Non-invasive Cardiac Evaluation in MitraClip Procedure
Non-invasive Cardiac Evaluation in MitraClip Procedure
The main finding of this study was that the reduction of mitral regurgitation with MitraClip procedure is associated with preserved ventricular end systolic elastance (single beat) not correlated with the reduction of EF, and unchanged ventriculo-arterial coupling defined as Ea/Ees(SB) at an early follow-up.
A percutaneous edge-to-edge procedure may be considered in patients with symptomatic severe MR who fulfill the echo criteria of eligibility, are judged inoperable or at high surgical risk by a 'heart team', and have a life expectancy greater than 1 year (recommendation class IIb, level of evidence C). The impact of percutaneous therapy allows the treatment of patients for whom the only alternative is amelioration using pharmacological therapy without a significant improvement in the duration or quality of life due to unacceptable surgical risk.
Our study confirms the hemodynamic effects of the MitraClip procedure for patients with severe mitral regurgitation. All patients presented a significant reduction of mitral regurgitation at the time of control (T1). The reduction of MV insufficiency was associated with lowering of PAPs, left ventricular and atrial volumes and amelioration of the NYHA class status.
We hypothesize that the observed reduction of the ejection fraction could not be an index of decreased systolic function, rather a consequence of a reduced preload, as evidenced by the reduction of the left atrial and ventricular volumes. Left ventricular unloading is considered one of the most important determinants of the reduction of clinical symptoms in patients after correction of mitral regurgitation by any technique (19). In the MitraClip procedure closing the MV regurgitant orifice lowers the regurgitation volume and the left ventricular and diastolic volumes during the next diastole.
The analysis of ventriculo-arterial coupling in this subset of patients produced interesting results.
Siegel et al. have shown that successful MV repair with the MitraClip system results in an immediate improvement in FSV, CO, and LV loading conditions and an acute reduction of the systemic vascular resistance.
A post-hoc analysis has demonstrated that the hemodynamic benefit of the percutaneous procedure is higher in a particular subset of patients with a low CI and a high left-sided filling pressure and PAP.
Ken-ichi Imasaka et al. demonstrated that the early surgical repair of organic mitral valve regurgitation influenced ventricular coupling in patients with preserved and impaired LV function. Measuring ventricular and arterial coupling before and 1 month after surgery, they showed that Ea increased after the procedure in all patients, but only patients with preserved function increased their contractility to rebalance ventricular coupling.
Most of our patients presented impaired function with a maintained optimal Ea/Ees(SB) ratio before the procedure. We demonstrated that contractility was preserved in all patients and that Ea was not increased after the procedure. As a consequence, the lack of variation in the Ea/Ees(SB) ratio is the expression of maintained ventriculo-arterial coupling and ventricular performance after the percutaneous closure of the defect. Considering stroke volume as a function of ventriculo-arterial coupling, we can deduce that, despite reducing the EF, the combination of the restoration of normal blood ejection and the preserved Ea/Ees ratio increases the forward "effective" stroke volume after the MitraClip procedure.
Our findings are supported by the recently published data by Gaemperli et al. who investigated the acute behavior of pressure volume relationships in patients undergoing Mitraclip procedure. Based on the invasive measurements obtained with conductance catheters during the intervention they found no acute variations of PV loop area and increased CI following MV repair.
Our study shows limitations due to its retrospective design and the small number of patients analyzed. Our results have been obtained in a non-invasive manner and we cannot exclude differences if data were obtained invasively monitoring ventricular and vascular load determinants, although recent evidence seems to support our results. However, this study is the first to non invasively describe midterm preserved ventricular performance and the low impact of MitraClip repair of MV regurgitation on LV afterload (Ea) in patients with impaired ventricular function. Larger prospective studies are needed to confirm these results focusing on relation between preservation of cardiomechanic parameters and clinical status during follow up in patients undergoing MitraClip procedure.
Discussion
The main finding of this study was that the reduction of mitral regurgitation with MitraClip procedure is associated with preserved ventricular end systolic elastance (single beat) not correlated with the reduction of EF, and unchanged ventriculo-arterial coupling defined as Ea/Ees(SB) at an early follow-up.
A percutaneous edge-to-edge procedure may be considered in patients with symptomatic severe MR who fulfill the echo criteria of eligibility, are judged inoperable or at high surgical risk by a 'heart team', and have a life expectancy greater than 1 year (recommendation class IIb, level of evidence C). The impact of percutaneous therapy allows the treatment of patients for whom the only alternative is amelioration using pharmacological therapy without a significant improvement in the duration or quality of life due to unacceptable surgical risk.
Our study confirms the hemodynamic effects of the MitraClip procedure for patients with severe mitral regurgitation. All patients presented a significant reduction of mitral regurgitation at the time of control (T1). The reduction of MV insufficiency was associated with lowering of PAPs, left ventricular and atrial volumes and amelioration of the NYHA class status.
We hypothesize that the observed reduction of the ejection fraction could not be an index of decreased systolic function, rather a consequence of a reduced preload, as evidenced by the reduction of the left atrial and ventricular volumes. Left ventricular unloading is considered one of the most important determinants of the reduction of clinical symptoms in patients after correction of mitral regurgitation by any technique (19). In the MitraClip procedure closing the MV regurgitant orifice lowers the regurgitation volume and the left ventricular and diastolic volumes during the next diastole.
The analysis of ventriculo-arterial coupling in this subset of patients produced interesting results.
Siegel et al. have shown that successful MV repair with the MitraClip system results in an immediate improvement in FSV, CO, and LV loading conditions and an acute reduction of the systemic vascular resistance.
A post-hoc analysis has demonstrated that the hemodynamic benefit of the percutaneous procedure is higher in a particular subset of patients with a low CI and a high left-sided filling pressure and PAP.
Ken-ichi Imasaka et al. demonstrated that the early surgical repair of organic mitral valve regurgitation influenced ventricular coupling in patients with preserved and impaired LV function. Measuring ventricular and arterial coupling before and 1 month after surgery, they showed that Ea increased after the procedure in all patients, but only patients with preserved function increased their contractility to rebalance ventricular coupling.
Most of our patients presented impaired function with a maintained optimal Ea/Ees(SB) ratio before the procedure. We demonstrated that contractility was preserved in all patients and that Ea was not increased after the procedure. As a consequence, the lack of variation in the Ea/Ees(SB) ratio is the expression of maintained ventriculo-arterial coupling and ventricular performance after the percutaneous closure of the defect. Considering stroke volume as a function of ventriculo-arterial coupling, we can deduce that, despite reducing the EF, the combination of the restoration of normal blood ejection and the preserved Ea/Ees ratio increases the forward "effective" stroke volume after the MitraClip procedure.
Our findings are supported by the recently published data by Gaemperli et al. who investigated the acute behavior of pressure volume relationships in patients undergoing Mitraclip procedure. Based on the invasive measurements obtained with conductance catheters during the intervention they found no acute variations of PV loop area and increased CI following MV repair.
Our study shows limitations due to its retrospective design and the small number of patients analyzed. Our results have been obtained in a non-invasive manner and we cannot exclude differences if data were obtained invasively monitoring ventricular and vascular load determinants, although recent evidence seems to support our results. However, this study is the first to non invasively describe midterm preserved ventricular performance and the low impact of MitraClip repair of MV regurgitation on LV afterload (Ea) in patients with impaired ventricular function. Larger prospective studies are needed to confirm these results focusing on relation between preservation of cardiomechanic parameters and clinical status during follow up in patients undergoing MitraClip procedure.
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