ACE Inhibition Preserves Renal Function Better thanbT-blockade in the Treatment of Essential Hypertension

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Abstract
Antihypertensive treatment can slow down the decline in glomerular filtration rate (GFR) with time. In patients with diabetic nephropathy, angiotensin converting enzyme (ACE) inhibition has been shown to be more effective in this regard than conventional antihypertensive therapy. Whether this applies to the much larger population of patients with essential hypertension is not yet known. In the present study, the effects of two different antihypertensive therapies on the loss of GFR with time, determined with Cr51-EDTA clearance after 6, 12 and 24 months of treatment, were assessed in a prospective, randomised, double-blind trial in 257 patients with essential hypertension. All had normal renal function and none had diabetes mellitus or glucosuria. Proteinuria (dipstick positive or trace) was detected in 7 patients initially. The two therapeutic modalities were the ACE inhibitor cilazapril and the bT-adrenoceptor blocking agent atenolol. Both therapies were equally effective in lowering sytolic blood pressure (e.g. from 168 mmHg to 152 mmHg with cilazapril and from 170 mmHg to 155 mmHg with atenolol after 6 months, p < 0.001 for both). However, atenolol was slightly but significantly more effective in lowering the diastolic blood pressure at 6, 12 and 24 months. The decline in GFR with time was significantly smaller with cilazapril than with atenolol. After 6 months the reduction in GFR was 1.0 vs. 4.0 ml/min × 1.73 m2, p = 0.008 (cilazapril vs. atenolol) and after 12 months the corresponding changes were 2.0 vs. 4.5 ml/min × 1.73 m2, p = 0.04 and after 24 months 3.0 vs. 4.0 ml/min × 1.73 m2, respectively (n.s.). In comparison with an age-matched normotensive population the cilazapril treated group did not differ as regards the decline in GFR with time, whereas the atenolol treated group showed a significantly greater fall. These results indicate that ACE inhibitor therapy in hypertensive patients prevents the decline in GFR with time better than a bT-blocker-based regimen, at least during the first year of treatment.