hypertension ( htn ) is the most common comorbidity in the world with significant public health implications     [ 1 , 2 ] . the overall u.s . prevalence of hypertension among adults ages 18 years in 20052008 was 30.9% and was highest among persons ages 65 years ( 69.7% )   and non - hispanic blacks ( 44% )     . the american heart association estimates that the incurred costs of hypertension are more than $ 93.5  billion per year , and that cardiovascular disease and stroke for which htn is the predominant risk factor , account for 17% of the total annual health expenditures in the united states . hypertension and its sequelae , heart failure ( hf ) , are a progressive disease . evidence shows that less than half of patients with heart failure survive five years ( after diagnosis ) , and less than a quarter of them live ten years after their initial diagnosis . framingham heart study showed that hypertensive patients were more likely to develop heart failure ( 142 cases of hf detected during the first 16 years of followup ) than those who were normotensive . the lifetime risk for development of hf among people with blood pressure ( bp ) > 160/90  mm  hg is double that of those with bp < 140/90  mm  hg . heart failure in comparison to the most prevalent gender malignancies ( bowel cancer in men and breast cancer in women ) , was associated with worse long - term survival     . over a million hospitalizations , contributing to more than 250,000 deaths     , and escalating billions of dollars in health care expenditure is the norm . the disastrous duo , htn and hf , should be recognized , and a tailored focus on management in special populations , high - risk ethnic minority groups especially blacks who are disproportionately burdened should be developed .   among racial groups , african - american adults have the highest rates ( 44% ) of hypertension in the world      and are more resistant      to treatment . in particular , black women have the highest prevalence      and the lowest blood pressure control     . the relative incidence of hf is 50% higher in african americans , 3% of whom have hf , compared with 2% of the general population     [ 13 , 14 ] . the disease occurs at an earlier age , and usually at a more advanced stage   along with increased hospitalization   and mortality . other causes of hf include coronary artery disease , valvular heart disease , diabetes , left ventricular hypertrophy and cardiomyopathies . overt clinical hf resulting from diastolic left ventricular dysfunction may be clinically indistinguishable from that resulting from systolic dysfunction . hf with preserved left ventricular function is observed in 30% to 50% of adult cases of hf . coronary artery disease and myocardial infarction is a principal cause of systolic left ventricular dysfunction followed by hypertension . a variety of neurohormonal systems , especially the renin - angiotensin aldosterone and sympathetic nervous systems are activated in response to the left ventricular dysfunction and such activation leads to abnormal ventricular remodeling . the inexorable progression to more severe stages of left ventricular dysfunction can be significantly reduced by effective therapy with neurohormonal blockade including angiotensin converting enzyme inhibitors ( aceis ) , beta blockers ( bbs ) , and aldosterone antagonists     . current understanding of the pathophysiology of hf has revolved around neurohormonal activation     [ 19 , 20 ] . this endothelial dysfunction may result from insufficient nitric oxide ( no ) secondary to either reduced endothelial production of no or to increase no inactivation [ 17 , 19 , 21 ] . in hf , a pronounced increase in angiotensin ii , with modestly reduced no is seen among whites . however , african americans with hf may exhibit greater no reduction ; conversely , angiotensin ii might be less elevated among whites . important studies are investigating gene variation among the races that may influence the risk of developing hypertension and its complications , such as single nucleotide polymorphisms in the genes encoding for 1-adrenergic receptors and a2c - adrenergic receptors . african americans who are homozygous for polymorphisms in both the 1-adrenergic and a2c - adrenergic receptor genes are at a 10-fold greater risk for heart failure , which is overexpressed in african - americans . groups with overexpression of transforming growth factor -1 ( tgf-1 ) , a cytokine involved in cardiac fibrosis and remodeling , vascular and renal disease , production of the vasoconstrictor , endothelin-1 , and stimulation of renin release , have a worse prognosis . other genetic polymorphisms in african americans that may influence heart failure risk include elevated production of endothelial nitric oxide synthase , aldosterone synthase , and the g protein 825-t allele . there are two major approaches to classifying the patient 's hf stage or clinical severity . the most common is the new york heart association ( nyha ) classification , mainly based on functional capacity and subjective level of symptoms severity . this scheme is fluid and its class fluctuates in the same patient depending on their subjective assessment and clinical status . the other approach , adopted by the american college of cardiology / american heart association ( acc / aha ) guidelines , emphasizes disease progression .   