rpcardioRational Pharmacotherapy in CardiologyРациональная Фармакотерапия в Кардиологии1819-64462225-3653«SILICEA-POLIGRAF» LLC10.20996/1819-6446-2020-10-06rpcardio-2291Research ArticlePOINT OF VIEWТОЧКА ЗРЕНИЯHaemodynamic Patterns of Severe Aortic StenosisГемодинамические варианты тяжелого аортального стенозаКомлевА. Е.KomlevA. E.

Комлев Алексей Евгеньевич – кардиолог, отдел сердечно-сосудистой хирургии, НИИ клинической кардиологии им. А.Л. Мясникова

121552, Москва, ул. 3-я Черепковская, 15а

Alexey E. Komlev – MD, Cardiologist, Department of Cardiovascular Surgery, Research Institute of Clinical Cardiology named after A.L. Myasnikov

Tretya Cherepkovskaya ul. 15a, Moscow, 121552 

pentatonika@bk.ruСаидоваМ. А.SaidovaM. A.

Саидова Марина Абдулатиповна – доктор медицинских наук, профессор, руководитель отдела ультразвуковых методов исследования, НИИ клинической кардиологии им. А.Л. Мясникова

121552, Москва, ул. 3-я Черепковская, 15а

Marina A. Saidova – MD, PhD, Professor, Head of Ultrasound Diagnostics Department, Research Institute of Clinical Cardiology named after A.L. Myasnikov

Tretya Cherepkovskaya ul. 15a, Moscow, 121552 

ИмаевТ. Э.ImaevT. E.

Имаев Тимур Эмвярович – доктор медицинских наук, главный научный сотрудник, сердечно-сосудистый хирург, отдел сердечно-сосудистой хирургии, НИИ клинической кардиологии им. А.Л. Мясникова

121552, Москва, ул. 3-я Черепковская, 15а

Timur E. Imaev – MD, PhD, Chief Researcher, Cardiovascular Surgeon, Department of Cardiovascular Surgery, Research Institute of Clinical Cardiology named after A.L. Myasnikov

Tretya Cherepkovskaya ul. 15a, Moscow, 121552  

ШитовВ. Н.ShitovV. N.

Шитов Виктор Николаевич – младший научный сотрудник, врач, отдел ультразвуковых методов исследования, НИИ клинической кардиологии им. А.Л. Мясникова

121552, Москва, ул. 3-я Черепковская, 15а

Viktor N. Shitov – MD, Junior Researcher, Ultrasound Diagnostics Department, Research Institute of Clinical Cardiology named after A.L. Myasnikov

Tretya Cherepkovskaya ul. 15a, Moscow, 121552 

АкчуринР. С.AkchurinR. S.

Акчурин Ренат Сулейманович – доктор медицинских наук, профессор, академик РАН, руководитель отдела сердечно-сосудистой хирургии, НИИ клинической кардиологии им. А.Л. Мясникова

121552, Москва, ул. 3-я Черепковская, 15а

Renat S. Akchurin – MD, PhD, Professor, Academician of the Russian Academy of Science, Head of Department of Cardiovascular Surgery, Research Institute of Clinical Cardiology named after A.L. Myasnikov

Tretya Cherepkovskaya ul. 15a, Moscow, 121552 

Национальный медицинский исследовательский центр кардиологииРоссияNational Medical Research Center of CardiologyRussian Federation202017102020165822830Copyright © Komlev A.E., Saidova M.A., Imaev T.E., Shitov V.N., Akchurin R.S., 20202020Комлев А.Е., Саидова М.А., Имаев Т.Э., Шитов В.Н., Акчурин Р.С.Komlev A.E., Saidova M.A., Imaev T.E., Shitov V.N., Akchurin R.S.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.rpcardio.online/jour/article/view/2291

