Marinobufagenin and left ventricular mass and geometry in patients with essential hypertension

Marinobufagenin (MBG), the endogenous cardiotonic inhibitor of the transmembrane adenosine triphosphatase sodium-potassium pump, is a steroid hormone with divergent effects on blood pressure and cardiovascular (CV) system. In response to sodium load, MBG stimulates natriuresis to compensate for body fluid overload but, in condition of sustained high sodium intake, its excessive production promotes a maladaptive pro-hypertensive effect. Since the role of MBG on the cardiac alterations frequently affecting hypertensive patients has been poorly investigated, we focused on gaining insight into this relationship in essential hypertension.

We studied the relationships between MBG, LV mass and geometry and investigated whether diuretic therapy modifies these associations in 180 incident-prevalent patients with essential hypertension.

Serum MBG levels were significantly lower in hypertensive patients than in normotensive individuals (P = 0.005) and strongly associated with the mass and muscle component of the left ventricle. On multivariable linear regression models, left ventricular mass index and the cardiac measurements posterior wall thickness, interventricular septal thickness, mean wall thickness, relative wall thickness increased in parallel with the decrease in serum MBG levels (P ≤ 0.01). Coherently, in a multivariable logistic model, the odds of having cardiac remodeling/hypertrophy increased by 9% for each 0.1 nmol/l MBG reduction (odds ratio: 1.09, 95% confidence interval: 1.01-1.18, P = 0.03). Furthermore, diuretic therapy modified the link between MBG and cardiac biomarkers by acting as an amplifier of the harmful effect of low MBG levels on these measures.

In patients with essential hypertension, lower circulating levels of MBG are associated with alterations in myocardial morphology whose severity is modified by the diuretic therapy that amplifies the noxious effect of low MBG levels.

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