Myocardial extracellular volume quantification by cardiac magnetic ressonace imaging in patients with primary hyperaldosteronism and renovascular hypertension

• Grant number: 14/05650-6
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2014
• End date: September 30, 2016
• Field of knowledge: Health Sciences - Medicine - Medical Radiology
• Principal Investigator: José Rodrigues Parga Filho
• Grantee: José Rodrigues Parga Filho
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

In Brazil, cardiovascular diseases are the leading cause of mortality and are associated with lianerly, continuasly, progressively and independently with the elevation of blood pressure. Population studies have estimated the prevalence of Hypertension hypertension in 22.3% to 43.9% (average 32.5%). Primary hyperaldosteronism (PHA) is a secondary cause of hypertension with estimated overall prevalence of 6.1 % to 13 % when only severe hypertension are considered. PHA patients seem to be at greater risk than essential hypertensive patients of target organ damage and adverse cardiovascular outcomes . Renovascular hypertension by renal artery stenosis accounts for 5% of cases of secondary systemic hypertention. Some work with these patients showed an increase in cardiovascular risk and higher rates of target organ damage . It is believed that much of this injury is caused by hormonal activation of the renin -angiotensin -aldosterone II . The mechanism of injury determined by excess aldosterone, present in both the PAH and renovascular hypertension patients, in the cardiovascular system remains unknown, but culminates in ventricular remodeling, hypertrophy and fibrosis .The presence of myocardial fibrosis is an independent predictor of ventricular arrhythmias and sudden death. The onset of cardiac magnetic resonance ( CMR ) with delayed myocardial enhancement ( RTM ) allowed the noninvasive diagnosis of focal areas of fibrosis, which largely correlate with histopathological findings, and, besides suggesting the etiology of cardiomyopathy, has shown recognized prognostic factors in several diseases. A new CMR sequence , still in clinical validation, called T1 mapping allows the evaluation of myocardial extracellular volume, which corresponds to the presence of histological interstitial fibrosis, with excellent correlation to histology. The T1 mapping and myocardial extracellular volume have been used to demonstrate the presence of diffuse myocardial fibrosis in symptomatic cardiomyopathies in various clinical settings, however, there is not, to date, research on the quantification of extracellular volume and interstitial fibrosis in patients with primary aldosteronism or renovascular hypertension newly diagnosed . The realization of the T1 mapping and quantification of extracellular volume in these populations may ultimately demonstrate the presence and assess the degree of myocardial interstitial fibrosis. (AU)