Are beta blockers a good choice for lowering blood pressure in black people?

According to the 2017 hypertension guidelines by the American College of Cardiology (ACC) and American Heart Association (AHA), beta blockers are not recommended as a first-line therapy for adults with hypertension.¹ These recommendations also apply to black hypertensive patients.² The Joint National Committee’s report on high blood pressure treatment also notes that monotherapy with beta blockers, as well as monotherapy with angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs), is less effective in lowering blood pressure in black patients than in white patients.³ Initial treatment with thiazide-type diuretics or calcium channel blockers is recommended for black patients with hypertension who do not have heart failure or chronic kidney disease.²

Black people, compared to white people, have a higher prevalence of hypertension, which is one of the major cardiovascular disease (CVD) risk factors.⁴ CVD is the leading cause of death for blacks, and intensive blood pressure control is extremely important in this population. Hypertension among black adults in the United States is often characterized by low cardiac output and high peripheral vascular resistance.⁵ Given this, certain types of beta blockers are more effective than others in this population. There are three subclasses of beta blockers (non-selective, beta-1-selective, and beta-1-alpha-selective) and each are different in how they affect the three adrenergic receptors (beta-1, beta-2, and alpha).^6,7

Non-vasodilating beta blockers lower blood pressure by reducing cardiac output,⁸ and clinical trials show that they are not as effective in black hypertensive patients as they are in white patients.^9,10 The Veterans Administration Cooperative study conducted a series of trials on different beta blockers.^11,12 When one study compared the effects of the beta blocker propranolol and the thiazide diuretic hydrochlorothiazide (HCTZ) in 683 hypertensive black and white patients,¹² 61.7% of whites, compared to 53.3% of blacks, achieved goal blood pressure on propranolol. There were no significant differences between the HCTZ and propranolol treatment in whites (55.3% vs. 61.7%). However, there was a statistically significant difference found in blacks on HCTZ and propranolol treatment (71.3% vs. 53.5%, p<0.001). In a smaller trial of 365 men, nadolol monotherapy was compared to combined therapy with a diuretic.^11,13 The study found that 77% of white and 31% of black patients responded to nadolol, whereas 46% of both white and black patients responded to diuretics. Another trial studied various antihypertensive medications (HCTZ, atenolol, clonidine, ACEI, and prazosin) in 140 hypertensive patients.¹⁴ The study found no statistical difference according to race with regards to mean changes in blood pressure from baseline to end of treatment phase. However, there were significant differences between drugs according to race and age. Younger whites responded best to captopril, atenolol, or clonidine, younger blacks to diltiazem, older whites to atenolol, diltiazem, captopril, clonidine, HCTZ, or prazosin, and older blacks to diltiazem or HCTZ. When atenolol was compared to placebo, the average reduction of diastolic/systolic blood pressure in older whites was 13 ± 6/12 ± 14 mm Hg and 6 ± 7/3 ± 10 mm Hg, respectively, and in older blacks was 11 ± 5/9 ± 11 mm Hg and 5 ± 7/3 ± 11 mm Hg, respectively. When compared to placebo, response to atenolol in older white patients was greater than 15% while it was less than 15% in older black patients.

In contrast to non-vasodilating beta blockers, vasodilating beta blockers, such as labetalol, nebivolol, and carvedilol, lower blood pressure by reducing vascular resistance while not affecting cardiac output.⁸ They are found to be equally effective in both blacks and whites.⁹ A study compared labetalol and propranolol monotherapies in 65 black and 75 white patients with mild-to-moderate hypertension.¹⁵ Labetalol was significantly more effective than propranolol in black patients in reducing standing systolic (p<0.02) and diastolic blood pressure (p<0.001). Propranolol was significantly more effective in white than in black patients (p<0.05), whereas labetalol was equally effective in both populations. Another study involving only black patients, comparing nebivolol to placebo, found that nebivolol significantly reduced mean sitting diastolic blood pressure at doses ≥5 mg (p<0.004) and systolic (p<0.044) blood pressure at doses ≥10 mg when compared to the placebo.⁵ In the US Carvedilol Heart Failure Trials, carvedilol showed benefits in 217 black and 877 nonblack patients with heart failure.¹⁶ For all measures of outcome (e.g., risk of all-cause death, risk of hospitalization, or risk of worsening heart failure), carvedilol showed more favorable outcomes when compared to placebo (p<0.05), and found no significant interaction between race and treatment (p>0.05). Analysis of the Carvedilol Heart Failure Registry found that in both black and white patients, carvedilol improved symptoms (33% vs. 28%, respectively) and reduced heart failure hospitalization rates (-58% vs. -56%, both p<0.001), with no significant differences between the races.¹⁷ Blacks and whites also had similar incidence and hazard ratio of death (6.9% vs. 7.5%, hazard ratio 1.2 vs. 1.0, p=0.276).

^References

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