Answers

Short answers

1 Transthoracic echocardiography, exercise testing, and coronary angiography.

2 This patient has aortic stenosis. No effective medical management exists for severe aortic stenosis. Drugs such as angiotensin converting enzyme inhibitors, digitalis, or diuretics can alleviate the symptoms of heart failure but do not slow or modify the progress of the disease. Valve replacement is recommended for patients with severe aortic stenosis (valve area <1.0 cm² or gradient >40 mm Hg) who have classic symptoms of syncope, angina, or dyspnoea; those with left ventricular systolic dysfunction (ejection fraction <50%); and those who require coronary artery bypass grafting or surgery on the aorta or heart valves.

3 Follow-up visits for patients with asymptomatic aortic stenosis should include echocardiographic assessment. Patients with moderate to severe calcification of the valve and peak aortic jet velocity >4 m/s should be re-evaluated every six months. If peak aortic jet velocity increases by >0.3 m/s/year or if other evidence of haemodynamic progression is present, surgery should be considered. If the patient remains asymptomatic, clinical re-evaluation every six months and echocardiographic re-evaluation every six to 12 months are recommended.

Long answers
Background
Aortic stenosis is the most common valvular lesion in the developed world. It mainly presents as calcific aortic stenosis and occurs in 2-7% of the population over the age of 65.¹ By 2020, about 3.5 million people in England are expected to have aortic sclerosis and 150 000 will have severe aortic stenosis.² About 80% of adult patients with symptomatic aortic stenosis are men. Because 1-2% of the population is born with a congenital bicuspid aortic valve and populations are ageing, aortic stenosis is becoming more common.³

1 Investigations
The characteristic systolic murmur guides further diagnostic investigations. An early peaking murmur is usually associated with a less stenotic valve, whereas a late peaking murmur is indicative of a more severe degree of stenosis. This is because a more stenotic valve takes longer for the ventricle to generate the pressures needed to force the blood past the lesion.⁴

Occasionally, the murmur may be faint and primary presentation may be heart failure of unknown cause. The disappearance of the second aortic sound is specific to severe aortic stenosis, although it is not a sensitive sign.

Echocardiography has become the key diagnostic tool to confirm the presence of aortic stenosis. It is used to assess the degree of valve calcification, left ventricular function, and wall thickness; detect the presence of other associated valve disease; and provide prognostic information. Doppler echocardiography should be done for the initial evaluation of patients suspected of having aortic stenosis, as well as in patients with established disease if symptoms develop or physical signs change. Aortic stenosis with a valve area <1.0 cm² is considered severe; however, when patients have an unusually small or large body surface area, a cut-off value of 0.6 cm²/m² is helpful.⁵

In physically active people, symptom development on exercise testing helps to predict the likelihood of symptomatic aortic stenosis developing in the next 12 months. Signs of subendocardial ischaemia may be suggested by ST segment depression and T wave inversion on the electrocardiogram during exercise testing. We did not perform exercise testing in our patient because he already had symptoms.

2 His condition and its management
This patient has aortic stenosis. Proper management relies on the identification of symptoms such as exertional shortness of breath, angina, dizziness, or syncope. On the basis of data obtained at autopsy in patients not treated surgically, the average time to death after the onset of various symptoms was three years for angina and syncope, two years for dyspnoea, and one and a half to two years for congestive cardiac failure.³

Medical

No effective drug treatment exists for severe aortic stenosis, and only a few drugs are available to alleviate symptoms. Patients with evidence of pulmonary congestion can benefit from cautious treatment with digitalis or diuretics, or both.

A recent observational drug withdrawal single blinded study, with randomisation of the order of tests, found that angiotensin converting enzyme inhibitors are safe and may provide short term benefit to patients with aortic stenosis.⁶ In patients with aortic stenosis, the afterload reduction caused by these inhibitors is partially blunted by a parallel increase in the transvalvular pressure gradient. However, these drugs improve stress haemodynamic variables in most patients with hypertension and aortic stenosis.

A prospective single blinded study conducted at Cleveland clinic, Ohio, showed that in patients with acute pulmonary oedema, left ventricular systolic dysfunction, and aortic stenosis, infusion of nitroprusside may help reduce congestion and improve symptoms.⁷ Atrial fibrillation has an adverse effect on atrial pump function and ventricular rate, hence prompt cardioversion is beneficial. According to recent guidelines antibiotic prophylaxis is not indicated for aortic stenosis.⁸

Several retrospective reports have shown beneficial effects of statins but the data are conflicting.^{9 10} Investigators have found histological similarities between the lesions seen in aortic stenosis and atheromatous coronary artery disease, and they have documented an association between traditional atherosclerotic risk factors and the development of calcific aortic valve disease.¹¹ The association of aortic stenosis with clinical features similar to atherosclerosis has led to the hypothesis that aggressive modification of risk factors, as for coronary heart disease, may slow or prevent disease progression in the valve leaflets.

