Antihypertensive Response to Thiazide Diuretic or Angiotensin Receptor Blocker in Elderly Hypertensives Is Not Influenced by Pretreatment Plasma Renin Activity

Plasma Renin Activity Is a Predictive Biomarker of Blood Pressure Response in European but not in African Americans With Uncomplicated Hypertension

BACKGROUND

Interindividual variability in blood pressure (BP) response to antihypertensives has been reported. Although plasma renin activity (PRA) is a potential biomarker for personalizing antihypertensive therapy in European American (EA) and African American (AA) hypertensives, clinical utility of PRA-guided prescribing is incompletely understood.

METHODS

Using systematic-phased approach, PRA's clinical utility was assessed. After categorizing by baseline PRA, clinic systolic BP (SBP) responses to metoprolol and chlorthalidone were compared in 134 EAs and 102 AAs enrolled in the Pharmacogenomics Evaluation of Antihypertensive Responses-2 (PEAR-2) trial. Receiver operating characteristic (ROC) analysis was conducted in EAs. Data from PEAR-2 AAs were used to estimate an optimal PRA cut point using multivariable linear regression models. The derived cut point in AAs was tested in a meta-analysis of 2 independent AA cohorts, and its sensitivity and specificity were assessed.

RESULTS

EAs with PRA < 0.65 ng/ml/hour had a greater decrease in SBP to chlorthalidone than metoprolol (by -15.9 mm Hg, adjusted P < 0.0001), whereas those with PRA ≥ 0.65 ng/ml/hour had a greater decrease in SBP to metoprolol than chlorthalidone (by 3.3 mm Hg, adjusted P = 0.04). Area under ROC curve (0.69, P = 0.0001) showed that PRA can predict SBP response among EAs. However, we observed no association between PRA and SBP response in PEAR-2 AAs. Among independent AA cohorts, those with PRA ≥ 1.3 ng/ml/hour (PEAR-2-derived cut point) responded better to atenolol/candesartan than hydrochlorothiazide (meta-analysis P = 0.01). However, sensitivity of the derived cut point was 10%.

CONCLUSIONS

PRA at the previously established 0.60-0.65 ng/ml/hour cut point is an effective predictive biomarker of BP response in EAs. However, we were unable to identify PRA cut point that could be used to guide antihypertensive selection in AAs.

TRIAL REGISTRATION

NCT01203852, NCT00246519, NCT00005520.

Influence of Age and Race on 24-Hour Ambulatory Blood Pressure Responses to Valsartan, Hydrochlorothiazide, and Their Combination: Implications for Clinical Practice

The effects of race and age on 24-hour mean ambulatory systolic blood pressure (maSBP) responses to sequential 4-week periods of angiotensin receptor blocker therapy (valsartan [VAL] 160 mg/d then 320 mg/d and combination VAL/hydrochlorothiazide [HCTZ] 320/12.5 mg/d) were compared in 304 patients with stage 1 or 2 hypertension. There were lesser blood pressure (BP) responses from baseline with VAL monotherapy in black than Caucasian patients (-2.9 and -4.0 mm Hg vs -8.2 and -9.3 mm Hg, respectively; P<.001 each) but VAL/HCTZ BP responses were similar in both groups (-12 vs -15 mm Hg). Participants 65 years and older had lower BP responses with VAL 160 mg/d and 320 mg/d than those younger than 65 years (-2.8 and -4.5 mm Hg vs -6.5 and -7.5 mm Hg, respectively; P<.001) but similar responses to VAL/HCTZ (-14 vs -17 mm Hg). No BP response differences were found between those older than and those younger than 55 years. The authors conclude that: (1) adding low-dose HCTZ (12.5 mg daily) to VAL is more effective than VAL titration, irrespective of age or race, (2) VAL BP efficacy is lower in blacks than Caucasians, and (3) ARB responses are diminished in patients older than 65 years. Guidelines for stage 1 or 2 hypertension that suggest age 55 should determine initial monotherapy choice (eg, ARB vs thiazide diuretic) or that fail to recommend initial ARB-thiazide combination therapy should be reconsidered.

