Repair Of Isolated Posterior Mitral Leaflet Prolapse-Chordal Replacement Versus Quadrangular Resection

Background Mitral valve repair(MVr) has been proven better than replacement for treating degenerative mitral regurgitation(MR). For posterior mitral leaflet(PML) prolapse, quadrangular resection(QR) proposed and standardized by Alain Carpentier has been the gold standard for many years, given its outstanding long-term results in MVr. However, leaflet resection has many drawbacks, including damaging the physiological structure of mitral valve(MV) and its accessories, changing the annular geometry and not being applicable if the prolapse is too wide or multi-segmental. Expanded polytetrafluoroethylene(e PTFE) chordal replacement(CR) is of much larger versatility. CR has been shown to reconstruct the MV-left ventricle continuity, restore the mobility of the original MV apparatus, and most physiologically recover the left heart function. This study aimed at assessing versatility, effectiveness, safety and mid-term results of CR versus QR for isolated degenerative PML(id PML) repair in our cardiovascular center(Cardiac surgery department of Ruijin hospital affiliated to Shanghai Jiao Tong university school of medicine).Methods 78 consecutive patients underwent MVr for id PML prolapse with MR between 4/2010 and 1/2014. According to surgeon preference, patients were treated with either QR(51, 59%) or CR(27, 41%). The mean follow-up time was 29.4 ± 14.0 months with an 87% completion rate. Outcomes were compared unmatched and after 1:1 propensity score matching(PSM).After a 1:1 PSM by using gender, age, baseline mitral regurgitation(MR) grade, left ventricular end-diastolic diameter(LVEDd), left ventricular ejection fraction(EF) and hypertension as 6 covariates, the differences in patients’ preoperative characteristics between group QR and group CR were evened for fair comparisons on surgical outcomes.Results 1. Although annulus plication(68.4%) or sliding leaflet technique(21.1%) were often and only carried out with QR, there was no significant difference in the size of annuloplasty rings implanted between group QR and group CR(p =.444), with size 28 mm rings mostly used.2. Median sternotomy was chosen more frequently with QR(QR 78.9% vs. CR 31.6%, p =.008), in contrast to CR using right lateral minithoracotomy more often(QR 21.1% vs. CR 68.4%, p =.008). Aortic cross-clamp time(ACCT) and cardiopulmonary bypass time(CPBT) were relatively shorter for group CR. Under median sternotomy, chordal replacement with “loop” technique(CR-l) demonstrated apparent advantage in the operative time.3. MVr was accomplished successfully in both groups. At discharge MR was rectified to a mild or less degree in both groups with the volume of residual MR slightly higher in group CR.4. No systolic anterior motion(SAM) of the anterior mitral leaflet(AML) or valverelated reoperation happened during the entire study. Although there was no significant difference in morbidity and mortality between two groups, more averse incidents occurred in group QR during hospital stay and follow-up. Group CR showed relatively shorter postoperative(QR 16.9d ± 14.7d vs. CR 10.2d ± 4.8d,p =.271) and total(QR 23.2d ± 16.0d vs. CR 16.5d ± 5.4d, p =.339) in-hospital time than group QR.5. The actuarial survival probability at 12, 24, 36 months after surgery in group QR and group CR were 95.7%, 95.7%, 95.7% and 100%, 100%, 100%, respectively(log rank p =.309). Overall freedom from above-mild MR(MR ≥ 2.5+) at 53 months after surgery was 91.4 ± 4.2%. Freedom from above-mild MR at 12, 24, 36 months after surgery in group QR and group CR were 100%, 100%, 100% and 95.5%, 90.4%, 76.5%, respectively(log rank p =.053). In group CR, freedom from above-mild recurrent MR with(MR > 0) and without residual MR(MR = 0) before discharge were 75.8 ±15.6% and 75.0 ± 15.8%(log rank p =.889).6. CR technique itself was the significant risk factor for recurrent MR(CR over QR, HR 2.40; 95% CI, 1.08 to 5.38; p =.032; CR-nl over QR, HR 3.20; 95% CI, 1.12 to 9.14; p =.030). The change rate of tricuspid regurgitation(TR) after surgery prognosticated the trend of MR recurrence(p =.005).Conclusion This study showed comparable results between QR and CR regarding their versatility, effectiveness and safety in treating id PML. Well adaptation for minimally invasive approach, shorter operative time and hospital stay, and less complications shed light on CR’s promising use for PML repair. Nonetheless, concerns should be given to choose appropriate patients for each technique, and close attention on the recurrence of MR should be put for patients after CR.