Patient-prosthesis mismatch in mitral annuloplasty for degenerative mitral regurgitation: an ignored issue

Predictors of mitral valve haemodynamics after mitral valve repair for degenerative mitral regurgitation

OBJECTIVE

Intraoperative predictors of functional mitral valve (MV) stenosis after surgical repair of mitral regurgitation (MR) caused by prolapse remain poorly characterised. This study evaluated the effect of annuloplasty size on postoperative MV haemodynamics during exercise and evaluated predictors of MV hemodynamics.

METHODS

104 patients were randomly assigned to leaflet resection or preservation for surgical repair of MR in the Canadian Mitral Research Alliance CardioLink-2 study. In this post hoc analysis, we compared MV haemodynamics between the two surgical groups and examined the relationship between annuloplasty size and MV haemodynamics 1 year after repair in the combined groups. Echocardiograms were performed at baseline and intraoperatively. Exercise transthoracic echocardiography was performed 1 year postoperatively. Multivariable linear regression analysis was used to identify predictors of exercise MV gradients at follow-up.

RESULTS

Mean age of participants was 65±10 years, and 83% were male. Median annuloplasty size was 34 (IQR 32-36). Dividing by the median, 48 (46%) had annuloplasty size of <34 mm and 56 (54%) had ≥34 mm. Mean and peak exercise gradients at 1 year were 11±5 mm Hg and 22±9 mm Hg in <34, and 6±3 mm Hg and 14±5 mm Hg in ≥34 (p<0.001). Rate of residual MR was similar in both groups. In multivariable analyses, annuloplasty size of ≥34 mm was associated with lower mean and peak exercise gradients at 12 months, after adjustment for repair type, age, sex, heart rate and body surface area (β -4.1, 95% CI -6 to -3, p<0.001, and β -7 95% CI -10 to -4, p<0.001, respectively). Intraoperative mean and peak MV gradients by transesophageal echocardiography independently predicted mean and peak resting and exercise gradients at follow-up (p<0.001). Similar results were obtained in both leaflet resection and preservation.

CONCLUSION

Annuloplasty size of ≥34 mm is associated with a 4 and 7 mm Hg reduction in mean and peak exercise MV gradients, respectively, 1 year post MV repair regardless of the repair strategy used. Intraoperative TEE MV gradients predict exercise MV gradients 1 year post repair.

TRIAL REGISTRATION NUMBER

NCT02552771.

Surgical mitral valve repair technique considerations based on the available evidence

Mitral valve regurgitation is the second most common valve disease in the western world. Surgery is currently the best tool for generating a long-lasting elimination of mitral valve regurgitation. However, the mitral valve apparatus is a complex anatomical and functional structure, and repair results and durability show substantial heterogeneity. This is not only due to differences in the underlying mitral valve regurgitation pathophysiology but also due to differences in repair techniques. Repair philosophies differ substantially from one surgeon to the other, and consensus for the technically best repair strategy has not been reached yet. We had previously addressed this topic by suggesting that ring sizing is "voodoo". We now review the available evidence regarding the various repair techniques described for structural and functional mitral valve regurgitation. Herein, we illustrate that for structural mitral valve regurgitation, resuspension of prolapsing valve segments or torn chordae with polytetrafluoroethylene sutures and annuloplasty can generate the most durable results paired with the best achievable hemodynamics. For functional mitral valve regurgitation, the evidence suggests that annuloplasty alone is insufficient in most cases to generate durable results, and additional subvalvular strategies are associated with improved durability and possibly improved clinical outcomes. This review addresses current strategies but also implausibilities in mitral valve repair and informs the mitral valve surgeon about the current evidence. We believe that this information may help improve outcomes in mitral valve repair as the heterogeneity of mitral valve regurgitation pathophysiology does not allow a one-size-fits-all concept.

Flow adjusted transmitral pressure gradient as a modified indicator of functional mitral stenosis after repair for degenerative mitral regurgitation

Background and Aim

After repair of degenerative mitral regurgitation (DMR), the focus is on functional mitral stenosis (FMS) when there is a decline of mitral hemodynamics. Yet, the clinical impacts and a standardized definition are still undecided. Since common mitral hemodynamic parameters are influenced by transmitral flow, the aim of this study is to seek the impact of flow adjusted transmitral pressure gradient (TMPG) by left ventricular stroke volume (LVSV) on the midterm outcomes.

Methods

Three hundred one patients who had undergone isolated mitral valve repair for degenerative lesions with annuloplasty prosthesis between October 2012 and June 2019 were included. Postoperative adverse events occurred in 20 patients (6.6%). Flow adjusted TMPG was defined as TMPG/LVSV.

