Impact of increased transmitral gradients after undersized annuloplasty for chronic ischemic mitral regurgitation

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.

Effect of Mitral Valve Gradient After MitraClip on Outcomes in Secondary Mitral Regurgitation: Results From the COAPT Trial

OBJECTIVES

The authors sought to evaluate the association between mean mitral valve gradient (MVG) and clinical outcomes among patients who underwent MitraClip treatment for secondary mitral regurgitation (SMR) in the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial.

BACKGROUND

In the COAPT trial, patients with heart failure (HF) and severe SMR who remained symptomatic despite guideline-directed medical therapy had marked 2-year reductions in mortality and HF hospitalizations after treatment with MitraClip.

METHODS

MitraClip-treated patients were divided into quartiles (Q) based on discharge echocardiographic MVG (n = 250). Endpoints including all-cause mortality, HF hospitalization, and health status measures at 2 years were compared between quartiles.

RESULTS

Mean MVG after MitraClip was 2.1 ± 0.4 mm Hg, 3.0 ± 0.2 mm Hg, 4.2 ± 0.5 mm Hg, and 7.2 ± 2.0 mm Hg in Q1 (n = 63), Q2 (n = 61), Q3 (n = 62), and Q4 (n = 64), respectively. There was no difference across quartiles in the 2-year composite endpoint of all-cause mortality or HF hospitalization (43.2%, 49.2%, 40.6%, and 40.9%, respectively; p = 0.80), nor in improvements in New York Heart Association functional class, Kansas City Cardiomyopathy Questionnaire score, or 6-min walk time. Results were similar after adjustment for baseline clinical and echocardiographic characteristics, post-procedure MR grade, and number of clips (all-cause mortality or HF hospitalization Q4 [44.6%] vs. Q1 to Q3 [40.3%]; adjusted hazard ratio: 1.23, 95% confidence interval: 0.60 to 2.51; p = 0.57).

CONCLUSIONS

Among HF patients with severe SMR, higher MVGs on discharge did not adversely affect clinical outcomes following MitraClip. These findings suggest that in select patients with HF and SMR otherwise meeting the COAPT inclusion criteria, the benefits of MR reduction may outweigh the effects of mild-to-moderate mitral stenosis after MitraClip.

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.

Long-term outcomes of etiology specific annuloplasty ring repair of ischemic mitral regurgitation

Background

Reductive annuloplasty repair of ischemic mitral regurgitation (IMR) is associated with high rates of recurrent MR, which may be improved with etiology-specific annuloplasty rings.

Methods

From October 2005 to May 2015, 128 consecutive patients underwent repair of IMR with the GeoForm ring. Clinical data was extracted from our local Society of Thoracic Surgeons database and electronic medical records. Mortality data was obtained from the Michigan State Social Security Death Index.

Results

The average age of patients was 65±11 years with mean pre-op left ventricular ejection fraction (LVEF) of 30%±10% and MR grade of 3.1±0.9 (0-4+). Thirty-day mortality was 4.7%, rate of renal failure 7.9%, rate of atrial fibrillation 27.3%, and no strokes were observed. Of the surviving patients, 89% (109/122) had a follow-up echocardiogram beyond 1 month with a mean echocardiographic follow-up of 59±39 months. LVEF improved from 30%±10% to 38%±14%, P<0.001) while end-diastolic (5.9±0.0 to 5.3±0.9 cm, P<0.001) and end-systolic (5.0±1.0 to 4.4±1.1 cm, P<0.001) left ventricular (LV) diameters decreased, as compared to pre-operative values. Seven patients were found to have recurrent moderate or greater IMR in follow-up to 10 years with three being due to ring dehiscence. One-, 5-, and 10-year freedom from recurrent moderate or severe IMR was 98%, 94%, and 80% respectively. One-, 5-, and 10-year survival was 91%, 77%, and 44%, respectively.

Conclusions

Overall, etiology-specific ring repair of IMR was associated with low rates of recurrent MR on long-term follow-up, coupled with significant LV reverse remodeling and improvement in ejection fraction.

