Cardiac resynchronisation therapy reduces functional mitral regurgitation during dynamic exercise in patients with chronic heart failure: an acute echocardiographic study

Dynamic Secondary Mitral Regurgitation: Current Evidence and Challenges for the Future

Heart failure (HF) is a challenging situation in healthcare worldwide. Secondary mitral regurgitation (SMR) is a common condition in HF patients with reduced ejection fraction (HFrEF) and tends to be increasingly associated with unfavorable clinical outcomes as the severity of SMR increases. It is worth noting that SMR can deteriorate dynamically under stress. Over the past three decades, the characteristics of dynamic SMR have been studied. Dynamic SMR contributes to the reduction in exercise capacity and adverse clinical outcomes. Current guidelines refer to the indication of transcatheter edge-to-edge repair (TEER) for significant SMR based on data from the Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation (COAPT) trial if symptomatic despite optimal guideline-directed medical therapy (GDMT) and cardiac resynchronization therapy (CRT), but nonpharmacological treatment for dynamic SMR remains challenging. In HFrEF patients with LV dyssynchrony and dynamic SMR, CRT can improve LV dyssynchrony and subsequently attenuate SMR at rest and during exercise. Also, a recent study suggests that TEER with GDMT and CRT is more effective in symptomatic patients with HFrEF and dynamic SMR than GDMT and CRT alone. Further studies are needed to evaluate the safety and efficacy of nonpharmacological treatments for dynamic SMR. In this review, current evidence and challenges for the future of dynamic SMR are discussed.

Dynamic left ventricular dyssynchrony and severe mitral regurgitation caused by exercise: should we go beyond the guidelines?

Guidelines for cardiac resynchronization therapy (CRT) have been established, but there may be a subgroup of patients not identified in these guidelines who may benefit from this therapy. We report a patient with a dynamic left ventricular dyssynchrony and severe mitral regurgitation caused by exercise successfully treated with CRT. Exercise testing should be considered in patients with left ventricular ejection fraction <35% and QRS <130 ms with severe heart failure symptoms that are unexplained by rest echocardiography evaluation in order to rule out ischemia and/or dynamic left ventricular dyssynchrony. In the presence of exercise-induced left ventricular bundle branch block, the implantation of CRT should be contemplated.

Therapeutic options for functional mitral regurgitation in chronic heart failure

INTRODUCTION

Mitral regurgitation is a common finding in patients with chronic heart failure and is associated with a progressive worsening of symptoms, reduced survival and increased cost of care. However, the use of mitral valve surgery for these patients remains controversial and has not been shown to improve survival. Consequently, research has been increasingly directed towards the nonsurgical management of this important co-morbidity of heart failure.

AREAS COVERED

The present review will describe the relevance of mitral regurgitation in people with chronic heart failure, the current options for percutaneous treatment and the evidence base for each of these.

EXPERT COMMENTARY

Although at present there are few solid data to guide heart teams in deciding what degree of mitral regurgitation to treat, in which patients, and with what, this situation is likely to change over the next two years with the release of the first large randomised trials of percutaneous interventions.

[Impact of mitral annuloplasty combined with surgical revascularization in ischemic mitral regurgitation]

INTRODUCTION

Ischemic Mitral Regurgitation (IMR) is a serious complication of coronary artery disease and is associated with a poor prognosis. The optimal surgical treatment of IMR involves controversies in its indications and modalities.

OBJECTIVES

To determine whether mitral annuloplasty associated with surgical revascularization improved short and mid terms outcomes compared with revascularization alone in patients with IMR.

METHODS

Between January 2007 and January 2011, 81 patients operated on Department of Cardiovascular Surgery "B" were included in this study divided into 3 groups. Group 1: 28 patients with IMR had mitral valve surgery associated with surgical revascularization. Group 2: 26 patients with IMR had surgical revascularization without mitral valve surgery. Group 3: 27 patients without IMR had isolated revascularization. Clinical end-points were operative mortality, late mortality, postoperative functional status (NYHA), and the Effective Regurgitant Orifice (ERO) at last follow-up. The mean follow-up was 5 years for groups 1 and 2 and 4 years for group 3.

