Resistant or Refractory Hypertension: Are They Different?

Prevalence and associated factors of obstructive sleep apnea in refractory hypertension

BACKGROUND

Refractory hypertension (RfHT) and obstructive sleep apnea (OSA) share common pathophysiological mechanisms and probably are intrinsically associated, but their prevalence, clinical profile, and polysomnography (PSG) pattern remain misunderstood.

OBJECTIVE

To describe OSA prevalence and PSG pattern of patients with RfHT in a large cohort of resistant hypertension (RHT).

METHODS

This is a cross-sectional study involving 418 RHT patients (30.9% male; mean age of 62.5 ± 9.9 years) who were submitted to full-night PSG. RfHT was defined as uncontrolled ambulatory blood pressure monitoring using five or more antihypertensive drugs, including spironolactone. Bivariate analysis compared RHT and RfHT and multivariate analysis was performed to assess the independent correlates of OSA.

RESULTS

A total of 90 patients (21.5%) were diagnosed with RfHT (26.7% male; mean age of 58.5 ± 8.3 years). In comparison with resistant ones, RfHT patients were younger, with higher smoking and previous cardiovascular diseases prevalence, especially stroke. There was no difference regarding anthropometric measures. OSA prevalence (80.0 vs. 82.9%) and moderate/severe OSA (51.1 vs. 57.0%) were similar in both groups as well as apnea-hypopnea index. In its turn, refractory hypertensive patients presented better sleep efficiency (78 vs. 71%), with higher total sleep time (315 vs. 281 min) and lower sleep latency (11 vs. 17 min). There was no difference regarding rapid eye movement sleep, oxygen saturation, microarousals index, and periodic limb movement.

CONCLUSION

In this large RHT cohort, resistant and refractory hypertensive patients have similar OSA prevalence, although refractory ones, which by definition use spironolactone, are younger and apparently have a better sleep pattern.

Refractory Hypertension: a Narrative Systematic Review with Emphasis on Prognosis

PURPOSE OF REVIEW

To perform a narrative systematic review on refractory hypertension (RfHT) with particular emphasis on prognosis.

RECENT FINDINGS

There were 37 articles on RfHT, 13 non-systematic reviews, and 24 original studies. RfHT, a recently described extreme phenotype of anti-hypertensive treatment failure, shall be defined as uncontrolled out-of-office blood pressure (BP) levels despite the use of at least 5 anti-hypertensive drugs, including a long-acting diuretic and a mineraloreceptor antagonist. Its prevalence ranges from 0.5 to 4.3% of general treated hypertensives and between 3.6 and 51.4% of patients with resistant hypertension (RHT). RfHT is associated with younger age, African ancestry, obesity, hypertension-mediated organ damage and clinical cardiovascular diseases, and with some comorbidities, such as diabetes and obstructive sleep apnea. Its physiopathological mechanisms probably involve sympathetic overactivity and not volume overload. Patients with RfHT have a worse prognosis than non-refractory RHT individuals, with higher risks of adverse cardiovascular and renal outcomes and of mortality. RfHT represents a rare but true extreme phenotype of anti-hypertensive treatment failure distinct from RHT and with a significantly worse prognosis. Identifying such individuals is important to tailor specific interventions.

Prevalence and clinical profile of refractory hypertension in a large cohort of patients with resistant hypertension

Refractory hypertension (RfHT) is an extreme phenotype of resistant hypertension (RHT) and is considered uncontrolled blood pressure (BP) despite the use of five or more antihypertensives. The objective of this study was to characterize the prevalence and clinical profile of RfHT patients in a historical cohort of patients with RHT at two different times: before and after the introduction of spironolactone. First, this cross-sectional study evaluated 1048 RHT patients (72.3% females, mean [SD] age: 61.2 [11.3] years) referred to a hypertension clinic (prespironolactone period). All patients were submitted to a standard protocol including clinical and complementary exams. Second, the analysis evaluated patients after the introduction of spironolactone (postspironolactone period). Statistical analysis included bivariate comparisons between patients with RHT and patients with RfHT and logistic regressions to assess the independent correlations of RfHT. A total of 146 patients (13.9%) remained refractory despite the use of at least five antihypertensives (prespironolactone period). After the introduction of spironolactone, the prevalence increased to 17.6%. For any criterion, RfHT patients were younger and more obese. In the initial period, current smoking and left ventricular hypertrophy were independently correlated with RfHT. Furthermore, after spironolactone use, RfHT patients had lower aortic stiffness and peripheral artery disease (PAD), pointing to a lower cardiovascular risk despite the lack of BP control. Younger age and lower prevalence of PAD correlated independently with RfHT. In conclusion, there was a high prevalence of RfHT, especially in younger and obese patients, and spironolactone use seemed to reduce cardiovascular risk despite the lack of BP control.

