Outcomes of Pseudo-Severe Aortic Stenosis Under Conservative Treatment
What are the outcomes with conservative treatment of patients with low-flow/low-gradient (LF/LG) pseudo-severe aortic stenosis (AS)?
In a European multicenter registry, LF/LG AS was defined as aortic valve area ≤1.0 cm2 or indexed valve area ≤0.6 cm2/m2, mean gradient <40 mm Hg, and left ventricular (LV) ejection fraction <40%; pseudo-severe AS was defined as LF/LG AS with intact LV contractile reserve upon administration of dobutamine, but a final aortic valve area ≥1.2 cm2 and mean gradient <40 mm Hg at peak dobutamine infusion. Among 305 patients from the European Registry, the outcomes of 107 patients with LF/LG AS and no aortic valve intervention were analyzed. Patients were divided into groups based on their response to dobutamine infusion: true-severe AS with LV contractile reserve (n = 43), pseudo-severe AS (n = 29), and no LV contractile reserve (n = 35).
The rate of death within 5 years was significantly lower in patients with pseudo-severe AS (43 ± 11%, n = 10) compared to patients with true-severe AS with LV contractile reserve (91 ± 6%, n = 33; p = 0.001) and patients with no LV contractile reserve (100%, n = 23; p < 0.001). Cox proportional hazard model analysis demonstrated that the hazard ratio for death among patients with pseudo-severe AS remained significantly lower than in the other groups, even after adjustment for currently established risk factors. The 5-year survival of pseudo-severe AS patients was comparable with that of propensity-matched patients with systolic heart failure and no evidence of valve disease.
In patients with pseudo-severe AS, 5-year survival with conservative treatment is better than with true-severe AS, and comparable to that of propensity-matched patients with LV systolic dysfunction and no evidence of valve disease. Further studies are needed to define optimal therapeutic management in these patients.
Patients with pseudo-severe AS have LV systolic dysfunction, but do not have severe AS, so it is not surprising that their outcomes resemble similar patients with LV systolic dysfunction, but without AS. Dobutamine stress echocardiography plays a clinical role among patients with LF/LG AS and decreased LV systolic function in order to determine whether AS is or is not severe, and to assess LV contractile reserve. If AS is truly severe, LV contractile reserve can help define perioperative risk, although patients with and without contractile reserve appear to benefit from intervention as long as they survive that intervention. Among patients who do not have severe AS (those with ‘pseudo-severe AS,’ in which a calcified aortic valve has a valve area <1.0 cm2 because of low cardiac output), there is no logical role for aortic valve intervention––a conclusion supported by the findings from this study.
Keywords: Incidence, Registries, Dobutamine, Proportional Hazards Models, Cardiomyopathies, Heart Failure, Ventricular Function, Risk Factors
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