What are the contraindications of Angiotensin Receptor Blockers (ARBs) and beta blockers?

Contraindications of ARBs and Beta Blockers

Both ARBs and beta blockers have specific contraindications that must be considered before prescribing, with angioedema being an important contraindication for ARBs and severe bradycardia, heart block, and active bronchospasm being key contraindications for beta blockers. 1

ARB Contraindications

Absolute Contraindications:

• Pregnancy: ARBs are contraindicated in pregnancy (Class C/D) due to fetal toxicity 2
• Known hypersensitivity to ARBs 2
• Co-administration with aliskiren in diabetic patients 2
• Bilateral renal artery stenosis: Can cause rapid decline in renal function 1
• History of angioedema with ACE inhibitors: While ARBs may be considered as alternatives in patients with ACE inhibitor-induced cough, caution is advised when substituting an ARB in patients who have experienced angioedema with ACE inhibitors, as some patients have also developed angioedema with ARBs 1

Relative Contraindications/Use with Caution:

• Hypotension: Systolic blood pressure <80 mmHg 1, 2
• Renal insufficiency: Monitor renal function closely 2
• Hyperkalemia: Monitor potassium levels regularly 1, 3
• Volume depletion: Correct before initiating therapy 2
• Combination with ACE inhibitors and aldosterone antagonists: Potentially harmful due to increased risk of hypotension, renal dysfunction, and hyperkalemia 1

Beta Blocker Contraindications

Absolute Contraindications:

• Severe bradycardia: Heart rate too low to support adequate cardiac output 1, 4
• Second or third-degree heart block without a pacemaker 1, 4
• Sick sinus syndrome without a pacemaker 4
• Cardiogenic shock 1
• Decompensated heart failure requiring inotropic support 1
• Active bronchospasm: Particularly in patients with severe asthma requiring airway support 1, 4

Relative Contraindications/Use with Caution:

• Risk factors for shock: Age >70 years, heart rate >110 beats per minute, systolic BP <120 mmHg, and late presentation 1
• Severe COPD: Particularly with FEV1 <50% of predicted value 5
• Asthma: History of asthma, especially if requiring chronic bronchodilator treatment 5
• Vasospastic disorders: Including Raynaud's phenomenon and Prinzmetal's angina 5, 4
• Severe peripheral arterial disease with rest pain or non-healing lesions 5
• Severe left ventricular dysfunction without established treatment plan 4
• Uncontrolled diabetes with frequent hypoglycemic episodes 5

Special Considerations

For ARBs:

• When switching from ACE inhibitors to ARBs due to cough, no washout period is required 2
• Monitor blood pressure, renal function, and potassium within 1-2 weeks after initiation 1, 2
• Particular caution in patients with diabetes mellitus and impaired renal function 1
• Avoid combination with ACE inhibitors due to increased risk of adverse effects without additional benefits 1, 2

For Beta Blockers:

• Start at low doses and titrate slowly in elderly patients and those with COPD 6
• Monitor lung function during initiation in patients with respiratory conditions 6
• Cardioselective beta blockers (bisoprolol, metoprolol) are preferred in patients with mild to moderate COPD or diabetes 1, 5
• In heart failure, use only evidence-based beta blockers (carvedilol, bisoprolol, metoprolol succinate) 1
• Temporary withholding may be necessary during acute decompensated heart failure 1

Monitoring Recommendations

1. For ARBs:

   • Blood pressure (including postural changes)
   • Renal function (serum creatinine, eGFR)
   • Serum potassium
   • Signs of angioedema

2. For Beta Blockers:

   • Heart rate and blood pressure
   • Signs of heart failure exacerbation
   • Respiratory function in patients with pulmonary disease
   • Blood glucose in diabetic patients

Remember that many traditional contraindications to beta blockers (such as stable COPD, diabetes, and mild peripheral vascular disease) have been reconsidered, and the benefits often outweigh the risks in secondary prevention after myocardial infarction 6, 4. Similarly, while caution is needed with ARBs in certain populations, their benefits in heart failure, hypertension, and diabetic nephropathy are substantial when used appropriately.