Prognostic significance of baseline and serial changes in electrocardiographic strain pattern in resistant hypertension

Cardiovascular and renal complications in patients with resistant hypertension

With an increased prevalence, resistant hypertension is recognized as an entity with a high cardiovascular morbidity and mortality. In a large cohort of patients with resistant hypertension, the crude incidence rate of total cardiovascular events reached 4.32 per 100 patient-years of follow-up (19.6 %), with a cardiovascular mortality of 8.3 % (incidence rate of 1.72 per 100 patient-years). Cardiovascular event rates are significantly higher in resistant hypertensives compared with non-resistant (18.0 % versus 13.5 %). In the same way, the prevalence of established cardiovascular and renal disease, as the asymptomatic organ damage (represented by left ventricular hypertrophy, carotid wall thickening, arterial stiffness, and microalbuminuria) is higher in these patients. Many studies have demonstrated a strong association between damage to these organs with higher blood pressure levels, the diagnosis of true resistant hypertension, and refractory hypertension. All efforts should be employed in order to control blood pressure and also to regress and/or prevent subclinical cardiovascular and renal damage. The focus should be on prevention of cardiovascular and renal complications, improving the prognosis of resistant hypertension.

Urinary albumin excretion at follow-up predicts cardiovascular outcomes in subjects with resistant hypertension

BACKGROUND

Renal function and albuminuria predict cardiovascular disease (CVD) in general population. However, their prognostic value in patients with resistant hypertension (RH) is somewhat unknown.

OBJECTIVE

To determine the ability of renal function and albuminuria to predict CVD in RH patients.

METHODS

One hundred and thirty-three RH (blood pressure [BP] ≥140/90mmHg despite treatment with ≥3 drugs) patients were evaluated. Median follow-up was 73 months. Primary endpoint was a composite of non-fatal cardiovascular events or cardiovascular death. Serum creatinine (SCr) and estimated glomerular filtration rate (eGFR) were determined. Microalbuminuria was defined as a urinary albumin-to-creatinine ratio (UACR) ≥30mg/g.

RESULTS

Twenty-two patients (16.5%) reached the primary endpoint. Long-term elevated UACR (66 vs. 17mg/g, P=0.045), but not at baseline, was associated with the primary endpoint, after adjusting for age, prior CVD, and both eGFR and office systolic-BP at baseline and during follow-up. Although baseline SCr and eGFR were associated with CVD, significance was lost after baseline risk adjustment. Baseline microalbuminuria prevalence was 45% and 41% in patients with and without CVD (P=0.813), while percentages of patients with microalbuminuria at follow-up were 67% and 28%, respectively (P=0.002). More patients with de novo CVD, compared with those without CVD, developed microalbuminuria at follow-up (28% vs. 6%) or had persistent microalbuminuria (39% vs. 21%), while fewer patients with CVD had microalbuminuria regression (11% vs. 19%) or remained normoalbuminurics (22% vs. 53%; overall P=0.005).

CONCLUSION

In RH patients, the inability to microalbuminuria regression, either due to persistence or new appearance, independently predicts CVD.

Resistant hypertension and target organ damage

Cardiovascular (CV) complications such as myocardial infarction, heart failure, stroke and renal failure are related to both the degree and the duration of blood pressure (BP) increase. Resistant hypertension (RH) is associated with a higher risk of CV complications and a higher prevalence of target organ damage (TOD). The relationship between CV disease and TOD can be bidirectional. Elevated BP in RH may cause CV structural and functional alterations, and the development or persistence of left ventricular hypertrophy, aortic stiffness, atherosclerotic plaques, microvascular disease and renal dysfunction, may render hypertension more difficult to control. Specifically, RH is related to several conditions, including obesity, sleep apnea, diabetes, metabolic syndrome and hyperaldosteronism, characterized by an overexpression of humoral and hormonal factors that are involved in the development and maintenance of TOD. Optimal therapeutic strategies, including pharmacological treatment and innovative invasive methodologies, have been shown to achieve adequate BP control and induce the regression of TOD, thereby potentially improving patient prognosis.

Prognostic factors in resistant hypertension: implications for cardiovascular risk stratification and therapeutic management

Resistant hypertension (RH) is defined as uncontrolled office blood pressure (BP) in spite of the use of at least three antihypertensive medications. Although its condition has a high prevalence, it is still understudied, and its prognosis is not well established. Some prospective studies evaluated the prognostic value of ambulatory BP monitoring, ECG and renal parameters. They pointed out that ambulatory BPs are important predictors of cardiovascular morbidity and mortality, whereas office BP has no prognostic value. The diagnosis of true RH and the nondipping pattern are also valuable predictors of cardiovascular outcomes. Moreover, several ECG (prolonged ventricular repolarization, serial changes in the strain pattern and left ventricular hypertrophy) and renal parameters (albuminuria and reduced glomerular filtration rate) are also powerful cardiovascular risk markers in RH. These markers and others yet unexplored, such as arterial stiffness and serum biomarkers, may improve cardiovascular risk stratification in these very high-risk patients.

