Why are beta‑blockers contraindicated in patients with severe aortic stenosis?

Why Beta-Blockers Are NOT Absolutely Contraindicated in Severe Aortic Stenosis

Beta-blockers are not contraindicated in severe aortic stenosis—this is an outdated teaching that has been replaced by evidence showing they are safe and even beneficial when specific indications exist, such as heart failure with reduced ejection fraction, post-myocardial infarction, arrhythmias, or angina. 1, 2

The Historical Misconception

The traditional teaching that beta-blockers are contraindicated in severe AS stems from theoretical concerns about:

• Negative inotropic effects potentially worsening cardiac output in a fixed-obstruction state 3
• Bradycardia reducing cardiac output when stroke volume cannot increase due to outflow obstruction 3

However, these theoretical concerns have not been supported by clinical evidence. 3

When Beta-Blockers ARE Appropriate in Severe AS

Beta-blockers should be used in severe AS when compelling indications exist: 1, 2

• Heart failure with reduced ejection fraction - provides mortality benefit even with severe AS 1, 2
• Post-myocardial infarction - continue standard post-MI therapy despite AS 1, 2
• Arrhythmias requiring rate control - appropriate for rhythm management 1, 2
• Angina pectoris - reduces myocardial oxygen consumption and valve gradients 1, 2

Supporting Evidence for Safety

The SEAS study demonstrated impressive outcomes in patients with severe AS already on beta-blockers: 1, 2

• 50% reduction in all-cause mortality (HR 0.5,95% CI 0.3-0.7)
• 23% reduction in cardiovascular events

Additionally, metoprolol has been shown to reduce valve gradients and myocardial oxygen consumption in moderate-severe AS. 1, 2

When to AVOID Beta-Blockers in Valvular Disease

The actual contraindication is for chronic aortic regurgitation/insufficiency, NOT aortic stenosis: 4, 1, 5

• Beta-blockers slow heart rate, which increases diastolic filling time 1, 5
• Longer diastole allows more time for regurgitant flow back into the left ventricle 1, 5
• This worsens the volume overload in aortic regurgitation 4, 1

In patients with both severe AS and moderate AR, avoid beta-blockers unless compelling indications (HFrEF, post-MI, life-threatening arrhythmias) are present. 5

Preferred First-Line Agents for Hypertension in Severe AS

When treating hypertension in severe AS without compelling indications for beta-blockers, use RAS inhibitors (ACE inhibitors or ARBs) as first-line therapy: 4, 1, 2

RAS inhibitors provide multiple benefits: 4, 1, 2

• Beneficial effects on LV fibrosis reduction
• Superior blood pressure control
• Reduction in dyspnea
• Improved effort tolerance

Treatment Algorithm for Severe AS

1. Assess for compelling indications: 1, 2

   • HFrEF, recent MI, arrhythmias, or angina → beta-blockers are appropriate

2. If no compelling indications exist: 1, 5, 2

   • Check for concurrent aortic regurgitation
   • If moderate or greater AR present → avoid beta-blockers
   • Use RAS inhibitors instead

3. Start low and titrate slowly: 4

   • Begin antihypertensive therapy at low doses
   • Gradually titrate upward as needed

4. Target blood pressure: 6

   • Aim for 130-139 mmHg systolic and 70-90 mmHg diastolic
   • Avoid lower BP targets

5. Cardiology co-management: 4, 5

   • Mandatory consultation for moderate-to-severe AS with hypertension

Critical Pitfalls to Avoid

• Don't withhold beta-blockers in severe AS with HFrEF - the mortality benefit outweighs theoretical concerns 1, 2
• Don't confuse AS with AR - beta-blockers are problematic in AR, not AS 4, 1, 5
• Use diuretics sparingly in patients with small LV chamber dimensions and LV hypertrophy 4, 2
• Recognize the "2 resistors in series" problem - hypertension plus AS increases complications significantly 4, 2