Effect of quinapril on the albumin excretion rate in patients with mild to moderate essential hypertension. Multicenter Study Group

Efficacy of eplerenone versus enalapril as monotherapy in systemic hypertension

This study compared the efficacy and tolerability of eplerenone and enalapril in 499 patients with stage 1 or 2 hypertension who were randomized to receive eplerenone or enalapril for 6 months in a 3-step titration-to-effect study. After 6 months, patients whose diastolic blood pressure (BP) was <90 mm Hg had their dosages down-titrated were followed for an additional 6 months. Diastolic BP was the primary end point. Eplerenone was as effective as enalapril in reducing both systolic BP (eplerenone, -14.5 mm Hg; enalapril, -12.7 mm Hg; p = 0.199) and diastolic BP (eplerenone, -11.2 mm Hg; enalapril, -11.3 mm Hg; p = 0.910) at 6 months. BP reductions at 12 months were also similar between groups (-16.5/-13.3 mm Hg for eplerenone, -14.8/-14.1 mm Hg for enalapril; p = 0.251 and 0.331, respectively). Withdrawal rates for adverse events (eplerenone 7.9%, enalapril 9.3% at 6 months) and treatment failures (eplerenone 23.3%, enalapril 22.8% at 6 months) were also equivalent. Approximately 2/3 of each group had normal BP with monotherapy treatment at 6 months. BP response was independent of renin levels in the eplerenone group, but not in the enalapril group. Both agents reduced albuminuria in patients who had an elevated value at baseline, with significantly greater improvement in patients treated with eplerenone versus enalapril (-61.5% vs -25.7%; p = 0.01). Both agents were similarly well tolerated, and there was no increased incidence of any sexual adverse events in the eplerenone group. Patients taking enalapril had a higher rate of cough. Both agents increased serum potassium levels, but <1% in each group reported adverse events from hyperkalemia. Eplerenone was as effective as enalapril as monotherapy in patients with stage 1 or 2 hypertension, was more effective in reducing albuminuria, and was well tolerated for 12 months.

Clinical value of microalbuminuria in hypertension

Microalbuminuria (MA) is a well recognized marker of cardiovascular complications in hypertension, but whether MA can predict adverse outcome in this clinical condition is still a subject for debate. The fact that in hypertensive cohorts those patients who showed an increase in albumin excretion rate also manifested an increased incidence of morbid events indicates that the presence of MA in hypertension may carry an increased cardiovascular risk. However, the prognostic significance of MA remains controversial because no results of prospective studies performed in hypertensive subjects without diabetes mellitus are available. Several factors can affect the prevalence of MA in hypertension, including severity of the disease, selection procedures, concomitant risk factors, degree of obesity, age, and sex distribution. This accounts for the large differences in the prevalence of MA that can be found in the literature, with prevalence rates going from a low of 4.7% to a high of 40%. There is still conflict over whether MA in hypertension is due to increased intraglomerular pressure or to glomerular damage. The data from the literature suggest that in subjects with mild hypertension the main determinant of albumin excretion rate is the haemodynamic load. In subjects with more severe hypertension and hypertensive complications, the augmented urinary albumin leak is probably the consequence of a systemic microvascular disturbance which involves the glomeruli. In this respect, the insulin resistance state often associated to high blood pressure appears as one of the main pathogenetic factors. Whether management of hypertensive populations may be improved by monitoring of albumin excretion rate and whether antihypertensive drugs which are more effective in decreasing urinary albumin can be more beneficial in patients with MA remains to be determined.

[Factors associated with changes in microalbuminuria during antihypertensive treatment]

BACKGROUND

The objective of the present study was to analyze the factors related with changes of microalbuminuria during antihypertensive treatment in patients with essential hypertension.

METHODS

One hundred and six patients (57 men, mean age 40.8 [SD 6.6] years) never treated with antihypertensive treatment were included. At the beginning and after one year, blood pressure biochemical profile and urinary albumin excretion (UAE) were measured. After the initial evaluation, 53 patients received angiotensin converting enzyme inhibitors (ACEi) and 53 beta-blockers (BB). Hydrochlorothiazide was added to achieve the blood pressure target < 140/90 mmHg.