Results

Common mitral hemodynamic parameters were not associated with adverse events. By multivariable analysis, patients’ age, left ventricular ejection fraction (LVEF) and mean TMPG/LVSV were isolated as independent predictors (adjusted hazard ratio: 1.05, 0.95, and 1.16; p = .037, .005, and .035). Flow adjusted TMPG was significantly higher in the full ring group compared to the partial band group (0.051 mmHg/ml, [0.038–0.068] vs. 0.041 mmHg/ml, [0.031–0.056]; p < .001) and had a significantly negative correlation with the size of the annuloplasty prosthesis (r = −0.37, p < .001).

Conclusions

Conventional mitral hemodynamic parameters were not associated with adverse cardiac events after repair for DMR. Adjustment by flow has a potential to advance pressure gradient to a more sensitive indicator of FMS associated with clinical outcomes.

In the VEST trial: are we missed to address the pathology incurred by the external stent?

In the VEST IV trial, the author concluded that external stenting of saphenous vein graft mitigates its remodeling and also significantly reduces the diffuse intimal hyperplasia and development of lumen irregularities at 4.5 years after coronary artery bypass grafting surgery. We also have valuable a suggestion in addition to external stenting that might nullify the pathology caused by the stent and might enhances graft patency.

Clinical Impact of Flow Adjusted Transmitral Pressure Gradient After Surgical Annuloplasty for Functional Mitral Regurgitation

Downsizing of mitral annulus due to mitral annuloplasty for ischemic functional mitral regurgitation (FMR) raises a new issue, functional mitral stenosis (FMS), defined as a decline of mitral hemodynamics. However, common mitral hemodynamic parameters are influenced by transmitral flow, therefore, the clinical impacts are still controversial. The aim of this study is to seek mitral hemodynamic indices (including transmitlra pressure gradient [TMPG] adjusted by left ventricular stroke volume [LVSV]) relevant to the mid-term outcomes after annuloplasty for ischemic functional mitral regurgitation (FMR). This study is a retrospective evaluation of mitral valve hemodynamic status by resting echocardiogram at several weeks after surgery. Eighty-one patients underwent mitral annuloplasty for ischemic FMR between September 2012 and June 2019. Postoperative adverse events occurred in 28 patients (34.6%), and the overall 5-year freedom from adverse events rate was 55.9%. Common mitral hemodynamic parameters were not associated with adverse events, but flow adjusted TMPG can be a correlative factor. By multivariable analysis, postoperative systolic pulmonary artery pressure and peak TMPG/LVSV were detected as independent predictors (adjusted hazard ratio 1.07 and 1.08, P < 0.001 and < 0.001). Additionally, risk stratification by peak TMPG (cut-off: 10 mm Hg) and LVSV (cut-off: 35 mL/m²) reflected the mid-term outcomes, perceptively (P = 0.007). Conventional mitral hemodynamic parameters were not associated with adverse cardiac events after annuloplasty for ischemic FMR. However, flow adjusted TMPG was identfied as an independent predictor, and risk stratification by peak TMPG and LVSV reflected the mid-term outcomes, perceptively.

Impact of type and size of annuloplasty prosthesis on hemodynamic status after mitral valve repair for degenerative disease

Objective

The aim of this study is to evaluate mitral valve hemodynamics after mitral valve repair for degenerative disease, and seek the impact of type/size of annuloplasty prosthesis on resting cardiac hemodynamics.

Methods

Between October 2012 and June 2019, 301 patients underwent isolated mitral valve repair for degenerative disease were enrolled. Correlation between postoperative mitral hemodynamics and type/size of annuloplasty prosthesis was evaluated.

Results

There were significant correlations between annuloplasty size and peak velocity (r = -0.41, p < 0.001), peak transmitral pressure gradient (TMPG) (r = -0.40, p < 0.001), mean TMPG (r = -0.41, p < 0.001), effective orifice area (EOA) (r = 0.26, p < 0.001), and pulmonary artery systolic pressure (r = -0.15, p = 0.010). In patients with larger annuloplasty prostheses (≥30 mm), the type of annuloplasty prosthesis (band or ring) did not influence the mitral hemodynamics, however, mean TMPG was significantly greater in patients with a full ring (2.9 mmHg [2.1-3.7] vs. 4.0 mmHg [2.8-5.0], p < 0.001) in patients with smaller annuloplasty (<30 mm). Left ventricular ejection fraction and stroke volume were significantly associated with an increase of TMPG (r = 0.14, p = 0.016 and r = 0.24, p < 0.001).

Conclusions

A larger partial band had the potential to improve mitral hemodynamics after mitral repair for degenerative disease. However, echocardiographic mitral hemodynamics was influenced by LV function. Therefore, a more accurate method is required to elucidate the true impact of mitral repair on hemodynamics.