RESULTS

There was no difference between the 3 groups regarding age, sex, cardiovascular risk factors, and extension of coronary artery disease. The Left Ventricle End Diastolic Diameter (LVEDD) and the Left Ventricle Ejection Fraction (LVEF) were slightly different. Late and operative mortality were higher in group 2 compared to groups 1 and 3. Postoperative functional status (NYHA) improved both in groups 1 and 2. In group 1, there was a decrease in ERO.

CONCLUSION

Mitral annuloplasty combined to revascularization improves symptoms, postoperative ERO and short- and mid-term survival compared with revascularization alone.

Coexistence of dynamic mitral regurgitation and dynamic left ventricular dyssynchrony in a patient with repeated episodes of acute pulmonary edema: improvement with cardiac resynchronization therapy

A 69-year-old woman with idiopathic dilated cardiomyopathy and chronic heart failure experienced repeated hospital admissions for acute pulmonary edema with no recognizable precipitating factor. Worsening mitral regurgitation was triggered by exercise echocardiography and significant intraventricular dyssynchrony was elicited by low-dose dobutamine stress echocardiography. After cardiac resynchronization therapy she remained free of hospitalizations for 12 months. This case highlights the dynamic nature of both functional mitral regurgitation and left ventricular dyssynchrony and illustrates how in some patients stress echocardiography can help to clarify clinical scenarios and help with the challenging task of selecting patients who will benefit from cardiac resynchronization therapy.

Secondary Mitral Regurgitation in Heart Failure with Reduced or Preserved Left Ventricular Ejection Fraction

Secondary mitral regurgitation (MR) has been extensively studied in heart failure due to reduced ejection fraction. In contrast, the occurrence and the pathogenesis of secondary MR are much less known in heart failure with preserved ejection fraction (HFpEF). The present review aimed at describing this common but ignored feature of HFpEF.

The use of exercise echocardiography in the evaluation of mitral regurgitation

Mitral regurgitation (MR) is the second most common valvular disease in western countries after aortic stenosis. Optimal management of patients with MR depends on the etiology of the regurgitation and is based predominantly on left ventricular function and functional status. Recent outcome studies report high risk subsets of asymptomatic patients with MR, and practice guidelines underscore the importance of a well-established estimation of exercise tolerance and recommend exercise testing to objectively assess functional status and hemodynamic factors.

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.

Radionuclide angiographic determination of regional left ventricular systolic function during rest and exercise in patients with nonischemic cardiomyopathy treated with cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) can improve global left ventricular (LV) function. However, limited data are available on regional LV contractility at rest and during exercise. The aim of the present study was to prospectively investigate the effects of CRT on regional LV ejection fraction (EF), global LVEF, and dyssynchrony, during rest and exercise, using radionuclide angiography. A total of 32 consecutive patients with heart failure and nonischemic cardiomyopathy underwent technetium-99m radionuclide angiography with bicycle exercise immediately after CRT implantation (during spontaneous rhythm and after CRT activation) and 3 months later. The regional EF was assessed in the interventricular septum and the lateral wall (LW). Intraventricular dyssynchrony was evaluated using Fourier phase analysis. During spontaneous rhythm, the EF was severely depressed in the septum compared to in the LW. CRT improved septal EF at rest and during exercise both at baseline (p <0.001) and after 3 months (p <0.05). The basal LW EF decreased during CRT (p <0.05, both at rest and during exercise). LV dyssynchrony decreased both at baseline and during follow-up, and the global LVEF showed improvement only at 3 months (p <0.001). In conclusion, in patients with nonischemic cardiomyopathy, CRT affects regional LV function by increasing the septal EF and reducing LW contractility, both at rest and during exercise. This was associated with an improvement in global LVEF and dyssynchrony.

Reduction in mitral regurgitation in patients undergoing cardiac resynchronization treatment: assessment of predictors by two-dimensional radial strain echocardiography

BACKGROUND

We utilized the novel approach of 2D radial strain (2-DRS) to evaluate whether left ventricular (LV) mechanical dyssynchrony in mid-LV segments corresponding to papillary muscles insertion sites can predict early mitral regurgitation (MR) reduction post-cardiac resynchronization therapy (CRT).

METHODS

We evaluated 32 patients undergoing CRT (mean age 64 +/- 17 years, 54% males) with MR grade > or =3 determined by the MR jet area/left atrial area ratio (JA/LAA).

