The review found that pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension was associated with acceptable perioperative morbidity and mortality and superior haemodynamic and survival outcomes compared to historical controls using medical treatment. These conclusions should be interpreted very cautiously in view of the lack of controlled data, failure to describe study quality, the restricted search and differences between studies.

To evaluate the safety and efficacy of pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension.

PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews and DARE searched for studies published from 1999 to February 2010. Search terms were reported. Reviewers checked the reference lists of retrieved studies.

Eligible studies were prospective or retrospective studies of PTE for chronic thromboembolic pulmonary hypertension. Studies were required to report outcomes of interest which included early (30-day) procedure-related morbidity and mortality, pulmonary haemodynamic and functional outcomes and/or survival. Studies with fewer than 20 participants or of specific patient subgroups were excluded.

Mean or median age of participants in the included studies ranged from 44 to 58 years. Mean or median preoperative pulmonary haemodynamic indices varied widely across studies. Few studies reported their selection criteria for PTE. Two studies included some participants who were undergoing medical treatment. Only one study clearly described the intervention used. Intensive care unit stay ranged from five to 11 days and hospital stay ranged from 13 to 19 days in the few studies that reported this information. Reported outcomes and their definitions varied widely. Studies were conducted during periods that spanned 1994 to 2009 in most cases at a single tertiary centre. Mean or median duration ranged from six months to five years, where stated.

Two reviewers independently selected the studies.

Two reviewers independently appraised study quality using published criteria for assessing case series. Specific assessment criteria were not reported.

Event rates were extracted for each outcome of interest, expressed as a percentage. Data on participants who underwent PTE combined with another intervention were excluded.

Two reviewers independently extracted the data.

Data were combined in a narrative synthesis. The range of values for each outcome was reported.

Nineteen observational cohort studies were included (2,729 participants, range 23 to 988): four prospective, 10 retrospective and the design of five was unclear. None included matched comparison groups.

Median 30-day mortality was 8% (range 1.3% to 24%; 19 studies). From 11% to 35% of participants had residual pulmonary hypertension (four studies). Pulmonary artery pressure and pulmonary vascular resistance significantly decreased postoperatively in all 17 studies that reported this outcome. The proportion of participants with New York Heart Association class III or IV symptoms decreased from a preoperative range of 60% to 100% to a postoperative range of 0% to 21% in 13 out of 14 studies. Five-year survival ranged from 74% to 88.7% (six studies). Other outcomes were reported in the review.

PTE for chronic thromboembolic pulmonary hypertension was associated with acceptable perioperative morbidity and mortality and superior haemodynamic and survival outcomes compared to historical controls using medical treatment.

The objectives and inclusion criteria of the review were clear in most respects but the restriction of the review to studies published from 1999 onward did not appear to have a clear clinical rationale. Relevant sources were searched for studies. The restriction to published studies meant that the review was at risk of publication bias. It was unclear whether the search was restricted by language; all selected studies were in English. Steps were taken to minimise bias during study selection, quality assessment and data extraction. Insufficient information was provided about the quality assessment criteria used and the quality of individual studies (such as selection procedures, follow-up rates) and this made it difficult to assess the reliability of study findings. As the authors noted, most studies neither stated how participants were selected nor described the intervention and there was marked heterogeneity in their choice of outcomes. Results varied markedly across studies. The authors' conclusions referred to comparison with historical controls, but the data for medical groups were not included in the results section of the review. There was no evidence that the surgical and medical groups were comparable at baseline.

The authors' conclusions should be interpreted very cautiously in view of the lack of controlled data, failure to describe study quality, the restricted search and differences between the studies.

Practice: The authors stated that PTE could be considered for patients with chronic thromboembolic pulmonary hypertension with preoperative pulmonary vascular resistance of over 1,000 dynes-sec-cm^-5 provided there was no evidence of arteriolar-capillary vasculopathy. They noted that the choice should be individualised according to comorbidities, age, level of available surgical expertise and the preferences of the patient and surgeon.

Research: The authors stated that high quality prospective studies were needed of PTE for chronic thromboembolic pulmonary hypertension and that the ideal way to compare treatment options would be a multi-institutional registry with a minimum dataset for all patients, which would record clinical outcomes regardless of treatment received.

Not stated.