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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 stentless aortic valve implantation increase perioperative risk? A critical appraisal of the literature and risk of bias analysis

B Murtuza, JR Pepper, C Jones, P Nihoyannopoulos, A Darzi, and T Athanasiou.

Review published: 2011.

Link to full article: [Journal publisher]

CRD summary

The authors concluded that stentless aortic replacement valves did not significantly increase perioperative risk of mortality and morbidity. Stentless valves did not demonstrate improved haemodynamic and clinical outcomes compared to stented valves. Given the poor quality of most of the available studies and the possibility that relevant studies were not identified, the authors' conclusions should be treated with caution.

Authors' objectives

To compare the impact of stentless aortic valve replacement (SL-AVR) versus stented aortic valve replacement (ST-AVR) on early valve-related mortality and morbidity.

Searching

MEDLINE was search for published studies up to April 2010. Search terms were reported. The related articles function was used to expand the search. References of included studies were handsearched.

Study selection

Randomised controlled trials (RCTs) that compared the impact of SL-AVR to ST-AVR on mortality and morbidity were eligible for inclusion.

Most of the included studies used the subcoronary technique for SL-AVR and the supra-annular technique for stented valve implantation. Exclusion criteria for patients varied between studies. The mean age of patients ranged from 55 years to 79 years. The percentage of males ranged from 15% to 85.7%. Primary outcomes of included studies were 30-day mortality, one month to one year valve-related mortality, neurological complications, renal failure, pulmonary complications, duration of intensive care unit stay and total length of stay. Secondary outcomes were cross-clamp time, cardiopulmonary bypass time, post-operative cardiac related morbidity, myocardial infarction, cardiac failure/low cardiac output, insertion of intra-aortic balloon pump, insertion of permanent pacemaker, atrial fibrillation and prosthetic valve endocarditis. Follow-up ranged from two to 94.2 months. Nearly half of the studies were carried out in the UK. Other studies were carried out in Poland, Germany, Italy, Canada and India.

The authors did not state how many reviewers performed the study selection.

Assessment of study quality

A validity assessment was performed using a modified version of the Jadad scale with items on randomisation, withdrawals and drop-outs, but which excluded the item on double-blinding. This gave a total maximum score of 3. Studies were also assessed using the Risk of Bias tool for adequate sequence generation, allocation concealment, blinding, incomplete outcome data assessed, freedom from selective reporting and freedom from other bias. This scale gave scores that ranged from -6 to 6. Jadad and Risk of Bias scores were combined to give a composite quality score.

The validity assessment was performed independently by two reviewers. Disagreements were resolved by consensus.

Data extraction

For dichotomous data the number of events in each group was extracted and used to calculate odds ratios (OR) for each study. For continuous data the mean difference between groups was calculated. Where there was a zero value in both groups the outcome was excluded. Where it was not possible to determine the mean and standard deviation data were excluded.

Two reviewers independently extracted data.

Methods of synthesis

For dichotomous data, the studies were combined using meta-analysis to produce a pooled odds ratio with 95% confidence intervals (CI). For continuous data, the weighted mean difference was calculated. Random-effects models were used. Statistical heterogeneity was assessed with Χ². For the outcome of 30-day mortality, sensitivity analyses were carried out for studies with a low risk of bias, studies of patients with a mean age of 70 years or more and studies predominantly of patients with aortic stenosis.

Results of the review

Eighteen RCTs were included for review (1,410 participants, range 17 to 223). Five studies scored 3 on the Jadad scale, two scored 2 and 11 scored 1. On the Risk of Bias tool, nine trials scored 3 or more, four scored 2, five scored zero and one scored -2.

Primary outcomes: There was no significant difference in 30-day mortality for patients who underwent SL-AVR compared to ST-AVR (OR 1.37, 95% CI 0.67 to 2.81; nine studies, 1,124 participants). There was no difference between groups in 30-day mortality when only high-quality studies were included, when only studies with a mean age of patients at 70 years or more were included and when only studies with predominantly aortic stenosis were included. There was also no significant difference between SL-AVR and ST-AVR groups in valve-related one-month to one-year mortality (OR 1.21, 95% CI 0.57 to 2.55; four studies, 664 participants), valve failure rate (OR 0.77, 95% CI 0.17 to 3.54; two studies, 309 participants), neurological complications (OR 1.09, 95% CI 0.54 to 2.19; nine studies, 956 participants), renal failure (OR 0.66, 95% CI 0.09 to 5.05; two studies, 77 participants) and pulmonary complications (OR 0.33, 95% CI 0.03 to 3.31; two studies, 137 participants). There was no evidence of significant statistical heterogeneity for any of these outcomes.

Cross-clamp times and cardiopulmonary bypass times were significantly shorter in the ST-AVR group (evidence of significant statistical heterogeneity for these outcomes, p<0.00001). There was no significant difference between SL-AVR and ST-AVR in length of intensive care unit stay, total length of stay, postoperative atrial fibrillation, postoperative myocardial infarction, need for permanent pacemaker, prosthetic valve endocarditis and need for intra-aortic balloon pump. There was evidence of significant statistical heterogeneity for total length of stay (p=0.003).

Authors' conclusions

Stentless aortic replacement valves did not significantly increase the perioperative risk of mortality or morbidity. However, they did not demonstrate improved haemodynamic or clinical outcomes compared to stented valves.

CRD commentary

The review addressed a clear question. Inclusion criteria were well defined for study design and intervention, but broad for outcomes and patients. Only one database was searched, so relevant data may have been missed. It appeared that no attempts were made to identify unpublished data and it was unclear whether the search was restricted by language, so language and publication biases could not be ruled out. Appropriate steps were taken during data extraction and validity assessment to minimise the risk of reviewer error and bias; it was unclear whether similar steps were taken at the study selection process. Study quality was evaluated by assessing risk of bias. Most of the available studies were of low quality and had small sample sizes and low event rates, which may have affected the reliability of the findings. Suitable methods were used to combine the studies and statistical heterogeneity was assessed. Sensitivity analyses were carried out for one outcome only.

Given the poor quality of most of the available studies and the possibility that relevant studies were not identified, the authors' conclusions should be treated with caution.

Implications of the review for practice and research

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

Research: The authors stated that further large-scale RCTs are needed with more stringent inclusion and exclusion criteria, low risk of bias and long-term clinical and haemodynamic follow-up.

Funding

Not stated.

Bibliographic details

Murtuza B, Pepper JR, Jones C, Nihoyannopoulos P, Darzi A, Athanasiou T. Does stentless aortic valve implantation increase perioperative risk? A critical appraisal of the literature and risk of bias analysis European Journal of Cardio-Thoracic Surgery 2011; 39(5): 643-652. [PubMed: 20850984]

Indexing Status

Subject indexing assigned by NLM

MeSH

Aged; Aged, 80 and over; Aortic Valve /surgery; Bias (Epidemiology); Female; Heart Valve Prosthesis /adverse effects; Heart Valve Prosthesis Implantation /adverse effects /methods /mortality; Hemodynamics; Humans; Male; Middle Aged; Prosthesis Design; Randomized Controlled Trials as Topic; Stents; Treatment Outcome

AccessionNumber

12011002736

Database entry date

27/03/2012

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: 20850984

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