Prognostic value of exercise tolerance testing in asymptomatic chronic nonischemic mitral regurgitation

Watchful surgery in asymptomatic mitral valve prolapse

The most common organic etiology of mitral regurgitation is degenerative and consists of mitral valve prolapse (MVP). Volume overload because of mitral regurgitation is the most common complication of MVP. Advocating surgery before the consequences of volume overload become irreparable restores life expectancy, but carries a risk of mortality in patients who are often asymptomatic. On the other hand, the post-surgical outcome of symptomatic patients is dismal and life expectancy is impaired. In the present article, we aim to bridge the gap between these two therapeutic approaches, unifying the concepts of watchful waiting and early surgery in a "watchful surgery approach".

New synthetic mitral valve model for human prolapsed mitral valve reconstructive surgery for training

The training process of young surgeons is highly desirable in order for them to gain an understanding of the quality of care and patient safety required during cardiac surgeries, however, it may take a few years of practice in order for them to properly develop these skills. Artificial life-like platforms and models are extremely recommended for teaching hands-on and real-world practice in both junior and even experienced medical professionals and surgeons. Suitable and accessible training tools are of significant importance for simulating a particular surgery in order to provide practice opportunities for a specific surgical procedure. In this study, we focussed on the simulation of the human mitral valve prolapse reconstructive surgery. An innovative, artificial, biomimetic model was designed and fabricated made of Cryogel biomaterial developed in our lab that is suitable for the precise practice on the mitral valve prolapse model. The proposed model is mainly made up of polyvinyl alcohol (PVA) cryogel, which is designed to resemble the geometric and mechanical properties of a diseased (prolapse) mitral valve. We simulated the constructive prolapsed mitral valve surgery entirely on a synthetic platform. The platform was made available to four certified cardiac surgeon and there were unanimously very positive with no considerable differences in the procedural assessments between them. The proposed model has a similar appearance and texture to that of a diseased mitral valve and holds consistent mechanical properties to those of the real tissue. The offered technology may be used for other cardiothoracic reconstructive surgeries with high precision and consistency.

Hemodynamic Characteristics in Significant Symptomatic and Asymptomatic Primary Mitral Valve Regurgitation at Rest and During Exercise

BACKGROUND

In severe asymptomatic primary mitral valve regurgitation without risk factors, surgery strategy is controversial. We sought to clarify whether being symptomatic corresponds to the hemodynamic burden and reduced exercise capacity. A better understanding of this may contribute to optimize timing of surgery.

METHODS AND RESULTS

Subjects with asymptomatic (New York Heart Association functional class I, n=29) or symptomatic (New York Heart Association functional class II and III, n=28) significant primary mitral valve regurgitation (effective regurgitant orifice, ≥0.30 cm²; left ventricular ejection fraction, >60%) were included. Right heart catheterization during rest and exercise, echocardiography, magnetic resonance imaging, and peak oxygen consumption test was performed. Symptomatic subjects had significantly higher pulmonary capillary wedge pressure at rest (14±4 versus 11±3 mm Hg; P=0.003) and at maximal exercise (30±6 versus 25±7 mm Hg; P=0.02) and higher mean pulmonary artery pressure (PAP) at rest (22±7 versus 18±4 mm Hg; P=0.005) and maximal exercise (46±8 versus 39±7 mm Hg; P=0.005) than asymptomatic subjects. Among asymptomatic subjects with normal resting value, exercise testing revealed a systolic PAP >60 mm Hg in 34%. Also the reverse response with minimal increase in pulmonary capillary wedge pressure and mean PAP during exercise was seen, especially in asymptomatic subjects. Among symptomatic subjects, we found a significant inverse correlation between resting mean PAP and left ventricular ejection fraction (r=-0.52; P=0.02) and right ventricular ejection fraction (r=-0.67; P<0.01). Peak oxygen consumption was equal and normal in both groups and correlated with left ventricular stroke volume but not with pulmonary capillary wedge pressure.

CONCLUSIONS

Symptoms in patients with severe mitral valve regurgitation relate to congestion (pulmonary capillary wedge pressure and PAP), but not to peak oxygen consumption, which is determined by forward left ventricular stroke volume. Exercise testing reveals a higher mitral valve regurgitation burden in apparently asymptomatic patients.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02961647.

