Valvular Heart Disease
Long-Term Results of Tricuspid Annuloplasty Using MC3 Ring for Functional Tricuspid Regurgitation
2018 年 82 巻 9 号 p. 2358-2363
詳細
2018 年 82 巻 9 号 p. 2358-2363
Background: This study aimed to evaluate the long-term results of tricuspid annuloplasty using the MC3 ring for functional tricuspid regurgitation (TR).
Methods and Results: Between 2004 and 2014, 249 patients underwent tricuspid ring annuloplasty using the MC3 ring for functional TR (FTR). Main etiologies of FTR were left-sided valvular disease (n=211) and left-to-right shunt (n=34). Based on the interval between the operation and last echocardiographic scan, patients were divided into short-term and long-term follow-up groups. Mean follow-up duration was 84.4±37.1 months. Operative death occurred in 8 patients (3.2%). Predischarge echocardiography showed that both TR grade and systolic pulmonary artery pressure were significantly decreased compared with preoperative values, and these values were sustained during follow-up in both the short-term and long-term follow-up groups. There were no ring-related complications in either the postoperative or follow-up period, except for permanent pacemaker implantation in 2 patients. The freedom from TR ≥moderate and tricuspid valve (TV)-related events at 10 years were 92.1% and 92.8%, respectively. TV annular size was a risk factor for the recurrence of TR ≥moderate (P=0.001), and 42 mm was the cutoff value for predicting the recurrence of TR ≥moderate.
Conclusions: Tricuspid annuloplasty using the MC3 ring for FTR provides satisfactory early results that are sustained during long-term follow-up. Preoperative TV annular size was associated with the recurrence of TR ≥moderate.
Tricuspid ring annuloplasty is widely used for treating functional tricuspid regurgitation (TR) and has exhibited better surgical results than suture annuloplasty with regard to recurrent TR.1–3 However, based on the type of prosthesis, some studies have reported relatively unfavorable results in terms of recurrent TR4,5 and various ring-related complications, such as dehiscence6 and complete atrioventricular block (CAVB).7,8 Since the Edwards MC3 annuloplasty ring (Edwards LifeScience, Irvine, CA, USA) was introduced in 2004, many studies have reported favorable early- and mid-term results regarding ring-related complications and other clinical outcomes.9,10 However, long-term follow-up results are still lacking.
The purpose of this study was to evaluate the long-term results of tricuspid annuloplasty (TAP) using the MC3 ring for functional TR and to identify risk factors for the development of recurrent TR.
The study protocol was reviewed by the appropriate institutional review board, and the study was approved as a minimal-risk retrospective study (Approval no, H-1706-110-859) that did not require individual consent. From December 2004 to June 2014, 262 patients underwent TAP using the MC3 ring: 13 patients with primary TR were excluded from the study, leaving 249 patients enrolled in the present study.
Echocardiographic EvaluationAll patients underwent preoperative transthoracic echocardiography, and the severity of TR was graded as 0 for no regurgitation, 1+ for mild regurgitation, 2+ for moderate regurgitation, 3+ for moderately severe regurgitation, and 4+ for severe regurgitation.11 Tricuspid valve (TV) annulus diameter was measured in the transthoracic apical 4-chamber view in late diastole at the time of maximal tricuspid opening.12 Predischarge follow-up echocardiography was performed for 100% of survivors and for 98.3% (245/249) of all patients at 9.4 days (range, 1–57 days) after surgery. During follow-up, routine echocardiographic evaluations were performed at the discretion of the operating surgeons, and 236 (97.9%) of the 241 early survivors underwent at least 1 echocardiographic examination after discharge. Based on the interval between the operation and last echocardiographic evaluation, the patients were divided into 2 groups: patients with an interval >60 months were assigned to the long-term follow-up group (n=111, mean follow-up duration: 92.1±22.7 months), and the others were assigned to the short-term follow-up group (n=125, mean follow-up duration: 29.7±20.6 months). Of the 236 patients, tricuspid annular diameter was measured in 172 (short-term follow-up group: 110 patients; long-term follow-up group: 62 patients) at both postoperative and follow-up echocardiography. We did not consider an event as TR recurrence when it improved naturally without the aid of an additional procedure. The last follow-up echocardiographic evaluation was performed at 49.6±41.8 months (range, 0.2–149.8 months) after surgery.
