Objective We addressed the paucity of data describing the characteristics and consequences of incident aortic stenosis (AS).

Methods Adults undergoing echocardiography with a native aortic valve (AV) and no AS were studied. Subsequent age-specific and sex-specific incidence of AS were derived from echocardiograms conducted a median of 2.8 years apart. Progressive AV dysfunction and individually linked mortality were examined per AS category.

Results 49 449 men (53.9%, 60.9±15.8 years) and 42 229 women (61.6±16.9 years) with no initial evidence of AS were identified. Subsequently, 6293 (6.9%) developed AS—comprising 5170 (5.6%), 636 (0.7%), 339 (0.4%) and 148 (0.2%) cases of mild, moderate, severe low-gradient and severe high-gradient AS, respectively. Age-adjusted incidence rates of all grades of AS were 17.5 cases per 1000 men/annum and 18.7 cases per 1000 women/annum: rising from ~5 to ~40 cases per 1000/annum in those aged <30 years vs >80 years. Median peak AV velocity increased by +0.57 (+0.36 to +0.80) m/s in mild AS compared with +2.75 (+2.40 to +3.19) m/s in severe high-gradient AS cases between first and last echocardiograms. During subsequent median 7.7 years follow-up, 24 577 of 91 678 cases (26.8%) died. Compared with no AS, the adjusted risk of all-cause mortality was 1.42-fold higher in mild AS, 1.92-fold higher in moderate AS, 1.95-fold higher in severe low-gradient AS and 2.27-fold higher in severe, high-gradient AS cases (all p<0.001).

Conclusions New onset AS is a common finding among older patients followed up with echocardiography. Any grade of AS is associated with higher mortality, reinforcing the need for proactive vigilance.