve surgery: wait and see vs. early operation

Mitral valve repair represents the optimal surgical treatment for severe degenerative mitral regurgitation. According to the current guidelines, mitral repair is indicated in the presence of symptoms and/or signs of left ventricular (LV) dysfunction. In asymptomatic patients with preserved LV function, surgery should be considered in the presence of atrial fibrillation (AF) and/or pulmonary hypertension. In asymptomatic patients with preserved LV function, normal pulmonary artery pressure, and no episodes of AF, surgical timing is still an object of debate. The controversial issue is whether, in those circumstances, a 'wait and see (watchful waiting)' approach should be followed or an 'early repair' policy should be preferred. Indeed, a randomized trial comparing the two strategies has never been performed. In the absence of evidence-based arguments definitely supporting any particular course of action, advantages, drawbacks, and requirements for both strategies will be discussed in this review on the basis of the most significant observational studies which have focused on this issue.

The importance of exercise echocardiography for clinical decision making in primary mitral regurgitation

Primary mitral regurgitation is generally an insidious disease with late onset of symptoms. Current European and American guidelines recommend surgery in severe primary mitral regurgitation when symptoms, overt left ventricular dysfunction, pulmonary hypertension or atrial fibrillation, occur. However, recent large studies reported an improved outcome in asymptomatic patients with severe mitral regurgitation referred for early mitral valve repair despite the risk of operative mortality or mitral valve replacement. Moreover, primary mitral regurgitation appears to have an important dynamic character in up to one-third of patients. This article provides an overview of the incremental evidence of the ability of exercise echocardiography to assess the functional repercussions of mitral regurgitation and the identification of high-risk patients who might benefit from early referral for surgery.

Watchful waiting for severe mitral regurgitation

Watchful waiting is an established treatment strategy for asymptomatic patients with severe organic mitral regurgitation. It is based on indications for surgery that are based on current European Society of Cardiology and American Heart Association/American College of Cardiology guideline recommendations, which are defined by symptom onset, impairment of left ventricular function, and left ventricular enlargement. Excellent outcome is achieved when patients are periodically followed with clinical and echocardiographic examinations and when surgery is performed in expert centers. The strategy is based on the recognition of mitral regurgitation at an early symptomatic stage, avoiding a delayed referral of these patients. There is an ongoing debate about whether surgery should be performed in asymptomatic patients with preserved ventricular function. Ultimately, decision-making needs to be individualized and to take individual patient-related factors and local resources (including the natural history of the disease, the risk of surgery, and the likelihood of successful mitral valve repair) into consideration to obtain an optimal outcome with medical and surgical management.

Quality of life after early mitral valve repair using conventional and robotic approaches

BACKGROUND

Early mitral valve (MV) repair of degenerative mitral regurgitation is associated with superior clinical outcomes compared with prosthetic replacement and restores normal life expectancy, even in those without symptoms. Although current guidelines recommend prompt referral for effective MV repair in those with severe mitral regurgitation, some are reluctant to pursue early correction due to the perception that short-term quality of life (QOL) may be adversely affected by the operation.

METHODS

Between January 2008 and November 2009, 202 patients underwent conventional transsternotomy or minimally invasive port-access robot-assisted MV repair, with or without patent foramen ovale closure or left Maze, and were mailed a postsurgical QOL survey.

RESULTS

Unadjusted QOL scores for patients undergoing MV repair were excellent early after the operation using both approaches. Robotic repair was associated with slightly improved scores on the Duke Activity Status Index, the Short Form-12 Item Health Survey Physical domain, and the Linear Analogue Self-Assessment frequency of chest pain and fatigue indices during the first postoperative year; however, differences between treatment groups became indistinguishable after 1 year. Robotic repair patients returned to work slightly quicker (median, 33 vs 54 days, p<0.001).

CONCLUSIONS

Functional QOL outcomes within the first 2 years after early MV repair are excellent using open and robotic platforms. A robotic approach may be associated with slightly improved early QOL and return to employment-based activities. These results may have implications regarding future evolution of clinical guidelines and economic health care policy.

Mitral Valve Prolapse With Mid-Late Systolic Mitral Regurgitation

Background—

Mitral regurgitation (MR) of mitral valve prolapse predominates in late systole but may be holosystolic or purely mid-late systolic, but the impact of MR timing on MR left ventricular and left atrial consequences and outcome is unknown. Whether effective regurgitant orifice (ERO) by the flow convergence method is similarly linked to outcome in mid-late systolic MR and holosystolic MR is uncertain.

Methods and Results—

We comprehensively and prospectively quantified MR in 111 patients with mitral valve prolapse and mid-late systolic MR and matched them to 90 patients with mitral valve prolapse and holosystolic MR for age, gender, atrial fibrillation, ejection fraction, and ERO (flow convergence). Mid-late systolic MR versus holosystolic MR groups were well matched, including for comorbidity, blood pressure, and heart rate (all P >0.10). Mid-late systolic MR versus holosystolic MR caused similar color jet area, midsystolic regurgitant flow, and peak velocity ( P >0.40). Despite identical ERO (0.25±0.15 versus 0.25±0.15 cm 2 ; P =0.53), the shorter duration of mid-late systolic MR (233±56 versus 426±50 ms; P <0.0001) yielded lower regurgitant volume (24.8±13.4 versus 48.6±25.6 mL; P <0.0001). MR consequences, systolic pulmonary pressure, and left ventricular and left atrial volume index (all P <0.001) were more benign in mid-late systolic MR versus holosystolic MR. Under medical management, fewer cardiac events (5 years: 15.8±4.6% versus 40.4±6.1%; P <0.0001) occurred in mid-late systolic MR versus holosystolic MR, requiring less mitral surgery. Multivariable analysis confirmed the independent association of mid-late systolic MR with benign consequences and outcomes (all P <0.01). Absolute ERO was not linked to outcome, in contrast to regurgitant volume.

Conclusions—

MR of mitral valve prolapse that is purely mid-late systolic causes more benign consequences and outcomes than holosystolic MR. Assessment may be misleading because jet area and ERO by flow convergence appear similar to those of holosystolic MR. However, shorter MR yields lower regurgitant volume, consequences, and benign outcomes. Instantaneous ERO by flow convergence should be interpreted in context, and in mid-late systolic MR, regurgitant volume provides information more reflective of MR severity. Therefore, for clinical management and surgical referral, clinicians should carefully take into account the timing and consequences of MR.