What Is the Optimal Mitral Valve Repair for Isolated Posterior Leaflet Prolapse to Achieve Long‐Term Durability?

Abstract

Background

This study assessed risk factors for mitral regurgitation (MR) recurrence or functional mitral stenosis during long‐term follow‐up in patients undergoing mitral valve repair for isolated posterior mitral leaflet prolapse.

Methods and Results

We assessed a consecutive series of 511 patients who underwent primary mitral valve repair for isolated posterior leaflet prolapse between 2001 and 2021. Annuloplasty using a partial band was selected in 86.3%. The leaflet resection technique was used in 83.0%, whereas the chordal replacement without resection was used in 14.5%. Risk factors were analyzed for MR recurrence ≥grade 2 or functional mitral stenosis with mean transmitral pressure gradient ≥5 mm Hg using a multivariable Fine–Gray regression model. The 1‐, 5‐, and 10‐year cumulative incidence of MR ≥grade 2 was 7.8%, 22.7%, and 30.1%, respectively, whereas that of mean transmitral pressure gradient ≥5 mm Hg was 8.1%, 20.6%, and 29.3%, respectively. Risk factors for MR ≥grade 2 included chordal replacement without resection (hazard ratio [HR], 2.50, P<0.001) and larger prosthesis size (HR, 1.13, P=0.023), whereas factors for functional mitral stenosis were use of a full ring (partial band versus full ring, HR, 0.53, P=0.013), smaller prosthesis size (HR, 0.74, P<0.001), and larger body surface area (HR, 3.03, P=0.045). Both MR ≥grade 2 and mean transmitral pressure gradient ≥5 mm Hg at 1 year post surgery were significantly associated with the long‐term incidence of reoperation.

Conclusions

Leaflet resection with a large partial band may be an optimal strategy for isolated posterior mitral valve prolapse.

Clinical Perspective.

What Is New?

• Leaflet resection and smaller prosthesis were protective factors for recurrent mitral regurgitation in patients with isolated posterior leaflet prolapse; however, smaller prosthesis and use of a full ring were risk factors for functional mitral stenosis.

• Both mitral regurgitation ≥grade 2 and functional mitral stenosis (mean transmitral pressure gradient ≥5 mm Hg) at 1 year post surgery were significantly associated with the long‐term incidence of reoperation.

What Are the Clinical Implications?

• Leaflet resection with a large partial band may be important to achieve long‐term durability after mitral valve repair for isolated posterior mitral valve prolapse.

• Avoiding mitral regurgitation ≥grade 2 and mean transmitral pressure gradient ≥5 mm Hg within 1 year post surgery can be important to prevent future reoperation.

Nonstandard Abbreviations and Acronyms

MR

mitral regurgitation

MTPG

mean transmitral pressure gradient

MVr

mitral valve repair

Posterior mitral valve leaflet prolapse is primarily repaired by either the conventional leaflet resection and suture technique or by chordal replacement using polytetrafluoroethylene artificial neochordae. ¹ , ² Previously, chordal replacement has been indicated in patients with anterior leaflet prolapse and leaflet resection has been indicated in patients with posterior leaflet prolapse. However, the “respect rather than resect” concept is becoming more widely recognized. The “respect” approach preserves leaflet tissue to ensure a larger coaptation surface and may result in lower leaflet stress than the “resect” approach. ² , ³ Recently, the ability to perform multiple intricate suturing with robotic assistance also prompted us to perform more chordal replacement. ⁴ , ⁵