RESULTS

Fifteen (47%) patients responded to CRT (JA/LAA) < 25%). Sixty-seven percent of responders had mild or no residual MR and 33% had mild-to-moderate MR, while 70% of nonresponders had grade 3 or 4 MR (P = 0.0001) post CRT. The percent reduction in LV end-systolic volume was significantly higher in responders (P = 0.03), as was improvement in LVEF (P = 0.007). Significant delay of time-to-peak 2-DRS in the midposterior and inferior segments prior to CRT was found in responders compared with nonresponders (580 +/- 58 vs. 486 +/- 94, P = 0.002 and 596 +/- 79 vs. 478 +/- 127 ms, P = 0.005, respectively). Responders also had higher peak positive systolic 2-DRS in the posterior and inferior segments compared to nonresponders (22 +/- 13 vs. 12 +/- 7%, P = 0.01 and 17 +/- 9 vs. 9 +/- 7%, P = 0.02, respectively). Logistic regression analysis showed that the differences in pre-CRT inferoanterior time-to-peak 2-DRS of >110 ms and MRJA/LAA <40% as well as 2-DRS >18% in the posterior wall were significant predictors of post-CRT improvement in MR.

CONCLUSION

The presence of a significant time-to-peak delay on 2-DRS between inferior and anterior LV segments, preserved strain of posterior wall, and MRJA/LAA <40% were found to be associated with significant MR reduction in patients post-CRT.

Mitral regurgitation

Mitral regurgitation affects more than 2 million people in the USA. The main causes are classified as degenerative (with valve prolapse) and ischaemic (ie, due to consequences of coronary disease) in developed countries, or rheumatic (in developing countries). This disorder generally progresses insidiously, because the heart compensates for increasing regurgitant volume by left-atrial enlargement, causes left-ventricular overload and dysfunction, and yields poor outcome when it becomes severe. Doppler-echocardiographic methods can be used to quantify the severity of mitral regurgitation. Yearly mortality rates with medical treatment in patients aged 50 years or older are about 3% for moderate organic regurgitation and about 6% for severe organic regurgitation. Surgery is the only treatment proven to improve symptoms and prevent heart failure. Valve repair improves outcome compared with valve replacement and reduces mortality of patient with severe organic mitral regurgitation by about 70%. The best short-term and long-term results are obtained in asymptomatic patients operated on in advanced repair centres with low operative mortality (<1%) and high repair rates (>/=80-90%). These results emphasise the importance of early detection and assessment of mitral regurgitation.

A mechanistic investigation into how long-term resynchronization therapy confers ongoing cardiac functional benefits and improved exercise capacity

The exact mechanisms underpinning the longer term benefits of cardiac resynchronization therapy (CRT) were not fully understood. It was still unclear whether there was any ongoing functional benefit conferred by the partial resynchronization of ventricular contraction. To resolve this, a randomized controlled double-blind crossover trial was conducted to investigate the impact of temporary cessation of CRT on cardiac function both at rest and during peak exercise. Fifteen patients with severe heart failure and a CRT device implanted at least 3 months previously were randomly assigned to have the CRT mode switched to either off or on during exercise tests with central hemodynamic measurements (including noninvasive cardiac output measured using rebreathing methods), then crossed over on separate days to the opposite CRT mode. There were no significant changes in hemodynamic variables at rest with either mode of CRT. When CRT was acutely turned off, there was 19% lower peak exercise cardiac power (2.10 +/- 0.46 vs 2.59 +/- 0.75 W; p <0.005), 6% lower mean arterial pressure (92 +/- 12 vs 98 +/- 13 mm Hg; p <0.05), and 11.5% lower peak cardiac output (10.4 +/- 1.9 vs 11.8 +/- 2.5 L/min; p <0.05). Exercise capacity was also diminished with lower peak oxygen uptake (15.7 +/- 4.3 vs 17.2 +/- 4.9 ml/kg/min; p <0.01) and shorter exercise duration (542 +/- 204 vs 587 +/- 212 seconds; p <0.05). These changes were seen without differences in peak respiratory exchange ratio and peak systemic vascular resistance. In conclusion, these observations provided evidence that after CRT, left ventricular resynchronization continued to confer cardiac functional benefits manifest during peak exercise, but imperceptible at rest.

Biventricular pacing: impact on exercise-induced increases in mitral insufficiency in patients with chronic heart failure

INTRODUCTION

Mitral regurgitation (MR) in chronic heart failure (CHF) patients frequently worsens with exercise. Cardiac resynchronization therapy (CRT) reduces MR at rest, but its effects on exercise-induced worsening of MR are incompletely explored. The present study examined the influence of CRT on MR during submaximal exercise in CHF patients.

