Contemporary differences between bicuspid and tricuspid aortic valve in chronic aortic regurgitation

Objective To comprehensively explore contemporary differences between bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients with chronic haemodynamically significant aortic regurgitation (AR). Methods Consecutive patients with chronic ≥moderate-severe AR from a tertiary referral centre (2006-2017) were included. All-cause mortality, surgical indications and aortic valve surgery (AVS) were analysed. Results Of 798 patients (296 BAV-AR, age 46±14 years; 502 TAV-AR, age 67±14 years, p<0.0001) followed for 5.5 (IQR: 2.9-9.2) years, 403 underwent AVS (repair in 96) and 154 died during follow-up. The 8-year AVS incidence was 60%±3% versus 53%±3% for BAV-AR and TAV-AR, respectively (p=0.014). The unadjusted (real-life) 8-year total survival was 93%±7% versus 71%±2% for BAV-AR and TAV-AR, respectively (p<0.0001), and became statistically insignificant after sole adjustment for age (p=0.14). The within-group relative risk of death in BAV-AR patients demonstrated a large age-dependent increase (two fold at 50-55 years, up to 10-fold at 70 years). The presence of baseline symptoms was significantly associated with death for both BAV-AR (p=0.039) and TAV-AR (p<0.0001), but the strength of the association decreased with age adjustment for BAV-AR (age-adjusted HR 2.43 (0.92-6.39), p=0.07) and not for TAV-AR (age-adjusted HR, 2.3 (1.6-3.3), p<0.0001). As compared with general population, TAV-AR exhibited baseline excess risk which further increased at left ventricular ejection fraction (LVEF) <60% and left ventricular end-systolic dimension index (LVESDi) >20 mm/m 2; similar thresholds were observed for BAV-AR patients. Conclusion BAV-AR patients were two decades younger than TAV-AR and underwent AVS more frequently, resulting in a considerable real-life survival advantage for BAV-AR that was determined primarily by age and not valve anatomy. Pragmatically, regardless of valve anatomy, patients with haemodynamically significant AR and age >50-55 years require a low-threshold for surgical referral to prevent symptom development where LVEF <60% and LVESDi >20 mm/m 2 seem appropriate referral thresholds.