However, the leaflet resection technique has the advantage of removing myxomatous degenerative segments, which may contribute to disease progression. However, the leaflet resection technique has the advantage of removing myxomatous degenerative segments, which may contribute to disease progression. Indeed, 1 study reported early failure after nonresectional mitral valve repair with artificial chordae despite no technical failure. ⁶ Nevertheless, a recent meta‐analysis found that leaflet resection and chordal replacement without resection were associated with similar survival rates or freedom from recurrent mitral regurgitation for posterior leaflet prolapse. ⁷ In addition, another recent randomized controlled trial reported that the mean mitral pressure gradient by stress echocardiography was not significantly different between the 2 techniques. ⁸ Thus, there is equipoise regarding the ideal surgical technique for mitral valve repair, especially for isolated posterior leaflet prolapse, and therefore, the decision to use either surgical strategy is based largely on surgeon preference. This study was performed to assess the risk factors for mitral regurgitation (MR) recurrence or functional mitral stenosis (MS) occurrence during long‐term follow‐up in patients undergoing mitral valve repair (MVr) for isolated posterior mitral leaflet prolapse.

Methods

Data Availability Statement

Anonymized data that support the findings of this study are available from the corresponding author upon reasonable request.

Ethical Statement

Data collection, analysis, and reporting were approved by the National Cerebral and Cardiovascular Center Institutional Review Board (Reference number: M30‐026, current approval date: March 31, 2022). All patients enrolled in the study provided written informed consent for release of information.

Study Cohort and Data Collection

The institutional surgical database contained a consecutive series of 890 patients who underwent primary MVr in the National Cerebral and Cardiovascular Center hospital between January 2001 and March 2021. A total of 381 patients diagnosed with MR by anterior leaflet prolapse, bileaflet prolapse, infective endocarditis, or functional classification type I or III were excluded, leaving a cohort of 511 patients with degenerative type II isolated posterior mitral leaflet prolapse who were enrolled in this study (Figure 1). Medical charts, surgical reports, and referral letters were reviewed for data collection. These were further supplemented by telephone interviews, including mortality event data, for patients under the care of distant physicians. Data collection was performed between January 2021 and December 2021. A total of 456/511 (89.2%) patients completed their final follow‐up visit with a median follow‐up period of 5.7 years (interquartile range [IQR]: 2.0–10.0), and 55/511 (10.8%) patients could not be contacted and were therefore defined as “lost.”

Figure 1. Patient selection flow chart.

A consecutive series of 511 patients who underwent primary mitral valve repair for isolated posterior leaflet prolapse between 2001 and 2021 were enrolled in this study. MR indicates mitral regurgitation; and MVr, mitral valve repair.

MVr: Surgical Indications and Techniques

The surgical indications for MVr were discussed by the institutional heart team with reference to published guidelines. ⁹ Annuloplasty was performed in all patients who underwent MVr. The prosthetic size was selected based on the intertrigonal distance measured with a sizer, without downsizing. The repair technique and selection of prosthesis type depended on the surgeon's preference, the year surgery was performed (smaller prosthesis tended to be used in cases that has been followed for a long time), or the size of the prolapsed leaflets. Although the triangular resection technique was the standard procedure for posterior leaflet prolapse in our institute, ¹⁰ recent minimally invasive approach prompted us to perform chordal replacement using CV4 polytetrafluoroethylene sutures (WL Gore & Associates, Newark, DE), including the loop technique for prolapse of multiple leaflets. ⁴ , ⁵ Regarding the surgical approach, a standard mini‐thoracotomy MVr and robotic MVr were introduced in 2011 and 2018, respectively. These methods have been reported previously. ⁴ , ⁵ , ¹¹ In this cohort, surgery was mainly performed by 3 independent surgeons who had each experienced over 100 cases of MVr.

Echocardiography

All patients were examined by standard transthoracic echocardiography within 2 weeks before surgery and within 1 week after surgery in accordance with the routine clinical practice guidelines of our institute. Follow‐up with transthoracic echocardiography after discharge occurred at 1 year post surgery and annually thereafter. MR grade was defined as 0, none, or trivial; 1, mild; 2, mild‐to‐moderate; 3, moderate; or 4, severe. Grade 4 MR was defined as central jet MR >40% of the left atrial area, holosystolic eccentric jet MR, vena contracta width >0.7 cm, regurgitant volume ≥60 mL, regurgitant fraction ≥50%, or an effective regurgitant orifice ≥0.40 cm². ⁹ Grade 3 MR was defined as vena contracta width 0.5 to 0.69 cm, regurgitant volume 45 to 59 mL, regurgitant fraction 40% to 49%, or an effective regurgitant orifice 0.3 to 0.39 cm², whereas grade 2 MR was defined as vena contracta width 0.3 to 0.49 cm, regurgitant volume 30 to 44 mL, regurgitant fraction 30% to 39%, or an effective regurgitant orifice 0.2 to 0.29 cm² in this study.

