Natural history and clinical burden of moderate aortic stenosis: a systematic review and explorative meta-analysis

Aims: The mortality risk of patients with moderate aortic stenosis is not well known, but recent studies suggested that it might negatively affect prognosis. We aimed to assess the natural history and clinical burden of moderate aortic stenosis and to investigate the interaction of patients' baseline characteristics with prognosis. Methods: Systematic research was conducted on PubMed. The inclusion criteria were inclusion of patients with moderate aortic stenosis; and report of the survival at 1-year follow-up (minimum). Incidence ratios related to all-cause mortality in patients and controls of each study were estimated and then pooled using a fixed effects model. All patients with mild aortic stenosis or without aortic stenosis were considered controls. Meta-regression analysis was performed to assess the impact of left ventricular ejection fraction and age on the prognosis of patients with moderate aortic stenosis. Results: Fifteen studies and 11 596 patients with moderate aortic stenosis were included. All-cause mortality was significantly higher among patients with moderate aortic stenosis than in controls in all timeframes analysed (all P < 0.0001). Left ventricular ejection fraction and sex did not significantly impact on the prognosis of patients with moderate aortic stenosis (P = 0.4584 and P = 0.5792), while increasing age showed a significant interaction with mortality (estimate = 0.0067; 95% confidence interval: 0.0007-0.0127; P = 0.0323). Conclusion: Moderate aortic stenosis is associated with reduced survival. Further studies are necessary to confirm the prognostic impact of this valvulopathy and the possible benefit of aortic valve replacement.