The randomised double blind placebo controlled Scottish Aortic Stenosis Lipid Lowering Trial Impact on Regression trial assessed the effect of statins but found no added benefits in the statin group.¹² The patients in this trial were over 18 years, they had calcific aortic stenosis, and they also had an aortic jet velocity of at least 2.5 m/s, with aortic valve calcification on echocardiography. An open label prospective study (Rosuvastatin Affecting Aortic Valve Endothelium) that evaluated 121 consecutive patients with asymptomatic moderate to severe aortic stenosis (aortic valve area 1.0 cm²; mean age 73.7 years, standard deviation 8.9; 57 men, 64 women) treated with and without statins found improved serum lipid and echocardiographic measures of aortic stenosis in the statin group.¹³ The types of patients enrolled in these two randomised studies differed, and it is too early to make any recommendations about the treatment of aortic stenosis with statins.

Surgical

Aortic stenosis is a mechanical obstruction and therefore requires mechanical correction. A few randomised prospective studies have shown that once symptoms develop, the patient’s life span is severely shortened unless the valve is replaced.^{14 15 16} In contrast, age corrected 10 year survival rates in patients who had surgery for aortic valve replacement approach the survival rate in the normal population.¹⁴ Therefore, in the absence of any serious comorbid conditions, aortic valve replacement is indicated in almost all symptomatic patients with severe aortic stenosis, even very elderly people. Age is not a contraindication to surgery, and these studies showed similar outcomes to those in age matched normal subjects in very elderly people.^{14 15}

About 40% of patients having aortic valve replacement have severe coronary artery disease and require concurrent coronary bypass grafting.⁵ The American Heart Association recommends aortic valve replacement in the following situations¹⁷:

• Patients with severe aortic stenosis with the classic symptoms of syncope, angina, or dyspnoea
  
• Patients with severe aortic stenosis who require coronary artery bypass grafting
  
• Patients with severe aortic stenosis who require surgery on the aorta or other heart valves
  
• Patients with severe aortic stenosis and left ventricular systolic dysfunction (ejection fraction <50%).
  

A prospective observational study of 2359 patients with aortic valve replacement suggested that advanced New York Heart Association functional class atrial fibrillation and pure aortic regurgitation were independent risk factors for death, whereas older age was not.¹⁴ Another retrospective observational study found significantly improved survival in patients with a low transvalvular gradient, severe aortic stenosis, and severe left ventricular systolic dysfunction who had an aortic valve replacement compared with those who did not.¹⁵

3 Management of patients with asymptomatic severe aortic stenosis
The management of patients with asymptomatic severe aortic stenosis is controversial. These patients have a good prognosis if they are followed up regularly to identify the onset of symptoms and are treated appropriately once symptoms develop. The recommendations for their follow-up are⁵:

• Follow-up visits should include echocardiographic assessment
  
• Patients with moderate to severe calcification of the valve and peak aortic jet velocity >4 m/s should be re-evaluated every six months
  
• If peak aortic jet velocity increases by >0.3 m/s/year or if other evidence of haemodynamic progression is present, surgery should be considered
  
• If the patient remains asymptomatic, clinical re-evaluations every six months and echocardiographic re-evaluations every six to 12 months are recommended.
  

Surgery has been suggested in asymptomatic severe aortic stenosis when left ventricular function is depressed solely because of severe aortic stenosis; the aortic valve is markedly calcified and peak aortic velocity is increasing rapidly (0.3 m/s/year); and when physically active patients have an abnormal exercise test and symptoms develop.⁵

The management of patients with low pressure gradients and low left ventricular ejection fraction is controversial. The European Society of Cardiology recommends surgery in such patients who have evidence of contractile reserve, because this improves long term outcome in most patients.⁵ Patients with low cardiac output and low aortic valve gradients can have either severe aortic stenosis or "pseudosevere" aortic stenosis, which can be distinguished by recalculating the valve area after inotropic stimulation. True severe aortic stenosis shows only small changes in valve area (<0.2 cm²) with increasing flow rate, but a substantial increase in gradients (>50 mm Hg). Pseudosevere aortic stenosis, however, shows a marked increase in valve area, but only minor changes in gradients. Patients with true severe aortic stenosis benefit from aortic valve replacement, but those with the pseudosevere variant do not benefit and surgery can even be harmful.³

Cite this as: BMJ 2009;338:a3009