Syncope: The Underestimated Threat in Severe Aortic Stenosis

Abstract

Objectives: Decision making in severe aortic stenosis (AS) requires a comprehensive pre-operative evaluation of the risk-to-benefit ratio. The aim of this study was to assess whether certain pre-operative symptoms are associated with outcome after surgical aortic valve replacement (SAVR).

Background: The cardinal symptoms of AS indicating a need for intervention are angina, symptoms of heart failure, and syncope. Nevertheless, it remains unknown whether the presence of these more advanced symptoms conveys an increased risk after SAVR and whether the detection of early symptoms in patients with asymptomatic AS should be emphasized more in routine clinical practice.

Methods: A total of 625 patients with isolated severe AS undergoing elective SAVR were prospectively enrolled in this long-term observational study.

Results: Patients experiencing syncope had significantly smaller left ventricular diameters (p = 0.02), left atrial diameters (p = 0.043), right ventricular diameters (p = 0.04), and right atrial diameters (p = 0.001), smaller aortic valve areas (p = 0.048), and lower indexed stroke volumes (p = 0.043) compared with patients without syncope. Syncope conveyed an increased risk for mortality after SAVR that persisted after multivariate adjustment for a bootstrap-selected confounder model, with an adjusted hazard ratio of 2.27 (95% confidence interval: 1.04 to 4.95; p = 0.04) for 1-year short-term mortality and an adjusted hazard ratio of 2.11 (95% confidence interval: 1.39 to 3.21; p < 0.001) for 10-year long-term mortality. In contrast, pre-operative dyspnea, angina, and reduced left ventricular function were not significantly associated with outcomes.

Conclusions: This long-term observational study in a large contemporary cohort of patients with AS for the first time demonstrates that syncope represents an underestimated threat in aortic stenosis, associated with poor prognosis after SAVR. Importantly, other primary indications for SAVR (i.e., dyspnea, angina, and decreased left ventricular function) were associated with significantly better post-operative outcomes than syncope. Patients experiencing syncope displayed a specific pathophysiologic phenotype characterized by a smaller aortic valve area, smaller cardiac cavities, and lower stroke volumes.

Keywords: aortic stenosis; aortic valve replacement; syncope.