Pharmacogenomics of Antihypertensive Drugs in Brazil: recent progress and clinical implications

BACKGROUND

The available antihypertensive drugs are effective and well tolerated agents. However, only about half of patients with treated hypertension achieve appropriate blood pressure control. Genetic and non-genetic factors contribute to the interindividual variability of the therapeutic response.

OBJECTIVE

This review constitutes a comprehensive update of the pharmacogenomics of antihypertensive drugs and their clinical implications in Brazil.

RESULTS

Twenty-five studies explored the influence of gene variants on drug response in patients with primary, resistant, or gestational hypertension. Variants in BDKRB2, NOS3, PRKCA, and VEGFA influenced the response to enalapril in patients with primary hypertension. AGT and MMP2 variants were associated with high risk of resistance to antihypertensive treatment, whereas NOS2 variants were related to low risk. Moreover, NAT2 slow acetylators showed an increased response to hydralazine in patients with resistant hypertension. HMOX1, NAMPT, MMP9, NOS3 and TIMP1 variants might be markers of drug responsiveness in hypertensive or preeclamptic pregnant women. Power and replication of studies, polygenic nature of response to therapy, and treatment with multiple drugs were important challenges to be overcome for identifying genetic predictors of antihypertensive response in Brazil.

CONCLUSION

Pharmacogenomic studies in Brazilian cohorts provide some evidences of variants, mainly in pharmacodynamics genes, which influence the response to antihypertensive drugs. However, some findings are limited by cohort size or therapeutic scheme and may be influenced by interactions with other genetic and non-genetic factors. Therefore, further investigations are needed to elucidate the contribution of pharmacogenomics to the efficacy and safety of antihypertensive therapy.

11-Beta Dehydrogenase Type 2 Activity Is Not Reduced in Treatment Resistant Hypertension

BACKGROUND AND OBJECTIVE

Decreased renal 11-beta dehydrogenase type 2 (11β-HSD2) activity, as reflected by an increased urinary free cortisol to cortisone ratio (UFF/UFE), is associated with having hypertension (HTN). The current study was conducted to determine if reduced 11β-HSD2 activity is also associated with having resistant HTN.

METHOD

We evaluated 55 consecutive patients with RHTN, defined as blood pressure (BP) ≥140/90 mm Hg despite using ≥3 antihypertensive medications including a diuretic, and 38 patients whose BP was controlled on ≤3 medications to serve as a non-RHTN comparator group. All patients underwent biochemical evaluation, including measurement of 24-hour urinary UFF/UFE.

RESULTS

The 2 study groups had similar demographic characteristics. Systolic, diastolic BP, and number of antihypertensive medications were greater in patients with uncontrolled RHTN vs. the control group (167.5 ± 28.2/91.2 ± 18.8 vs. 126.6 ± 11.4/77.8 ± 8.65 mm Hg and 4.31 ± 1.23 vs. 2.74 ± 0.6, respectively). The 24-hour UFF was 13.6 ± 11.8 vs. 14.3 ± 10.7 µg/24 h and UFE was 64.9 ± 36.3 vs. 76.1 ± 44 µg/24 h such that the UFF/UFE was 0.22 ± 0.16 vs. 0.19 ± 0.09 in RHTN vs. the control group. This ratio was not associated to age, race, gender, and body mass index.

CONCLUSION

An elevated UFF/UFE was not present in this large cohort of patients with uncontrolled RHTN. This suggests that reduced conversion of cortisol to cortisone does not contribute to the development of RHTN.

Prognostic Value of C-Reactive Protein in Resistant Hypertension

BACKGROUND

C-reactive protein (CRP) is a biomarker of systemic low-grade inflammation and a cardiovascular risk predictor in several clinical conditions. However, its prognostic value has never been examined in patients with resistant hypertension.

METHODS

In a prospective study, 476 patients with resistant hypertension had CRP levels measured at baseline, together with other clinical laboratory variables, including ambulatory blood pressures (BPs). Primary end points were a composite of major fatal or nonfatal cardiovascular events, all-cause mortality, and cardiovascular mortality. Multiple Cox regression assessed the associations between CRP levels and end points.

RESULTS

Median CRP was 3.8mg/l (interquartile range: 2.0-7.2mg/l). After a median follow-up of 9 years, 103 major cardiovascular events occurred, and 120 patients died, 62 from cardiovascular causes. Patients with CRP levels above the median value had a doubled excess risk of major cardiovascular events (95% confidence interval: 1.29-3.06; P = 0.002) and an 86% higher risk of cardiovascular death (95% confidence interval: 1.07-3.25; P = 0.029), after adjustments for potential confounders including traditional cardiovascular risk factors and ambulatory BP and dipping pattern. A high CRP equally predicted coronary (hazard ratio: 2.04; 95% confidence interval: 1.10-3.76; P = 0.023) and cerebrovascular events (hazard ratio: 2.72; 95% confidence interval: 1.30-5.67; P = 0.007). In interaction and sensitivity analyses, CRP levels were stronger predictors of worse cardiovascular outcomes in younger and obese patients, and in those with uncontrolled ambulatory BPs and with the nondipping pattern.

CONCLUSIONS

In patients with resistant hypertension, elevated serum CRP levels is predictive of worse cardiovascular prognosis above and beyond other cardiovascular risk factors, including ambulatory BP levels and dipping patterns.

