bicuspid aortic valve
EBM at the bedside-bicuspid aortic valves and familial screening
The original proponents of EBM have always argued for “evidence at the bedside” so that we can make the best decisions for patients nearest to the point “where the rubber hits the road”. How often do we clinicians actually look up the evidence in real time during or soon after a consultation to change the management or the advice we give to a patient?
I saw a lady in her 40s in our cardiology clinic this week. She has been followed up every 1-2 years in clinic for bicuspid aortic valve (BAV). Basically, the aortic valve is at the outflow of the left ventricle (the major pump of the heart) and usually has three cusps which open and close to ensure flow of blood in the right direction through and out of the heart. In bicuspid valves, people are born with only two cusps and over their lifetime, they are more prone to developing narrowing of the valve (“aortic stenosis”), with a significant probability of needing aortic valve replacement during their lifetime. The idea of screening and surveillance is that any narrowing or malfunction of the aortic valve can be picked up early, and the person can be referred for surgery more quickly and effectively than if their disease had progressed.
BAV is the most common abnormality of the heart valves, occurring in 1- 2% of the general population and is twice as common in males as in females. Reassuringly, a recent cohort study of patients with BAV found that they have similar survival rates to the normal population. However, “given that serious complications will develop in over a third of patients with BAV, the bicuspid valve may be responsible for more deaths and morbidity than the combined effects of all the other congenital heart defects”. The potential problems are narrowing or leaking of the aortic valve, infective endocarditis and enlargement or “dilatation” of the aorta. In other words, BAV is common, has serious complications and there is a treatment which improves survival (aortic valve replacement). Therefore, BAV is a condition which meets Wilson’s criteria for screening.
I was asked by the lady if her children were at risk of BAV and whether they should be screened. I did not know the exact answer so I looked online with the patient. There is a 30% risk of aortic dilatation or BAV in first degree relatives (parents, children or siblings) of people with BAV. A more recent study showed that 20% of first degree relatives of people with BAV may have undetected BAV themselves. It turns out there are no NICE guidelines or formal UK/European guidelines for whether we should be screening relatives or how we should be doing it.
Interestingly, across the pond, the Americans have guidelines for familial screening and the literature seems to suggest it. Therefore adult children of patients with BAV should have an echocardiogram to check that they do not have a BAV which would mean that they should also be followed up. Valvular heart disease is a bigger health issue than we imagine.
There are four take home messages for me. First, EBM can be done at the bedside-it is meant to be the most practical of clinical sciences. Second, there is no harm as a clinician in saying “I don’t know” and looking it up. Third, sometimes it is the obvious clinical questions which are still unanswered or debatable. Finally, practice can be changed.