What are the recommended doses of metoprolol and ivabradine (Corlanor) to administer before coronary computed tomography angiography to achieve a target heart rate of ≤60 bpm?

Heart Rate Control for Coronary CT Angiography

For coronary CT angiography, administer oral metoprolol 100 mg 60-90 minutes before the scan, followed by intravenous metoprolol 5 mg boluses every 5 minutes (maximum 15 mg total) if heart rate remains >60 bpm at scan time. 1, 2

Target Heart Rate and Rationale

• The target heart rate is ≤60 bpm to minimize motion artifacts and optimize image quality 1, 2
• For scanners with temporal resolution of 250 ms, heart rate of 60 bpm is essential to minimize coronary motion artifacts 1
• For scanners with temporal resolution of at least 167 ms, heart rate up to 75 bpm produces acceptable image quality 1
• Dual-source CT scanners can achieve acceptable image quality at heart rates up to 90 bpm, potentially eliminating the need for pharmacological heart rate control 1

Metoprolol Dosing Protocol

Oral Administration (Primary Strategy)

• Metoprolol 100 mg orally 60 minutes before scanning is the standard approach 2
• This achieves heart rate ≤65 bpm in 83% of patients and ≤60 bpm in 65% of patients 2
• Alternative timing: Long-acting beta-blocker (bisoprolol or atenolol) administered at bedtime the night before scanning significantly reduces heart rate upon arrival and at scan time 3

Intravenous Administration (Supplemental)

• If heart rate remains >60 bpm after oral dosing, give metoprolol 5 mg IV bolus over 1-2 minutes 1, 4, 2
• Repeat 5 mg IV boluses every 5 minutes as needed, maximum total IV dose 15 mg 1, 4, 2
• The median effective IV dose is 20 mg when used as sole agent, though this exceeds the 15 mg maximum recommended for acute cardiac conditions 5
• Target heart rate <65 bpm is achieved successfully in 98.1% of patients with IV metoprolol titration 5

Ivabradine (Corlanor) Considerations

Ivabradine is not mentioned in any coronary CT angiography guidelines or protocols. The provided evidence does not support its use for heart rate control before coronary CT. Beta-blockers remain the standard of care because they:

• Prolong diastolic rest period when coronary artery velocity is lowest 1
• Have established safety profiles in this setting 2, 5
• Achieve target heart rate in the vast majority of patients 2, 5

Critical Contraindications to Verify Before Administration

• Hypotension or systolic blood pressure <100-120 mmHg 4, 6
• Second or third-degree AV block without functioning pacemaker 1, 4, 6
• PR interval >0.24 seconds 4
• Heart rate <60 bpm at baseline 4
• Active asthma or severe reactive airway disease 1, 4, 6
• Decompensated heart failure or signs of low cardiac output 4, 6
• High-degree AV block 6

Alternative Agent: Diltiazem

• For patients with contraindications to beta-blockers (especially asthma or bronchospastic disease), use diltiazem 240 mg orally or 0.25-0.60 mg/kg IV 2, 6, 7
• Diltiazem is effective and safe for heart rate reduction in coronary CT angiography 7
• However, oral verapamil 240 mg showed poor response with all patients maintaining heart rate >70 bpm in one study 2
• Diltiazem produces less RR interval variability during acquisition compared to metoprolol 7

Monitoring Requirements

• Check blood pressure and heart rate before each IV bolus 4
• Auscultate for bronchospasm during IV administration 4
• Monitor for symptomatic bradycardia or hypotension 4, 5
• Major complications occur in only 0.44% of patients with proper screening 5

Image Quality Correlation

• Severe motion artifact (Grade 3) occurs in only 0.9% of patients with heart rate ≤60 bpm 2
• Severe motion artifact increases to 50% in patients with heart rate >70 bpm 2
• Image quality is closely related to heart rate, making adequate rate control essential 2

Common Pitfalls to Avoid

• Do not administer the full 15 mg IV dose as a single rapid bolus—this significantly increases risk of hypotension and bradycardia 4
• Do not skip screening for contraindications—proper patient selection is essential for safety 6, 5
• Do not use metoprolol in patients with vasospastic or vasoocclusive disease 6
• Exercise caution in patients with decompensated heart failure—wait for clinical stabilization 6

Adjunctive Medication

• Sublingual nitroglycerin immediately before scanning achieves coronary vasodilation and improves image quality 1
• Nitroglycerin is contraindicated in patients taking erectile dysfunction medications or those with severe anemia 6
• Use cautiously in patients with aortic stenosis or other preload-dependent cardiac pathologies 6