Surgical ProceduresAll operations were performed under aortic and bicaval cannulation, moderate hypothermia, and cold cardioplegic arrest through a median sternotomy. Left-sided valve lesions or congenital anomalies were treated first, and the TV was examined through an oblique right atriotomy. Arrhythmia surgery (modified Cox maze IV procedure or left-sided maze procedure) was usually performed using a cryoablator or bipolar radiofrequency ablator prior to left-sided valve surgery. The indications of TAP for functional TR were TR of grade 1+ or more with (1) annular dilatation or (2) preoperative pulmonary artery systolic pressure (PASP) >50 mmHg. Annular dilatation was evaluated by measuring the intercommissural distance of the septal leaflet with the aid of the tricuspid ring annuloplasty sizer. Annular dilatation was diagnosed when the annulus was larger than the ring sizer matching the intercommissural distance of the septal leaflet.13 According to the surgeon’s preference, not all patients who met the indications underwent TAP. The size of the ring was based on the intercommissural distance of the septal leaflet and the area of the leaflet attached to the chordae originating from the anterior papillary muscle.
Evaluation of Clinical OutcomesOperative death was defined as any death within 30 days after surgery or during the same hospital admission. Patients underwent regular postoperative follow-up at the outpatient clinic at 3- to-4-month intervals. Clinical follow-up ended on December 31, 2016. If patients did not visit the clinic at the scheduled time, they were contacted by telephone to confirm their condition. Follow-up was completed in all patients, and the mean follow-up duration was 84.4±37.1 months (range, 0.1–146.5 months). According to established guidelines, the following were considered TV-related events (TVREs):14 cardiac death, TV reoperation, TR ≥moderate, and permanent pacemaker (PPM) insertion within 14 days after surgery.
Statistical AnalysisStatistical analyses were performed using IBM SPSS statistical software version 21.0 (IBM Inc., Armonk, NY, USA) and R software version 3.4.2 (https://www.r-project.org/). Data are expressed as the mean±standard deviation, as median with range, or as proportions. Repeated measures ANOVA was used to compare values at 3 time points in the short-term follow-up group (preoperative, predischarge, and after 2.5 years of follow-up) and in the long-term follow-up group (preoperative, predischarge, and after 7.7 years of follow-up). Bonferroni’s corrections were used for post hoc analysis. Survival rates were estimated using the Kaplan-Meier method. Risk factors for time-related events were analyzed using the Cox proportional hazard model. Variables with a P value <0.05 in the univariate analysis were entered into the multivariable analysis. The minimal P value approach was used to estimate an optimal cutoff value of TV annular size that predicted the development of moderate or greater TR.15 P<0.05 was considered statistically significant.
The preoperative characteristics of the present study group are summarized in Table 1. The etiologies of functional TR were left-sided valve lesion (n=210), left-to-right shunt (n=34), mixed lesion (n=4), and right-sided valve lesion (n=1). A total of 168 patients (67.5%) had preoperative atrial fibrillation, and 140 patients (56.2%) had rheumatic valve disease. The severity of TR was mild in 133 patients (53.4%), moderate in 77 (30.9%), moderately severe in 11 (4.4%), and severe in 28 (11.2%). Preoperative TV annular size and PASP were 35.8±7.3 mm and 48.4±14.9 mmHg, respectively. The concomitant procedures included mitral valve surgery (n=210), aortic valve surgery (n=70), arrhythmia surgery (n=157), and atrial septal defect closure (n=38) (Table 2). The mean cardiopulmonary bypass and aortic cross-clamp times were 221±64 and 147±50 min, respectively.