The authors present up-to-date review of clinical pathophysiology of aortic stenosis (AS) based on differentiation of its haemodynamic patterns, and some actual issues of instrumental diagnostics and classification of AS. The variety of clinical presentations of AS is based on diverse combination of pathological changes of haemodynamics. In Russian cardiology, there is no clear pathophysiological classification of AS despite of its relevance under the progress of surgical and transcatheter treatment of AS. The authors suggest the pilot haemodynamic classification of AS which includes 6 types (0-5) based on different combination of the following variables: left ventricle ejection fraction, stroke volume, mean aortic systolic pressure gradient. Severe AS with low transaortic pressure gradient in patients with depressed systolic function of the left ventricle (so called «low flow-low» gradient phenomenon) is referred to as the most frequent, classical haemodynamic pattern of low-gradient AS. The prevalence of this variant is about 10% among European population of patients with severe AS. The inconsistence between aortic valve area and mean pressure gradient is as common as in 35-40% of patients with AS, however, in 30-50% of these cases, AS is not severe. Severe AS is a surgical disease that should be treated in a surgical way in all patients but those in whom predicted risk overbalances potential benefits of the procedure. The use of integrated clinical and instrumental approach for identification of a true sever AS is the matter of great concern, as both overestimation and underestimation can misguide the clinical decision-making process. Verification of severe AS in patients with classical and paradoxical low flow-low gradient AS with specific indications for surgical treatment regarded is further emphasized in the paper. Since transcatheter aortic valve implantation has become a commonly recognized alternative to surgical aortic valve replacement, its role in the treatment of severe AS with different haemodynamic patterns is also discussed. The authors stress on the necessity of using tailored approach for treatment of AS regarding different clinical and pathophysiological scenarios: high gradient AS with preserved ejection fraction, classical and paradoxical low flow-low gradient AS.

В работе изложен современный взгляд на клиническую патофизиологию аортального стеноза (АС), основанный на выделении его различных гемодинамических вариантов, освещены некоторые актуальные вопросы инструментальной диагностики и классификации АС. В основе разнообразия клинических проявлений АС лежат различные комбинации патологических изменений гемодинамики. В отечественной кардиологии отсутствует четкая патофизиологическая классификация АС, потребность в которой актуализирована в связи с расширением возможностей хирургического и транскатетерного лечения АС. Авторы предлагают собственную рабочую классификацию гемодинамических вариантов АС, включающую 6 типов (0-5), выделяемых на основании различных комбинаций следующих показателей: фракция выброса левого желудочка (ФВ ЛЖ), ударный объем левого желудочка, средний градиент давления на аортальном клапане (АК). Тяжелый АС с низким градиентом у больных со сниженной систолической функцией левого желудочка (так называемый феномен «low flow-low gradient») является наиболее частым, «классическим» гемодинамическим вариантом АС с низким градиентом. Распространенность этого варианта составляет около 10% среди пациентов с тяжелым АС в европейской популяции. Несоответствие между показателями площади и градиентов давления на АК встречается у 35-40% всех пациентов с АС, однако в 30-50% этих случаев АС в действительности не является тяжелым. Стратегической доминантой в лечении аортальных пороков сердца является постулат о том, что АС тяжелой степени есть хирургическое заболевание, требующее хирургического лечения у всех больных, за исключением ситуаций, когда риск операции превышает ее потенциальную пользу. В связи с этим крайне важно использовать комплексный клинико-инструментальный подход к выявлению истинно тяжелого АС, поскольку как гипердиагностика, так и, в особенности, гиподиагностика приводят к неверным решениям в отношении лечебной тактики. Особое внимание уделено различным способам верификации истинно тяжелого АС у больных с классическим и парадоксальным феноменом «low flow-low gradient», обсуждены показания и особенности тактики лечения этих пациентов. Помимо традиционного хирургического протезирования в условиях искусственного кровообращения, у пациентов высокого хирургического риска рассматриваются также показания к транскатетерной имплантации АК в различных гемодинамических ситуациях. Авторами подчеркивается важность дифференцированного клинико-патофизиологического подхода к выбору оптимальной тактики у больных с различными вариантами тяжелого АС: с высоким градиентом и сохраненной ФВ ЛЖ, классическим и парадоксальным вариантом АС со сниженным градиентом.

