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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Does minimal-access aortic valve replacement reduce the incidence of postoperative atrial fibrillation?

B Murtuza, JR Pepper, RD Stanbridge, A Darzi, and T Athanasiou.

Review published: 2008.

CRD summary

The authors discovered there may be no difference in rates of postoperative atrial fibrillation after minimal access aortic valve replacement compared to conventional aortic valve replacement and recommended further research. Although the conclusions appeared to be supported by the evidence, the limited literature search and lack of information about study quality mean that some caution in interpretation may be required.

Authors' objectives

To compare the incidence of postoperative atrial fibrillation associated with minimal access aortic valve replacement and conventional aortic valve replacement.

Searching

MEDLINE was searched to July 2007. Search terms were reported. PubMed's related articles function was also used. The reference lists of included studies were handsearched. The search was limited to published studies in English.

Study selection

Randomised controlled trials and non-randomised comparative studies were eligible for inclusion, provided they compared minimal access aortic valve replacement with conventional aortic valve replacement and reported the incidence of postoperative atrial fibrillation (primary review outcome). Other outcomes of interest in the review were intensive care unit stay, total length of stay, ventilation time, respiratory failure, cerebrovascular accident, chest infection, pleural or pericardial effusion and transfusion rate (surrogate outcomes). Minimal access was defined as any surgical route other than complete median sternotomy or full thoracotomy. Studies of minimal access aortic valve replacement re-operation were included. Studies of supraventricular tachycardia were excluded.

Participants in the included studies were predominantly male with a mean/median age of 59 to 69 years. All studies (where reported) included participants presenting with aortic regurgitation, aortic stenosis and/or mixed disease, but specific inclusion criteria varied widely across studies. The range of participant prognostic factors explored in individual studies also varied. Mean cardiopulmonary bypass time ranged from 67 to 110 minutes across study groups. Mean cross-clamp time ranged from 49 to 79 minutes (where reported). Detailed information on other intraoperative variables was provided in the review. None of the included studies reported atrial fibrillation incidence as a primary outcome. The definition and ascertainment of atrial fibrillation differed across studies.

The authors stated neither how the papers were selected for the review nor how many reviewers performed the selection.

Assessment of study quality

Non-randomised studies were evaluated using a modification of the Newcastle-Ottawa scale (which evaluates the quality of participant selection, group comparability and outcome assessment). Randomised controlled trials and studies matched for four or more independent predictors of postoperative atrial fibrillation (listed in the review) were designated high quality. Two reviewers independently determined with complete agreement which studies were high quality.

Data extraction

Odds ratios were calculated from the numbers of events in the control and intervention groups of each study, with 95% confidence intervals. Data were also extracted on surrogate outcomes from studies that reported a difference of at least 10 per cent between the two groups in atrial fibrillation incidence. Two reviewers independently extracted the data, with complete agreement.

Methods of synthesis

Data were combined using a random-effects model to obtain pooled odds ratios and 95% confidence intervals. Sensitivity analyses were conducted to investigate the impact on results of differences between the included studies in quality and a number of intraoperative variables (myocardial protection, venting and cannulation strategies, cardiopulmonary bypass time and cross-clamp time). Statistical heterogeneity was assessed using the Χ2 test.

Results of the review

Ten studies were included (n=2,262): two randomised controlled trials (n=120); three non-randomised prospective studies (n=634); and five non-randomised retrospective studies (n=1,508). Five studies were designated high quality.

Minimal access aortic valve replacement versus conventional aortic valve replacement:

Incidence of atrial fibrillation (10 studies) displayed no statistically significant difference between the groups (odds ratio 0.85, 95% confidence interval: 0.66, 1.11, p=0.24). No evidence of significant statistical heterogeneity was found. The statistical significance of findings did not change when only high-quality studies were included in analysis.

Sensitivity analyses indicated that intraoperative variables did not significantly affect the findings, with the one exception of a statistically significant effect in favour of minimal access aortic valve replacement was found with the exclusion of studies reporting differences in cardiopulmonary bypass time, or if the means were not stated (odds ratio 0.63, 95% confidence interval: 0.47, 0.85). No evidence of significant heterogeneity was found.

Surrogate outcomes (three studies) showed no statistically significant difference between the groups reported in intensive care unit stay, total length of stay, ventilation time, incidence of chest infections or cerebrovascular accident. Findings were inconsistent for other surrogate outcomes.

Authors' conclusions

There may be no difference in rates of postoperative atrial fibrillation after minimal access aortic valve replacement compared to conventional aortic valve replacement.

CRD commentary

The objectives and inclusion criteria of the review were clear. As only one database was searched and the search was limited to published studies in English, so some studies may have been missed and the review was prone to publication and language biases. Steps were taken to minimise the risk of bias and error in the review by having more than one reviewer independently extract data and define which studies were high quality. However, the authors did not state whether rigorous methods were used to select studies for the review. Appropriate criteria were used to evaluate the quality of observational studies, but the individual findings were not reported or (apparently) taken fully into account in determining which were high quality. It did not appear that the quality of randomised controlled trials was assessed. Suitable statistical methods appeared to be used to combine studies, assess for heterogeneity and investigate differences between the studies. Potential sources of bias were acknowledged in the text, including the lack of large randomised controlled trials and lack of control for relevant confounders in the primary studies (which were not specifically designed to assess atrial fibrillation rates). Although the authors' conclusions appeared supported by the evidence presented, some caution in interpretation may be required in view of the limited literature search and lack of information about study quality.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that large randomised controlled trials and/or prospective comparative studies (well matched for all known predictors of atrial fibrillation) were needed to compare conventional aortic valve replacement and minimal access aortic valve replacement for clinical and cost-effectiveness outcomes. Older patients would be the most informative participant group for such studies.

Funding

Not stated.

Bibliographic details

Murtuza B, Pepper J R, Stanbridge R D, Darzi A, Athanasiou T. Does minimal-access aortic valve replacement reduce the incidence of postoperative atrial fibrillation? Texas Heart Institute Journal 2008; 35(4): 428-438. [PMC free article: PMC2607094] [PubMed: 19156237]

Other publications of related interest

Murtuza B, Pepper JR, Stanbridge RD, Jones C, Rao C, Darzi A, Athanasiou T. Minimal access aortic valve replacement: is it worth it? Annals of Thoracic Surgery 2008;85(3):1121-31.

Indexing Status

Subject indexing assigned by NLM

MeSH

Aortic Valve /pathology /surgery; Aortic Valve Insufficiency /pathology /surgery; Atrial Fibrillation /epidemiology /etiology /prevention & control; Confidence Intervals; Great Britain /epidemiology; Heart Valve Prosthesis Implantation /adverse effects /methods; Humans; Incidence; Odds Ratio; Postoperative Complications /prevention & control; Risk Factors; Sensitivity and Specificity; United States /epidemiology

AccessionNumber

12009102704

Database entry date

29/07/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 19156237

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