BACKGROUND: Studies reported that low flow and normal flow low-gradient (LF/NF LG) aortic stenosis (AS) are consistent with moderate AS and advocated for watchful waiting until mean gradient reaches 40 mmHg (high gradient [HG]), while others reported a significant benefit from aortic valve replacement (AVR) despite LG, leaving uncertainties regarding the optimal therapeutic strategy. We sought to compare the prognostic impact of LF/HG LF/LG, NF/HG and NF/LG after surgical AVR.
METHODS AND RESULTS NF/HG was present in 601 (40%), NF/LG in 405 (27%), LF/HG in 246 (17%) and LF/LG in 238 (16%). Baseline characteristics of the 4 flow/gradient patterns are shown and compared in Table 1. As evaluated by the weight of explanted valve, the vast majority of the patients have a severe AS (>70%), even in LG groups where severely heavy valve were less frequent (p < 0.001). During a median follow-up of 2.4 [1.04-4.29] years, 167 patients died. Patients with LF had increased 30-day (10 [2.3%] vs 8 [0.9%], p=0.03) and cumulative all-cause mortality (adjusted HR: 1.53 [95% CI: 1.11-2.11], p < 0.01). Interestingly, patients with LF/HG exhibited the highest mortality after AVR (Figure 1A; HR:2.01 [95% CI: 1.33-3.03], p < 0.01), which remained significant after comprehensive multivariate adjustment (Figure 1B, HR=1.96 [1.29-2.98], p < 0.01). LFLG AS had an outcome as good as NF/HG AS (HR=1.06 [0.66-1.67], p=0.86).
CONCLUSION: In our cohort of severe symptomatic AS patients with preserved LVEF, the vast majority had anatomically severe AS, despite a LG present in 43% of our population, thus refuting the impossibility of severe AS in LG - even in NF - patients. Moreover, paradoxical LF/HG had the worst post-operative survival, suggesting the waiting the MG to reach 40 mmHg may be detrimental and early AVR preferable. This should prompt further research to test the superiority of early AVR vs. watchful waiting until the gradient reaches 40 mmHg in paradoxical LF/LG AS.