тяжелый аортальный стенозгемодинамический паттернклассический феномен «низкая фракция выброса-низкий градиент»парадоксальный феномен «низкая фракция выброса-низкий градиент»транскатетерная имплантация аортального клапанаsevere aortic stenosishaemodynamic patternclassical low flow-low gradientparadoxical low flow-low gradienttranscatheter aortic valve replacementReferencesBaumgartner H., Hung J., Bermejo J., et al. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. Eur J Echocardiogr. 2009;10:1-25. DOI:10.1093/ejechocard/jen303.Baumgartner H., Hung J., Bermejo J., et al. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. Eur J Echocardiogr. 2009;10:1-25. DOI:10.1093/ejechocard/jen303.Nishimura R.A., Otto C.M., Bonow R.O., et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: Executive summary. A report of the American College of Cardiology/American heart association task force on practice guidelines. J Am Coll Cardiol. 2014;63:2438-88. DOI:10.1016/j.jacc.2014.02.537.Nishimura R.A., Otto C.M., Bonow R.O., et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: Executive summary. A report of the American College of Cardiology/American heart association task force on practice guidelines. J Am Coll Cardiol. 2014;63:2438-88. DOI:10.1016/j.jacc.2014.02.537.Pibarot P., Dumesnil J.G. Low-flow low-gradient aortic stenosis with normal and depressed left ventricular ejection fraction. J Am Coll Cardiol. 2012;60:1845-53. DOI:10.1016/j.jacc.2012.06051.Pibarot P., Dumesnil J.G. Low-flow low-gradient aortic stenosis with normal and depressed left ventricular ejection fraction. J Am Coll Cardiol. 2012;60:1845-53. DOI:10.1016/j.jacc.2012.06051.Clavel M.A., Burwash I.G., Pibarot P. Cardiac imaging for assessing low-gradient severe aortic stenosis. J Am Coll Cardiol Imaging. 2017;10:185-202. DOI:10.1016/j.jcmg.2017.01.002.Clavel M.A., Burwash I.G., Pibarot P. Cardiac imaging for assessing low-gradient severe aortic stenosis. J Am Coll Cardiol Imaging. 2017;10:185-202. DOI:10.1016/j.jcmg.2017.01.002.Sathyamurthy I., Jayanthi K. Low flow low gradient aortic stenosis: clinical pathways. Indian Heart Journal. 2014;66:672-7. DOI:10.1016/j.ihj.2014.10.423.Sathyamurthy I., Jayanthi K. Low flow low gradient aortic stenosis: clinical pathways. Indian Heart Journal. 2014;66:672-7. DOI:10.1016/j.ihj.2014.10.423.Dewey T.M., Brown D.L., Herbert M.A., et al. Effect of concomitant coronary artery disease on procedural and late outcomes of transcatheter aortic valve implantation. Ann Thorac Surg. 2010;89(3):758- 67. DOI:10.1016/j.athoracsur.2009.12.033.Dewey T.M., Brown D.L., Herbert M.A., et al. Effect of concomitant coronary artery disease on procedural and late outcomes of transcatheter aortic valve implantation. Ann Thorac Surg. 2010;89(3):758- 67. DOI:10.1016/j.athoracsur.2009.12.033.Акчурин Р.С., Комлев А.Е. Хирургическое лечение аортальных пороков сердца. В: Чазов Е.И., ред. Руководство по кардиологии. М.: Практика; 2014. C. 290-2.Аkchurin R.S., Komlev А.E. Surgical treatment of aortic heart disease. In: Chazov E.I., ed. Cardiology Guide. Moscow: Praktika; 2014. pp. 290-2 (In Russ.)Garbi M., MacCarthy P., Shah A.M., Chambers J.B. Classical and paradoxical low-flow low-gradient aortic stenosis: a heart failure perspective. Structural Heart. 2018;2:3-9. DOI:10.1080/24748706.2017.1384876.Garbi M., MacCarthy P., Shah A.M., Chambers J.B. Classical and paradoxical low-flow low-gradient aortic stenosis: a heart failure perspective. Structural Heart. 2018;2:3-9. DOI:10.1080/24748706.2017.1384876.Chambers J. Low “gradient”, low flow aortic stenosis. Heart. 2006;92:554-8. DOI:10.1136/hrt.2005.079038.Chambers J. Low “gradient”, low flow aortic stenosis. Heart. 