title: Complete versus partial preservation of mitral valve apparatus during mitral valve replacement: meta-analysis and meta-regression of 1535 patients.
abstract: OBJECTIVE
  To determine if there is any real difference between complete preservation (CP) and partial preservation (PP) of the mitral valve apparatus during mitral valve replacement (MVR) in terms of hard outcomes.
  
  
  METHODS
  MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles were searched for clinical studies that compared outcomes [30-day mortality, postoperative low cardiac output syndrome (LCOS), 5-year mortality or left ventricle ejection fraction (LVEF) before and after surgery] between MVR-CP vs MVR-PP during MVR until July 2012. The principal summary measures were odds ratios (ORs) with 95% confidence interval (CI)--for categorical variables (30-day mortality, postoperative LCOS, 5-year mortality); difference means and standard error (SE)--for continuous variables (LVEF before and after surgery) and P values (that will be considered statistically significant when <0.05). The ORs were combined across studies using DerSimonian-Laird random effects weighted model. The same procedure was executed for continuous variables, taking into consideration the difference in means.
  
  
  RESULTS
  Eight studies (2 randomized and 6 non-randomized) were identified and included a total of 1535 patients (597 for MVR-CP and 938 for MVR-PP). There was no significant difference between MVR-CP or MVR-PP groups in the risk for 30-day mortality (OR 0.870; 95% CI 0.50-1.52; P = 0.63) or postoperative LCOS (OR 0.35; 95% CI 0.11-1.08 and P = 0.07) or 5-year mortality (OR 0.70; 95% CI 0.43-1.14; P = 0.15). Taking into consideration LVEF, neither MVR-CP nor MVR-CP demonstrated a statistically significant improvement in LVEF before and after surgery, and both strategies were not different from each other. No publication bias was observed.
  
  
  CONCLUSIONS
  We found evidence that argues against any superiority between both techniques of preservation (complete or partial) of mitral valve apparatus during MVR.
authors: Division of Cardiovascular Surgery, Pronto Socorro Cardiológico de Pernambuco - PROCAPE, Recife, Brazil.
authors: Michel Pompeu Barros De Oliveira
authors: MP
authors: Sá
authors: Rodrigo Renda
authors: RR
authors: Escobar
authors: Paulo Ernando
authors: PE
authors: Ferraz
authors: Frederico Pires
authors: FP
authors: Vasconcelos
authors: Ricardo Carvalho
authors: RC
authors: Lima
mesh_terms: D002815:Chordae Tendineae / Q000601:surgery; D006801:Humans; D008943:Mitral Valve / Q000601:surgery*; D058386:Mitral Valve Annuloplasty / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D008944:Mitral Valve Insufficiency / Q000601:surgery; D016017:Odds Ratio; D059351:Organ Sparing Treatments; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome
keywords: Chordae tendineae; Heart valve prosthesis implantation; Meta-analysis