Timing surgery in mitral regurgitation: defining risk and optimising intervention using stress echocardiography

Mitral regurgitation (MR) is the second most common form of valvular disease requiring surgery. Correct identification of surgical candidates and optimising the timing of surgery are key in management. For primary MR, this relies upon a balance between the peri-operative risks and rates of successful repair in patients undergoing early surgery when asymptomatic with the potential risk of irreversible left ventricular dysfunction if intervention is performed too late. For secondary MR, recognition that this is a highly dynamic condition where MR severity may change is key, although data on outcomes in determining whether concomitant valve intervention is performed with revascularisation has raised questions regarding timing of surgery. There has been substantial interest in the use of stress echocardiography to risk stratify patients in mitral regurgitation. This article reviews the role of stress echocardiography in both primary and secondary mitral regurgitation and discusses how this can help clinicians tackle the challenges of this prevalent condition.

Clinical Use of Doppler Echocardiography in Organic Mitral Regurgitation: From Diagnosis to Patients' Management

Knowledge of mitral regurgitation (MR) is essential for any care provider, and not only for those directly involved in the management of cardiovascular diseases. This happens because MR is the most frequent valvular lesion in North America and the second most common form of valve disease requiring surgery in Europe. Furthermore, due to the ageing of the general population and the reduced mortality from acute cardiovascular events, the prevalence of MR is expected to increase further. Doppler echocardiography is essential both for the diagnosis and the clinical management of MR. In the present article, we sought to provide a practical step-by-step approach to help either performing a Doppler echocardiography or interpreting its findings in light of contemporary knowledge on organic (but not only) MR.

Importance of exercise capacity in predicting outcomes and determining optimal timing of surgery in significant primary mitral regurgitation

BACKGROUND

In primary mitral regurgitation (MR), exercise echocardiography aids in symptom evaluation and timing of mitral valve (MV) surgery. In patients with grade ≥3 primary MR undergoing exercise echocardiography followed by MV surgery, we sought to assess predictors of outcomes and whether delaying MV surgery adversely affects outcomes.

METHODS AND RESULTS

We studied 576 consecutive such patients (aged 57±13 years, 70% men, excluding prior valve surgery and functional MR). Clinical, echocardiographic (MR, LVEF, indexed LV dimensions, RV systolic pressure) and exercise data (metabolic equivalents) were recorded. Composite events of death, MI, stroke, and congestive heart failure were recorded. Mean LVEF was 58±5%, indexed LV end-systolic dimension was 1.7±0.5 mm/m(2), rest RV systolic pressure was 32±13 mm Hg, peak-stress RV systolic pressure was 47±17 mm Hg, and percentage of age- and gender-predicted metabolic equivalents was 113±27. Median time between exercise and MV surgery was 3 months (MV surgery delayed ≥1 year in 28%). At 6.6±4 years, there were 53 events (no deaths at 30 days). On stepwise multivariable survival analysis, increasing age (hazard ratio of 1.07 [95% confidence interval, 1.03 to 1.12], P<0.01), lower percentage of age- and gender-predicted metabolic equivalents (hazard ratio of 0.82 [95% confidence interval, 0.71 to 0.94], P=0.007), and lower LVEF (0.94 [0.89 to 0.99], P=0.04) independently predicted outcomes. In patients achieving >100% predicted metabolic equivalents (n=399), delaying surgery by ≥1 year (median of 28 months) did not adversely affect outcomes (P=0.8).

CONCLUSION

In patients with primary MR that underwent exercise echocardiography followed by MV surgery, lower achieved metabolic equivalents were associated with worse long-term outcomes. In those with preserved exercise capacity, delaying MV surgery by ≥1 year did not adversely affect outcomes.

Usefulness of preoperative exercise tolerance to predict late survival and symptom persistence after surgery for chronic nonischemic mitral regurgitation

Exercise duration during exercise treadmill testing (ETT) predicts long-term outcome among asymptomatic patients with mitral regurgitation. However, the prognostic value of preoperative exercise duration in patients who undergo mitral valve surgery is unknown. We examined findings among 45 prospectively followed (average 9.2 ± 4.3 years) patients (aged 54.8 ± 12.0 years, 45% men) with chronic isolated severe MR who underwent ETT before mitral valve surgery to test the hypotheses that exercise duration predicts long-term postoperative survival and persistent symptoms within 2 years after operation. During follow-up, 11 patients died; of these, 8 had persistent symptoms. Among patients who exercised >7 minutes, average annual postoperative all-cause and cardiovascular mortality risks were 0.75% (both endpoints) versus 5.4% and 4.8%, respectively, versus those who exercised ≤7 minutes (p = 0.003 all-cause, p = 0.007 cardiovascular). Exercise duration predicted postoperative deaths (p <.02 all cause, p <.04 cardiovascular) even when analysis was adjusted for preoperative variations in age, gender, medications, history of atrial fibrillation, and peak exercise heart rates. Other ETT, echocardiographic, and clinical variables were not independently associated with these outcomes when exercise duration was considered in the analysis. Preoperative exercise duration also predicted postoperative (New York Heart Association functional class ≥II) symptom persistence (p = 0.012), whereas other ETT, echocardiographic and clinical variables did not (NS, all). In conclusion, among patients who undergo surgery for chronic nonischemic mitral regurgitation, preoperative exercise duration, unlike many commonly used descriptors, is useful for predicting postoperative mortality and symptom persistence. Future research should determine whether interventions to improve exercise tolerance before mitral valve surgery can modify these postoperative outcomes.

