Epidemiología y situación actual de la estenosis aórtica en España

Abstract

Introduction: The change in the population pyramid that has taken place in the Spanish society in recent decades has led to a significant change in the burden and etiology of the pathology treated in health centers. Progressive population aging due to marked increases in life expectancy together with a significant decrease in the birth rate has led to the current scenario where the degenerative pathologies are the most frequently encountered. In this sense, aortic stenosis is one of the most prevalent valvular diseases, and the main cause of valvular intervention (whether surgical or percutaneous) in our country, being a pathology mainly degenerative and therefore keeping a strong relationship with age. Demographic models forecast a rapidly aging composition for the next four decades. This will bring a significant burden of disease associated with age. It is expected that, given the etiological change experienced by valvular disease, where the rheumatic cause already accounts for a minority of cases and the underlying etiology is mostly degenerative, the number of people affected by aortic stenosis will multiply. Despite this expected growth, epidemiological data for this disease in Spain is practically non-existent. Objectives: The objectives of this study are: 1) To establish the prevalence of aortic stenosis in the Spanish echocardiography laboratories; 2) To characterize the profile of patients with aortic stenosis, with special interest in its severe forms and taking into account the different phenotypes described in previous literature; 3) To establish the prevalence of previously unknown aortic stenosis in the general population of advanced age (≥65 years) and 4) To estimate the number of people who currently have undiagnosed aortic stenosis, and project this estimate to the future based on the demographic models of the National Institute of Statistics for our country. Methods: The work is divided into two phases, hospital and community. In the hospital phase, all patients referred for an echocardiogram in ten Spanish hospitals are included prospectively and consecutively during an inclusion period of three months. The participating centers have a general case report form where, together with the total number of echocardiograms performed, additional echocardiographic information of those patients with any degree of aortic stenosis is provided. With the data from this phase of the study, the prevalence of aortic stenosis in Spanish echocardiography laboratories is determined and a descriptive analysis of the pathology is carried out according to the recommendations of the main cardiovascular imaging societies. The community phase presents a cross-sectional design that aims to determine the prevalence of unknown aortic stenosis in the elderly population. For this purpose, non-selected volunteers who attend the flu vaccination campaign are included consecutively. The prevalence of the disease and the characteristics of the patients are analyzed and with these data, population estimates are made based on data from the National Institute of Statistics. Results: During the hospital phase of the study, 29,502 patients were included, in whom the diagnosis of some degree of aortic stenosis was confirmed in 2,109 (prevalence 7.1%). Aortic stenosis was mild in 25.6% of cases, moderate in 37.0%, and severe in the remaining 37.4%. The mean age was 75.2 years (standard deviation 10.9) and 51.4% were men. The main cause was degenerative (93.4%), with rheumatic etiology being a minority (3.4%). The female sex was highly associated with the rheumatic cause (relative risk = 5.4), which also frequently presented in association with other significant valve diseases and a greater presence of right ventricular dysfunction. Within severe aortic stenosis, the most frequent phenotype was the classic high gradient and normal flow (49.9%). However, 39,9% of the patients diagnosed with severe stenosis showed a mean gradient <40mmHg. Among them, the most frequently described behavior was that of normal flow and low gradient. 24% of the patients in this group would be reclassified to moderate stenosis if the aortic annulus was not different to that of the rest of severe stenosis. Paradoxical severe stenosis (low flow and low gradient with preserved ejection fraction) appeared in 12.3% of cases and was a distinct phenotype, with older subjects, different ventricular remodeling, and greater association with poor prognostic parameters such as significant coexisting valve disease, atrial fibrillation, or right ventricular dysfunction. During the community phase of the study, 522 volunteers were included, in which some degree of stenosis was documented in 22 (4.2%), generally mild or moderate. The coexistence of other significant valve diseases was very common in this type of patient (68.2%). Patients with unknown aortic stenosis had low frailty punctuation (13.2% of frail patients), moderate comorbidity (mean Charlson index 2.13; standard deviation 0.92), and low estimated surgical risk scores (54,5% with a mortality score less than 4% according to the Society of Thoracic Surgeons scale). According to the prevalence obtained and current demographic composition, 470,073 cases of unknown aortic stenosis were estimated in our country. The future estimate according to the demographic projections of the National Institute of Statistics points to 992,435 cases by 2060. Conclusions: Aortic stenosis is a highly prevalent pathology in hospital and community settings. In a very significant percentage of cases, the severity parameters are discordant, being the final echocardiographic diagnosis many times conditioned by an important component of subjectivity to. This is of particular importance in low-gradient groups, where the prognosis and therapeutic benefit is controversial. The current number of estimated cases of unknown aortic stenosis indicates that it would strikingly higher than that of diagnosed patients, and the projection is that it will double in the next forty years. It is necessary to standardize diagnostic criteria to establish the prognosis of a significant number of individuals with forms of aortic stenosis with discordant severity parameters. This is of particular interest when the number of subjects who will require valve replacement therapy will multiply in the coming years Healthcare system policymakers must be aware of the current and future burden of aortic stenosis on an elderly population, in order to be able to deal with the present and future challenges with the best healthcare perspective and optimal management of resources.