Statistical Analysis

Categorical data in Tables 1, 2, or 3 are presented as numbers (%). Continuous data were checked for a normal distribution using the Shapiro–Wilk test. For normally distributed data, continuous data are shown as mean +/− SD. If the data distribution was not normal, the median and IQR were used. A Kaplan–Meier analysis method was used to assess the mortality, whereas a competing risk model was used to assess the incidence of reoperation, MR recurrence, or functional MS occurrence (Figure 2). To assess the independent effects of risk factors for MR recurrence (Table 4) or functional MS occurrence (Table 5), the multivariable Fine–Gray regression model was used with the following 9 variables: patient age, sustained atrial fibrillation, body surface area (BSA), main procedure (leaflet resection or chordal replacement without resection), prosthesis type (partial band or full ring), prosthesis size, multiple segments prolapse, surgical approach (sternotomy or minimally invasive approaches), and untreated hypertension. These variables were selected based on prior knowledge and clinical experience. The number of explanatory variables was determined on the basis of the frequency of MR recurrence ≥grade 2 or functional MS occurrence ≥mean transmitral pressure gradient (MTPG) 5 mm Hg during follow‐up. There were no missing data in explanatory variables. A 2‐sided P value <0.05 was considered statistically significant. All statistical analyses were performed using statistical software (R v4.0.3; The R Foundation for Statistical Computing, Vienna, Austria).

Table 1.

Patient Characteristics

Variable	n=511
Sex, male, n (%)	317 (62.0%)
Body surface area, m2	1.63 (0.21)
Age, y	62 (54–71)
New York Heart Association classification ≥III	34 (6.7%)
Preoperative echocardiography findings
LV diastolic diameter, mm	58 (54–62)
LV systolic diameter, mm	35 (32–39)
Left atrial diameter, mm	47 (43–52)
LV ejection fraction, %	63 (58–67)
MR grade, grade 0–4	4 (4–4)
MR ≥grade 3	511 (100%)
TR grade, grade 0–4	1 (0–2)
TR ≥grade 3	47 (9.2%)
Cause of mitral regurgitation
Degenerative	511 (100%)
Functional classification
Type 2	511 (100%)
Location of prolapsed segments
P1 prolapse	58 (11.4%)
P2 prolapse	387 (75.7%)
P3 prolapse	143 (28.0%)
Multiple segments prolapse	76 (14.9%)
Atrial fibrillation
Paroxysmal, terminated within 7 d	53 (10.4%)
Persistent, persisting for ≥7 d	48 (9.4%)
Longstanding persistent, persisting for >1 y	25 (4.9%)
Permanent	13 (2.5%)
Noncardiac comorbidities
Hypertension	230 (45.0%)
Hypercholesterolemia	140 (27.4%)
Diabetes	43 (8.4%)
Renal dysfunction, serum creatinine level >1.5	7 (1.4%)

Continuous variables with a normal distribution are presented as mean (SD), whereas continuous variables with a nonnormal distribution are presented as median (interquartile range). Categorical variables are presented as count (%). LV indicates left ventricular; MR, mitral regurgitation; and TR, tricuspid regurgitation.

Table 2.