Resistant Hypertension: Novel Insights

Hypertension is the most common chronic disease and the leading risk factor for disability and premature deaths in the world, accounting for more than 9 million deaths annually. Resistant hypertension is a particularly severe form of hypertension. It was described 50 years ago and since then has been a very active field of research. This review aims at summarizing the most recent findings on resistant hypertension. The recent concepts of apparent- and true-resistant hypertension have stimulated a more precise definition of resistant hypertension taking into account not only the accuracy of blood pressure measurement and pharmacological class of prescribed drugs but also patient adherence to drugs and life-style recommendations. Recent epidemiological studies have reported a 10% prevalence of resistant hypertension among hypertensive subjects and demonstrated the high cardiovascular risk of these patients. In addition, these studies identified subgroups of patients with even higher morbidity and mortality risk, probably requiring a more aggressive medical management. In the meantime, guidelines provided more standardized clinical work-up to identify potentially reversible causes for resistant hypertension such as secondary hypertension. The debate is however still ongoing on which would be the optimal method(s) to screen for non-adherence to hypertension therapy, recognized as the major cause for (pseudo)-resistance to treatment. Recent randomized clinical trials have demonstrated the strong benefit of anti-aldosterone drugs (mostly spironolocatone) as fourth-line therapies in resistant hypertension whereas clinical trials with device-based therapies displayed contrasting results. New trials with improved devices and more carefully selected patients with resistant hypertension are ongoing.

Beyond Resistant Hypertension

Obstructive sleep apnea (OSA) is an independent cause of resistant hypertension (RH) but its association with refractory hypertension (RfH), a recently described form of severe hypertension, has not yet been investigated. This study seeks to analyze the association between the presence and severity of OSA/OSA syndrome with RfH and to compare it with a group of patients with OSA/OSA syndrome and RH. We conducted a multicenter, cross-sectional study of consecutive patients diagnosed with RH by means of 24-hour ambulatory blood pressure monitoring. Those patients with blood pressure levels ≥130/80 mm Hg, despite taking at least 5 antihypertensive drugs, were considered to have true RfH. All patients underwent a sleep study and completed a detailed clinical history related to OSA, current medication, and cardiovascular diseases. Overall, 229 patients were included (mean age, 58.3 years; 63% male), of whom 42 (18.3%) satisfied the criteria for RfH. Compared with those with RH, patients with RfH had a higher cardiovascular risk profile, higher blood pressure measurements, and a 2-fold greater risk of having both severe OSA (odds ratio, 2.1, with a prevalence of apnea-hypopnea index ≥15, 95.2% and apnea-hypopnea index ≥30, 64.3%) and OSA syndrome (apnea-hypopnea index ≥5+Epworth Sleepiness Scale >10; odds ratio, 1.9; 52.4% versus 37.3%; P=0.023), as well as higher OSA severity (apnea-hypopnea index, 41.8 versus 33.8 events/h; P=0.026). Patients with RfH had an even greater prevalence and severity of OSA and OSA syndrome than RH patients, highlighting the need to identify these patients to refer them to sleep units on a preferential basis.

Resistant and refractory hypertension: two sides of the same disease?

