Hamirani YS, Dietl CA, Voyles W, et al. Acute aortic regurgitation. Circula- tion. 2012;126:1121 6. 2. Stout KK, Verrier ED. Acute valvular regurgitation. Circulation. 2009;119:3232 41. 3. Lalani T, Cabell CH, Benjamin DK, et al. Analysis of the impact of early sur- gery on in-hospital mortality of native valve endocarditis: use of propensity score and instrumental variable methods to adjust for treatment-selection bias. Circulation. 2010;121:1005 13. 4. Patel PA, Bavaria JE, Ghadimi K, et al. Aortic regurgitation in acute type-A aortic dissection: a clinical classification for the perioperative echocardiog- rapher in the era of the functional aortic annulus. J Cardiothorac Vasc Anesth. 2018;32:586 97. 5. Trost JC, Hillis LD. Intra-aortic balloon counterpulsation. Am J Cardiol. 2006;97:1391 8. 4.3. Chronic AR 4.3.1. Diagnosis of Chronic AR 1. Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for noninva- sive evaluation of native valvular regurgitation: a report from the Ameri- can Society of Echocardiography. Developed in collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr. 2017;30:303 71. 2. Detaint D, Messika-Zeitoun D, Maalouf J, et al. Quantitative echocar- diographic determinants of clinical outcome in asymptomatic patients with aortic regurgitation: a prospective study. JACC Cardiovasc Imaging. 2008;1:1 11. 3. Pizarro R, Bazzino OO, Oberti PF, et al. Prospective validation of the prog- nostic usefulness of B-type natriuretic peptide in asymptomatic patients with chronic severe aortic regurgitation. J Am Coll Cardiol. 2011;58:1705 14. 4. Bonow RO, Picone AL, McIntosh CL, et al. Survival and functional results after valve replacement for aortic regurgitation from 1976 to 1983: im- pact of preoperative left ventricular function. Circulation. 1985;72:1244 56. 5. Cunha CL, Giuliani ER, Fuster V, et al. Preoperative M-mode echocardiog- raphy as a predictor of surgical results in chronic aortic insufficiency. J Thorac Cardiovasc Surg. 1980;79:256 65. 6. 