Cause of Mitral Regurgitation and Surgical Details

Variable	n=511
Main repair technique
Triangular leaflet resection	424 (83.0%)
With sliding plasty technique	10 (2.0%)
Chordal replacement	74 (14.5%)
Number of neochords	2 (2, 3)
Cleft suture	13 (2.5%)
Annuloplasty
Partial band	441 (86.3%)
Full ring	70 (13.7%)
Prosthesis size	30 (28, 31)
Surgical approach
Sternotomy	261 (51.1%)
Standard mini‐thoracotomy	118 (23.1%)
Robotic	132 (25.8%)
Concomitant procedures
Tricuspid valve repair	82 (16.0%)
Coronary artery bypass grafting	31 (6.1%)
Maze procedure	123 (24.1%)
Operation time, min	183 (111–215)
Cardiopulmonary bypass time, min	101 (84–123)
Cross clamp time, min	68 (56–86)

Continuous variables are presented as median (interquartile range), and categorical variables are presented as number (%).

Table 3.

In‐Hospital Outcomes and Postoperative Echocardiographic Findings

Variable	n=511
Early death, in hospital or 30 d	0
Conversion to replacement	0
Resurgical intervention	3 (0.6%)
Intensive care unit length of stay, d	2 (1–2)
Hospital length of stay, d	10 (7–14)
Complications
Mechanical support	0
Myocardial infarction	1 (0.2%)
Dissection	3 (0.6%)
Stroke	2 (0.4%)
Respiratory failure	6 (1.2%)
Renal failure	4 (0.8%)
Deep infection	1 (0.2%)
Systolic anterior motion	4 (0.8%)
Echocardiographic findings at 1 wk post surgery
LV diastolic diameter, mm	50 (46–53)
LV systolic diameter, mm	36 (31–39)
Left atrial diameter, mm	41 (36–46)
LV ejection fraction, %	50 (42–57)
Mitral regurgitation grade, grade 0–4
Grade 0–1	488 (95.1%)
Grade 2	25 (4.9%)
Grade 3	0
Grade 4	0
Mean pressure gradient, mm Hg	2.4 (2.0–3.0)
≥5 mm Hg	34 (6.9%)
≥10 mm Hg	0

Continuous variables with a nonnormal distribution are presented as median (interquartile range), and categorical variables are presented as number (%). LV indicates left ventricular.

Figure 2. Cumulative incidence of reoperation, moderate MR, and functional MS by a competing risk model.

The 1‐, 5‐, and 10‐year cumulative incidence of reoperation with death as a competing risk was 1.8%, 3.2% and 5.7%, respectively. The 1‐, 5‐, and 10‐year cumulative incidence of MR ≥grade 3 with death and reoperation as competing risks was 2.4%, 7.4%, and 11.2%, respectively, whereas that of MR ≥grade 2 was 7.8%, 22.7%, and 30.1%, respectively. The 1‐, 5‐, and 10‐year cumulative incidence of MTPG ≥10 mm Hg with death and reoperation as competing risks was 0%, 0.7%, and 2.5%, respectively, whereas that of MTPG ≥5 mm Hg was 8.1%, 20.6%, and 29.3%, respectively. MR indicates mitral regurgitation; MS, mitral stenosis; MTPG, mean transmitral pressure gradient; and MVr, mitral valve repair.

Table 4.

Risk Factors for Recurrent Mitral Regurgitation ≥Grade 2 Using a Multivariable Fine–Gray Regression Model

Variable	Hazard ratio	95% CI	P value
Age	1.01	0.99–1.03	0.23
Atrial fibrillation	1.71	0.99–2.95	0.054
Body surface area	0.62	0.22–1.74	0.37
Main procedure
Chordal replacement without resection vs leaflet resection	2.50	1.46–4.27	<0.001*
Multiple leaflet prolapse	1.50	0.93–2.43	0.095
Prosthesis type
Partial band vs full ring	0.94	0.55–1.62	0.83
Prosthesis size	1.13	1.02–1.25	0.023*
Surgical approach
Sternotomy vs minimal invasive approaches	0.94	0.57–1.56	0.81
Untreated hypertension	0.75	0.33–1.67	0.48

^*Indicates statistical significance.

Table 5.

