Estenosis aórtica severa con fracción de expulsión normal de flujo bajo paradójico y bajo gradiente

Abstract

Introductionsevere aortic stenosis impacts the morbidity and mortality of patients. It is defined as a valve area < 1cm2 or < than 0.6cm2/m2 of BSA, transvalvular gradients > 40mm Hg and peak velocities > 4m/s. When patients have severe aortic stenosis and preserved left ventricle ejection fraction, these values are expected to be high, but a subset of patients where these values are lower has been found and this fact has led to reassess the cutoff points to define the disease. ObjectiveTo assess the prevalence of paradoxical low-flow/low-gradient severe aortic stenosis with preserved ejection fraction and determine the hemodynamic characteristics and clinical impact in patients. MethodsA retrospective study conducted during 1999–2010 in an echocardiography service, which evaluated 839 patients with severe aortic stenosis and preserved left ventricle ejection fraction. The sample was divided into two groups: normal flow group, defined as an indexed stroke volume > 35mL /m2 and paradoxical low-flow group, with indexed stroke volume ≤ 35mL/m2 and their hemodynamic characteristics, valvular and ventricular geometry as well as survival were evaluated. Results49.1% were classified as paradoxical low-flow and 50.9 % as normal flow. The average age was 66.4 years and 56.1% were women. The average mean arterial pressure was 92.5mm Hg, mean gradient 41.2mm Hg and mean ejection fraction 60%. When comparing the two groups, patients with paradoxical low flow had higher valvular-arterial impedance (6.2 versus 4.25mm Hg/mL/m, p<0.001), greater LV diastolic diameter (4.76 versus 4.62cm, p<0.001) and higher systemic vascular resistance (2.18 versus 1.51mm Hg * min/L, p<0.001). There was no differen ce in survival. ConclusionParadoxical low-flow/low-gradient aortic stenosis is a common entity that is associated with increased left ventricular afterload. To improve the treatment of these patients it is necessary to reassess the diagnostic criteria and obtain a more thorough evaluation of myocardial function in addition to the left ventricle ejection fraction. Although there was no difference in survival between the two groups, previous studies warn that these patients require closer monitoring and better understanding of their physiology.