This review evaluated percutaneous drug eluting stent implantation for unprotected left main coronary artery disease. The authors concluded that there are potentially favourable early and midterm results in selected patients. The reliability of the authors' conclusion is unclear, given that this was a poorly reported review, with limitations in the search strategy, the review process and the synthesis of studies.

To evaluate percutaneous drug eluting stent (DES) implantation for unprotected left main (ULM) coronary artery disease.

BioMed Central, clinicaltrials.gov, Google Scholar and PubMed were searched from January 2000 to September 2006 to identify relevant published studies for the review.

Studies of 20 patients or more undergoing percutaneous coronary intervention (PCI) with DES implantation for the treatment of ULM coronary artery disease, and with at least 6 months follow up, were eligible for inclusion in the review. For the included studies, the comparators were bare metal stents (BMS) and coronary artery bypass grafting (CABG). Where reported, the majority of patients were male, with an age range between 59 and 73 years and some had reported co-morbidities. The primary outcomes of interest were major adverse cardiovascular events (MACEs) (specified as composite of death, nonfatal myocardial infarction, target vessel revascularisation (TVR)) or major adverse cerebrocardiovascular events (MACCEs) at the longest follow-up. Secondary outcomes were defined as individual components of MACE. The median follow up was 10 months (range 6 to 19 months).

The authors did not state how the papers were selected for the review or how many reviewers performed the selection.

Study quality was assessed by assigning a rating of A (low), B (moderate), C (high) or D (incomplete reporting) in terms of selection, performance, attrition and detection biases. The authors did not state how the validity assessment was performed.

Data were extracted as means and standard deviations (SD) and medians (range) for continuous data, or as proportions for categorical data. The means of percentage rates and 95% confidence intervals (CI) were calculated. Study investigators were contacted for further information, where necessary.

The authors did not state how the data were extracted for the review or how many reviewers performed the data extraction.

Data (means of percentage rates) for patients treated with DES were pooled using a random effects meta analysis, using inverse variance weighting. For non-randomised comparisons, logarithmic transformation of data was carried out prior to pooling the adjusted risk estimates. Sensitivity analysis was carried out using a fixed effect model (DerSimonian-Laird). Heterogeneity was explored using the I² test. Funnel plots and regression analysis were used to assess small study bias.

Seventeen studies (including 16 cohorts, n=2,095 patients) were included in the review. There were eight observational studies of DES; six non-randomised comparisons of PCI with DES and BMS; and three non-randomised comparisons of PCI with DES and CABG. Comparative data were not presented for the non-randomised trials. Overall study quality was reported to be moderate.

PCI with DES

The analysis of 13 studies showed that pooled data for overall in-hospital death were 2.3% (95% CI: 1.1, 3.4; I2 = 7.4%) and in-hospital myocardial infarction were 2.5% (95% CI: 1.2, 3.8, I² = 27%). Midterm follow-up (median 10 months) showed MACE in 16.5% (95% CI: 11.7, 21.3; I² = 84%, 16 studies), death in 5.5% (95% CI: 3.4, 7.7, I² = 64%, 15 studies) and TVR in 6.5% (95% CI: 3.7, 9.2, I² = 80%, 15 studies). A further increase in MACE (17.7%) was noted as follow-up extended beyond 6 months.

PCI with DES versus BMS

The analysis of three studies (n=396) showed statistically significant favourable results for PCI with DES in terms of MACE (0.34, 95% CI: 0.16, 0.71, p=0.004, I² = 45.3%) and TVR (0.34, 95% CI: 0.12, 0.94; p=0.04, I² = 0%) with pooled data.

PCI with DES versus CABG

The analysis of two studies (n=422) showed a statistically significant favourable result for PCI with DES in terms of MACCE. The pooled result was 0.46 (95% CI: 0.24, 0.90; p=0.02, I² = 0%).

Sensitivity analysis confirmed the results of the random-effects analyses and there was no statistically significant evidence of small study bias. The authors stated that reporting of other events was incomplete. Further results are reported in the paper.

PCI with DES suggests favourable early and midterm results in carefully selected patients with ULM. However, a cautious interpretation of results based on non-randomised studies is advised.

The review question was reasonably specified and detailed inclusion criteria were stated in all areas apart from participants. The search strategy appeared to use some relevant sources. Attempts were made to minimise language bias in the search, but the restriction to published studies may mean that relevant studies were missed. Validity assessment of the included studies was carried out and the results of this were used to support the cautious conclusion for the review. Lack of clarity in the reporting meant that it was unclear whether the method of synthesis was appropriate and the decision to pool small numbers of studies in some analyses was not fully justified. The included studies were heterogeneous and this was appropriately explored in the analysis. There were no details given regarding how any aspect of the review process was carried out, raising genuine uncertainty about the reliability of the findings. This appeared to be a poorly-reported review of observational and non-randomised studies. Although the authors acknowledge some clear limitations in the review, the overall reliability of the authors' cautious conclusion is unclear.

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

Research: The authors stated that randomised controlled trials comparing percutaneous DES implantation versus surgical revascularisation are needed.

Not stated.

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.