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.

Stress testing in valvular heart disease: clinical benefit of echocardiographic imaging

Symptom development represents one of the most important indications for surgical intervention in patients with significant valvular heart disease. Exercise testing has an established role in the assessment of exercise capacity and symptomatic status in patients with severe valvular heart disease who claim to be asymptomatic. In these patients, clinical decision can be influenced by the results of exercise testing. In addition to the assessment of symptomatic response to exercise, stress echocardiography can provide valuable information on exercise-induced changes in valve hemodynamics, ventricular function and pulmonary artery pressure. Abnormal left ventricular response to exercise, increase in pulmonary pressure or change in the hemodynamic severity of the valvular disease adds to the prognostic value of elicited symptoms. In this article we discuss the validated indications, proven prognostic values and potential influence on clinical decisions of stress echocardiography in left valvular heart diseases.

Stress Doppler echocardiography in valvular heart diseases: utility and assessment

This article is a review on the role of stress echocardiography in valvular heart diseases, describing what the validated indications are, how to perform the test and the utility of performing this examination. Most valve diseases are characteristically dynamic and this dynamic component is best appreciated by exercise Doppler echocardiography. Dobutamine stress echocardiography is also useful in patients with severe aortic stenosis and left ventricular dysfunction. The main advantage of stress echocardiography is to concomitantly allow the evaluation of symptoms, exercise capacity and the hemodynamic consequences of valve diseases, especially in patients with severe valve diseases who deny symptoms or present equivocal symptoms. It also provides important prognostic information and may help to optimize surgical timing in difficult cases. Whether these data should be integrated in the management of patients needs further validation.

Degenerative mitral valve regurgitation: best practice revolution

Degenerative mitral valve disease often leads to leaflet prolapse due to chordal elongation or rupture, and resulting in mitral valve regurgitation. Guideline referral for surgical intervention centres primarily on symptoms and ventricular dysfunction. The recommended treatment for degenerative mitral valve disease is mitral valve reconstruction, as opposed to valve replacement with a bioprosthetic or mechanical valve, because valve repair is associated with improved event free survival. Recent studies have documented a significant number of patients are not referred in a timely fashion according to established guidelines, and when they are subjected to surgery, an alarming number of patients continue to undergo mitral valve replacement. The debate around appropriate timing of intervention for asymptomatic severe mitral valve regurgitation has put additional emphasis on targeted surgeon referral and the need to ensure a very high rate of mitral valve repair, particularly in the non-elderly population. Current clinical practice remains suboptimal for many patients, and this review explores the need for a ‘best practice revolution’ in the field of degenerative mitral valve regurgitation.

The emerging role of exercise testing and stress echocardiography in valvular heart disease

Exercise testing has an established role in the evaluation of patients with valvular heart disease and can aid clinical decision making. Because symptoms may develop slowly and indolently in chronic valve diseases and are often not recognized by patients and their physicians, the symptomatic, blood pressure, and electrocardiographic responses to exercise can help identify patients who would benefit from early valve repair or replacement. In addition, stress echocardiography has emerged as an important component of stress testing in patients with valvular heart disease, with relevant established and potential applications. Stress echocardiography has the advantages of its wide availability, low cost, and versatility for the assessment of disease severity. The versatile applications of stress echocardiography can be tailored to the individual patient with aortic or mitral valve disease, both before and after valve replacement or repair. Hence, exercise-induced changes in valve hemodynamics, ventricular function, and pulmonary artery pressure, together with exercise capacity and symptomatic responses to exercise, provide the clinician with diagnostic and prognostic information that can contribute to subsequent clinical decisions. Nevertheless, there is a lack of convincing evidence that the results of stress echocardiography lead to clinical decisions that result in better outcomes, and therefore large-scale prospective randomized studies focusing on patient outcomes are needed in the future.