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Syncope Threat in Severe Aortic Stenosis
Study Questions:
Among patients with severe aortic stenosis (AS), are preoperative symptoms associated with outcomes after surgical aortic valve replacement (SAVR)?
Methods:
A total of 625 patients with isolated severe AS (Vmax >4.0 m/s, mean gradient ≥40 mm Hg, and aortic valve area <1.0 cm2) undergoing elective SAVR for symptoms (exertional dyspnea, exertional angina, or syncope) or left ventricular (LV) systolic dysfunction (LV ejection fraction [LVEF] ≤50%) were prospectively enrolled in a long-term observational study at a single university-affiliate tertiary European hospital. Preoperative characteristics and postoperative outcomes (defined as all-cause mortality, derived from a national Death Registry) were compared between groups with and without preoperative syncope.
Results:
Compared to patients without syncope (n = 558), patients with preoperative syncope (n = 67) had significantly smaller LV diameter (end-diastolic diameter 45 [42-51] mm vs. 50 [45-54] mm, p = 0.02), left atrial diameter (55 [48-60] mm vs. 56 [52-62] mm, p = 0.04), right ventricular diastolic diameter (30 [27-33] mm vs. 31 [28-34] mm, p = 0.04), and right atrial diameter (49 [46-54] mm vs. 53 [48-57] mm, p = 0.001), smaller aortic valve area (0.55 [0.50-0.80] cm2 vs. 0.60 [0.55-0.70] cm2, p = 0.048), and lower LV stroke volume index (38 [34-45] ml/m2 vs. 42 [35-49] ml/m2, p = 0.04). Syncope conveyed an increased risk for mortality after SAVR that persisted after multivariate adjustment for a bootstrap-selected confounder model (1-year [short-term] adjusted hazard ratio, 2.27; 95% confidence interval, 1.04-4.95; p = 0.04; 10-year [long-term] adjusted hazard ratio, 2.11; 95% confidence interval, 1.39-3.21; p < 0.001). In contrast, preoperative dyspnea, angina, and reduced LV systolic function were not significantly associated with postoperative outcomes.
Conclusions:
This long-term observational study suggests that preoperative syncope among patients undergoing SAVR is associated with a pathophysiologic phenotype characterized by smaller aortic valve area, smaller cardiac cavities, and lower stroke volume index; and that preoperative symptoms of syncope were associated with a worse postoperative prognosis compared to patients with angina, dyspnea, or LV systolic dysfunction but without syncope.
Perspective:
This large, single-center, observational study suggests that patients with severe AS who underwent SAVR with preoperative syncope had similar aortic valve Vmax and mean gradient, but a smaller LV cavity and lower LV stroke volume index, compared to patients with severe AS and no preoperative syncope; associated with worse post-SAVR short- and long-term all-cause mortality. There were nonsignificant trends toward more women and a higher prevalence of diabetes mellitus among patients with syncope; and, in general, all patients appear to have had far advanced AS before SAVR (Vmax 5.0 [4.5-5.4] m/s, mean gradient 63 [52-77] mm Hg, valve area 0.60 [0.50-0.70] cm2, valve area index 0.32 [0.27-0.37] cm2/m2). One interpretation is that syncope among patients with severe AS is accompanied by a specific phenotype with a smaller LV; another interpretation of the study findings is that, among patients with far advanced AS, even more severe AS accompanied by a small LV cavity and occult LV systolic dysfunction (lower stroke volume index despite similar LVEF) is accompanied by a worse postoperative prognosis and by a higher incidence of preoperative syncope. That is, syncope might be (literally) the symptom, not the disease. And the clinical message might be to pursue intervention for severe symptomatic AS prior to a very late stage of disease.
Keywords: Angina Pectoris, Aortic Valve Stenosis, Atrial Fibrillation, Cardiac Surgical Procedures, Diabetes Mellitus, Diagnostic Imaging, Diastole, Dyspnea, Heart Valve Diseases, Heart Valve Prosthesis, Phenotype, Stroke Volume, Syncope, Transcatheter Aortic Valve Replacement, Ventricular Function, Left
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