The aortic valve normally has three cusps, but an abnormal aortic valve from birth can be bicuspid (two cusps), unicuspid (one cusp) or quadricuspid (four cusps).
Less than three cusps (bicuspid and unicuspid) tend to create valve stenosis over time, but overwhelmingly the most common cause for severe aortic stenosis (AS) is calcific disease in older adults. There are a number of associations between severe calcific AS and cardiovascular risk factors, but other than traditional risk factor modification (including blood pressure control), no single treatment has been shown to modify progression of AS once it develops.
Our research group has shown that mild, moderate and severe AS are all common and associated with a significant risk for premature mortality. Severe AS is under-diagnosed and under-treated worldwide, and in Australia we estimate approximately 100,000 Australians have severe AS and approximately 56,000 of them will be expected to die before receiving valve intervention.
Detection of severe AS is a critically important step since symptoms may not be a good guide to AS severity. We recommend regular (at least yearly) auscultation for all patients over the age of 50 years since new onset AS may progress rapidly in some patients. If any degree of AS is suspected, we recommend transthoracic echocardiography as the first test (not stress echo) to determine AS severity.
Patients with mild AS should be followed with repeat echocardiography at two years (unless indicated earlier) and careful control of cardiovascular risk factors. Moderate AS should be referred to a cardiologist with expertise in valvular heart disease for careful review and close monitoring of AS severity. Some patients with moderate AS behave more like severe AS (with associated symptoms) and may be considered for valve intervention.
All patients with severe AS should be seen by a cardiologist with specific expertise in valvular heart disease with a view to valve intervention at the appropriate time, except in circumstances where valve intervention is inappropriate or contraindicated (such as short prognosis terminal disease or advanced dementia).
Identification and monitoring of patients with AS is imperfect using current methods, and we are investigating new AI methods to help streamline diagnosis and management decisions.
The first-line treatment of severe AS is valve intervention, either by surgical aortic valve replacement (SAVR) or transcatheter valve intervention (TAVI), depending on patient age and comorbidities. Due to the lower risk of valve intervention in recent years, more patients are now being considered. Recent trials have shown major benefits of valve intervention across the spectrum of surgical risk.
In summary then, aortic stenosis (AS) is common in older Australians and may not be identified without a high clinical suspicion and regular auscultation. Any murmur in older individuals should prompt an echo at least once, to identify the cause of the murmur.
If aortic stenosis, it should be carefully followed, and moderate or greater AS should be referred to a cardiologist with specific expertise in valvular heart disease. Severe AS with symptoms is a Class I indication for aortic valve intervention.
Key messages
- Aortic stenosis is common in older people
- High level clinical suspicion is needed for diagnosis
- Valve intervention is first-line management in severe AS.
– References available on request
Author competing interests