The main goal of therapy in heart failure is to treat the
underlying cause of the left ventricular dysfunction and remove
all the precipitating factors, thus improving the quality
of life and length of survival. This means that therapy should
be targeted towards relief of both pulmonary and systemic
congestion in the short term, and slowing of the progression
and potentially reversing the course of left ventricular dysfunction
and prolonging survival in the long term. These can both be
targeted with the use of either non-pharmacological or pharmacological
approaches.
Initially, attention should be directed at reducing the standard
coronary risk factors. This is particularly important in people
with diabetes when aiming to prevent the development of heart
disease as well as preventing the progression of heart disease
to heart failure.
Steps to minimise the risks include:
• stopping smoking.
• losing weight (where necessary).
• limiting alcohol consumption.
• dietary changes.
• exercising.
• lowering cholesterol levels.
• lowering blood pressure.
Recommendations for cholesterol levels can be seen in the
Viewpoint on Revascularisation procedures in coronary heart
disease.
Pharmacological
options
Even when patients successfully control their lifestyle risk
factors for heart failure, most will still need medication
and many receive two or more drugs. The pharmacological agents
available for the treatment of heart failure are outlined
below.
| 1. |
ACE inhibitors
ACE inhibitors inhibit the conversion of angiotensin I
to angiotensin II and are used in the treatment of hypertension,
heart failure and diabetic nephropathy. The SOLVD, CONSENSUS,
and VHEFT II trials all demonstrated improved survival
in people with heart failure with the use of ACE inhibitors
[Cohn et al, 1986;
Cohn et al, 1991; Pfeffer et al, 1992; The CONSENSUS Trial
Study Group, 1987; The SOLVD Investigators, 1992].
Both the HOPE and TRACE studies demonstrated the beneficial
effects of ACE inhibitors and found that these were more
profound in people with diabetes when compared with those
without diabetes
[Gustafsson et al, 1999; Heart Outcomes Prevention Evaluation
Study Investigators, 2000; Yusuf et al, 2000]. These
findings imply that ACE inhibitors have anti-ischemic
and anti-remodelling effects that appear to be interrelated
[Lavine and Gellman,
2002].
However, ACE inhibitors may not be effective in all patients.
Initiation of ACE inhibitor treatment is contraindicated
in bilateral renal artery stenosis and angioedema during
previous ACE inhibitor therapy [Remme
and Swedberg, 2001]. These agents are excreted by
the kidneys and may accumulate in people with renal insufficiency.
In addition to this, ACE inhibitors also inhibit bradykinin
degradation, which may be responsible for the cough sometimes
seen with their use [Lavine
and Gellman, 2002].
ACE inhibitors are currently the only pharmacological
agents that have been demonstrated to halt the transition
from left ventricular dysfunction to heart failure. However,
the dosages used are often too low and care should be
taken to ensure the maximum effect is achieved [Lavine
and Gellman, 2002].
|
| 2. |
Diuretics
Diuretics promote the excretion of urine. Loop diuretics
are the main class of diuretics used in heart failure.
By blocking ion transport in the loop of Henle, they help
avoid volume overload. However, they can cause potassium
depletion, prerenal azotemia and other electrolyte disorders,
which can become more acute in the setting of renal insufficiency,
as can be seen in some people with diabetes [Lavine
and Gellman, 2002]. If hyperkalaemia persists, the
patient may be switched to potassium-sparing diuretics
[Remme and Swedberg,
2001].
Care should be taken to ensure diuretics are used appropriately
as overuse may produce fatigue and electrolyte imbalance,
and underuse can cause congestion [Lavine
and Gellman, 2002].
|
| 3. |
Beta-blockers
Beta-blockers were initially contraindicated in people
with heart failure but now have an important role in symptomatic
relief and survival benefits. Beta-blockers have demonstrated
improvements in ejection fraction, reductions in risk
of heart transplant and mortality [Heidenreich
et al, 1997; Lechat et al, 1998; Merit-HF Study Group,
1999; The International Steering Committee, 1997; Waagstein
et al, 1993]. Results from the MOCHA trial suggested
that higher doses are more advantageous [Cohn
et al, 1997; Merit-HF Study Group, 1999; Zuanetti, 2000].