Elevated Mitral Valve Pressure Gradient Is Predictive of Long-Term Outcome After Percutaneous Edge-to-Edge Mitral Valve Repair in Patients With Degenerative Mitral Regurgitation ( MR ), But Not in Functional MR

Background This study analyzed the effects on long-term outcome of residual mitral regurgitation ( MR ) and mean mitral valve pressure gradient ( MVPG ) after percutaneous edge-to-edge mitral valve repair using the MitraClip system. Methods and Results Two hundred fifty-five patients who underwent percutaneous edge-to-edge mitral valve repair were analyzed. Kaplan-Meier and Cox regression analyses were performed to evaluate the impact of residual MR and MVPG on clinical outcome. A combined clinical end point (all-cause mortality, MV surgery, redo procedure, implantation of a left ventricular assist device) was used. After percutaneous edge-to-edge mitral valve repair, mean MVPG increased from 1.6±1.0 to 3.1±1.5 mm Hg ( P<0.001). Reduction of MR severity to ≤2+ postintervention was achieved in 98.4% of all patients. In the overall patient cohort, residual MR was predictive of the combined end point while elevated MVPG >4.4 mm Hg was not according to Kaplan-Meier and Cox regression analyses. We then analyzed the cohort with degenerative and that with functional MR separately to account for these different entities. In the cohort with degenerative MR , elevated MVPG was associated with increased occurrence of the primary end point, whereas this was not observed in the cohort with functional MR . Conclusions MVPG >4.4 mm Hg after MitraClip implantation was predictive of clinical outcome in the patient cohort with degenerative MR . In the patient cohort with functional MR , MVPG >4.4 mm Hg was not associated with increased clinical events.

Serial Changes of Transmitral and Transtricuspid Pressure Gradients After Simultaneous Mitral and Tricuspid Ring Annuloplasty

BACKGROUND

Although flexible-ring annuloplasty is more inclined to increase the transmitral gradient over time, its effect on the tricuspid annulus is unknown. This study was conducted to evaluate serial changes in mean pressure gradient (mPG) across tricuspid and mitral valves after simultaneous dual implantation of flexible bands.

METHODS

Seventy-one (71) patients (median age, 61.6 years; IQR: 50.8-69.0 years) underwent simultaneous mitral/tricuspid annuloplasties using St. Jude Tailor rings. Serial mPGs across mitral and tricuspid valves were evaluated at three postoperative time points: predischarge, 3 years, and 5 years. To gauge the effects and clinical outcomes of prophylactic intervention, patients were categorised as tricuspid regurgitation (TR)≥moderate or TR<moderate. The median follow-up period was 125 months (IQR: 109-137 months).

RESULTS

Unlike transmitral mPG, which increased over time (predischarge, 2.94; 3 years, 3.61; 5 years, 3.87; p<0.0005), transtricuspid mPG did not change (predischarge, 1.65; 3 years, 1.69; 5 years, 1.69; p=0.906). Preoperative TR grade had no impact on serial changes in transtricuspid mPG (TR≥moderate, p=0.542; TR<moderate, p=0.608). Three observed late recurrences of TR≥moderate degree displayed TR≥moderate at baseline, and overall mortality was higher in the TR≥moderate group (p=0.01).

CONCLUSIONS

Flexible-band annuloplasty did not promote stenosis of tricuspid valves at mid-term follow-up. These findings confirm the safety of prophylactic tricuspid annuloplasty (via flexible band) as an adjunct to mitral annuloplasty.

Predicting functional mitral stenosis after restrictive annuloplasty for ischemic mitral regurgitation

BACKGROUND

Although it has been realized that restrictive mitral valve annuloplasty (MVA) may re-sult in clinically significant functional mitral stenosis (MS), it still cannot be predicted. The purpose of this study was to identify risk factors for clinically significant functional MS following restrictive MVA surgery for chronic ischemic mitral regurgitation (CIMR).

METHODS

One hundred and fourteen patients who underwent restrictive MVA with coronary artery bypass grafting (CABG) for treatment of CIMR were retrospectively reviewed. Clinically significant functional MS was defined as resting transmitral peak pressure gradient (PPG) ≥ 13 mmHg.

