The joint session with the ESC Working Group on Valvular Heart Disease was dedicated to the practical management of aortic regurgitation (AR).
Julien Magne (Liège, Belgium) reviewed the prevalence and prognosis of AR. The prevalence of moderate or severe AR is estimated between 1 and 4% from different series in industrialised countries. The prevalence increases with age, which illustrates the predominance of degenerative heart valve disease. In the Euro Heart Survey, AR accounted for 10% of native valve disease.
The natural history of AR is poor, as attested by the 83% rate of cardiac events at 10 years. Sudden death is rare, with a yearly rate of 0.2-0.3%, but asymptomatic left ventricular dysfunction occurs in 1.3% of patients per year. The main prognostic factors for survival are NYHA functional class, left ventricular size and systolic function, and the severity of AR as assessed by quantitative criteria. Serum BNP levels seems to have an incremental prognosis value when combined with other factors. In particular, the combination of serum BNP level and effective regurgitant orifice area has good properties of discrimination on outcome.
The presentation of Andreas Hagendorff (Leipzig, Germany) was dedicated to the evaluation of AR. The quantitation of the severity of AR is a key issue. Although quantitative measurements using Doppler echocardiography are more accurate and have been shown to have a prognostic value, they require expertise and are subject to errors of measurements, in particular when they combine a number of different measurements, such as the estimation of the regurgitant fraction or the effective regurgitant orifice area. As stressed by EAE and ESC guidelines, it is necessary to use an integrative approach combining different measurements and checking their consistency. There is now a consensus for not using the colour jet flow area for quantitating AR because of its lack of reliability.
The evaluation of the anatomy and mechanisms of AR has implications regarding the type of surgery. An accurate examination is particularly needed if a conservative surgery is considered on the aortic valve and/or the aortic root. In these cases, transoesophageal examination is frequently needed. Echocardiographic findings enable valve anatomy to be classified into three groups which contribute to determine the suitability to aortic valve repair. Anatomical evaluation should also focus on ascending aorta, which is frequently enlarged in degenerative etiologies and AR due to bicuspid aortic valves. Different diameters should be measured at four levels: aortic annulus, Valsalva sinuses, sino-tubular junction, and tubular ascending aorta.
The last main issue in AR evaluation is to assess its consequences on the left ventricle, which are a major determinant of outcome and, therefore, play an important role in the indications for surgery. Left ventricular diameters have been widely validated by prognostic studies. Echocardiographic measurements of left ventricular volumes are less accurate.
The impact of AR on left ventricular function was the subject of the third presentation which was given by Catherine Otto (Seattle, USA). Left ventricular enlargement is initially a compensatory mechanism enabling stroke volume to be increased and compensate for the regurgitant volume. The other haemodynamic consequence is pressure overload due to increased afterload in AR. However, after the initial compensatory period of left ventricular enlargement and hypertrophy, irreversible changes of myocardium occur. They are characterized by cell necrosis, fibrosis and molecular changes. The clinical consequence is an irreversible impairment of left ventricular systolic function leading to heart failure. From a clinical perspective, the aim is to establish thresholds of left ventricular consequences of AR which should lead to surgical correction of AR to avoid irreversible left ventricular damage. Thresholds of left ventricular diameters and ejection fraction have been derived from prognostic studies and are used in guidelines as indications for surgery in asymptomatic AR. Left ventricular diameters should be measured using 2D-guided M-mode. Left ventricular volumes are theoretically more appropriate than diameters to fully assess the remodeling process. However, the evaluation of left ventricular volumes using 2D echo are less accurate and reproducible than diameters. 3D echo and cardiac magnetic resonance imaging enable left ventricular volumes to be assessed with better reproducibility than 2D echo. However, prospective studies assessing the prognostic value of left ventricular volume are scarce as compared with older studies using M-mode assessment of left ventricular diameters. Preliminary data suggest that impairment of strain rate indices may be useful to detect left ventricular impairment at an early stage.
The last presentation of the session was dedicated to the timing of surgery in AR and was given by Pilar Tornos (Barcelona). In acute AR, prompt surgery is mandatory because of the poor hemodynamic tolerance of regurgitant volume in a non-dilated left ventricle. In chronic AR, indications for surgery should take into account symptoms, left ventricular enlargement and ejection fraction, and the size of the ascending aorta. Patients with severe AR should undergo surgery as soon as symptom appear, post-operative survival being significantly impaired when patients are operated on in NYHA class III or IV. In asymptomatic patients, surgery is indicated when left ventricular ejection fraction falls below 50% of when end-systolic diameter exceeds 50 mm or, better, 25 mm/m² of body surface area. The use of indexed values is particularly important in women and patients of small stature to avoid too late intervention. Finally, whatever the severity of AR, surgery should be considered when the maximum diameter of ascending aorta exceeds 55 mm to prevent aortic complications. Intervention is indicated at an earlier stage (50 mm) in patients with Marfan syndrome and bicuspid aortic valve.
Studies have demonstrated that post-operative survival was better when patients were operated in accordance with guidelines. On the other hand, when patients are seen for the first time with severe symptoms and severe impairment of left ventricular ejection fraction, they should not be denied surgery. Although the results are less satisfying than for with early surgery, survival and symptoms are improved as compared with spontaneous outcome.