[Prevalence of target organ damage and metabolic abnormalities in resistant hypertension]

BACKGROUND AND OBJECTIVE

Patients with resistant hypertension (RH) are relatively frequently visited in specialized units of hypertension. The aim of this study was to assess the prevalence of target organ damage, central obesity and metabolic syndrome in a cohort of patients with RH consecutively included in the Register of Resistant Hypertension of the Spanish Society of Hypertension (SHE-LELHA).

PATIENTS AND METHODS

Cross-sectional, multicenter epidemiologic study in usual clinical practice conditions. Patients with clinical diagnosis of resistant hypertension, that is, office systolic and diastolic blood pressure ≥ 140 mm Hg and/or ≥ 90 mm Hg, respectively, despite a prescribed therapeutic schedule with an appropriate combination of three or more full-dose antihypertensive drugs, including a diuretic, were consecutively recruited from specialized hypertension units spread through Spain. Demographic and anthropometric characteristics as well as cardiovascular risk factors and associated conditions were recorded, and all the subjects underwent 24-h ambulatory blood pressure monitoring. Left ventricular hypertrophy was considered as a left ventricular mass index ≥ 125 g/m(2) in males and ≥ 110 g/m(2) in females. Left atrial enlargement was defined as an indexed left atrium diameter ≥ 26 mm/m(2). Microalbuminuria was defined as a urinary albumin/creatinine ratio ≥ 22 mg/g in males and ≥ 31 mg/g in females.

RESULTS

513 patients were included, aged 64±11 years old, 47% women. Central obesity was present in 65.7% (CI 95% 61.6-69.9), 38.6% (CI 95% 34.4-42.8) had diabetes and 63.7% (CI 95% 59.4-67.9) had metabolic syndrome. The prevalence of left ventricular hypertrophy and left atrial enlargement, determined by echocardiography was 57.1% (CI 95% 50.8-63.5) and 10.0% (CI 95% 6.3-13.7) respectively. Microalbuminuria was found in 46.6% (CI 95% 41.4-51.8) of the subjects. Patients with metabolic syndrome were significantly older (65.4±11 and 62.5±12 years; P=.0052), presented a higher prevalence of diabetes (52.0% vs. 16.6; P<.0001) and were treated more frequently with ≥ 4 antihypertensive drugs (65.1 vs. 50.0%, P=.011).

CONCLUSION

The prevalence of central obesity, metabolic syndrome and target organ damage is very high in resistant hypertensive subjects.

Resistant hypertension and left ventricular hypertrophy: an overview

Available data on subclinical cardiac damage in resistant hypertension (RH) are rather scanty. Thus, we sought to review the literature focusing on the association between RH and left ventricular hypertrophy (LVH). A MEDLINE search was performed to identify relevant articles using the key words "resistant hypertension, " "refractory hypertension," "left ventricular hypertrophy," "cardiac damage," and "left ventricular dysfunction." Full articles published in the English language in the last two decades (December 1, 1989, to July 31, 2010) reporting studies in adult or elderly individuals, were considered. Checks of the reference lists of selected articles complemented the electronic search. A total of 11 cross-sectional and longitudinal studies, including 3325 patients attending outpatient hypertension clinics, were considered. Prevalence rates of echocardiographic LVH, as assessed by updated criteria, ranged from 55% to 75% of patients with RH, peaking to 91% in the subgroup with concomitant electrocardiographic (ECG) LV strain. Reduction in ECG-LVH induced by treatment showed a relevant beneficial impact on cardiovascular prognosis. These data support the view that initial and on-treatment assessment of LVH in patients with RH is important for cardiovascular risk monitoring and therapeutic strategies decision-making.

Benefits from treatment and control of patients with resistant hypertension

Resistant hypertension is commonly found in everyday clinical practice. However, the risks of resistant hypertension, as well as the benefits of treatment and control of blood pressure in patients with resistant hypertension remain vaguely clarified. Data from small clinical studies and observational cohorts suggest that patients with resistant hypertension are at increased cardiovascular risk, while control of blood pressure offers substantial benefits. It has to be noted however that data from appropriate large randomized studies are missing, and resistant hypertension remains remarkably understudied. Resistant hypertension has attracted significant scientific interest lately, as new therapeutic modalities become available. The interventional management of resistant hypertension either by carotid baroreceptor stimulation or renal sympathetic denervation is currently under investigation with promising preliminary results. This review presents available evidence regarding the benefits of treatment and control of blood pressure in patients with resistant hypertension and offers a critical evaluation of existing data in this field.