2006;92:554-8. DOI:10.1136/hrt.2005.079038.Iung B., Baron G., Butchart E.G., et al. A prospective survey of patients with valvular heart disease in Europe: The Euro Heart Survey on Valvular heart Disease. Eur Heart J. 2003;24:1231-43. DOI:10.1016/s0195-668x(03)00201-x.Iung B., Baron G., Butchart E.G., et al. A prospective survey of patients with valvular heart disease in Europe: The Euro Heart Survey on Valvular heart Disease. Eur Heart J. 2003;24:1231-43. DOI:10.1016/s0195-668x(03)00201-x.Monin J.L., Quere J.P., Monchi M., et al. Low-gradient aortic stenosis: operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics. Circulation. 2003;108:319-24. DOI:10.1161/01.CIR.0000079171.43055.46.Monin J.L., Quere J.P., Monchi M., et al. Low-gradient aortic stenosis: operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics. Circulation. 2003;108:319-24. DOI:10.1161/01.CIR.0000079171.43055.46.Clavel M.A., Burwash I.G., Mundigler G., et al. Validation of conventional and simplified methods to calculate projected valve area at normal flow rate in patients with low flow, low gradient aortic stenosis: the multicenter TOP (True or Pseudo Severe Aortic Stenosis) study. J Am Soc Echocardiogr. 2010;23:380-6. DOI:10.1016/j.echo.2010.02.002.Clavel M.A., Burwash I.G., Mundigler G., et al. Validation of conventional and simplified methods to calculate projected valve area at normal flow rate in patients with low flow, low gradient aortic stenosis: the multicenter TOP (True or Pseudo Severe Aortic Stenosis) study. J Am Soc Echocardiogr. 2010;23:380-6. DOI:10.1016/j.echo.2010.02.002.Cueff C., Serfaty J.M., Cimadevilla C., et al. Measurement of aortic valve calcification using multislice computed tomography: correlation with haemodynamic severity of aortic stenosis and clinical implication for patients with low ejection fraction. Heart. 2011;97:721-6. DOI:10.1136/hrt.2010.198853.Cueff C., Serfaty J.M., Cimadevilla C., et al. Measurement of aortic valve calcification using multislice computed tomography: correlation with haemodynamic severity of aortic stenosis and clinical implication for patients with low ejection fraction. Heart. 2011;97:721-6. DOI:10.1136/hrt.2010.198853.Baumgartner H., Falk V., Bax J.J., et al. 2017 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J 2017;38:2739-91. DOI:10.1093/eurheartj/ehx391.Baumgartner H., Falk V., Bax J.J., et al. 2017 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J 2017;38:2739-91. DOI:10.1093/eurheartj/ehx391.Genereux P., Pibarot P., Redfors B., et al. Staging classification of aortic stenosis based on the extent of cardiac damage. Eur Heart J 2017;38:3351-8. DOI:10.1093/eurheartj/ehx381.Genereux P., Pibarot P., Redfors B., et al. Staging classification of aortic stenosis based on the extent of cardiac damage. Eur Heart J 2017;38:3351-8. DOI:10.1093/eurheartj/ehx381.Clavel M.A., Magne J., Pibarot P. Low-gradient aortic stenosis. Eur Heart J. 2016;37:2645-57. DOI:10.1093/eurheartj/ehw096.Clavel M.A., Magne J., Pibarot P. Low-gradient aortic stenosis. Eur Heart J. 2016;37:2645-57. DOI:10.1093/eurheartj/ehw096.Tribouilloy C., Levy F., Rusinaru D., et al. Outcome after aortic valve replacement for low-flow/lowgradient aortic stenosis without contractile reserve on dobutamine stress echocardiography. J Am Coll Cardiol. 2009;53:1865-73. DOI:10.1016/j.jacc.2009.02.026.Tribouilloy C., Levy F., Rusinaru D., et al. Outcome after aortic valve replacement for low-flow/lowgradient aortic stenosis without contractile reserve on dobutamine stress echocardiography. J Am Coll Cardiol. 