Harnett, David T.

Abstract Aims Aortic regurgitation (AR) arises from leaflet disease and/or dilatation of the functional aortic annulus complex. Understanding the mechanisms of AR informs surgical planning of valve and aorta repair. This study investigates the mechanisms, aetiologies, and outcomes of isolated native severe AR in a consecutive cohort of patients. Methods and results Patients with moderate-to-severe (3+)/severe (4+) native valve AR, identified from our institutional echocardiography database (2014–2018), were included. Exclusions were significant concomitant valve disease, endocarditis, or aortic dissection. AR was classified per the El-Khoury system: Type I (normal leaflet motion: Ia–ascending aorta/sinotubular junction dilatation, Ib–aortic root dilation, Ic–aortic annular dilation), Type II (leaflet prolapse), and Type III (leaflet restriction). Valve anatomy and clinical outcomes, including mortality and surgical intervention, were analyzed. Of 282 patients (77.3% male), 58.5% had multiple AR mechanisms. Type II (leaflet prolapse) was most common (48.6%), followed by Type III (36.2%). Bicuspid aortic valve (BAV) represented 35.5% of the population, with leaflet prolapse observed in 72%. Multiple mechanisms were more frequent in BAV (77% vs. 48%, P < 0.001). After a median follow-up of 4.7 years (available for 97.5% of patients), 158 (57.5%) underwent an intervention with 48.7% having an aortic valve repair or valve-sparing aortic root replacement. Conclusion Although leaflet prolapse (Type II) was the pre-dominant AR mechanism, multiple contributing mechanisms were often present, particularly in BAV patients. Aortic valve repair accounted for nearly half of surgical interventions, underscoring the importance of mechanism identification to optimize repair and avoid valve replacement.