Objective: To study contemporary etiologies, mechanisms, and corresponding surgical approaches in isolated aortic regurgitation (AR). Patients and Methods: Consecutive patients undergoing surgery for moderately severe and severe AR were retrospectively identified from January 1, 2006, through October 20, 2017. Intraoperative echocardiograms, surgical reports, and pathology reports were reviewed. Results: Of 382 patients (54±16 years, 82% men), there were 207 (54%) tricuspid (TAV), 167 (44%) bicuspid (BAV), 5 quadricuspid, and 3 unicuspid aortic valves. Isolated AR mechanisms (n=116, 30%) included cusp prolapse (n=44, 11%), restriction/retraction (n=33, 9%), aortic root dilatation (n=33, 9%), perforation (n=5, 1%), and fenestration (<1%); mixed mechanisms were present in 266 (70%). The most common mixed mechanism was root dilatation and prolapse (27% BAV vs 16% TAV, P=.01). Valve repair (AVr) was performed in 31% BAV and 23% TAV (P=.06). Aortic surgery was more common in BAV (37% vs 27%, P<.001). Overall, root dilatation was associated with AVr. In TAV, cusp prolapse and restriction/retraction were associated with replacement; in BAV, prolapse was associated with AVr. AR etiology was idiopathic in 43% TAV patients, 47% of whom had root dilatation. Conclusions: BAV accounted for 44% of surgical referrals for AR and, compared with TAV, was more often associated with prolapse, root dilatation, and mixed mechanisms of AR. Because mechanisms affected the choice of AVr differently in BAV and TAV, comprehensive mechanistic description of surgical AR is critical.
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