Author + information
- Maurizio Taramasso, MD, PhDa,∗ (, )
- Mara Gavazzoni, MDa,
- Shingo Kuwata, MD, PhDa,
- Pascal Meier, MDb and
- Francesco Maisano, MDa
- aCardiovascular Surgery Department, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
- bCardiology Department, KantonsSpital Graubünden, Chur, Switzerland
- ↵∗Address for correspondence:
Dr. Maurizio Taramasso, Cardiovascular Surgical Department, University Hospital of Zurich, Rämistrasse 100, 8091 Zurich, Switzerland.
In this issue of JACC: Cardiovascular Interventions, Ikenaga et al. (1) showed for the first time in a structured way and in a substantial number of patients that the changes in pulmonary vein (PV) flow pattern following MitraClip (Abbott Vascular, Santa Clara, California) implantation have an important and independent association with clinical outcomes. The study has limitations, being single-center, retrospective, observational, and includes patients with mixed etiologies of mitral regurgitation (MR) (both degenerative and functional) without any differentiation. Yet, the clinical message is extremely relevant for the interventional community: evaluation of the immediate result after MitraClip implantation should be performed in a more integrated way, taking into account both residual MR (color jet) and its hemodynamic effect.
Invasive Hemodynamic Assessment
Invasive hemodynamic measurements should be mandatory results assessment, shifting the paradigm of evaluation of MitraClip results from an echocardiography-based color Doppler evaluation to a hemodynamic-based approach. Live monitoring of hemodynamic changes during MitraClip procedures is routinely used in our daily clinical practice, because it has been observed to have an important impact on outcomes, independently from residual color jet, and it represents a valuable tool to guide decision making. In our practice, after transseptal puncture, 2 parallel wires are inserted in the left superior pulmonary vein through the transseptal sheath. While one wire is conventionally used to introduce the MitraClip Steerable Guide Catheter, the adjacent wire is used to deliver a 5-F pigtail catheter into the pulmonary vein. This parallel wire is used to continuously monitor left atrial (LA) pressure during all the phases of the implantation. A second 5-F pigtail catheter is inserted in the left ventricle (LV), retrograde through the aortic valve, in order to monitor LV pressures. The 2 pressure lines are constantly observed during the procedure and used to guide decision making.
The ideal situation should be as the color jet is reduced, the V-wave and mean LA pressure are reduced as well, with an increase in the systolic blood pressure and no residual gradient. It is not infrequent to observe a discrepancy between the color Doppler result and hemodynamic changes, with many patients having a residual color jet, but dramatic reduction of V-wave and mean LA pressure or having no residual MR and no gradient at echocardiographic assessment, but a significant invasive gradient. It has been observed in our experience that the most important predictor of outcome after MitraClip implantation is reduction of the mean LA pressure, independent from a residual color jet. Therefore, we have already switched in our practice from color-based to hemodynamic-based assessment of the outcomes (Figure 1). Reduction of mean LA pressure and absence of an invasive gradient should be the main determinants to drive the procedure and to guide the operator in case of discrepancies.
Noninvasive Hemodynamic Assessment
Echocardiographic assessment of residual MR after MitraClip implantation presents several challenges and can be inaccurate due to the double orifice configuration of the valve and/or the presence of multiple regurgitant jets, suggesting the need for adjunctive tools (2–5). Evaluation of pulmonary venous flow is an easy and reproducible technique, which is widely used to aid in the assessment of quantification of the severity of MR and should be routinely used after MitraClip implantation.
As a matter of fact, the most important determinants of outcomes after MitraClip implantation are residual MR and increased transvalvular gradient (6,7). Because residual relevant MR is associated with increased risk of mortality after MitraClip implantation, the decision making and the procedural strategy during the intervention assume a crucial importance. The operators have to face several difficult situations or “gray zones” from a decisional standpoint, and intraprocedural decisions can have a strong impact on procedural outcomes, long-term results, and prognosis. Many questions commonly present. What should be done in the case of a residual jet? In case of a second or third clip implantation, would the adjunctive benefit of more MR reduction be nullified by the incremental increase in the gradient? What should be done in the case of MR reduction, but a significant increase in transmitral gradient? The answers to each are not always clear, suggesting that a more integrated approach, in conjunction with conventional methods (color jet and echocardiographic gradient solely), is needed to guide such decisions.