2009;53:1865-73. DOI:10.1016/j.jacc.2009.02.026.Quere J.P., Monin J.L., Levy F., et al. Influence of pre-operative left ventricular contractile reserve on postoperative ejection fraction in low gradient aortic stenosis. Circulation. 2006;113:1738-44. DOI:10.1161/CIRCULATIONAHA.105.568824.Quere J.P., Monin J.L., Levy F., et al. Influence of pre-operative left ventricular contractile reserve on postoperative ejection fraction in low gradient aortic stenosis. Circulation. 2006;113:1738-44. DOI:10.1161/CIRCULATIONAHA.105.568824.Clavel M.A., Webb J.G., Rode´s-Cabau J., et al. Comparison between transcatheter and surgical prosthetic valve implantation in patients with severe aortic stenosis and reduced left ventricular ejection fraction. Circulation. 2010;122:1928-36. DOI:10.1161/CIRCULATIONAHA.109.929893.Clavel M.A., Webb J.G., Rode´s-Cabau J., et al. Comparison between transcatheter and surgical prosthetic valve implantation in patients with severe aortic stenosis and reduced left ventricular ejection fraction. Circulation. 2010;122:1928-36. DOI:10.1161/CIRCULATIONAHA.109.929893.Lauten A., Zahn R., Horack M., et al. German Transcatheter Aortic Valve Interventions Registry Investigators. Transcatheter aortic valve implantation in patients with low-flow, low-gradient aortic stenosis. J Am Coll Cardiol Intv. 2012;5:552-9. DOI:10.1016/j.jcin.2012.04.001.Lauten A., Zahn R., Horack M., et al. German Transcatheter Aortic Valve Interventions Registry Investigators. Transcatheter aortic valve implantation in patients with low-flow, low-gradient aortic stenosis. J Am Coll Cardiol Intv. 2012;5:552-9. DOI:10.1016/j.jcin.2012.04.001.Jander N. Low-gradient 'severe' aortic stenosis with preserved ejection fraction: New entity, or discrepant definitions? Eur Heart J Suppl. 2008;10:e11-15. DOI:10.1093/eurheartj/sun016.Jander N. Low-gradient 'severe' aortic stenosis with preserved ejection fraction: New entity, or discrepant definitions? Eur Heart J Suppl. 2008;10:e11-15. DOI:10.1093/eurheartj/sun016.Tribouilloy C., Rusinaru D., Marechaux S., et al. Low-gradient, low-flow severe aortic stenosis with preserved left ventricular ejection fraction: characteristics, outcome, and implications for surgery. J Am Coll Cardiol. 2015;65:55-66. DOI:10.1016/j.jacc.2014.09.080.Tribouilloy C., Rusinaru D., Marechaux S., et al. Low-gradient, low-flow severe aortic stenosis with preserved left ventricular ejection fraction: characteristics, outcome, and implications for surgery. J Am Coll Cardiol. 2015;65:55-66. DOI:10.1016/j.jacc.2014.09.080.Ozkan A., Hachamovitch R., Kapadia S.R., et al. Impact of aortic valve replacement on outcome of symptomatic patients with severe aortic stenosis with low gradient and preserved left ventricular ejection fraction. Circulation. 2013;128:622-31. DOI:10.1161/CIRCULATIONAHA.112.001094.Ozkan A., Hachamovitch R., Kapadia S.R., et al. Impact of aortic valve replacement on outcome of symptomatic patients with severe aortic stenosis with low gradient and preserved left ventricular ejection fraction. Circulation. 2013;128:622-31. DOI:10.1161/CIRCULATIONAHA.112.001094.Clavel M.A., Dumesnil J.G., Capoulade R., et al. Outcome of patients with aortic stenosis, small valve area and low-flow, low-gradient despite preserved left ventricular ejection fraction. J Am Coll Cardiol. 2012;60:1259-67. DOI:10.1016/j.jacc.2011.Clavel M.A., Dumesnil J.G., Capoulade R., et al. Outcome of patients with aortic stenosis, small valve area and low-flow, low-gradient despite preserved left ventricular ejection fraction. J Am Coll Cardiol. 2012;60:1259-67. DOI:10.1016/j.jacc.2011.Hachicha Z., Dumesnil J.G., Bogaty P., Pibarot P. Paradoxical low flow, low gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival. Circulation. 