Risk Factors for Mitral Stenosis Occurrence (Mean Transmitral Pressure Gradient ≥5 mm Hg) Using a Multivariable Fine–Gray Regression Model

Variable	Hazard ratio	95% CI	P value
Age	1.00	0.98–1.02	0.77
Atrial fibrillation	1.61	0.91–2.89	0.10
Body surface area	3.03	1.02–8.97	0.045*
Main procedure
Chordal replacement without resection vs leaflet resection	1.54	0.72–3.27	0.26
Multiple leaflet prolapse	1.62	0.99–2.64	0.052
Prosthesis type
Partial band vs full ring	0.53	0.32–0.88	0.013*
Prosthesis size	0.74	0.67–0.83	<0.001*
Surgical approach
Sternotomy vs minimal invasive approaches	1.44	0.77–2.67	0.25
Untreated hypertension	1.66	0.92–2.98	0.092

^*Indicates statistical significance.

Results

Baseline Characteristics and Surgical Details

The baseline characteristics of the study cohort are described in Table 1. The median age was 62 years (IQR: 54–71) and the mean BSA was 1.63 (SD: 0.21). All patients underwent MVr for degenerative type II isolated posterior mitral leaflet prolapse. MR was as severe as grade 4 (IQR: 4–4), using a severity range of 0–4, whereas left ventricular contraction was well preserved. Regarding prolapse location, P1, P2, and P3 leaflet prolapse occurred in 58 (11.4%), 387 (75.7%), and 143 (28.0%) patients, respectively. Multiple segments prolapse occurred in 76 (14.9%) patients.

Operative details are shown in Table 2. Leaflet resection was performed in 424 patients (83.0%), whereas chordal replacement without resection was performed in 74 patients (14.5%). Thirteen patients (2.5%) underwent MVr by only cleft suture of posterior leaflets without resection or chordal replacement. The median number of neochords used was 2 (IQR: 2–3, range 2–4). Sliding plasty technique was additionally performed in 10 patients anticipating the possibility of postoperative systolic anterior motion. Annuloplasty was performed in all patients with a median prosthesis size of 30 mm (IQR: 28–31). A partial band was used in 441 patients (86.3%). Surgical approaches included sternotomy in 261 (51.1%) patients, standard mini‐thoracotomy in 118 (23.1%), and robotics in 132 (25.8%). The surgical time and cross clamp time for isolated mitral valve repair were 183 (IQR: 111–215) and 68 (IQR: 56–86) minutes.

In‐Hospital Outcomes

In‐hospital outcomes are listed in Table 3. There were no in‐hospital deaths or conversions to mitral valve replacement. Intraoperative systolic anterior motion was observed in 4 patients (2 with chordal replacement and 2 with leaflet resection). Three patients required in‐hospital re‐repair: 1 patient with recurrent MR caused by suture dehiscence, 1 patient with hemolysis caused by residual MR after chordal replacement, and 1 patient with severe MR caused by systolic anterior motion. In‐hospital sinus rhythm was restored in 108 of 123 patients (87.8%) after the Cryo‐Maze procedure. Echocardiography at 1 week post surgery showed that the percentage of patients with MR grade 0 to 1 was 95.1%. The percentage of patients with MR grade 2 was 4.9%. There were no patients with MR ≥grade 3. The percentage of patients with MTPG ≥5 mm Hg was 6.9%.

Long‐Term Outcomes

During the median follow‐up of 5.7 years (IQR: 2.0–10.0) years postoperatively, there were 23 mortality events, caused by sudden death in 8 patients, a malignant tumor in 6 patients, infection in 4 patients, cerebrovascular events in 3 patients, gastrointestinal ischemia in 1 patient, and end‐stage liver cirrhosis in 1 patient. Survival rate by the Kaplan–Meier analysis was 99.8% at 1 year, 97.9% at 5 years, and 93.0% at 10 years, respectively.

