Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. The Cochrane Heart Group have produced more than 200 reviews, covering a very wide range of conditions and interventions. In December 2019, they published a new review comparing different procedures for patients with severe aortic stenosis and we asked the lead author, Ahmed Kolkailah, from the Department of Medicine at Cook County Health in Chicago, USA to tell us about the condition and the review’s findings.

Ahmed: Aortic stenosis is a narrowing in the heart’s left ventricular outflow at the juncture of the aortic valve. If left untreated, its natural course is progressive worsening. The severity of aortic stenosis is categorized into mild, moderate, and severe. We focused on the severe group, for whom the symptoms may include exertional shortness of breath, chest pain, or transient loss of consciousness. 
The definitive, standard treatment for these patients has long been surgical aortic valve replacement, or SAVR. More recently, a less invasive approach has emerged, called transcatheter aortic valve implantation, or TAVI. TAVI is known to offer benefits to individuals who are not suitable for surgery or are at higher risk of surgical complications. We did our Cochrane review to find out whether TAVI is also beneficial to people with severe aortic stenosis who are deemed to have a low surgical risk.
We identified four eligible clinical trials which included just over 2800 patients, who had been randomised to either TAVI or SAVR. The trials were multicentre and mostly included patients over 70 years of age, with a higher proportion of men than women. In general, we rated the quality of evidence as moderate.
Pooling the results of the trials in a meta-analysis suggests that, in the short term (meaning during hospitalisation and up to 30 days of follow‐up), there is probably little or no difference between TAVI and SAVR in the risk of death due to any cause, stroke, myocardial infarction, or death due to cardiac causes. TAVI may reduce the risk of rehospitalisation, and although we are uncertain whether there is an important difference between TAVI and SAVR on the duration of hospital admissions, TAVI appears to be associated with a shorter length of hospital stay. Looking at other outcomes, people who underwent TAVI had a lower risk of atrial fibrillation, acute kidney injury, and bleeding, but a higher risk of permanent pacemaker implantation.
In conclusion, more randomised trials with longer follow‐up are needed to further assess and validate the durability of TAVI for severe aortic stenosis in patients deemed to have a low surgical risk. It would also be important to address patient‐centred outcomes, such as pain scores, quality of life, and recovery time. We also believe that the inclusion of younger participants, with a more equal distribution of men and women, would further enhance the current evidence and guide well-informed, multidisciplinary clinical decision-making.”

Monaz: If you would like to read more about the current evidence, and watch for updates of the review as new trials become available, you can find it at Cochrane Library dot com with a search for 'valve implantation for severe aortic stenosis'.