CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 4, July/August 2011
AFRICA
173
care for further investigation and modification of therapeutic
strategy. Refractory hypertension is defined as poorly controlled
blood pressure in a patient receiving three or more antihyperten-
sive agents prescribed at optimal doses, one of which must be a
diuretic.
16
However, before diagnosing refractory hypertension,
it is important to exclude pseudo-resistance, which may emanate
from patient non-adherence to prescribed therapy, ‘white coat’
hypertension or inaccurate measurement of blood pressure,
among other factors.
Risk factors for refractory hypertension include presence of
left ventricular hypertrophy, older age, obesity, African race,
chronic kidney disease, diabetes mellitus and obstructive sleep
apnoea.
16
Table 2 summarises the important conditions that need
to be considered in the investigation of a patient with refractory
hypertension.
Compelling indications for treatment of
hypertension
In the report by Parker and colleagues,
6
knowledge of the compel-
ling indications for the management of hypertension was found
to be quite poor among the primary healthcare doctors studied.
The South African hypertension guidelines provide a rational
and evidence-based approach for the management of individuals
with hypertension.
17
In the presence of certain conditions, the
first-line recommended agents vary, as discussed below.
•
Angiotensin converting enzyme (ACE) inhibitors should be
first-line agents in the presence of heart failure, asymptomatic
left ventricular dysfunction, diabetes mellitus, coronary artery
disease and proteinuric kidney disease.
•
Angiotensin II receptor blockers (ARBs) have similar indica-
tions as ACE inhibitors, and may be preferable where there is
electrocardiographic evidence of left ventricular hypertrophy
or intolerance to ACE inhibitors.
•
Diuretics are the usual recommended first-line therapy in
the absence of compelling indications, and are useful agents
in the presence of volume overload. Chlorthalidone is the
preferred thiazide diuretic for essential hypertension, but is
not available in most African countries.
•
Calcium channel blockers (CCBs) have no absolute indica-
tions, but may be useful for rate control in atrial fibrillation
and in patients with angina pectoris. CCBs are preferable to
beta-blockers in those with obstructive airway disease.
•
Beta-blockers may be considered as first-line treatment
(but are usually given in combination with an ACE inhibi-
tor) after acute myocardial infarction, in stable patients with
heart failure, asymptomatic left ventricular dysfunction, for
rate control in atrial fibrillation, and for symptom control in
ischaemic heart disease. In the absence of these conditions,
beta-blockers should not be first line or given as monotherapy,
especially in patients older than 60 years, where they have
been associated with higher rates of stroke, coronary artery
disease and all cardiovascular events, compared to other anti-
hypertensives.
18
•
Alpha-blockers are not recommended as first-line agents or
as monotherapy because of the increased risk of heart failure
and increased cardiovascular events associated with their use.
Recommendations
Doctors should aim to treat all hypertensive patients to target, as
hypertension is a modifiable risk factor for CVD. It is the amount
of blood pressure reduction that determines the absolute reduc-
tion in cardiovascular risk and not the choice of antihypertensive
therapy. Hence, the aim should be to lower blood pressure at all
costs. The management strategy should take into account the
patient’s individual needs and preferences.
People with hypertension should have the opportunity to
make informed decisions about their care and treatment, as this
will likely increase their adherence to the prescribed medica-
tion. Good communication between healthcare professionals,
especially doctors, and patients is essential. Care of people with
hypertension needs to be supported by provision of evidence-
based information such as the South African hypertension
guidelines.
17
Lifestyle interventions need to be offered to all patients.
These include weight loss, smoking cessation, moderation of
alcohol intake, increased physical activity, reduced dietary intake
of salt, saturated fats and cholesterol, and adequate dietary intake
of potassium, calcium and magnesium. Each of these lifestyle
changes has been shown to reduce blood pressure and improve
overall well-being. However, there is no evidence for the routine
prescription of calcium, potassium and magnesium supplements
to aid the management of hypertension. Furthermore, excessive
TABLE 2. CONDITIONSASSOCIATEDWITH
REFRACTORY HYPERTENSION
1. Sub-optimal antihypertensive therapy
2. Extracellular volume expansion
3. Poor adherence to medical and dietary therapy
4. Secondary hypertension
5. Undiagnosed kidney disease
6. Primary aldosteronism
7. Ingestion of substances that elevate blood pressure (alcohol,
herbal remedies, oral contraceptive pill, anti-depressant medica-
tions, non-steroidal anti-inflammatories)
8. Office or ‘white coat’ hypertension
9. Lifestyle and diet (e.g. high salt intake)
10. Pseudohypertension
TABLE 1. RISK FACTORS FOR HYPERTENSION
Essential hypertension
Secondary hypertension
More common and more severe
in blacks, older people and
women
Primary renal disease
High salt intake
Renovascular disease
Hypertension in parents
Primary aldosteronism
Excess alcohol intake
Phaeochromocytoma
Obesity
Cushing’s syndrome
Physical inactivity
Pregnancy
Dyslipidaemia (independent of
obesity)
Sleep apnoea
Certain personality traits
(e.g. Type A personality)
Drugs (e.g. oral contraceptive
pill, non-steroidal anti-inflamma-
tory drugs)
High intake of fructose from
sweetened beverages
Other endocrinopathies (e.g.
hyperthyroidism, hypothyroidism,
hyperparathyroidism, acromegaly,
etc)
Multiple genetic polymorphisms Aortic coarctation