Systematic review and meta-analysis of the prevalence of resistant hypertension in treated hypertensive populations

BACKGROUND

Although treatment-resistant hypertension (RH) is a serious burden on population health, there exists uncertainty about its prevalence. Hence, the objectives of this work were to systematically review and critically appraise the literature and to conduct a meta-analysis on the prevalence of RH in treated hypertensive populations.

METHODS

PubMed, Cochrane Library, CRD York databases, and study bibliographies were systematically searched for observational and interventional studies that report disease frequency in adult populations. The pooled prevalence was obtained through random-effect modeling. Furthermore, quality assessment, publication bias diagnostics, meta-regression, subgroup analysis by sex, and sensitivity analysis were performed.

RESULTS

Out of 318 retrieved studies, 20 observational studies and 4 randomized control trials (RCTs) with a total population of 961,035 were included. The random-effect method for observational studies and RCTs yielded RH prevalence ratios of 13.72% (95% confidence interval (CI) = 11.19%-16.24%) and 16.32% (95% CI = 10.68%-21.95%), respectively. Yet, most studies were incapable of ruling out pseudo-resistance caused by white-coat effect, poor medication adherence, and suboptimal dosing. Differences in RH prevalence by sex were negligible. Meta-regression analysis showed that study-level characteristics had no statistically significant influence on RH prevalence. The inclusion of further studies in the sensitivity analysis concurred with the baseline results (13.19%; 95% CI = 10.89%-15.49%).

CONCLUSIONS

Researchers should enhance comparability of future empirical evidence through homogeneous methodologies and comparable baseline populations. This meta-analysis concludes that RH is a frequent phenomenon and further harmonization in terms of RH definition and measurement would be necessary to clearly distinguish true treatment resistance from pseudo-resistance.

Factors associated with diastolic dysfunction in patients with resistant hypertension: resist-POL study

BACKGROUND

Diastolic dysfunction has been shown to be an independent factor of cardiovascular diseases in patients with hypertension. Very often, obstructive sleep apnea (OSA) and metabolic syndrome (MS) coexist with resistant hypertension (RHTN) and may lead to diastolic dysfunction. Thus, the purpose of this study was to investigate whether OSA and MS are associated with diastolic dysfunction in patients with RHTN independently from other factors, including age, left ventricular mass index (LVMI), and blood pressure (BP).

METHODS

Data from 155 patients (n = 92 men and 63 women) were analyzed. All patients underwent thorough examination, including biochemical evaluations, ambulatory blood pressure monitoring, polysomnography with assessment of apnea/hypopnea index (AHI), and echocardiography. LVMI and diastolic function parameters were obtained.

RESULTS

Patients were divided into 2 groups based on the presence or absence of diastolic dysfunction: group 1 (E' < 10cm/second; n=87) and group 2 (E' > 10cm/second; n = 68). AHI, LVMI, and 24-hour systolic BP/diastolic BP values were higher in group 1. E' correlated with AHI (r = -0.25; P < 0.001), LVMI (r = -0.36; P < 0.0001), 24-h systolic BP/24-h diastolic BP (r = -0.28, P < 0.001; r = -0.30, P < 0.001, respectively), glucose level (r = -0.26; P < 0.01), and abdominal obesity (r = -0.28; P < 0.0001). In multivariable models decreased E' was independently related to the presence of MS or abdominal obesity when separate components of MS were included in the model. Age and 24-hour systolic BP were independently associated with decreased E'. However, the relationship of decreased E' with 24-hour systolic BP was nonsignificant if LVMI was included in the multivariable model.

CONCLUSIONS

MS and abdominal obesity were independently associated with diastolic dysfunction in patients with RHTN. OSA was not confirmed to be an independent factor of diastolic dysfunction.

Is home blood pressure monitoring useful in the management of patients with resistant hypertension?

BACKGROUND

Ambulatory blood pressure (BP) monitoring (ABPM) is a cornerstone in resistant hypertension (RHT) management. However, it has higher cost and lower patients' acceptance than home BP monitoring (HBPM). Our objective was to evaluate HBPM usefulness in the management of patients with RHT.

METHODS

A total of 240 patients were submitted to 24-hour ABPM and 5-day HBPM (triplicate morning and evening measurements). Patients with uncontrolled office BP (≥140/90mm Hg) were classified as true RHT (daytime or home BP ≥135/85mm Hg) or white-coat RHT (daytime or home BP <135/85mm Hg), and patients with controlled office BP were classified as masked RHT (daytime or home BP ≥135/85mm Hg) or controlled RHT (daytime or home BP <135/85mm Hg). Sensitivity, specificity, predictive values, and likelihood ratios for HBPM were calculated. Agreement between the procedures was evaluated using kappa coefficients and the Bland-Altman method.

RESULTS

Mean office BP was 157±26/84±16mm Hg, mean daytime BP was 134±18/77±13mm Hg, and mean home BP was 143±20/76±14mm Hg. The ABPM and HBPM diagnoses were 35% and 48%, respectively, for true RHT; 36% and 23%, respectively, for white-coat RHT; 7% and 17%, respectively, for masked RHT; and 22% and 13%, respectively, for controlled RHT. HBPM overestimated systolic BP by 8.8 (95% confidence interval (CI) = 6.8-10.7) mm Hg and diastolic BP by 0.2 (95% CI = -1.0 to 1.4) mm Hg. The specificity, sensitivity, and positive and negative predictive values of HBPM in detecting controlled ambulatory BP were 91%, 55%, 89%, and 59%.

CONCLUSIONS

HBPM presented good agreement with ABPM and can be used as a complementary method in the follow-up of resistant hypertensive patients, particularly in those with controlled ambulatory BPs.