MR grade after MVr throughout the follow‐up period is shown in Figure 3. There were 37 cases with recurrent MR ≥grade 3 and 71 cases with recurrent MR grade 2 during follow‐up. The cumulative incidence of reoperation, moderate MR, and functional MS by a competing risk model is shown in Figure 2. The 1‐, 5‐, and 10‐year cumulative incidence of reoperation with death as a competing risk was 1.8%, 3.2%, and 5.7%, respectively. The 1‐, 5‐, and 10‐year cumulative incidence of MR ≥grade 3 with death and reoperation as competing risks was 2.4%, 7.4%, and 11.2%, respectively, whereas that of MR ≥grade 2 was 7.8%, 22.7%, and 30.1%, respectively.

Figure 3. MR grade after MVr for isolated posterior leaflet prolapse throughout the follow‐up period.

MR indicates mitral regurgitation; and MVr, mitral valve repair.

Regarding functional MS occurrence during follow‐up, there were 8 cases with severe functional MS (MTPG ≥10 mm Hg) and 95 cases with moderate functional MS (10 mm Hg>MTPG ≥5 mm Hg). The 1‐, 5‐, and 10‐year cumulative incidence of MTPG ≥10 mm Hg with death and reoperation as competing risks was 0%, 0.7%, and 2.5%, respectively, whereas that of MTPG ≥5 mm Hg was 8.1%, 20.6%, and 29.3%, respectively.

Risk Factors Associated With MR Recurrence (≥Grade 2) or Functional MS Occurrence (≥ MTPG 5 mm Hg) by a Multivariable Fine–Gray Regression Model

Risk factors for MR recurrence ≥grade 2 with death and reoperation as competing risks by the multivariable Fine–Gray regression model included chordal replacement without resection (hazard ratio [HR], 2.50 [95% CI, 1.46–4.27], P<0.001) and larger prosthesis size (HR, 1.13 [95% CI, 1.02–1.25], P=0.023) (Table 4 and Figure 4), whereas factors for functional MS occurrence (MTPG ≥5 mm Hg) were use of a full ring (partial band versus full ring, HR, 0.53 [95% CI, 0.32–0.88], P=0.013), smaller prosthesis size (HR, 0.74 [95% CI, 0.67–0.83], P<0.001), and larger BSA (HR, 3.03 [95% CI, 1.02–8.97], P=0.045) (Table 5 and Figure 4).

Figure 4. Risk factors for MR recurrence ≥grade 2 with death and reoperation as competing risks.

The multivariable Fine–Gray regression model included chordal replacement without resection (hazard ratio [HR], 2.50 [95% CI, 1.46–4.27], P<0.001) and larger prosthesis size (HR, 1.13 [95% CI, 1.02–1.25], P=0.023) (Table 4), whereas factors for functional MS occurrence (MTPG ≥5 mm Hg) were use of a full ring (partial band vs full ring, HR, 0.53 [95% CI, 0.32–0.88], P=0.013), smaller prosthesis size (HR, 0.74 [95% CI, 0.67–0.83], P<0.001), and larger BSA (HR, 3.03 [95% CI, 1.02–8.97], P=0.045). BSA indicates body surface area; MICS, minimally invasive cardiac surgery; MR, mitral regurgitation; MS, mitral stenosis; and MTPG, mean transmitral pressure gradient.

Comparison of the Long‐Term Incidence of Reoperation in Patients With or Without MR Recurrence (≥ Grade 2) or MS Occurrence (≥ MTPG 5mm Hg) at 1 Year Post Surgery

The cumulative incidence of reoperation with death as a competing risk, separated into patients with and without MR recurrence ≥grade 2 at 1 year post surgery, was investigated. The 1‐, 5‐, and 10‐year incidences of reoperation were 3.4% (95% CI, 0.6–10.5), 12.8% (95% CI, 4.9–24.7), and 18.1% (95% CI, 6.8–33.8), respectively, in the MR recurrence ≥grade 2 group, whereas they were 0.6% (95% CI, 0.1–1.9), 0.8% (95% CI, 0.2–2.7), and 3.3% (95% CI, 1.1–7.3), respectively, in the non‐MR recurrence group (P<0.001).