classified as stages a , b , c , and d , each of these stages has definable characteristics and recommended interventions . to emphasize the progressive nature of hf and the need to prevent its development or progression to end - stage disease ( stage d )     [ 18 , 23 ] , current hf guidelines define patients in stage a as those at increased risk for hf without evidence of structural heart disease or symptoms of hf     . stage a represents a critically important group because many of the risk factors including hypertension can be effectively controlled and by doing so may prevent development of cardiovascular diseases including hf . patients are in stage b when they present with evidence of structural heart disease but without current or prior symptoms of hf . stage c is recognized by the presence of structural heart disease and current or prior symptoms of hf . stage d patients are those who have refractory heart failure requiring frequent hospitalization and specialized interventions . several studies have shown the efficacy of treatment of hypertension in preventing hf [ 2427 ] . treatment of hypertension reduces the incidence of hf by about 50% .   in recent years , significant advances have been made in increasing awareness , treatment , and control of blood pressure . several large , randomized clinical trials have shown that specific classes of medication have mortality benefit in patients with heart failure     [ 2834 ] . in the most recent guidelines      for the diagnosis and management of hf in adults , the american college of cardiology foundation ( accf)/american heart association ( aha ) recognized the need for specific recommendations for special population . lifestyle modifications have been shown to reduce blood pressure , increase drug efficacy , and decrease cardiovascular risk . long - term primary prevention of hypertension includes weight reduction in overweight / obese individuals . weight loss intervention was associated with a 21% reduction in the incidence of hypertension over a 36-month period     . dietary practices , reducing intake of dietary sodium to < 1.5  g nacl [ 3 , 36 ] , low potassium , magnesium , and saturated fat intake , increased calcium intake     , decreased consumption of alcohol , have demonstrated greater bp reduction in blacks . these practices are most successful when reinforced with comprehensive education and counseling     [ 39 , 40 ] . exercise training , regular aerobic physical activity for at least 30 minutes per day most days , has been shown to reduce recurrent cardiac events in patients with lv dysfunction from ischemic heart disease and is recommended under close medical supervision . culturally cognizant and sensitive modalities should be implemented to help guide improved compliance of therapeutic lifestyle changes ( tlc ) in special populations     [ 43 , 44 ] . despite lifestyle modifications , most patients with hypertension need pharmacologic therapy for better bp control . in the united states , pharmacological treatment of hypertension before development of structural heart disease or symptoms of hf is mainly based on studies looking at prevention of end - organ damage . specific classes of medication are recommended for patients in stages b - d that have shown benefit in reducing mortality and number of hospitalizations . the reader should refer to the major guidelines for full treatment recommendations of hf in the general population     [ 18 , 23 , 46 ] . .   however , ethnic minorities who are at greater risk for developing hf remain underrepresented in most clinical trials .   according to a recent paper by mitchell et al . treatment of hf in african americans  a call to action  , most of the available evidence is based on limited representation of african americans in these trials or posthoc analysis of limited evidence . these papers once again summarize the available evidence in hf management in african americans and call for more therapeutic trial focused in these high - risk population . the african american heart failure trial ( a - heft ) was the first heart failure large trial to focus specifically on the african - american population and evidence represented approximately 50% of all african americans ever studied in heart failure trials     . this is randomized placebo - controlled double blind study of fixed dose isosorbide dinitrate / hydralazine ( isbd / hyd ) ( figure 2 ) . in an effort to summarize efficacy of available treatments , psaty et al the database included 192,478 patients from 42 trials randomized to 7 treatment strategies including placebo . low - dose diuretics proved the most effective first - line treatment for preventing cardiovascular disease and mortality including hf . the allhat trial showed that diuretics are as effective as calcium channel blockers or acei in preventing cardiovascular disease outcomes including hf . the allhat study also has suggested that thiazide - diuretic therapy is useful in preventing disease progression     . although , allhat trials and other trials showed diuretics is the first - line of antihypertensive therapy and is still the most commonly prescribed antihypertensive medications , this is challenged by recent studies as published in february jacc and presented