Acute decompensation with heart failure, angina, or syncope may be the first indication of undiagnosed aortic stenosis, but should be uncommon when the disorder is known and managed by watchful waiting. There is a lack of information on the proportion of patients with acute decompensated aortic stenosis with and without a prior diagnosis and their outcomes.

We examined the records of patients with aortic stenosis (International Classification of Diseases code 135.0) admitted to 3 UK hospitals between January 2015 and January 2016. We determined the number of admissions with acute decompensation and the proportion in whom aortic stenosis was and was not previously known. The characteristics and outcomes in the 2 groups were compared.

Of 684 patients with aortic stenosis, 543 (79%; 95% confidence interval [CI], 76-82) were elective admissions and 141 (21%; 95% CI, 18-24) were emergencies with acute decompensation; 86 of 141 patients (61%; 95% CI, 52-69) with known aortic stenosis were under watchful waiting and 55 of 141 patients (39%; 95% CI, 31-48) did not have a prior diagnosis. In-hospital mortality was 16% versus 13%, respectively (P = .48). There were no statistically significant differences in characteristics or clinical presentation between the 2 groups (P > .1 for all comparisons).

Approximately 1 in 5 patients admitted to the hospital with aortic stenosis have life-threatening complications due to their disorder. More than half of such patients are actively monitored for aortic stenosis before admission, exposing shortcomings of the watchful waiting management strategy. Measures to identify symptomatic patients earlier and shorten the time between symptom onset and surgery have the potential to substantially reduce morbidity and mortality.