The cumulative incidence of reoperation, separated into patients with and without MS occurrence (MTPG ≥5 mm Hg) at 1 year post surgery, was also investigated. The 1‐, 5‐, and 10‐year incidences of reoperation were 5.3% (95% CI, 0.9–15.9), 8.4% (95% CI, 2.1–20.3), and 12.9% (95% CI, 3.7–28.0), respectively, in the MTPG ≥5 mm Hg group at 1 year post surgery, whereas they were 0.3% (95% CI, 0–1.5), 1.7% (95% CI, 0.5–4.1), and 3.4% (95% CI, 1.3–7.1), respectively, in the non‐MS group (P=0.003).

Learning Curve Related to Different Repair Techniques or Approaches

To clarify the influence of the learning curve of a new approach or technique on their outcomes, we classified the patients into 6 groups based on the approach and technique: Sternotomy+Resection (n=249), Sternotomy+Neochords (n=8), Thoracotomy+Resection (n=116), Thoracoromy+Neochords (n=0), Robotic+Resection (n=59), and Robotic+Neochords (n=66), and compared the MR recurrence of the initial 50 cases in each group by a competing risk model with death as a competing risk. The results showed that a rate of MR recurrence ≥grade 2 was significantly higher in the groups treated with neochords than in those with leaflet resection, even in the initial 50 cases (Robotic+Neochords versus other groups; gray test P<0.001; Figure 5). The rate of MR recurrence in patients who were treated with leaflet resection was low regardless of the approach, even when the initial 50 cases were analyzed.

Figure 5. Cumulative incidence of recurrent MR≥grade 2, separated by an approach or technique.

The results showed that a rate of MR recurrence ≥grade 2 was significantly higher in the groups treated with neochords than in those with leaflet resection, even in the initial 50 cases (Robotic+Neochords vs other groups; gray test P<0.001). The rate of MR recurrence in patients who were treated with leaflet resection was low regardless of the approach, even when the initial 50 cases were analyzed. MR indicates mitral regurgitation.

Discussion

The incidence of morbidity and mortality after MVr was quite low and short‐term echocardiographic findings confirmed that MVr for isolated posterior leaflet prolapse was effective. Follow‐up echocardiography revealed the excellent long‐term durability of MVr. The rate of reoperation was as low as 5.7% at 10 years. The recurrence of severe MR or occurrence of severe MS were also rarely observed; however, MR ≥grade 2 or moderate functional MS (MTPG ≥5 mm Hg) occurred relatively frequently during the follow‐up period. The rate of recurrent MR ≥grade 2 increased from 4.9% at 1 week to 30.1% at 10 years post surgery, whereas that of MTPG ≥5 mm Hg increased from 6.9% at 1 week to 29.3% at 10 years. We demonstrated that the chordal replacement without resection and larger prosthesis size were independent risk factors for recurrent MR ≥grade 2, whereas use of a smaller full ring and larger BSA were risk factors for functional MS (MTPG ≥5 mm Hg).

Mitral valve regurgitation should be treated with a view to 20 years of durability because the patients who underwent mitral procedures are often young. Indeed, the median age of our cohort was 62 years old. Under the circumstances, we consider that avoiding MR ≥ grade 2 and MTPG ≥5 mm Hg within 10 years post surgery can be important to achieve valve durability over 20 years. In fact, our study showed that both MR ≥grade 2 and MTPG ≥5 mm Hg at 1 year post surgery were significantly associated with the long‐term incidence of reoperation (18.1% versus 3.3% at 10 years and 12.9% versus 3.4% at 10 years, respectively). Imielski et al have also shown that reducing the intraoperative MR grade to less than mild is important for long‐term outcomes. ¹² In addition, functional MS diagnosed when the MTPG was >5 mm Hg is associated with new‐onset atrial fibrillation and tricuspid regurgitation development post surgery in long term. ¹³ Therefore, the results of this study indicate that leaflet resection with a large partial band may improve the long‐term durability and prognosis after MVr for isolated posterior mitral valve prolapse.