However, the general rule is to start at very low doses
and uptitrate to the wanted effect. If the patient experiences
side effects, efforts should be made not to discontinue
beta-blocker therapy, as their proven efficacy is sizeable
[Cohn et al, 1997].
It has also been suggested that the effects of this therapy
may be even greater in people with diabetes [Lavine
and Gellman, 2002].
|
| 4. |
Inotropic agents
Inotropic agents, including digoxin, increase the force
of contraction of cardiac muscle. Although digoxin has
been used for over 30 years, its efficacy has only recently
been established. Digoxin exerts its effects on the force
of contraction by increasing the availability of myocardial
calcium, increasing ejection fraction, reducing symptoms,
improving exercise capacity and decreasing the number
of hospitalisations [Garg,
1996; Packer et al, 1993]. Its effect on mortality
is neutral, but it does appear to work across the severity
spectrum, including patients with diabetes [Garg,
1996].
|
| 5. |
Vasodilators
The use of vasodilators, such as nitrates, has now been
superceded by the use of ACE inhibitors. However, the
use of hydralazine has demonstrated efficacy in improving
survival, increasing ejection fraction and reducing symptoms,
even if its effects are not as salutary as ACE inhibitors
[Cohn et al, 1986;
Cohn et al, 1991]. For this reason, isosorbide dinitrate
and hydralazine are often recommended for those patients
who are unable to tolerate ACE inhibitors. It must also
be remembered that the use of nitrates alone may assist
with symptoms of pulmonary congestion and angina in patients
with left ventricular dysfunction and coronary artery
disease [Lavine and
Gellman, 2002].
|
| 6. |
Angiotensin II receptor antagonists
Angiotensin II receptor antagonists have a similar
effect to ACE inhibitors but do not have as many associated
renal problems [Cody
et al, 1988; Textor, 1997]. However, those patients
who are intolerant to ACE inhibitors may also be intolerant
of this therapy [Lavine
and Gellman, 2002].
Recently, the angiotensin II inhibitor losartan has been
shown to increase parasympathetic activity in the heart.
This implies that angiotensin II inhibitors could slow
the progression of autonomic dysfunction, which is associated
with increased mortality [Maser
and Lenhard, 2002]. However, more research is needed
in this area.
|
| 7. |
Aldosterone antagonists
Aldosterone antagonists reduce mortality and
hospitalisation when used in addition to maintenance therapy
(digoxin, diuretic and ACE inhibitor) [Pitt
et al, 1999].
|
| 8. |
Calcium channel antagonists
Calcium channel antagonists are rarely used as a main
therapy for heart failure but some may be useful in the
therapy of hypertension in people with heart failure [Lavine
and Gellman, 2002].
|
Non-pharmacological
options
| 1. |
Sodium intake
Controlling sodium intake is more important in the management
of advanced heart failure than in mild heart failure [Remme
and Swedberg, 2001]. Sodium restriction assists with
fluid volume control and minimizes the dosage of heart
failure drugs used [McConaghy
and Smith, 2002]. However, salt substitutes should
be used with caution, as they may contain potassium. In
large quantities, in combination with an ACE inhibitor,
they may lead to hyperkalaemia [Good
et al, 1995].
|
| 2. |
Exercise training
Patients with stable heart failure should be encouraged
to carry out daily physical and leisure time activities
that do not induce symptoms [McConaghy
and Smith, 2002; Remme and Swedberg, 2001]. Moderate
exercise can prevent muscle de-conditioning and improve
quality of life [Tokmakova
et al, 1999]. However, strenuous or isometric exercises
should be discouraged and work tasks assessed for suitability
[Remme and Swedberg,
2001].
|
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