METHODS

Eleven patients with CHF who were treated with CRT underwent echocardiography while performing steady-state exercise during four conduction modes (intrinsic rhythm, right ventricular [RV], biventricular [BiV] and left ventricular [LV] pacing). Measurements of MR were jet area planimetry, effective regurgitant orifice area, peak MR flow rate and regurgitant volume.

RESULTS

At rest and during exercise, there were no differences in dyssynchrony between intrinsic rhythm and RV pacing. BiV and LV pacing reduced dyssynchrony at rest and during exercise compared with intrinsic conduction and RV pacing, and there were no differences in the magnitude of these effects between these two pacing modes. At rest, RV pacing increased MR compared with intrinsic conduction (MR regurgitant volume; P<0.05), whereas BiV and LV pacing reduced MR (reductions in effective regurgitant orifice area and jet area; P<0.02, and MR flow rate; P<0.05 with BiV pacing from intrinsic conduction). MR significantly increased on exercise with intrinsic rhythm and RV pacing, whereas with LV and BiV pacing, there were no significant exercise-induced increases in any MR variable. There were relationships between changes in measures of dyssynchrony and reductions in MR at rest and during exercise.

CONCLUSIONS

CRT reduces MR at rest and during exercise, and prevents exercise-induced MR. Reductions in MR during exercise correlate with improvements in dyssynchrony.

Exercise does not enhance the prognostic value of Doppler echocardiography in patients with left ventricular systolic dysfunction and functional mitral regurgitation at rest

BACKGROUND

Functional mitral regurgitation (MR) is a powerful predictor of poor prognosis in patients with chronic heart failure (CHF) due to left ventricular systolic dysfunction (LVSD). However, severity of MR varies with dynamic exercise. Accordingly, we sought to assess the prognostic value of exercise-induced changes in functional MR in patients with LVSD and functional MR at rest.

METHODS

One hundred four patients with chronic heart failure due to LVSD (ejection fraction [EF] < 45%) and functional MR at rest underwent conventional continuous 2-dimensional Doppler echocardiography at rest and during maximal symptom-limited exercise. The primary end point of the study was all-cause mortality. The median follow-up period was 20 months.

RESULTS

Fifty-six patients (54%) had ischemic cardiomyopathy. When feasible, all 56 patients with ischemic cardiomyopathy had undergone revascularization procedures before enrollment into the study. In the whole patient cohort, resting LV end-diastolic volume was 205 +/- 76 mL and EF was 26% +/- 9%. Univariate predictors of death were functional class (New York Heart Association), LV EF, LV end-diastolic volume, resting mitral effective regurgitant orifice, mitral E deceleration time, tricuspid annular plane systolic excursion < or = 14 mm, systolic blood pressure, LV EF, and trans-tricuspid pressure gradient response to exercise. Exercise-induced change in mitral effective regurgitant orifice did not predict survival (HR 0.99, 95% CI 0.94-1.04, P = .63). By Cox multivariate analysis, resting LV end-diastolic volume and tricuspid annular plane systolic excursion < or = 14 mm were the independent predictors of death.

CONCLUSIONS

Exercise Doppler echocardiography does not refine the predictive value of resting Doppler echocardiography in patients with LVSD and functional MR at rest.

[Ischemic mitral regurgitation: contributions of exercise echocardiography and new therapeutic perspectives]

The ischemic mitral regurgitation is defined by a left ventricular muscle disease affecting the function of normal mitral valve leaflets. This kind of mitral regurgitation is founded in about 20% of the ischemic cardiomyopathy and is attributed to the remodelling of the left ventricular shape. Its development is associated to a significantly worse prognosis. Frequently this ischemic mitral regurgitation will be associated to episode of acute heart failure decompensation. Its diagnosis is sometimes challenging as the degree of regurgitation might be extremely variable and affected by loading conditions. Echocardiography and especially exercise stress echocardiography has been demonstrated as an extremely powerful tool for its diagnosis and the prognostic evaluation. Its treatment should include the pharmacological treatment of the chonic heart failure and we are still waiting data in regard to the prognostic role of surgical mitral valvuloplastie. Works are still ongoing.