PPARA gene and phenprocoumon: a new predictor of response variability.

Phenprocoumon is an anticoagulant used for thromboembolic disorder prophylaxis metabolized mainly by CYP3A4. However, polymorphisms in this gene did not explain the observed variability. PPARA (peroxisome proliferator-activated receptor-α) is a nuclear receptor that, among others, influences CYP3A4 gene expression. The aim of this study was to determine whether PPARA gene polymorphisms and the CYP3A4*22 allele are associated with phenprocoumon dose variability. A total of 198 patients on a stable dose of phenprocoumon were included in the study. Genotyping was performed by allele discrimination using standardized TaqMan assays. Differences between the average phenprocoumon dose and genotypes/haplotypes were assessed by analysis of variance and multiple linear regression analyses. Patients with the PPARA rs4253728A allele needed higher phenprocoumon doses. However, the effect size (3%) of this association was small. The CYP3A4*22 allele was not associated with the dose of phenprocoumon. As this is the first report of an association between PPARA gene polymorphisms and phenprocoumon dose, future studies are warranted to confirm these results.

Effect of fluid and dietary sodium restriction in the management of patients with heart failure and preserved ejection fraction: study protocol for a randomized controlled trial.

BACKGROUND: Although half of all patients with heart failure (HF) have a normal or near-normal ejection fraction and their prognosis differs little from that of patients with a reduced ejection fraction, the pathophysiology of HF with preserved ejection fraction (HF-PEF) is still poorly understood, and its management poorly supported by clinical trials. Sodium and fluid restriction is the most common self-care measure prescribed to HF patients for management of congestive episodes. However, its role in the treatment of HF-PEF remains unclear. This trial seeks to compare the effects of a sodium- and fluid-restricted diet versus an unrestricted diet on weight loss, neurohormonal activation, and clinical stability in patients admitted for decompensated HF-PEF. METHODS/DESIGN: This is a randomized, parallel trial with blinded outcome assessment. The sample will include adult patients (aged ≥18 years) with a diagnosis of HF-PEF admitted for HF decompensation. The patients will be randomized to receive a diet with sodium and fluid intake restricted to 0.8 g/day and 800 mL/day respectively (intervention group) or an unrestricted diet, with 4 g/day sodium and unlimited fluid intake (control group), and followed for 7 days or until hospital discharge. The primary outcome shall consist of weight loss at 7 days or discharge. The secondary outcome includes assessment of clinical stability, neurohormonal activation, daily perception of thirst and readmission rate at 30 days. DISCUSSION: Assessment of the effects of sodium and fluid restriction on neurohormonal activation and clinical course of HF-PEF can promote a deeper understanding of the pathophysiology and progression of this complex syndrome. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT01896908 (date of registration: 8 August 2013).

A new algorithm for weekly phenprocoumon dose variation in a southern Brazilian population: role for CYP2C9, CYP3A4/5 and VKORC1 genes polymorphisms.

Phenprocoumon is widely used in prophylaxis and treatment of thromboembolic disorders. However, its pharmacokinetics and pharmacodynamics vary according to several genetic and non-genetic factors. Phenprocoumon metabolism is mediated by CYP2C9 and CYP3A enzymes. Moreover, VKORC1 is phenprocoumon target of action. Therefore, the aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) in VKORC1, CYP2C9, CYP3A4 and CYP3A5 genes with the variance of weekly phenprocoumon dose as well as to develop an algorithm for dose prediction based on genetic and environmental factors. A total of 198 patients with stable phenprocoumon dose, 81% of European ancestry, were investigated. Genotypes were determined by allelic discrimination with TaqMan assays. Polymorphisms -1639G>A and 1173C>T in VKORC1 and the presence of CYP2C9*2 and/or CYP2C9*3 are associated with lower doses. On the other hand, 3730G>A in VKORC1 gene is associated with higher doses. No association was found between CYP3A4*1B, CYP3A5*3 and CYP3A5*6 polymorphisms. Among non-genetic factors, gender, height, age and use of captopril, omeprazole, simvastatin and ß-blockers are associated with dose. Two algorithms were derived: one for the whole sample explained 42% of dose variation and one for patients of European ancestry only which explained 46% of phenprocoumon dose. The mean absolute difference between observed and predicted dose was low in both models (3.92 mg/week and 3.54 mg/week, for models 1 and 2, respectively). However, more studies with other genes and environmental factors are needed to test and to improve the algorithm.

Echocardiography-based left ventricular mass estimation. How should we define hypertrophy?

