Effect of angiotensin II blockade on cardiac hypertrophy and remodelling: a review

Abstract

Activation of the renin-angiotensin system both systemically and locally seems to be of importance for cardiovascular hypertrophy and remodelling. The octapeptide angiotensin II definitively plays a central role. In the reversal, for example, of left ventricular hypertrophy, so far the most important independent risk factor for an adverse outcome, blocking of the renin-angiotensin system with ACE inhibition has been shown to be particularly effective. In cardiac tissue, however, ACE inhibition has been suggested to inhibit only a fraction of angiotensin II formed, indicating that other enzymatic pathways can be of importance. From a theoretical point of view a more complete blockade of the angiotensin II type 1 receptor would offer a more effective attenuation of the unfavourable effect of angiotensin II. Experimentally, losartan, a novel selective angiotensin II receptor type 1 antagonist has been shown to decrease cardiac hypertrophic response in models of both hypertension and volume cardiac hypertrophy as well as reverse hypertrophy in spontaneously hypertensive rats. TCV-116, another selective angiotensin II antagonist, also effectively reverses cardiac hypertophy and interstitial fibrosis in the rat. The only report so far regarding the effect of angiotensin II blockade on cardiac hypertrophy in essential hypertension suggests a more favourable short-term effect on cardiac hypertrophy for the same blood pressure reduction with losartan compared with atenolol in a small population of mild to moderate hypertensives. In the perspective of the well-established positive effects of ACE inhibition on the remodelling process in the remaining viable myocardium after myocardial infarction, involving myocyte hypertrophy, interstitial fibrosis and progressive dilatation, it is reassuring that angiotensin II blockade has been shown to perform equally well as ACE inhibition after experimental coronary ligation. In summary, the development of cardiovascular hypertrophy in hypertension is a serious prognostic indicator and selective angiotensin II blockade is a new anti-hypertensive treatment modality with promising properties, especially for prevention and reversal of cardiac hypertrophy including pathological fibrosis and cardiac remodelling after myocardial infarction. Thus, taking into account the shortcomings of today's anti-hypertensive treatment to achieve normalisation of excessive cardiovascular morbidity and mortality, as well as the seemingly great importance of the renin-angiotensin system for hypertension-induced functional and structural abnormalities, a therapy based on a specific All antagonist could offer obvious advantages in a high risk hypertensive patient with cardiovascular hypertrophy. This hypothesis will be investigated in a large prospective trial (Losartan Intervention For End-point reduction in hypertension: The LIFE Study).