Key messages
- We did not find enough high-certainty evidence to answer whether the best way to undertake aortic valve replacement was through the conventional full-size incision in the breastbone or a smaller incision at the top of the breastbone.
- None of the important problems that occur after heart surgery were more common in either group.
What is aortic valve replacement?
Aortic valve replacement is a common operation performed to replace one of the valves of the heart. The reasons for needing this include valves that do not open properly or do not close properly, which can happen with ageing. People with aortic valve disease can experience chest pain, breathlessness, collapse or sudden death.
How can aortic valve replacement be performed?
The most common way of performing the operation is by opening the whole length of the breastbone. Another method involves a smaller 'keyhole'-type cut that only divides a small part of the breastbone. Doing it this way makes the scar smaller, but can also make the operation more challenging because it is more difficult to see and reach the heart. This might make the operation longer and less safe, even though it looks smaller from the outside.
What did we want to find out?
We wanted to find out if the smaller 'keyhole'-type cut (limited sternotomy) was better than the usual full cut down the breastbone (full sternotomy) when performing aortic valve replacement surgery in adults. We wanted to see if both were as safe and effective as each other.
What did we do?
We updated a review that we had previously written on the topic. We searched for studies that compared limited sternotomy with full sternotomy in adults undergoing aortic valve replacement. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as the study methods and sizes.
What did we find?
We found 14 studies with 1395 participants from Europe, Russia, and North Africa. There was a mixture of different conditions needing aortic valve replacement. Most of these people were 60 to 70 years old and approximately half were male. The participants in each group were similar.
There may be no difference between the groups in the number of people who died as a result of having surgery. If 25 out of every 1000 people who had the full-size cut in their breastbone died after the operation, around 23 (somewhere between 11 and 48) in every 1000 would die using the 'keyhole' operation. Because that range goes from two times less to two times more, it is difficult to say whether the operation is definitely better or worse.
The amount of time that surgeons needed to use a heart-lung machine to support the heart while doing the 'keyhole' operation may have been on average around 11 minutes longer – not a large amount. The amount of time that the heart was completely stopped to do the 'keyhole' operation may be six minutes longer on average, though we were not confident in the evidence.
None of the important problems that occur after heart surgery were more common in either group (infections around the heart, irregular heart rhythms or the need for an urgent reoperation because of bleeding), although again it was uncertain if the evidence was robust enough. Participants probably bled slightly less after having minimally invasive surgery. In the operation with the smaller cut, the average blood loss was 153 mL less. There may be no change in pain and quality of life may not have been any different between the two groups.
Limited sternotomy possibly costs more per operation to perform, by about 1190 pounds sterling.
What are the limitations of the evidence?
We were not very confident in the evidence. One of the main problems with the studies was that they were small and may not have picked up subtle differences between the groups. Because problems after heart surgery are rare, we need to assess lots of people having operations in order to spot small changes. Another problem is that surgeons tend to have lots of slightly different ways in which they do operations. There were also differences in practice, meaning that measurements might not have been taken at the same time, in the same way. We need to be careful about making conclusions about which differences in the groups in this review were due to the smaller incision and which were due to these other factors.
How up to date is this evidence?
This review updates our previous review. The evidence is up to date to August 2021.
The evidence was of very low to moderate certainty. Sample sizes were small and underpowered to demonstrate differences in some outcomes. Clinical heterogeneity was also noted.
Considering these limitations, there may be little to no effect on mortality. Differences in extracorporeal support times are uncertain, comparing upper hemi-sternotomy to full sternotomy for aortic valve replacement.
Before widespread adoption of the minimally invasive approach can be recommended, there is a need for a well-designed and adequately powered prospective randomised controlled trial. Such a study would benefit from also performing a robust cost analysis. Growing patient preference for minimally invasive techniques merits thorough quality of life analyses to be included as end points, as well as quantitative measures of physiological reserve.
Aortic valve disease is a common condition easily treatable with cardiac surgery. This is conventionally performed by opening the sternum ('median sternotomy') and replacing the valve under cardiopulmonary bypass. Median sternotomy is well tolerated, but as less invasive options become available, the efficacy of limited incisions has been called into question. In particular, the effects of reducing the visibility and surgical access have raised safety concerns with regard to the placement of cannulae, venting of the heart, epicardial wire placement, and de-airing of the heart at the end of the procedure. These difficulties may increase operating times, affecting outcome. The benefits of smaller incisions are thought to include decreased pain; improved respiratory mechanics; reductions in wound infections, bleeding, and need for transfusion; shorter intensive care stay; better cosmesis; and a quicker return to normal activity. This is an update of a Cochrane review first published in 2017, with seven new studies.
To assess the effects of minimally invasive aortic valve replacement via a limited sternotomy versus conventional aortic valve replacement via median sternotomy in people with aortic valve disease requiring surgical replacement.
We performed searches of CENTRAL, MEDLINE and Embase from inception to August 2021, with no language limitations. We also searched two clinical trials registries and manufacturers' websites. We reviewed references of primary studies to identify any further studies of relevance.
We included randomised controlled trials comparing aortic valve replacement via a median sternotomy versus aortic valve replacement via a limited sternotomy. We excluded trials that performed other minimally invasive incisions such as mini-thoracotomies, port access, transapical, transfemoral or robotic procedures. Although some well-conducted prospective and retrospective case-control and cohort studies exist, these were not included in this review.
Two review authors independently assessed trial papers to extract data, assess quality, and identify risk of bias. A third review author provided arbitration where required. We determined the certainty of evidence using the GRADE methodology and summarised results of patient-relevant outcomes in a summary of findings table.
The review included 14 trials with 1395 participants. Most studies had at least two domains at high risk of bias. We analysed 14 outcomes investigating the effects of minimally invasive limited upper hemi-sternotomy on aortic valve replacement as compared to surgery performed via full median sternotomy.
Upper hemi-sternotomy may have little to no effect on mortality versus full median sternotomy (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.45 to 1.94; 10 studies, 985 participants; low-certainty evidence). Upper hemi-sternotomy for aortic valve replacement may increase cardiopulmonary bypass time slightly, although the evidence is very uncertain (mean difference (MD) 10.63 minutes, 95% CI 3.39 to 17.88; 10 studies, 1043 participants; very low-certainty evidence) and may increase aortic cross-clamp time slightly (MD 6.07 minutes, 95% CI 0.79 to 11.35; 12 studies, 1235 participants; very low-certainty evidence), although the evidence is very uncertain. Most studies had at least two domains at high risk of bias.
Postoperative blood loss was probably lower in the upper hemi-sternotomy group (MD -153 mL, 95% CI -246 to -60; 8 studies, 767 participants; moderate-certainty evidence). Low-certainty evidence suggested that there may be no change in pain scores by upper hemi-sternotomy (standardised mean difference (SMD) -0.19, 95% CI -0.43 to 0.04; 5 studies, 649 participants). Upper hemi-sternotomy may result in little to no difference in quality of life (MD 0.03 higher, 95% CI 0 to 0.06 higher; 4 studies, 624 participants; low-certainty evidence). Two studies reporting index admission costs concluded that limited sternotomy may be more costly at index admission in the UK National Health Service (MD 1190 GBP more, 95% CI 420 GBP to 1970 GBP, 2 studies, 492 participants; low-certainty evidence).