in the european society of htn meetings . however , the diuretics used in the allhat trials was chlorthalidone a long acting thiazide ( shown to effectively lower bp and improve survival ) , not really the same as hydrochlorothiazide ( hctz ) which is the most commonly prescribed antihypertensive thiazide at a dose of 12.525  mg . ( st luke roosevelt hospital , new york , ny ) , published the analysis of 18 trials on   hctz where the antihypertensive effect of hctz at the dose that is most often used12.5 to 25  mg a day  is consistently inferior to that of most other antihypertensive drug . the other limitation of diuretics as first line therapy in african americans is not only not adequate but also , has multiple side effects like dm , electrolyte abnormalities and urecemia , to mention a few . however , there is still a role of diuretics in combination with neurohormonal ( renin angiotensin aldosterone axis ) blockade and when there is compelling indication .   according to the recent consensus statement of the international society on hypertension in blacks ( ishb ) , chlorthalidone furthermore , the ishb consensus statement reinforces , patient above goal bp ( sbp / dbp15/10 ) with ( goal bp < 130/80 ) end organ damage ( hf , lvh , kidney disease ) or without end organ damage ( goal bp < 135/85 ) should be on at least on combination pharmacotherapy . use of beta blockers ( bb ) as treatment for hypertension has come under scrutiny . conducted a meta - analysis of 13 trials , which included 105,951 patients showing that atenolol did not improve outcomes in terms of stroke and cardiovascular events . in stage b chf ( nyha class i ) , defined by the presence of reduced left ventricular ejection fraction ( lvef ) < 40 percent in otherwise asymptomatic individuals , aceis and bbs are recommended . iii ) manifest left ventricular dysfunction and overt symptoms ; in these individuals , aceis and bbs are also indicated . bbs are also recommended in hf because of clinical studies demonstrating decreased morbidity and mortality , and improvement in hf symptoms . aldosterone antagonists may provide additional benefit in patients with severe left ventricular dysfunction , usually late stage c ( nyha class iii low - dose spironolactone ( 12.525  mg daily ) , when added to standard therapy , decreased mortality by 34 percent     . in the eplerenone postacute myocardial infarction heart failure efficacy and survival study ( ephesus ) , eplerenone reduced mortality by 15% in patients following a recent mi with lvef < 40% , 90% of whom had hf symptoms     . patients were excluded who had a serum creatinine of < 2.5  mg / dl and hyperkalemia . the v - heft i and ii are a large - scale trial that compared different vasodilators with placebo and among themselves . v - heft i showed , the mortality rate was significantly lower for the total cohort ( african americans and whites ) in isdn / hyd arm compared to patients treated with prazosin or placebo added to digitalis and diuretics ( figure 1 )     .    in v - heft ii , though isbd / hyd was statistically inferior to enalapril in effect on mortality , patients taking isbd / hyd experienced similar mortality rate in   patients taking isbd / hyd in   v - heft - ii   as those in v - heft - i taking isbd / hyd . posthoc analysis of v - heft i showed isbd / hyd significantly reduced mortality in african american patients but not in white patients . the reanalysis of v - heft ii , demonstrated the annual mortality rate african american ( 12.9 ) patients receiving isbd / hyd was 12.9% compared with 12.8% for african americans receiving enalapril . due to difference in outcomes in african americans in v - heft , the african american heart failure trial ( a - heft ) definitive study was designed . the a - heft was terminated earlier than anticipated completion date due to a significant ( 43% ) reduction in mortality in patients receiving combination ( isdn / hyd ) compared to the placebo arm .    adding the combination of a fixed - dose of isdn / hyd ( 20  mg/37.5  mg ) to a standard medical regimen for hf , including acei and bbs , is recommended in order to improve outcomes for patients self - described as african americans , with nyha functional class iii or iv chf     . furthermore , genomic evidence from the grahf ( genetic risk assessment of heart failure in african americans ) arm of the african american heart failure trial ( a - heft ) showed that blacks with the more common tt phenotype ( 61% ) of the aldosterone synthase gene ( cyp11b2 ) showed greater responsiveness to the combination of isosorbide dinitrate and hydralazine     . the vast majority of blacks will have no identified cause for their htn     . past studies elucidating the pathophysiological mechanisms have shown conflicting information and further investigations exploring the complex relationships and interactions are warranted     . there are , however , several secondary forms of htn in blacks that are prominent and preventable . we will focus on the most common , preventable and treatable secondary form of hypertension ,   obstructive sleep apnea ( osa ) . the prevalence of osa in hypertensive populations is estimated to range between ( 3040% )   and in heart failure at 53% ; apnea - hypopnea index ( ahi ) 10/h )     . it is an independent risk