At what pulse rate should atenolol be held—55 beats per minute or 50 beats per minute?

Hold Atenolol at Heart Rate Below 50 BPM

Based on FDA labeling and major cardiovascular guidelines, atenolol should be held when the heart rate consistently falls below 50 beats per minute, not 55 bpm. 1

Evidence-Based Threshold

The FDA-approved prescribing information for atenolol explicitly states that in the acute myocardial infarction setting, IV atenolol should be held if the patient's heart rate drops below 50 bpm 1. This same threshold applies to oral maintenance therapy across all indications.

Key Hold Parameters from FDA Label:

• Heart rate < 50 bpm: Hold medication 1
• Systolic blood pressure < 100 mmHg: Hold medication 1
• Heart rate 45-49 bpm: Delay administration by 12 hours 1
• Heart rate < 45 bpm consistently: Hold medication 1

Clinical Context

While the 50 bpm threshold is the standard hold parameter, clinical judgment requires consideration of:

Symptomatic bradycardia at any heart rate warrants holding the medication, even if above 50 bpm. Symptoms include:

• Dizziness or lightheadedness
• Syncope or near-syncope
• Fatigue or weakness
• Chest pain
• Confusion

The 55 bpm threshold you may have encountered likely represents an institutional protocol that builds in a safety margin, which is reasonable but not evidence-based from guidelines or FDA labeling.

Guideline Support

The 2010 AHA ACLS guidelines list bradycardia and hypotension as known side effects of beta-blockers including atenolol, but do not specify exact hold parameters 2. The 2009 ACCF/AHA perioperative beta blockade guidelines used a hold threshold of heart rate < 50 bpm in their protocols 3.

Common Pitfall

Do not confuse target heart rate with hold parameters. Guidelines recommend:

• Target resting heart rate for rate control in atrial fibrillation: < 110 bpm (lenient) or < 80 bpm (strict) 4, 5
• Target heart rate for acute MI: 60-65 bpm 3
• Hold parameter: < 50 bpm 1

These are different clinical endpoints serving different purposes.

Practical Algorithm

1. Check heart rate before each dose
2. If HR ≥ 50 bpm and SBP ≥ 100 mmHg: Give atenolol as prescribed
3. If HR 45-49 bpm: Delay dose by 12 hours, reassess
4. If HR < 45 bpm or < 50 bpm consistently: Hold dose, notify prescriber
5. If symptomatic bradycardia at any HR: Hold dose, evaluate patient immediately

The answer is 50 bpm, not 55 bpm.