Hypertension: renin-angiotensin-aldosterone system alterations

Blockers of the renin-angiotensin-aldosterone system (RAAS), that is, renin inhibitors, angiotensin (Ang)-converting enzyme (ACE) inhibitors, Ang II type 1 receptor antagonists, and mineralocorticoid receptor antagonists, are a cornerstone in the treatment of hypertension. How exactly they exert their effect, in particular in patients with low circulating RAAS activity, also taking into consideration the so-called Ang II/aldosterone escape that often occurs after initial blockade, is still incompletely understood. Multiple studies have tried to find parameters that predict the response to RAAS blockade, allowing a personalized treatment approach. Consequently, the question should now be answered on what basis (eg, sex, ethnicity, age, salt intake, baseline renin, ACE or aldosterone, and genetic variance) a RAAS blocker can be chosen to treat an individual patient. Are all blockers equal? Does optimal blockade imply maximum RAAS blockade, for example, by combining ≥2 RAAS blockers or by simply increasing the dose of 1 blocker? Exciting recent investigations reveal a range of unanticipated extrarenal effects of aldosterone, as well as a detailed insight in the genetic causes of primary aldosteronism, and mineralocorticoid receptor blockers have now become an important treatment option for resistant hypertension. Finally, apart from the deleterious ACE-Ang II-Ang II type 1 receptor arm, animal studies support the existence of protective aminopeptidase A-Ang III-Ang II type 2 receptor and ACE2-Ang-(1 to 7)-Mas receptor arms, paving the way for multiple new treatment options. This review provides an update about all these aspects, critically discussing the many controversies and allowing the reader to obtain a full understanding of what we currently know about RAAS alterations in hypertension.

Treatment of isolated systolic hypertension in the elderly

Systolic hypertension is a major health economy problem within our aging society. Increased arterial stiffness is the vascular phenotype of systolic hypertension, especially of the large arteries. Elevated systolic blood pressure is even more associated with cardiovascular morbidity and mortality than diastolic blood pressure. Treatment of systolic hypertension in the elderly should be based on nonpharmacological measures and medical therapy if the systolic hypertension cannot be controlled by conservative therapy alone. The HYVET study provided evidence-based medicine data showing that, in the very elderly, lowering blood pressure to a level of 150/80 mmHg is still very beneficial. Antihypertensive therapy needs to be tailored in the elderly because of comorbid conditions, such as ischemic heart disease, heart failure, atrial fibrillation, renal insufficiency and diabetes. Angiotensin-converting enzyme inhibitors or angiotensin II-receptor blockers should be considered in combination with diuretics or with a dihydropyridine calcium antagonist. β-blockers seem to be less effective for cardiovascular disease protection in comparison with other antihypertensive drug classes, such as diuretics, dihydropyridines, angiotensin-converting enzyme inhibitors or angiotensin II-receptor blockers. Major effort is required to reduce the therapeutic inertia and increase therapeutic adherence for better blood pressure control in the elderly with systolic hypertension.

Renin and prorenin as biomarkers in hypertension

PURPOSE OF REVIEW

This review examines the evidence that plasma renin and/or prorenin level may be used to guide therapy in hypertension and as an independent risk factor for future cardiovascular events.

RECENT FINDINGS

A large number of retrospective analyses of patient populations in clinical trials, in whom 'baseline' renin measurements were available, supports that high renin, but not high prorenin levels, are indicative of future cardiovascular disease and death, particularly in patients with kidney dysfunction and/or hypertension. The relationship is not affected by the use of renin-angiotensin system (RAS) blockers. High renin levels also tend to support the use of RAS inhibitors as first-choice antihypertensive agents. However, the added value of a renin measurement on top of traditional risk factors is modest, and the pressure response to RAS blockade, even in high-renin patients, varies widely.

SUMMARY

Measuring 'baseline' renin as a marker of future cardiovascular events or to determine the choice of drug is of limited value in an individual patient.