Could a lipid oxidative biomarker be applied to improve risk stratification in the prevention of cardiovascular disease?

There is significant evidence demonstrating the influence of oxidative stress on atherosclerosis and cardiovascular diseases (CVD). However, oxidative biomarkers have not been applied to follow patients under primary or secondary prevention. Many factors can explain this paradox: the higher complexity of the methods applied to quantify oxidative markers, the high variability observed among the studies, the lack of reference values, and the weak correlation with clinical endpoints. This review presents the role of the major reactive oxygen species (ROS) involved in cardiovascular pathophysiology and how they can be neutralized by endogenous and exogenous antioxidants based on classical and recent studies, highlighting the importance of the secondary products of fatty acid oxidation as potential biomarkers. Furthermore, we discuss the great variability of oxidative stress biomarkers, using as an example data obtained from 55 studies. Among the molecules directly formed from lipid oxidation, such as malondialdehyde (MDA), oxidized LDL (oxLDL), and isoprostanes (F2-IsoP), and those associated with general oxidative conditions (ferric-reducing antioxidant power (FRAP), superoxide dismutase (SOD), glutathione (GSH)), MDA was the most lipid biomarker evaluated in the treatments and proved to be an independent factor compared with traditional markers used in the algorithms to stratify the patient's risk. Finally, this review suggests four steps to follow, aiming to include MDA in the algorithms applied to estimate CVD risk.

Clinical relevance of oxidative stress biomarkers in cardiovascular prevention / Relevância clínica de biomarcadores de estresse oxidativo na prevenção cardiovascular

Cardiovascular diseases involve hyperlipidemia, inflammation and oxidative stress. Although this relationship is well established, only biomarkers associated with hyperlipidemia and inflammation are currently in clinical practice for diagnosis and evaluation of patient treatment. Our hypothesis is that oxidative stress biomarkers may be an independent risk factor and may assist in cardiovascular risk stratification and contribute to improving current scores. Thus, the objective of this study was to investigate which are the biomarkers and methodologies were used in clinical studies in humans with different health conditions. With the results obtained in the first part, we selected studies conducted in healthy individuals and in individuals under primary and secondary cardiovascular prevention in order to evaluate the most frequent biomarkers, the results obtained according to the individual's profile and the methodology used, and correlate with different health conditions. We observed that malondialdehyde (MDA) was the most frequent lipid biomarker of oxidative stress applied in the studies, but it presented significant variability in the results and a weak correlation with clinical outcomes. The result of this study demonstrates the importance of carrying out a multicentric study to validate the MDA values in individuals with different health conditions and the standardization of the methodology based on high performance liquid chromatographyy (HPLC)

As doenças cardiovasculares envolvem hiperlipidemia, inflamação e estresse oxidativo. Embora essa relação esteja bem estabelecida, apenas biomarcadores associados à hiperlipidemia e inflamação são atuais na prática clínica para diagnóstico e avaliação do tratamento do paciente. Nossa hipótese é que biomarcadores de estresse oxidativo podem ser um fator de risco independente e podem auxiliar na estratificação de risco cardiovascular e contribuir para melhorar os escores atuais. Assim, o objetivo deste estudo foi investigar primeiramente quais são os biomarcadores e metodologias utilizados nos estudos clínicos em humanos em diferentes condições de saúde. Com os resultados obtidos na primeira etapa, selecionamos os estudos conduzidos em indivíduos saudáveis e em prevenção cardiovascular primária e secundária a fim de avaliar os biomarcadores mais utilizados, os resultados obtidos conforme o perfil do indivíduo e a metodologia utilizada e finalmente correlacionar com as diferentes condições de saúde. Observamos que o malondialdeído (MDA) foi o biomarcador lipídico de estresse oxidativo mais frequente nos estudos, porém apresentou importante variabilidade nos resultados e fraca correlação com desfechos clínicos. O resultado desse estudo demonstra a importância da realização de um estudo multicentrico para validação dos valores de MDA nos diferentes perfis de indivíduos e a padronização metodológica baseada na cromatografia líquida de alta eficiência (HPLC)