| Variables | Total (n=249) |
|---|---|
| Age (years) | 56.1±12.8 |
| Male, n (%) | 91 (36.5) |
| NYHA functional class ≥3 | 79 (31.7) |
| TR etiology | |
| Left-sided valve lesion | 210 (84.3) |
| Left-to-right shunt lesion | 34 (13.7) |
| Mixed lesion | 4 (1.6) |
| Right-sided valve lesion | 1 (0.4) |
| Risk factors, n (%) | |
| Smoking | 41 (16.6) |
| Overweight (BMI >25 kg/m2) | 58 (23.3) |
| Diabetes mellitus | 29 (11.6) |
| Hypertension | 49 (19.7) |
| History of stroke | 26 (10.6) |
| Chronic renal failure | 61 (24.7) |
| Atrial fibrillation | 168 (67.5) |
| Cardiothoracic ratio | 0.60±0.07 |
| Rheumatic valve disease | 140 (56.2) |
| Previous cardiac surgery | 17 (7.0) |
| Preoperative echocardiography | |
| LVEF (%) | 58.5±39.3 |
| PASP (mmHg) | 48.4±14.9 |
| Left atrial size (mm) | 57.6±12.4 |
| TV annular size (mm) | 35.8±7.3 |
| TV annular size/ BSA (mm/m2) | 22.7±5.0 |
| TR grade ≥moderate | 116 (46.6) |
Data are mean±SD or n (%). BMI, body mass index; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; PASP, pulmonary artery systolic pressure; TR, tricuspid regurgitation; TV, tricuspid valve.
| Variables | Total (n=249) |
|---|---|
| Concomitant surgery, n (%) | |
| MV surgery (replacement: repair) | 50 (20.1): 160 (64.3) |
| AV surgery (replacement: repair) | 65 (26.1): 5 (2.0) |
| Arrhythmia surgery | 157 (63.1) |
| ASD closure | 38 (15.4) |
| Aorta surgery | 15 (6.0) |
| CABG | 8 (3.2) |
| Other | 7 (2.8) |
| Ring size (mm), n (%) | |
| 26–28 | 76 (30.5) |
| 30–32 | 134 (53.8) |
| 34–36 | 39 (15.6) |
| CPB time (min) | 221±64 |
| ACC time (min) | 147±50 |
Data given as the mean±SD or n (%). ACC, aortic cross-clamp; ASD, atrial septal defect; AV, aortic valve; CABG, coronary artery bypass graft; CPB, cardiopulmonary bypass; MV, mitral valve.
The operative mortality rate was 3.2% (8 of 249 patients). The causes of death were low cardiac output syndrome (n=3), left ventricular rupture (n=2), sepsis (n=2), and hypoxic brain damage (n=1). Postoperative morbidities included new-onset atrial fibrillation (n=16), acute kidney injury (n=14), low cardiac output syndrome (n=11), respiratory complications (n=10), bleeding requiring reoperation (n=10), stroke (n=6), and mediastinitis (n=1) (Table 3). There were no ring-related complications, such as CAVB, ring dehiscence, thrombosis or infective endocarditis. In the short-term follow-up group, the severity of TR significantly improved after surgery from 1.71±0.93 to 0.62±0.61 (P<0.001), and was preserved at 0.61±0.51 during follow-up (P>0.999, Figure 1A). In the long-term follow-up group, the TR grade also significantly decreased after surgery from 1.71±0.99 to 0.68±0.49 (P<0.001), and was preserved at 0.64±0.71 during follow-up (P>0.999, Figure 1B).
| Variables | Total (n=249) |
|---|---|
| Operative death, n (%) | 8 (3.2) |
| Postoperative complications, n (%) | 38 (15.3) |
| AF (new onset) | 16 (6.4) |
| Acute kidney injury | 14 (5.6) |
| LCOS | 11 (4.4) |
| Bleeding reoperation | 10 (4.0) |
| Respiratory complications | 10 (4.0) |
| Stroke | 6 (2.4) |
| Mediastinitis | 1 (0.4) |
Data are n (%). AF, atrial fibrillation; LCOS, low cardiac output syndrome.
Serial changes in tricuspid regurgitation (TR) grade in the (A) short-term follow-up and (B) long-term follow-up groups.
PASP significantly decreased from 48.5±16.6 mmHg to 40.1±10.7 in the short-term follow-up group (P<0.001) and from 47.4±13.3 to 36.8±10.5 mmHg in the long-term follow-up group following surgery (P<0.001). PASP was sustained during follow-up in both groups (P=0.580 and P>0.999, for short- and long-term groups, respectively). In 172 patients who had tricuspid annular size measured at both postoperative and follow-up echocardiography, it significantly decreased from 34.3±7.0 mm to 23.4±2.2 mm in the short-term follow-up group (P<0.001) and from 36.3±6.5 mm to 23.4±2.1 mm in the long-term follow-up group (P<0.001) on postoperative echocardiography. Decreased tricuspid annular size was sustained during follow-up in both the short-term (23.4±2.1 mm) and long-term (23.1±2.3 mm) follow-up groups (P>0.999 and P=0.294, respectively).