factor for htn , nondipping of blood pressure and increased bp variability   and follows a dose - dependent relationship . a prospective study showed that the odds of developing hypertension over 48 years was 2.89 times more likely for participants who had ahi  15/h compared to ahi  0 , independent of known confounders . cross - sectional data has shown 2.38-times increased likelihood of having heart failure in association with osa , independent of confounders ( n = 6424 ) [ 67 , 68 ] . osa has been shown to act through various mechanisms , independent of blood pressure , in promoting left - ventricular ( lv ) hypertrophy , diastolic     , and systolic      dysfunction , and overt heart failure . these mechanisms include the hemodynamic consequences of repetitive increases in left - ventricular transmutable wall pressure and over time impaired vigil heart rate modulation leading to lv hypertrophy and ventricular remodeling . additionally , osa patients without overt heart failure have more impaired diastolic relaxation than those without osa . emerging evidence illustrates patients with osa have more active atherosclerotic disease with a greater degree of vessel involvement and more vulnerable plaques than do patients without the disease , resulting in greater cardiovascular burden . the definite treatment for osa , long - term adherence to continuous positive airway pressure ( cpap ) therapy , has shown to suppress sympathetic activity     , lower blood pressure , reduce right ventricular volume     , and improve systolic function in patients with hf     . systematic reviews , meta - analyses , and randomized controlled trials have shown statistically significant net reduction in blood pressure with cpap , especially in patients with increased ahi events     [ 7883 ] . a recent 3-year study ( n = 340 ) by durn - cantolla et al . reported that participants assigned to cpap therapy for 3 months had mean 24-hour ambulatory blood pressure decreased by 2.1  mmhg ( 0.4 to 3.7 ) mmhg ( p = .01 ) for systolic and 1.3 ( 0.2 to 2.3 ) mm  hg ( p = .02 ) for diastolic blood pressures     . similar evidence from randomized trials showed up to 9% increase in lvef      and increased quality of life ( qol ) and functional capacity among patients treated with 13 months of cpap therapy     . furthermore , among patients with no overt failure , cpap therapy has been shown to reverse impaired diastolic relaxation . there is a need for further randomized clinical trials with cpap therapy among high - risk ethnic minorities especially blacks to assess whether treatment of osa has similar long - term effects and to evaluate the effect on htn and hf morbidity and mortality . taking into consideration , lifestyle and pharmaceutical interventions , our changing health care community needs to emphasize the essential nature of the patient - provider relationship and establish trust and collaboration . in the past , this has been accomplished through physician , patients , family member , and other caretaker awareness , increased education of both provider and patients , and establishment of community outreach programs . these measures have contributed to an increase in compliance and a reduction in the risk of hospitalizations [ 23 , 87 ] . we recommend an additional emphasis on the implementation of specialty care in patients with heart failure in collaboration with the primary care provider . the dramatic improvement in the management of hf and hypertension over the last 50 years has allowed us to start to target specific populations and provide more evidence - based treatment that will lead to an improvement in mortality . there are disparities in the prevalence , treatment , and control of hypertension and the incidence and morbidity and mortality of heart failure between blacks , a diverse and heterogeneous population , and whites . the management team needs to take into consideration new evidence and develop tailored strategies for effective treatment , especially for hypertension , one of the main causes of hf and many other cardiovascular complications in african africans .
hypertension ( htn ) is the most common co - morbidity in the world , and its sequelae , heart failure ( hf ) is one of most common causes of mortality and morbidity in the world . 
 current understanding of pathophysiology and management of htn in hf is mainly based on studies , which have mainly included whites . among racial groups , 
 african - american adults have the highest rates ( 44% ) of hypertension in the world and are more resistant to treatment . 
 there is an emerging consensus on the significance of racial disparities in the pathophysiology and treatment options of hypertension and heart failure . 
 however , african americans had been underrepresented in all the trials until the initiation of the a - heft trial . since the recognition of obstructive sleep apnea ( osa ) as an important medical condition , 
 large clinical trials have shown benefits of osa treatment among patients with htn and hf . 
 this paper focuses on the pathophysiology , causes of secondary hypertension , and treatment of hypertension among african - american patients with heart failure . 
 there is increasing need for randomized clinical trials testing innovative treatment options for african - american patients .