RESULTS

The average of UAE was 32.1 (43.1) mg/24 h, and 41 (39%) patients had microalbuminuretics. After 12 months of treatment, a significative fall of systolic BP (-20.6 [8.03] mmHg, p < 0.001), and diastolic BP (-14.18 [10.34] mmHg, p < 0.001) were observed, whereas baseline glucose increases (3.08 [11.07] mg/dl, p = 0.006). The changes of UAE were only related with the baseline UAE values. Neither, age, sex, baseline diastolic BP and changes in diastolic BP were significantly related with the changes in UAE. In spite of similar mean BP reduction (medial BP 17.4 [10.9] vs 14.8 [10.4] mmHg), UAE only was reduced in patients treated with ACEi (LogUAE: 0.203 [0.872] mg/24 h; p < 0.04). In addition, in patients treated with BB a significative increase in baseline glucose (4.4 [12.3] mg/dl; p = 0.013) and uric acid (1.18 [4.18]; p = 0.031) were observed.

CONCLUSIONS

In patients with essential hypertension, changes in microalbuminuria depends of the initial UAE values and the kind of antihypertensive treatment. ACEi produced higher UAE reduction and lower derangement of the glucose metabolism than BB.

Renal protection by antihypertensive drugs: insights from microalbuminuria studies

During the last few years there has been a renewed interest in blood-pressure (BP)-induced kidney damage, owing to a progressive increase in the incidence and prevalence of hypertension and vascular diseases as a cause of end-stage renal disease (ESRD). The need to prevent ESRD demands continued efforts so as to identify early those people with hypertension who are at risk and to provide them with effective antihypertensive therapy. This review analyses what is needed in terms of surrogate endpoints for monitoring kidney damage and what is known about the impact of antihypertensive treatments in reducing the BP burden on the kidney in non-diabetic subjects. Although glomerular filtration rate (GFR) and proteinuria are useful surrogate endpoints for patients with nephropathy and GFR below or close to the threshold value for renal insufficiency, it is clear that monitoring changes in either GFR or proteinuria does not provide a sensitive endpoint for subjects with the mildest forms of renal disease, e.g. essential hypertensive patients who are at risk of developing kidney damage. In this case microalbuminuria may be useful, although unequivocal evidence demonstrating that microalbuminuria is a risk marker for developing renal insufficiency in non-diabetic renal diseases has not existed until now, and whether a decrease in microalbuminuria is of prognostic significance in patients with essential hypertension remains to be demonstrated. The beneficial effects of the antihypertensive agents on microalbuminuria are also proportional to BP reduction. If a large enough BP reduction is achieved there seem to be, at most, only minimal differences among the antihypertensive drug classes. Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers have additional beneficial effects on microalbuminuria independent of the BP reduction, owing to their direct role in glomerular haemodynamics. The heterogeneity in the changes in urinary albumin excretion during antihypertensive treatment may be related to the different factors involved in the presence of microalbuminuria or structural end-organ damage, or both.

Treatment of patients with essential hypertension and microalbuminuria

There has been increasing interest in the question of whether microalbuminuria can be used in the risk stratification of patients with essential hypertension. A cluster of cardiovascular and/or renal risk factors may be associated with microalbuminuria in hypertension. Despite this, prospective data about the potential role of microalbuminuria as a prognostic marker of cardiovascular and/or renal risk have been sparse and inconclusive until now. Blood pressure values have been considered the most important determinant of microalbuminuria in essential hypertension; however, hyperinsulinaemia--a metabolic component-was noted to be present in conjunction with high blood pressure. Furthermore, 2 other factors may be also related to microalbuminuria: salt sensitivity and renal structural changes (nephrosclerosis). We are now aware that the clinical and physiological implications of abnormal urinary albumin excretion (UAE) are much broader than anticipated, possibly involving haemodynamic, metabolic and vascular components overlapping several clinical syndromes. Achievement of short term UAE reduction with antihypertensive treatment depends on structural abnormalities established in the glomerulus, the extent of blood pressure reduction and the antihypertensive drug class used. In terms of UAE reduction, better results are obtained with ACE inhibitors or angiotensin II antagonists such as losartan and valsartan, than with other antihypertensive classes, although their true impact in preserving renal function needs to be assessed. The capacity of new calcium antagonists, such as amlodipine, lacidipine or mibefradil, to reduce UAE also needs to be assessed further. Thus, microalbuminuria may be seen as an integrated marker of risk and should be assessed in recently diagnosed patients with essential hypertension. In microalbuminuric patients, the target should be to decrease blood pressure < 135/85 mm Hg, reduce salt intake to around 100 mmol/day and prescribe a low-calorie diet if obesity is present. ACE inhibitors or angiotensin II antagonists have more potential benefits than the other classes of antihypertensive drugs in reducing UAE. Finally, a yearly assessment of microalbuminuria is recommended during treatment, to monitor the impact of therapy.