Minimally invasive versus conventional mitral valve surgery: a systematic review and meta-analysis of randomised clinical trials

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  Figure 1. Flow diagram for the study selection process according to the referred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 statement. *Nine studies reporting data on eight randomised clinical trials, considering that Spezziale et al13 and Nasso et al15 partially share the same patient population. ** Studies were excluded during the screening phase based on title and abstract review.

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  Figure 2. Summary of findings of Grading of Recommendations Assessment, Development and Evaluation (GRADE). aImprecision −2: Optimal Information Size (OIS) estimated at 1416 participants. The calculation considered α=0.05 and β=0.20, based on the study (Malik, 2015) with the highest mortality incidence of 6.86% and RR=0.50. The CI crosses the null effect line and both clinical relevance thresholds (RR≤0.75 and ≥1.25 for categorical outcomes), and the sample did not meet OIS criteria (31 events), so we downgraded the certainty of evidence by two levels. With fewer than 100 total events, this outcome likely will never meet the OIS threshold, regardless of the control group event proportion. bImprecision −1: OIS estimated at 1016 participants. The calculation considered α=0.05 and β=0.20, based on the study (Shah, 2013) with the highest mediastinitis incidence of 9.37% and RR=0.50. Although the CI does not cross the null effect line, it surpasses the lower clinical relevance threshold (RR≤0.75 and ≥1.25 for categorical outcomes), and the sample did not meet OIS criteria (31 events). We downgraded the certainty of evidence by one level. With fewer than 100 total events, this outcome likely…

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  Figure 3. Meta-analysis of perioperative mortality (A), wound infection (B) and acute kidney injury (C). The diamond in the graph represents the pooled risk ratio (RR) of the included studies, along with the 95% CI. A result was considered significant (p≤0.05) when the diamond did not intersect the central vertical line, indicating that the estimated effect was outside the non-significance range. The squares correspond to the point estimates of the treatment effect for each individual study, with their size proportional to the weight assigned to each study in the meta-analysis; the horizontal lines extending from the squares represent the 95% CIs of these studies. CMVS, conventional mitral valve surgery via sternotomy; MIMVS, minimally invasive mitral valve surgery; RR, risk ratio.