Patients undergoing heart valve surgery are at a higher risk of developing complications after surgery, such as damage to the kidneys, compared with patients who undergo coronary artery surgery alone. The injury to organs is associated with an increased risk of death, longer stay in hospital and higher costs of care. A systemic inflammatory response is thought to be responsible for this effect. One possible mechanism for this response is activation of white blood cells (leucocytes) as they come into contact with the heart and lung bypass machine during surgery. In an attempt to avoid this inflammation response, special filters have been developed that capture the leucocytes while patients are on the bypass machine.
The authors of this review evaluated whether these filters were safe to use and effective in reducing the risk of death, length of stay in intensive care and hospital, impairment of kidney functioning, costs of care, and improving quality of life in patients undergoing heart valve surgery. We searched the literature and found eight studies, comprising at least 185 patients, that met our inclusion criteria for the review. However, only one study with 24 participants could provide data on any of our review outcomes. The study showed that length of stay in intensive care and length of stay in hospital were not different between patients who had surgery with the leukodepletion filter compared to a standard filter. None of the studies reported on death rates or five of the seven secondary outcomes that the review aimed to evaluate.
The authors concluded that there were not enough good quality trials in patients undergoing valve surgery to determine whether leukodepletion works. More good quality research studies with relevant outcome measures are required. A forthcoming study will help to clarify the findings in a future update of the review.
There are currently insufficient good quality trials with valve surgery patients to inform recommendations for changes in clinical practice. A future National Institute for Health Research (NIHR)-funded feasibility study (recruiting mid-year 2013) comparing leukodepletion with a standard arterial line filter in patients undergoing elective heart valve surgery (the ROLO trial) will be the largest study to date and will make a significant contribution to future updates of this review.
There is some evidence for the benefits of leukodepletion in patients undergoing coronary artery surgery. Its effectiveness in higher risk patients, such as those undergoing heart valve surgery, particularly in terms of overall clinical outcomes, is currently unclear.
To assess the beneficial and harmful effects of leukodepletion on clinical, patient-reported and economic outcomes in patients undergoing heart valve surgery.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 3 of 12) in The Cochrane Library, the NHS Economic Evaluations Database (1960 to April 2013), MEDLINE Ovid (1946 to April week 2 2013), EMBASE Ovid (1947 to Week 15 2013), CINAHL (1982 to April 2013) and Web of Science (1970 to 17 April 2013) on 19 April 2013. We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), the US National Institutes of Health (NIH) clinical trials database and the International Standard Randomised Controlled Trial Number Register (ISRCTN) in April 2013 for ongoing studies. No language or time period restrictions were applied. We examined the reference lists of all included randomised controlled trials and contacted authors of identified trials. We searched the 'grey' literature at OpenGrey and handsearched relevant conference proceedings.
Randomised controlled trials comparing a leukocyte-depleting arterial line filter with a standard arterial line filter, on the arterial outflow of the heart-lung bypass circuit, in elective patients undergoing heart valve surgery.
Data were collected on the study characteristics, three primary outcomes (1. post-operative in-hospital all-cause mortality within three months, 2. post-operative all-cause mortality excluding inpatient mortality < 30 days, 3. length of stay in hospital, 4. adverse events and serious adverse events) and seven secondary outcomes (1. tubular or glomerular kidney injury, 2. validated health-related quality of life scales, 3. validated renal injury scales, 4. use of continuous veno-venous haemo-filtration, 5. length of stay in intensive care, 6. costs of care). Data were extracted by one author and verified by a second author. Insufficient data were available to perform a meta-analysis or sensitivity analysis.
Eight studies were eligible for inclusion in the review but data on prespecified review outcomes were available from only one, modestly powered (24 participants) study (Hurst 1997). There were no differences between a leuko-depleting versus standard filter in length of stay in the intensive care unit (ICU) (mean difference (MD) 0.80 days; 95% confidence interval (CI) -0.24 to 1.84) or length of hospital stay (MD 0.20 days; 95% CI -1.78 to 2.18).