Refractory hypertension (RfH) is an extreme phenotype of resistant hypertension (RH), being considered an uncontrolled blood pressure besides the use of 5 or more antihypertensive medications, including a long-acting thiazide diuretic and a mineralocorticoid antagonist. RH is common, with 10-20% of the general hypertensives, and its associated with renin angiotensin aldosterone system hyperactivity and excess fluid retention. RfH comprises 5-8% of the RH and seems to be influenced by increased sympathetic activity. RH patients are older and more obese than general hypertensives. It is strongly associated with diabetes, obstructive sleep apnea, and hyperaldosteronism status. RfH is more frequent in women, younger patients and Afro-americans compared to RFs. Both are associated with increased albuminuria, left ventricular hypertrophy, chronic kidney diseases, stroke, and cardiovascular diseases. The magnitude of the white-coat effect seems to be higher among RH patients. Intensification of diuretic therapy is indicated in RH, while in RfH, therapy failure imposes new treatment alternatives such as the use of sympatholytic therapies. In conclusion, both RH and RfH constitute challenges in clinical practice and should be addressed as distinct clinical entities by trained professionals who are capable to identify comorbidities and provide specific, diversified, and individualized treatment.

Controlled Versus Uncontrolled Resistant Hypertension: Are They in the Same Bag?

PURPOSE OF REVIEW

Resistant hypertension (RHTN) is a condition in which besides the antihypertensive therapy using at least three different drugs (including a diuretics), brachial blood pressure does not reach the target (e.g., 140/90 mmHg).

RECENT FINDINGS

Despite the diversity of clinical presentations, we divide RHTN in two major groups according to blood pressure and number of drugs taken: controlled (C-RHTN) and uncontrolled (UC-RHTN) resistant hypertension, with refractory hypertension (RfHTN) included in the latter subgroup. Both C-RHTN and UC-RHTN are heterogenic and complex syndromes. To better approach this matter, the some pathophysiological mechanisms (increased volemia, hyperactivity, plasma cortisol, adipocitokines, and other pro-inflammatory factors), have a pivotal clinical role. Some features (African ethnic, obesity, age > 60, LV hypertrophy, and vascular stiffness) increase the risk of refractoriness as well as worst prognosis. Based on increased target organ damage, cardiovascular risk and events will be addressed in this review. Our conclusion is that although both C-RHTN and UC-RHTN are extreme phenotypes of hard-to-control BP, some mechanisms of the disease and clinical expressions are distinct. According to these differences, "UC-RHTN and C-RHTN are not in the same bag."

Managing resistant hypertension: focus on mineralocorticoid-receptor antagonists

Mineralocorticoid-receptor antagonists (MRAs) have proven to be effective in some types of hypertension, especially in resistant hypertension (RHTN). In this phenotype of hypertension, the renin-angiotensin-aldosterone pathway plays an important role, with MRAs being especially effective in reducing blood pressure. In this review, we show the relevance of aldosterone in RHTN, as well as some clinical characteristics of this condition and the main concepts involving its pathophysiology and cardiovascular damage. We analyzed the mechanisms of action and clinical effects of two current MRAs - spironolactone and eplerenone - both of which are useful in RHTN, with special attention to the former. RHTN represents a significant minority (10%-15%) of hypertension cases. However, primary-care physicians, cardiologists, nephrologists, neurologists, and geriatricians face this health problem on a daily basis. MRAs are likely one of the best pharmacological options in RHTN patients; however, they are still underused.

Refractory and resistant hypertension: characteristics and differences observed in a specialized clinic

Resistant hypertension (RH) is defined as uncontrolled blood pressure (BP) despite the use of ≥3 anti-hypertensive drugs, or controlled requiring use of ≥4 drugs. Recently, a new definition for an extreme phenotype of RH (uncontrolled BP using at least five drugs) has emerged-the refractory hypertension (RfH). Although characteristics of RH are well established, little is known about this newly described subgroup. For this work, 116 subjects with RH were enrolled from a specialized clinic and divided into RH (n = 80) and RfH (n = 36). Subjects were submitted to echocardiography, 24-hour ambulatory BP measurement and biochemical analyses. Logistic regression analysis demonstrated that: (1) white-coat effect (odds ratio [OR], 3.23; 95% confidence interval [CI], 1.12-9.27; P = .03), (2) black race (OR, 6.67; 95% CI, 1.99-16.16; P < .001), and (3) left ventricular mass index (OR, 1.02; 95% CI, 1.01-1.03; P = .04) were independent predictors of refractoriness. In conclusion, RfH and RH present different patient characteristics, and these phenotypic aspects can be useful for better understanding this harder-to-treat subgroup.