Aortic stenosis is thought to have a long, asymptomatic latent phase during which the risk of sudden death is low. In fact symptoms can be revealed by treadmill exercise in a large proportion of apparently asymptomatic patients.¹ Patients may limit exercise to avoid symptoms or may fail to recognise the presence of exertional breathlessness or ascribe it to old age or some other condition. Such patients may then present in heart failure with relatively advanced disease when the left ventricle decompensates.² Even in the presence of overt symptoms, physicians may fail to make the diagnosis³ often in the mistaken belief that severe aortic stenosis cannot coexist with systemic hypertension.⁴ Sometimes heart failure is precipitated in truly asymptomatic aortic stenosis by myocardial infarction, sepsis or another stress like non-cardiac surgery. For these reasons, the initial presentation for about 5% of patients having surgery is with heart failure⁵ rather than exertional chest pain or breathlessness. The four year survival of patients with a low ejection fraction and mean transaortic pressure difference < 30 mm Hg is only 35% compared with a survival of 60% if the mean pressure difference is > 30 mm Hg.⁶ Management decisions centre on confirming the grade of aortic stenosis and determining whether the left ventricle is likely to recover after surgery.

WHAT IS LOW “GRADIENT”, LOW FLOW AORTIC STENOSIS?

Criteria for grading aortic stenosis with normal left ventricular function are given in table 1. However, the transaortic velocity and derived pressure difference are flow-dependent while effective orifice area by the continuity equation is relatively flow-independent (fig 1). Heart failure causing low systolic flow can therefore lead to a patient with severe aortic stenosis having an apparently moderate transaortic pressure difference associated with a low effective orifice area. The hope in this clinical situation is that aortic valve replacement will …