NHE-1 hyperactivity correlates with ABPM in patients without cardiac hypertrophy (CH): a new strategy to early identify subjects with higher risk of CH?

STABILE N; COR S; ZAVALA M; SALAZAR MG; MARCH C ; VILLA-ABRILLE MC; ESPECHE W; LEIVA C; DE IRAOLA A; ENNIS IL

Congreso; XXIV Congreso Argentino de Hipertensión Arterial-Premios IASH; 2017

Myocardial Na+/H+exchanger-1 (NHE-1) hyperactivity playsa crucial role in pathological cardiac hypertrophy (PCH) and the progressionto heart failure. Moreover, NHE-1 is hyperactive in blood cells fromhypertensive compare to non-hypertensive individuals. Myocardial stretch due tothe hemodynamic overload would induce NHE-1 hyperactivity. Since PCH couldprecede the diagnosis of hypertension, at least by office based estimations ofblood pressure (BP), we aim to determine whether NHE-1 activity could be anearly indicator of increased risk of PCH in subjects with normal or slightlyelevated BP. Platelet NHE-1 activity, ambulatory BP monitoring (ABPM) andoffice base BP were recorded in 38 non diabetic subjects without evidence oftarget organ damage and not taking antihypertensive drugs (18 men, 48±12 yearsold, BMI 28.9±5.4 Kg/m2, office BP 133±12/ 82±9 mmHg). One patient with PCHdiagnosed by echocardiography was excluded. NHE-1 activity (initial rate of pHirecovery from induced intracellular acidosis) was higher in the upper tercileof mean BP estimated by ABPM (p=0.018). However, this relationship was notevident when office-based mean BP was used (p=0.827). Interestingly, NHE-1activity increased abruptly with mean BP by ABPM > 100 mmHg. Even thoughmean BP from office-based measurements correlated with ABPM values (rho =0,394, p = 0.017), NHE-1 activity only significantly correlated with the latter(rho = 0,338, p 0.041) but not with the former (rho = 0.180, p = 0.294). Inconclusion, there is a significant correlation between platelet NHE1 activityand mean BP only when it is estimated by ABPM. Office-based BP categories seemnot to adequately represent the hemodynamic load at which the heart is exposed.Therefore, NHE-1 activity, especially in the subgroup of subjects withprehypertension hypertension stage I, emerges as a promising diagnostic tool tohelp identify patients with higher risk of target organ damage, i.e. PCH.