2007;115:2856-64. DOI:10.1161/CIRCULATIONAHA.106.668681.Hachicha Z., Dumesnil J.G., Bogaty P., Pibarot P. Paradoxical low flow, low gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival. Circulation. 2007;115:2856-64. DOI:10.1161/CIRCULATIONAHA.106.668681.Clavel M.A., Messika-Zeitoun D., Pibarot P., et al. The complex nature of discordant severe calcified aortic valve disease grading: new insights from combined doppler-echocardiographic and computed tomographic study. J Am Coll Cardiol. 2013;62:2329-38. DOI:10.1016/j.jacc.2013.08.1621.Clavel M.A., Messika-Zeitoun D., Pibarot P., et al. The complex nature of discordant severe calcified aortic valve disease grading: new insights from combined doppler-echocardiographic and computed tomographic study. J Am Coll Cardiol. 2013;62:2329-38. DOI:10.1016/j.jacc.2013.08.1621.Maes F., Boulif J., Pierard S., et al. Natural history of paradoxical low gradient ‘severe’ aortic stenosis. Circ Cardiovasc Imaging. 2014;7:714-22. DOI:10.1161/CIRCIMAGING.113.001695.Maes F., Boulif J., Pierard S., et al. Natural history of paradoxical low gradient ‘severe’ aortic stenosis. Circ Cardiovasc Imaging. 2014;7:714-22. DOI:10.1161/CIRCIMAGING.113.001695.Dayan V., Vignolo G., Magne J., et al. Outcome and impact of aortic valve replacement in patients with preserved LV ejection fraction and low gradient aortic stenosis: a meta-analysis. J Am Coll Cardiol. 2015;66:2594-603. DOI:10.1016/j.jacc.2015.09.076.Dayan V., Vignolo G., Magne J., et al. Outcome and impact of aortic valve replacement in patients with preserved LV ejection fraction and low gradient aortic stenosis: a meta-analysis. J Am Coll Cardiol. 2015;66:2594-603. DOI:10.1016/j.jacc.2015.09.076.Tarantini G., Covolo E., Razzolini R., et al. Valve replacement for severe aortic stenosis with low transvalvular gradient and left ventricular ejection fraction exceeding 0.50. Ann Thorac Surg. 2011;91:1808-15. DOI:10.1016/j.athoracsur.2011.02.057.Tarantini G., Covolo E., Razzolini R., et al. Valve replacement for severe aortic stenosis with low transvalvular gradient and left ventricular ejection fraction exceeding 0.50. Ann Thorac Surg. 2011;91:1808-15. DOI:10.1016/j.athoracsur.2011.02.057.Minners J., Allgeier M., Gohlke-Baerwolf C., et al. Inconsistent grading of aortic valve stenosis by current guidelines: haemodynamic studies in patients with apparently normal left ventricular function. Heart. 2010;96:1463-68. DOI:10.1136/hrt.2009.181982.Minners J., Allgeier M., Gohlke-Baerwolf C., et al. Inconsistent grading of aortic valve stenosis by current guidelines: haemodynamic studies in patients with apparently normal left ventricular function. Heart. 2010;96:1463-68. DOI:10.1136/hrt.2009.181982.Eleid M.F., Nishimura R.A., Sorajja P., Borlaug B.A. Systemic hypertension in low gradient severe aortic stenosis with preserved ejection fraction. Circulation. 2013;128:1349-53. DOI:10.1161/CIRCULATIONAHA.113.003071.Eleid M.F., Nishimura R.A., Sorajja P., Borlaug B.A. Systemic hypertension in low gradient severe aortic stenosis with preserved ejection fraction. Circulation. 2013;128:1349-53. DOI:10.1161/CIRCULATIONAHA.113.003071.Little S.H., Chan K.L., Burwash I.G. Impact of blood pressure on the doppler echocardiographic assessment of aortic stenosis severity. Heart. 2007;93:848-55. DOI:10.1136/hrt.2006.098392.Little S.H., Chan K.L., Burwash I.G. Impact of blood pressure on the doppler echocardiographic assessment of aortic stenosis severity. Heart. 2007;93:848-55. DOI:10.1136/hrt.2006.098392.

The authors declare that there are no conflicts of interest present.