Left ventricular hypertrophy is an important risk factor in cardiovascular disease and echocardiography has been widely used for diagnosis. Although an adequate methodologic standardization exists currently, differences in measurement and interpreting data is present in most of the older clinical studies. Variability in border limits criteria, left ventricular mass formulas, body size indexing and other adjustments affects the comparability among these studies and may influence both the clinical and epidemiologic use of echocardiography in the investigation of the left ventricular structure. We are going to review the most common measures that have been employed in left ventricular hypertrophy evaluation in the light of some recent population based echocardiographic studies, intending to show that echocardiography will remain a relatively inexpensive and accurate tool diagnostic tool.

Remodelamento ventricular pós-infarto do miocárdio: conceitos fundamentais e perspectivas emergentes / Post-myocardial infarction ventricular remodeling: basic concepts and emerging perspectives

Remodelamento ventricular se refere ao processo fisiopatológico caracterizado por alterações da morfologia ventricular e que, freqüentemente, culmina em dilatação das cavidades cardíacas. O processo de dilatação ventricular pós-infarto ocorre após um dano isquêmico agudo e irreversível, sendo influenciado primordialmente por três fatores interdependentes: o tamanho do infarto, o estresse da parede ventricular e o processo de cicatrização tecidual. Os meios mais eficientes de evitar ou minimizar o aumento nas dimensões ventriculares após um infarto são através da limitação do dano isquêmico e da redução da pós-carga e da tensão da parede ventricular. Recentemente, o papel da síntese e degradação da matriz extracelular nos processos relacionados com o remodelamento ventricular pós-infarto vem recebendo grande interesse. A modulação da atividade de uma família de enzimas proteolíticas, as metaloproteinases, responsáveis pela degradação de proteínas da matriz extracelular, emergiu como uma estratégia terapêutica potencial para pacientes em risco de desenvolver quadros de falência miocárdica. Dados promissores, utilizando modelos de infarto experimental, sugerem que esse tipo de abordagem poderá ter um papel relevante no tratamento do remodelamento ventricular pósinfarto. De forma similar, diversos investigadores têm avaliado estratégias inovadoras de tratamento que se baseiam no conceito de que a regeneração do tecido miocárdico é factível e segura, envolvendo o uso de terapias com células pluripotentes. Inúmeros estudos experimentais já avaliaram o uso destas células em diferentes modelos de lesão miocárdica, demonstrando resultados consistentemente benéficos em aspectos funcionais. Estudos clínicos estão sendo desenvolvidos em todo o mundo, incluindo iniciativas no Brasil, para definir o papel destas estratégias de tratamento na reversão do remodelamento ventricular pós-infarto.

Postinfarction ventricular remodeling is a pathophysiological process characterized by changes in ventricular geometry and frequently leading to progressive chamber dilatation. The process of postinfarction ventricular dilatation, which is a result of an acute and irreversible ischemic injury, is mainly influenced by three interdependent factors: infarct size, ventricular wall stress and the tissue healing process. The most efficient strategies in order to avoid or minimize increases in ventricular dimension after an infarction involve attempts to limit the ischemic damage and afterload and ventricular wall stress reduction. The role of the synthesis and degradation of the extracellular matrix in processes related to the postinfarction ventricular remodeling has recently received increasing interest. Modulation of the activity of several proteolytic enzymes - the metalloproteinases, which are responsible for the degradation of the extracellular matrix - has emerged as a potential therapeutic strategy for patients at risk of developing heart failure. Preliminary experimental data on animal models suggest that this approach may have a relevant role in the management of postinfarction ventricular remodeling. Similarly, several investigators have evaluated innovative treatment strategies based on the concept that the myocardial tissue regeneration using pluripotent cells is feasible and safe. Several experimental studies have shown that the use of pluripotent cells in different models of myocardial damage results in significant improvement in functional outcomes. Clinical studies that are being developed worldwide, including in Brazil, will define the role of such strategies to reverse postinfarction ventricular remodeling.

Pathophysiology of atherosclerotic plaque development and rupture: an overview.

Atherosclerosis is predominantly a clinically silent process, and a substantial percentage of patients are first aware of its consequences through the acute and catastrophic event of thrombosis. Extensive basic and clinical research in the 1990s revealed that plaque disruption initiates the majority of thromboses. Furthermore, recent studies indicate that inflammation plays a major role in the pathophysiology, from initiation of the atheroma to the actual thrombosis itself. Attention has now focused on morphological, mechanical, and biochemical characteristics that increase plaque vulnerability, as determination of these features may allow identification of plaques that are most likely to cause symptoms and acute events in the future. This article reviews basic pathophysiologic aspects of atherosclerotic plaque development and rupture to provide the necessary background for understanding the crucial role of inflammation in acute coronary syndromes.