In the case of a residual color jet after the implantation of a first clip, the operator has to decide whether to proceed with a second clip implantation, and this decision is mainly driven by the severity of the residual jet and by the risk of increase of the gradient by adding a further clip. Often the situation is clear, and the decision is relatively easy. In the presence of severe residual MR and large mitral valve area, with low transmitral gradient, the decision to proceed with an additional clip is obvious. Similar is the situation of effective reduction of the color jet, where in absence of valvular gradient, the decision would be to accept that result. The use of an adjunctive technique such as systolic/diastolic velocity time integral (Svti/Dvti) ratio is extremely useful to guide decisions in gray situations, which are not so infrequent. A typical example would be the case of a residual jet with an increase of the gradient after the implantation of a further clip. In such a case, the evaluation of the pulmonary flow would assume a crucial importance: in the presence of an improvement of the pulmonary flow, the result should be accepted despite the presence of a residual color jet; in case of no changes in the pulmonary flow, a further clip would be considered.
The decision whether to reposition or remove a clip, or to proceed with further clip implantation should never be solely based on the assessment of the color jet, but should rather be based on an integrated judgment of further echocardiographic and hemodynamic tools, shifting the conventional paradigm toward a functional and physiological rather than anatomic approach. The same concept should be applied to other structural mitral interventions, including annuloplasty and valve replacement.
The concept of including different etiologies can support the value of PV Doppler evaluation in all clinical settings. Despite this, evaluating PV Doppler changes can have different clinical implications in degenerative (DMR) versus functional (FMR) mitral regurgitation.
In the setting of pure DMR, atrial function and volume are the most important factors affecting PV flow in the short term, so in this setting, short-term changes in PV Doppler after the procedure can strongly reflect the impact of MitraClip implantation on MR. The positive predictive value of significant change in PV Doppler is very strong. Therefore, given the more frequent eccentric jet of DMR, the negative predictive value could be poor, and only color flow imaging can help to understand hemodynamic involvement.
In the case of FMR, long-standing high LV end-diastolic pressures and longer neurohormonal activation mainly leads to structural alteration of LA function. In such cases of poor LV function and increased LA stiffness, color Doppler evaluation of residual MR could have several pitfalls (underestimation of residual MR). Significant changes in PV Doppler immediately after the procedure, irrespective of color Doppler, identifies patients in which good remodeling after MV repair is expected, being the ones with still preserved LA/LV interaction.
So, Svti/Dvti is not only a predictor of outcome, but also a marker of more advanced heart failure disease, that is characterized mostly by less compliance of the atrial and ventricular cavities. As proof of concept, in the present study at baseline, patients with lower Svti/Dvti had more advanced heart failure, with more frequent FMR, higher levels of brain natriuretic peptide, reduced LV function, and greater dilation of cardiac chambers.
So, the questions that remain to be clarified are as follows: “Should we obtain the same results on MR when the PV flow pattern is not changing during the procedure? Could we be satisfied with lesser results based on color flow when the PV flow is clearly getting better? When we treat with FMR, is the most important clinical point to find the hemodynamic stage at which escalation of the procedure is no more useful. The right target for each patient may be reached by using a combination of the 2 methods: less color flow MR reduction and no changes in PV flow. Future studies are expected to compare residual MR as color Doppler and PV Doppler for DMR and FMR to confirm this observation.
↵∗ Editorials published in JACC: Cardiovascular Interventions reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Interventions or the American College of Cardiology.
Dr. Taramasso has been a consultant for Abbott, Boston Scientific, 4tech, and CoreMedic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
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