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Aortic Stenosis - is watchful wait a good strategy?

Dr Chee L Khoo

Aortic stenosis (AS) is the most common valvular heart disorder in Australia. About 3% of people >75 yo have AS and most are diagnosed on incidental auscultation of the praecordium or when echocardiogram is done for other reasons. The valve progressively narrows over years leading to cardiac failure. Sadly, once symptomatic, AS is rapidly fatal and often valve replacement is necessary. All of us have a handful of patients under watchful wait while being monitored by the cardiologist.listening_to_large_heart_400_clr_13716

When one of our patients previously not known to have AS, presents to hospital in a decompensated state from AS, it makes us all feel rather inadequate to have “missed” the diagnosis. Do patients with known AS (under watchful wait) fare better than those that were not known to have AS (i.e. diagnosis missed) when they decompensate? Is watchful wait a reasonable strategy then? Should we be operating on these patients BEFORE they decompensate?

A recent study that examines the characteristics and outcomes of patients presenting to hospital with acute decompensation due to AS should make us feel good and bad.

Records of patients with AS admitted to 3 UK hospitals between January 2015 and Jan 2016 were examined. Characteristics and outcomes of patients admitted with acute decompensation in whom AS was and was not known were compared.

Overall, 684 patients with AS in acute decompensation were admitted  for surgery. 79% were elective while 21% were emergencies. Note that of the 141 patients admitted for emergency surgery, 61% of them were known to have AS and were under the watchful monitoring when they decompensate. Unfortunately, the in-hospital mortality for the emergency group was 16% but there were no significant difference between the group with known prior AS and the group without prior diagnosis of AS.

What does this UK study tell us?
Current clinical guidelines recommend surgery for patients with severe AS AND symptomatic. In other words, you have severe AS but asymptomatic, you are to wait till you have symptoms before surgery is recommended. But this UK study shows that a significant number of these patients will acutely decompensate while being monitored and require emergency surgery.
Unfortunately, even once the patient become symptomatic and a decision is made to undergo surgery, the time required for pre-operative investigations like coronary angiogram can lead to further “wait” during which the patient can further decompensate.

So, should we be operating on these patients when they are asymptomatic? This is still unresolved. Should we be monitoring these patients much more frequently? Perhaps, as family physicians, frequent communication between patients and their physician and patient education could be used to prompt patients to present early if symptoms of SOB, dizziness, chest tightness and unexplained tiredness or fatigue emerge in between cardiology visits.

The median time between referral for surgery and acute decompensation in this study was 42 days. Perhaps, we can learn from the study and institute measures are needed to minimise delay, such as a time-limited pathway from referral to surgery, similar to those successfully used in other areas of medicine, such as the management of acute myocardial infarction or cancer treatment, where delays may worsen outcome.

Naturally, this study also emphasises the need for opportunistic cardiac auscultation in older patients with any symptom of reduced exercise capacity, breathlessness or unexplained tiredness and the need for ready access to echocardiography to identify the disorder and allow timely intervention.

Reference:

David S. Wald,  Sam Williams, Fatima Bangash,  Jonathan P. Bestwick, Watchful Waiting in Aortic Stenosis: The Problem of Acute Decompensation. American Journal of Medicine 2017. Article in press.

The views expressed are views of the authors and do not necessarily represent the views of the board of SSW GP Link

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