Long-Term Clinical OutcomesAmong the 241 survivors, there were 28 late deaths, 5 of which were cardiac deaths. The overall survival rate at 5 and 10 years was 88.9% and 81.6%, respectively. TVREs occurred in 17 patients, including cardiac death (n=13), development of TR ≥moderate (n=6), and TV reoperation (n=1). Freedom from TVREs at 5 and 10 years was 94.2% and 92.8%, respectively. There were no cases of PPM insertion within 14 days after surgery. However, 2 patients underwent PPM implantation for CAVB at 77 and 93 months, respectively, after surgery.
During follow-up, 6 patients developed moderate or severe TR (moderate=4, severe=2) at 47.5 months after surgery. The causes were hemodynamic effect with mild annular dilation (n=3, mean annulus size 32.4 mm), recurrent severe annular dilatation (n=1, annulus size 43 mm), hemodynamic effect without annular dilatation (n=1, annulus size 25 mm) and secondary change in mitral paravalvular leakage (n=1). Freedom from the development of TR ≥moderate at 5 and 10 years was 98.7% and 92.1%, respectively. In the univariate analyses, TV annular size, TR grade, severe TR, TV annular index, cardiothoracic ratio, coronary artery disease, and previous cardiac surgery were significant risk factors for the development of TR ≥moderate. In the multivariate analysis, TV annular size remained the only significant factor associated with the development of TR ≥moderate (hazard ratio, 1.197; 95% confidence interval, 1.072–1.337). A TV annular size of 42 mm was the best cutoff value for predicting the development of moderate or severe TR using the minimal P value approach (Figure 2).
Kaplan-Meier curves for freedom from tricuspid regurgitation (TR) ≥moderate in (A) entire study population and (B) 2 groups divided by the cutoff value of tricuspid valve (TV) annular size.
This study had 2 main findings. First, TAP using the MC3 ring for functional TR showed satisfactory early- and long-term outcomes regarding ring-related complications, recurrence of TR, and TVREs. Second, preoperative TV annular size was a risk factor for the development of TR ≥moderate, and the cutoff value was 42 mm (Table 4).
| Variables | Univariate analysis | Multivariable analysis | |
|---|---|---|---|
| P value | Hazard ratio (95% CI) | P value | |
| TV annular size | 0.001 | 1.197 [1.072–1.337] | 0.001 |
| TR grade | 0.002 | ||
| Severe TR | 0.008 | 6.179 [0.934–40.879] | 0.059 |
| TV annular size/BSA | 0.012 | ||
| Cardiothoracic ratio | 0.024 | ||
| Coronary artery disease | 0.033 | ||
| Previous cardiac surgery | 0.038 | ||
BSA, body surface area; TR, tricuspid regurgitation; TV, tricuspid valve.