On the other hand, a recent meta‐analysis found that leaflet resection and chordal replacement without resection are associated with similar survival or freedom from recurrent mitral regurgitation for posterior leaflet prolapse. ⁷ However, David et al clearly stated that late recurrent MR is largely due to progression of the degenerative process ¹⁴ and leaflet resection remains an important part of the reconstructive procedures of the MV, particularly in patients with advanced myxomatous degeneration of the MV. In fact, in their great study to reveal the long‐term durability of MVr using chordal replacement, 73.4% of chordal replacement was combined with leaflet resection for posterior leaflet prolapse. ¹⁵ Our findings are consistent with their statement, and we believe that the myxomatous leaflet resection contributes to its long‐term valve durability; therefore, leaflet resection should be applied especially for younger patients.

Functional MS after MVr is recognized to be important because of the risk of late atrial fibrillation occurrence or reoperation. ¹³ , ¹⁶ Several reports have shown that a full ring, a smaller annuloplasty, or leaflet resection technique are associated with increased MTPG. ¹³ , ¹⁷ , ¹⁸ , ¹⁹ , ²⁰ In this study, we showed that use of a smaller full ring and larger BSA were independent risk factors for functional MS, but leaflet resection was not a risk factor for it. This finding is in line with the recent randomized study. ⁸ Note that this study also showed a larger annuloplasty was associated with MR recurrence in the long term, but use of a partial band was not. These data suggest that selection of a partial band and proper sizing considering their BSA may be important for long‐term durability in patients with isolated posterior mitral leaflet prolapse.

MVr in patients with small mitral leaflets with less progression of myxomatous degeneration, valvular inflammation, or calcification is still challenging. Leaflet resection with a large partial band might be impossible in patients with these small leaflets because of their insufficient coaptation length after repair. Additionally, El‐Eshmawi et al found that MS causing late failure of MVr is frequently associated inflammatory or calcific changes in the valve as well as use of a smaller ring. ¹⁶ Recently, a newly developed mitral prosthesis valve characterized by RESILIA tissue to prevent structural valve deterioration became available. ²¹ , ²² Therefore, we should consider that mitral valve replacement may be one of the options for such patients. Under these circumstances, it has become increasingly important to select a strategy of mitral valve surgery based on the patient's backgrounds, mitral valvular lesions, and expected long‐term durability.

Limitations

This study was primarily limited by its retrospective and single‐center design, as well as its relatively small event number, which limited performance of a statistically valid analysis of reoperation (19 events), functional MS occurrence with MTPG ≥10 mm Hg (8 events), and MR recurrence ≥grade 3 (37 events). Additionally, immediate postrepair data, such as coaptation height and length, annulus diameters, or leaflet dimensions, are important for assessing durability after MVr; however, these data were not routinely measured by intraoperative transesophageal echocardiography in our institute, so we could not obtain data from our medical records. Additionally, data regarding the effective mitral orifice area or coaptation length, which we considered to be important in this study, were sometimes missing from patient reports. We considered that recalculation of the effective orifice area or coaptation length from the recorded film would substantially reduce the accuracy and objectivity. Therefore, MTPG was selected to assess functional MS after repair for type II dysfunction. Finally, 58 patients (10.5%) were lost to follow‐up. These patients were not contactable by telephone and their treating physicians were unknown. However, there were no differences in the background characteristics, outcomes, or follow‐up period (median: 5.1 years) of these patients, until the most recent follow‐up, compared with patients who completed follow‐up.

Conclusions

Leaflet resection of myxomatous degenerative segment contributes to the prevention of recurrent MR after MVr for isolated posterior mitral leaflet prolapse. Selection of a partial band and proper sizing considering BSA is important for avoiding occurrence of functional MS in the long term.

Sources of Funding

None.

Disclosures

None.