Low-Flow/Low-Gradient Severe Aortic Valve Stenosis Shows Insignificant Ejection Fraction Improvement after Aortic Valve Replacement

Objectives: A subgroup of patients with severe aortic valve stenosis present with low transvalvular flow and gradient falsely suggesting moderate disease. Aim of this study is to assess the improvement of left ventricular ejection function (LVEF) in patients with low-flow/low-gradient severe aortic valve stenosis after aortic valve replacement (AVR).

Methods: We performed a retrospective study, which included 16 patient with low-flow/low-gradient (LFLG) and 32 patients with low-flow/high-gradient (LFHG) severe aortic valve stenosis that underwent AVR from 2001 to 2016. Ejection fraction was measured preoperatively, at discharge, 3 months and 1 year postoperatively. Repeated measures ANOVA, Student's t-test, Pearson's and Spearman's correlation and multiple linear regression were performed to assess for and identify factors leading to LVEF improvement.

Results: The mean age of the patients was 72.2 ± 9.7 vs 73 ± 7.8 years (p = 0.748), the mean LVEF was 26.9 ± 6% vs 28.7 ± 6% (p = 0.338) and the mean transvalvular gradient was 31.8 ± 6.9mmHg vs 59 ± 16.3 mm Hg (p < 0.0005) in the LFLG and LFHG groups respectively. The in-hospital mortality was 18.8% in the LFLG vs 6.3% in the LFHG group (p = 0.316). There was no significant improvement of LVEF in the LFLG group. There was a significant improvement of LVEF at discharge (12.4 ± 10.7%, p = 0.023), 3 months (22.6 ± 13.2%, p < 0.0005) and 1 year postoperatively (27.6 ± 11.4%, p < 0.0005) in the LFHG group. Factors significantly associated with LVEF improvement at discharge were previous coronary interventions (p = 0.049), mean transvalvular gradient (p < 0.0005) and aortic valve area (p = 0.009), at 3 months gender (p = 0.029), smoking (p = 0.013), pulmonary disease (p = 0.003), mean transvalvular gradient (p = 0.001), aortic valve area (p = 0.006) and duration of cardiopulmonary bypass (p = 0.048) and at 1 year gender (p = 0.007), pulmonary disease (p = 0.003), mean transvalvular gradient (p = 0.033) and aortic valve area (p = 0.030).

Conclusion: Low-flow severe aortic valve stenosis has a high mortality after AVR. Patients with low-flow/low-gradient have worse prognosis seen in a failed improvement of LVEF in a midterm follow-up compared with low-flow/high-gradient severe aortic valve stenosis.