<qa>  What is the main reason for the systolic blood pressure reduction?Most of clinical trials, performed with the aim to show a reduction of the systolic blood pressure in hypertensive patients, show that reduction of systolic blood pressure is independent from the class of tested drugs as diuretics, β blockers, Ca channel blockers or inhibitors of RAS seem to have roughly the same efficacy. These findings have been used as an argument to support the notion that the antihypertensive therapy efficacy in reducing cardiovascular risk depends on the magnitude of the blood pressure fall rather than on the mechanism of action of the drug. This view contrasts with the well established notion that the secondary prevention capacity in other cardiovascular diseases differs among these classes of drugs with minor difference on the prevention of heart failure or stroke between the Ca antagonist and the other classes of drugs. 