RESULTS

During the follow-up period (range 6-12 months), 28 (24.56%) patients developed clinically significant functional MS. The PPG at follow-up was significantly higher than that measured in the early postoperative stage (3-5 days after surgery). Moreover, there was a linear correlation between the two measurements (r = 0.398, p < 0.001). Annuloplasty size ≤ 27 mm and early postoperative PPG ≥ 7.4 mmHg could predict clinically significant functional MS at 6-12 months postoperatively.

CONCLUSIONS

Chronic ischemic mitral regurgitation patients treated with restrictive MVA and CABG have significant increases in PPG postoperatively. Annuloplasty size ≤ 27 mm and early postopera-tive PPG ≥ 7.4 mmHg can predict clinically significant functional MS at 6-12 months after surgery.

A Comparison of 2 Mitral Annuloplasty Rings for Severe Ischemic Mitral Regurgitation: Clinical and Echocardiographic Outcomes

Controversies regarding the choice of annuloplasty rings for treatment of ischemic mitral regurgitation still exist. Aim of the study is to compare early performance of 2 different rings in terms of rest and exercise echocardiographic parameters (transmitral gradient, systolic pulmonary artery pressure, and mitral valve area), clinical outcomes, and recurrence of mitral regurgitation. From January 2008 till December 2013, prospectively collected data of patients who underwent coronary artery bypass grafting and undersizing mitral valve annuloplasty for severe chronic ischemic mitral regurgitation at our Institution were reviewed. A total of 93 patients were identified; among them 44 had semirigid Memo 3D ring implanted (group A) whereas 49 had a rigid profile 3D ring (group B). At 6 months, recurrent ischemic mitral regurgitation, equal or more than moderate, was observed in 4 and 6 patients in the group A and B, respectively (P = 0.74). Group A showed certain improved valve geometric parameters such as posterior leaflet angle, tenting area, and coaptation depth. Transmitral gradient was significantly higher at rest in the group B (P < 0.0001). During exercise, significant increase of transmitral gradient and systolic pulmonary artery pressure was observed in group B (P < 0.0001). Mitral valve area was not statistically significantly smaller at rest in between groups (P = 0.09); however, it significantly decreased with exercise in group B (P = 0.01). At midterm follow-up, patients in group B were more symptomatic. In patients with chronic ischemic mitral regurgitation, use of semirigid Memo 3D ring when compared to the rigid Profile 3D may be associated with early improved mitral valve geometrical conformation and hemodynamic profile, particularly during exercise. No difference was observed between both groups in recurrent mitral regurgitation.

Mitral Valve Stenosis after Open Repair Surgery for Non-rheumatic Mitral Valve Regurgitation: A Review

Mitral stenosis (MS) after mitral valve (MV) repair is a slowly progressive condition, usually detected many years after the index MV surgery. It is defined as a mean transmitral pressure gradient (TMPG) >5 mmHg or a mitral valve area (MVA) <1.5 cm(2). Pannus formation around the mitral annulus or extending to the mitral leaflets is suggested as the main mechanism for developing delayed MS after MV repair. On the other hand, early stenosis is thought to be a direct result of an undersized annuloplasty ring. Furthermore, in MS following ischemic mitral regurgitation (MR) repair, subvalvular tethering is the hypothesized pathophysiology. MS after MV repair has an incidence of 9-54%. Several factors have been associated with a higher risk for developing MS after MV repair, including the use of flexible Duran annuloplasty rings versus rigid Carpentier-Edwards rings, complete annuloplasty rings versus partial bands, small versus large anterior leaflet opening angle, and anterior leaflet tip opening length. Intraoperative echocardiography can measure the anterior leaflet opening angle, the anterior leaflet tip opening dimension, the MVA and the mean TMPG, and may help identify patients at risk for developing MS after MV repair.

Mitral valve area during exercise after restrictive mitral valve annuloplasty: importance of diastolic anterior leaflet tethering

BACKGROUND

Restrictive mitral valve annuloplasty (RMA) for secondary mitral regurgitation might cause functional mitral stenosis, yet its clinical impact and underlying pathophysiological mechanisms remain debated.

