Angiotensin II Type 2 Receptors and Cardiac Hypertrophy in Women With Hypertrophic Cardiomyopathy

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Abstract
The development of left ventricular hypertrophy in subjects with hypertrophic cardiomyopathy (HCM) is variable, suggesting a role for modifying factors such as angiotensin II. Angiotensin II mediates both trophic and antitrophic effects, via angiotensin II type 1 (AT1-R) and angiotensin II type 2 (AT2-R) receptors, respectively. Here we investigated the effect of the AT2-R gene A/C3123polymorphism, located in the 3′ untranslated region of exon 3, on left ventricular mass index (LVMI) in 103 genetically independent subjects with HCM (age, 12 to 81 years). LVMI and interventricular septum thickness were determined by 2D echocardiography. Extent of hypertrophy was quantified by a point score (Wigle score). Plasma prorenin, renin, and ACE were determined by immunoradiometric or fluorometric assays, and genotyping was performed by polymerase chain reaction. In men, no associations between AT2-R genotype and any of the measured parameters were observed, whereas in women, LVMI decreased with the number of C alleles (211±19, 201±18, and 152±10 g/m2in women with the AA, AC, and CC genotype, respectively;P=0.015). Similar C allele–related decreases in women were observed for interventricular septum thickness (P=0.13), Wigle score (P=0.05), plasma renin (P=0.03), and plasma prorenin (P=0.26). Multiple regression analysis revealed that the AT2-R C allele–related effect on LVMI (β=−30.7±11.1,P=0.010) occurred independently of plasma renin, the AT1-R gene A/C1166polymorphism, or the ACE gene I/D polymorphism. In conclusion, AT2-Rs modulate cardiac hypertrophy in women with HCM, independently of the circulating renin-angiotensin system. These data support the contention that AT2-Rs mediate antitrophic effects in humans.