Although the normal TV annulus has a complicated 3D structure with a nonplanar and bimodal-elliptical shape, in functional TR the annulus becomes larger, more planar, and circular, losing its 3D annular shape.16,17 However, most of the previously used TV prosthetic rings (Carpentier-Edward classic ring, Cosgrove-Edwards annuloplasty system, and Duran AnCore ring) have a planar shape. Therefore, the MC3 ring, the first 3D ring designed to fit the configuration of the normal TV annulus, was developed to improve the results of TV repair by restoring the normal geometry of the TV annulus.18
After the MC3 ring was introduced in 2004, many studies reported excellent early- and mid-term results.9,10 The present study demonstrated that the excellent early results from using the MC3 ring were sustained during long-term follow-up. In the present study, the MC3 ring showed good durability regarding recurrent TR, and the freedom from development of TR ≥moderate at 5 and 10 years was 98.7% and 92.1%, respectively. These values were relatively higher than in previous studies using the other prosthetic ring.19,20 A previous meta-analysis showed that the freedom from moderate or greater TR at 8 and 15 years among patients who underwent TR repair with the prosthetic ring was 88.5% and 78.9%, respectively.3
Possible explanations for the lower recurrence rate of TR include the following. (1) The rigid and 3D characteristics of the MC3 ring may affect long-term durability. The evidence is still insufficient, but most studies have shown that rigid rings have better clinical outcomes than flexible rings in terms of recurrent TR.4,5,21,22 The 3D characteristics of the MC3 ring could also contribute to long-term durability in restoring the normal TV annular shape. Pfannmüller and colleagues reported that rigid rings increased the risk of ring dehiscence compared with flexible rings, because rigid rings could increase the shear forces between the ring and TV annulus.6 Considering that the MC3 ring has a rigid characteristic, it may also carry a risk of dehiscence. However, the MC3 ring fitted to the annulus restores the normal annulus shape, which could help promote the natural motion of the TV annulus and dramatically decrease the shear force. Moreover, to our knowledge, a correlation between dehiscence and use of the MC3 ring has not yet been reported. (2) The baseline characteristics of this study may have led to relatively better results than in previous studies. According to our indications, we performed aggressive surgery for functional TR. Therefore, more than half of the patients had mild TR. Usually, RV function and TV annular size tend to be preserved among patients with less severe TR. Decreased progression of the disease could lead to restoration of function following TAP. (3) The present study included patients who had functional TR caused by left-to-right shunt lesions. These patients would be stable after correcting the congenital anomaly. Prosthetic valves or repaired valves could cause structural valve deterioration, nonstructural valve dysfunction, or recurrent valvular lesions at the repaired valve. In that case, TR could become aggravated even if a ring was implanted. However, the patients who had congenital defect corrected did not have additional risks for developing left-sided valvular disease.
In this study, only 2 patients underwent PPM implantation for CAVB at 77 and 93 months after surgery. However, it was unclear whether pacemaker implantation was related to TAP using the MC3 ring, because the patients underwent a concomitant modified Cox maze IV procedure, and the events occurred too late postoperatively. We thought that the incomplete design of the MC3 ring would help prevent injury to the atrioventricular node and that our surgical technique of placing an annuloplasty suture in the lateral portion of the septal annulus would contribute to a low incidence rate of PPM insertion. The first septal suture should be placed from the lateral part of the septal annulus to the midline of the septal annulus and should not be placed over the midline of the septal annulus.
In the present study, preoperative TV annular size was associated with the development of moderate or greater TR. A possible explanation is that the incomplete ring could not cover the entire diseased annulus. Although the length of the septal leaflet was preserved compared with the posterior and anterior leaflets, the septal leaflet was also dilated.23 No study has compared the use of complete and incomplete rings in the TV, but incomplete rings are associated with higher rates of recurrent MR in the mitral position.24,25 The other possible explanation is that a large-sized ring was implanted because of inappropriate sizing. Sometimes it is difficult to define the border between the septal leaflet and the commissure. Therefore, the possibility of oversizing exists, especially when the septal annulus and septoposterior commissure are severely dilated. Navia and colleagues reported that the use of larger annuloplasty rings increased the risk of early and late recurrence of TR.22
The minimal P value approach revealed that a TV annular size of 42 mm was the cutoff value for predicting the development of moderate or greater TR. Although the number of events was relatively small, when a patient has a severely dilated TV annulus that is over the cutoff value, alternative techniques, such as TV replacement or additional repair techniques (pericardial patch enlargement of the tricuspid leaflets or edge-to-edge ‘clover’ technique), could improve the success of the outcome for the patient. Additional studies should be performed to determine the optimal cutoff value for predicting recurrent TR.
Study LimitationsThe present study has several limitations that must be noted. First, it was a retrospective observational study conducted at a single institution. Therefore, the number of patients enrolled was relatively small with respect to drawing definitive conclusions. Second, we could not show changes in RV functional outcomes because we did not obtain specific data regarding RV function-related parameters by echocardiography. Third, the indication for TAP was not strictly adapted for all patients because of the retrospective nature of the study and surgeon’s discretion.
TAP using the MC3 ring for functional TR showed excellent early- and long-term outcomes regarding ring-related complications, recurrence of TR, and TVREs. Preoperative TV annular size was a risk factor for the development of TR ≥moderate, and the cutoff value was 42 mm. Efforts to prevent recurrent TR, such as modifications of the techniques, might be needed when patients have a severely dilated TV annulus (>42 mm).
None.