OBJECTIVES

The purpose of our study was to assess the hemodynamic and clinical impact of effective orifice area (EOA) after RMA and its relationship with diastolic anterior leaflet (AL) tethering at rest and during exercise.

METHODS

Consecutive RMA patients (n = 39) underwent a symptom-limited supine bicycle exercise test with Doppler echocardiography and respiratory gas analysis. EOA, transmitral flow rate, mean transmitral gradient, and systolic pulmonary arterial pressure were assessed at different stages of exercise. AL opening angles were measured at rest and peak exercise. Mortality and heart failure readmission data were collected for at least 20 months after surgery.

RESULTS

EOA and AL opening angle were 1.5 ± 0.4 cm(2) and 68 ± 10°, respectively, at rest (r = 0.4; p = 0.014). EOA increased significantly to 2.0 ± 0.5 cm(2) at peak exercise (p < 0.001), showing an improved correlation with AL opening angle (r = 0.6; p < 0.001). Indexed EOA (EOAi) at peak exercise was an independent predictor of exercise capacity (maximal oxygen uptake, p = 0.004) and was independently associated with freedom from all-cause mortality or hospital admission for heart failure (p = 0.034). Patients with exercise EOAi <0.9 cm(2)/m(2) (n = 14) compared with ≥0.9 cm(2)/m(2) (n = 25) had a significantly worse outcome (p = 0.048). In multivariate analysis, AL opening angle at peak exercise (p = 0.037) was the strongest predictor of exercise EOAi.

CONCLUSIONS

In RMA patients, EOA increases during exercise despite fixed annular size. Diastolic AL tethering plays a key role in this dynamic process, with increasing AL opening during exercise being associated with higher exercise EOA. EOAi at peak exercise is a strong and independent predictor of exercise capacity and is associated with clinical outcome. Our findings stress the importance of maximizing AL opening by targeting the subvalvular apparatus in future repair algorithms for secondary mitral regurgitation.

Mitral inflow patterns after MitraClip implantation at rest and during exercise

BACKGROUND

MitraClip implantation reduces mitral regurgitation effectively but decreases mitral valve area, creating iatrogenic mitral stenosis. Evaluation with transesophageal echocardiography intraprocedurally is necessary to measure mitral regurgitation and mitral valve pressure gradient (MVPG) to determine whether it is necessary and safe to place more clips. The aim of this study was to investigate whether these intraprocedural hemodynamics represent postprocedural measurements and whether exercise is affected by the stenosis.

METHODS

In this retrospective single-center study, 51 patients who underwent MitraClip implantation were included. Measurements were performed intraprocedurally using transesophageal echocardiography and postprocedurally using transthoracic echocardiography. In 23 of these patients, exercise echocardiography was performed at follow-up.

RESULTS

Intraprocedural mean MVPG was 3.0 ± 1.6 mm Hg and increased to 4.3 ± 2.2 mm Hg postprocedurally (P < .001). During exercise, mean MVPG increased significantly compared with rest conditions (from 3.6 ± 1.7 to 6.3 ± 2.7 mm Hg, P < .001). Six patients had mean resting MVPGs ≥ 5 mm Hg at follow-up and had higher systolic pulmonary artery pressure (sPAPs) than patients with mean MVPGs < 5 mm Hg (47 ± 7 vs 35 ± 12 mm Hg, P = .035). Higher MVPG and sPAP did not lead to more symptoms of heart failure. Receiver operating characteristic curve analysis showed an estimated cutoff point for intraprocedural pressure half-time of 91 msec to identify patients with mitral stenosis and sPAP ≥ 50 mm Hg postprocedurally.

CONCLUSIONS

Mean MVPG during MitraClip implantation measured by TEE underestimates the hemodynamics in daily life, of which operators should be aware when deciding on placing one or more clips. Pressure half-time seems to be the most robust parameter compared with mean and maximum MVPG and may contribute to this decision. Patients with higher mean MVPGs after MitraClip implantation have higher sPAPs at follow-up. However, more symptoms of heart failure were not detected at follow-up.