From the Guidelines
Angiotensin receptor blockers (ARBs) are a crucial component in the management of cardiomyopathy, particularly in patients with reduced ejection fraction, as they have been shown to reduce morbidity and mortality by blocking the harmful effects of angiotensin II on the heart 1.
Mechanism of Action
ARBs prevent angiotensin II from binding to its receptors, which reduces blood pressure, decreases afterload on the heart, and inhibits harmful cardiac remodeling. This mechanism helps improve cardiac function, reduce symptoms like shortness of breath and fatigue, and slow disease progression in patients with cardiomyopathy.
Dosage and Administration
Treatment with ARBs is typically started at a low dose and gradually increased to the target dose as tolerated, with regular monitoring of blood pressure, kidney function, and potassium levels. Commonly used ARBs include losartan, valsartan, and candesartan, with dosages ranging from 25-100 mg daily for losartan, 40-320 mg daily for valsartan, and 4-32 mg daily for candesartan 1.
Benefits and Side Effects
ARBs are particularly beneficial in patients with reduced ejection fraction and are often used when ACE inhibitors are not tolerated due to cough or angioedema. However, side effects may include hypotension, hyperkalemia, and worsening kidney function, especially in patients with pre-existing renal impairment.
Clinical Recommendations
The use of ARBs in cardiomyopathy is recommended to reduce morbidity and mortality, especially in patients with reduced ejection fraction, and should be considered as part of a comprehensive treatment plan that includes evidence-based beta blockers and aldosterone antagonists in selected patients 1.
From the FDA Drug Label
- 1 Mechanism of Action Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II)] is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system, and an important component in the pathophysiology of hypertension. Losartan and its principal active metabolite block the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor found in many tissues, (e.g., vascular smooth muscle, adrenal gland).
The mechanism of action of losartan in cardiomyopathy is through the blockage of angiotensin II at the AT1 receptor, which reduces the vasoconstrictor and aldosterone-secreting effects of angiotensin II. This can help to reduce the workload on the heart and improve cardiac function in patients with cardiomyopathy 2.
- Key points:
- Blockage of angiotensin II at the AT1 receptor
- Reduction of vasoconstrictor effects
- Reduction of aldosterone-secreting effects However, the provided text does not directly address how losartan works in cardiomyopathy.
From the Research
Angiotensin-Receptor Blockers (ARBs) in Cardiomyopathy
- ARBs are a class of medications used to treat heart failure with reduced ejection fraction (HFrEF) 3, 4, 5, 6
- They work by blocking the action of angiotensin II, a potent vasoconstrictor that can increase blood pressure and worsen heart failure symptoms
- ARBs have been shown to improve clinical outcomes in patients with HFrEF, including reducing mortality and hospitalization rates 3, 4, 5, 6
Combination Therapy with ARBs
- ARBs are often used in combination with other medications, such as angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and mineralocorticoid receptor antagonists (MRAs) 3, 4, 5, 6
- This combination therapy has been shown to be more effective than using any one medication alone in improving clinical outcomes in patients with HFrEF 3, 4, 5, 6
- The use of sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitor (ARNI), has also been shown to be beneficial in patients with HFrEF, particularly in those with chronic obstructive pulmonary disease (COPD) 4
Benefits and Risks of ARBs in Cardiomyopathy
- ARBs have been shown to reduce the risk of heart failure hospitalization and cardiovascular death in patients with HFrEF 3, 4, 5, 6
- However, ARBs may also increase the risk of hyperkalemia, particularly when used in combination with other medications that increase potassium levels 3, 4, 5, 6
- The benefits and risks of ARBs in cardiomyopathy should be carefully considered and individualized for each patient, taking into account their specific clinical characteristics and comorbidities 3, 4, 5, 6