This case is meant to highlight the appropriate investigations, follow-up, and management of patients found to have an asymptomatic murmur of severe aortic stenosis on routine physical exam. Aortic stenosis is the most common valvular condition across Europe and North America, affecting 2–7% of individuals over the age of 65 years.¹ The most common cause of aortic stenosis is calcification of either a congenitally bicuspid valve (more common if under 70 years of age) or a tricuspid valve (more common over 70 years of age).²

Aortic stenosis is a progressive condition with significant interpatient variability. A prospective study has shown an average increase in mean aortic gradients of 7 mmHg per year and a decrease in valve area of 0.1 cm² per year.³

While severe aortic stenosis carries an increased risk of sudden cardiac death, this rarely occurs (<1%/year) without the development of any of the classic symptoms including angina, heart failure, and syncope.³ Symptoms tend to develop when the aortic valve area is less than 1 cm² or the mean transvalvular gradient is more than 40 mmHg. Thus, severe aortic stenosis is defined as a valve area less than 1cm², mean gradient greater than 40 mmHg or jet velocity greater than 4.0 m per second.⁴ Following the onset of symptom development in patients with severe aortic stenosis, the mean survival is 2–3 years without surgical intervention.⁵ Conversely, aortic valve replacement is not indicated in asymptomatic patients despite having severe aortic stenosis and preserved left ventricular function.

Given the strong association of increased mortality with symptom development, close clinical follow- up is recommended. The frequency of clinical follow-up depends on multiple factors including the degree of stenosis, left ventricular function, functional capacity, and patient compliance. Patient education regarding the natural history of aortic stenosis and how to properly interpret their symptoms is essential to clinical follow-up. Often, patients will not report one or more of the classic triad of symptoms. A slight change in exercise capacity or exertional dyspnea may be their only tell-tale sign of progressing disease. Due to the gradual onset of symptoms related to aortic stenosis, it is not uncommon for patients to fully appreciate the severity of their symptoms after their aortic valve has been replaced. The ACC/AHA 2006 practice guidelines recommend (Class I) that patients with severe aortic stenosis undergo yearly echocardiograms to evaluate the severity of aortic stenosis, left ventricular hypertrophy, and function.⁴

Until recently, aortic stenosis was a Class I indication for the use of antibiotics in preventing bacterial endocarditis.⁶ However, more recent guidelines have removed acquired and congenital valvular disease as an indication for the use of prophylactic antibiotics in the prevention of bacterial endocarditis. Antibiotics continue to be recommended with dental procedures in patients with a prosthetic valve.⁷

Can this patient with severe but asymptomatic aortic stenosis undergo activities requiring significant exertion? What is the role of exercise stress testing in aortic stenosis? Was the cardiac catheterization indicated at this time?

This patient, with a history of severe but asymptomatic aortic stenosis, wants to undertake a new level of exercise. The ACC/AHA practice guidelines recommend against competitive sports with high dynamic or static muscular demands.⁴ However, can we risk stratify the average patient who wants to undertake an increase in exercise?

Currently, the evidence suggests that routine exercise stress testing of patients with aortic stenosis is not warranted.⁸ With confounding variables such as left ventricular hypertrophy and reduced coronary flow reserve, ST segment depression during exercise stress testing of patients with aortic stenosis adds little prognostic value. Electrocardiographic ST segment depression during exercise occurs in 80% of patients with asymptomatic aortic stenosis. However, exercise stress testing in patients with asymptomatic severe aortic stenosis may add other prognostic information including exercise- induced symptoms and abnormal blood pressure response (fall of >10mmHg or a blunted blood pressure rise of <20mmHg).^4,8