Impact of Moderate Aortic Stenosis on Long-Term Clinical Outcomes: A Systematic Review and Meta-Analysis

BackgroundThe clinical course of patients with moderate aortic stenosis (AS) remains incompletely defined.ObjectivesThis study sought to analyze the clinical course of moderate AS and compare it with other stages of the disease.MethodsMultiple electronic databases were searched to identify studies on adult moderate AS. Random-effects models were used to derive pooled estimates. The primary endpoint was all-cause death. The secondary endpoints were cardiac death, heart failure, sudden death, and aortic valve replacement.ResultsAmong a total of 25 studies (12,143 moderate AS patients, 3.7 years of follow-up), pooled rates per 100 person-years were 9.0 (95% CI: 6.9 to 11.7) for all-cause death, 4.9 (95% CI: 3.1 to 7.5) for cardiac death, 3.9 (95% CI: 1.9 to 8.2) for heart failure, 1.1 (95% CI: 0.8 to 1.5) for sudden death, and 7.2 (95% CI: 4.3 to 12.2) for aortic valve replacement. Meta-regression analyses detected that diabetes (P = 0.019), coronary artery disease (P = 0.017), presence of symptoms (P < 0.001), and left ventricle (LV) dysfunction (P = 0.009) were associated with a significant impact on the overall estimate of all-cause death. All-cause mortality was higher in patients with reduced LV ejection fraction (<50%) than with normal LV ejection fraction: 16.5 (95% CI: 5.2 to 52.3) and 4.2 (95% CI: 1.4 to 12.8) per 100 person-years, respectively. Compared with moderate AS, the incidence rate difference of all-cause mortality was -3.9 (95% CI: -6.7 to -1.1) for no or mild AS and +2.2 (95% CI: +0.8 to +3.5) for severe AS patients.ConclusionsModerate AS appears to be associated with a mortality risk higher than no or mild AS but lower than severe AS, which increases in specific population subsets. The impact of early intervention in moderate AS patients having high-risk features deserves further investigation.