The goal of this clinical trial is to describe which type and dose of commonly used heart rate reducing drugs (metoprolol, atenolol, or ivabradine) has the swiftest heart rate reduction from baseline in patients aged 30 to 80 years with a heart rate > 65 beats per minute undergoing cardiac computed tomography for the evaluation of coronary artery disease. The main question it aims to answer is

• Which type of heart reducing drug and dose has the swiftest heart rate reduction before cardiac computed tomography?

This single-center, prospective, randomized, double-blind, clinical trial will include patients undergoing cardiac computed tomography. Two phases will be conducted: a pilot study (dose-finding phase) and a randomized trial (superiority phase). In the first dose-finding phase participants (N=150) will be randomized 1:1 in six arms (arms contain lower and higher doses of atenolol, metoprolol and ivabradine). Following an interim analysis, a superiority phase will be conducted using two parallel groups, non-diabetics (N=100) and diabetics (N=100), in a placebo-controlled head-to-head randomized 2:2:1 three-arms trial comparing the fastest betablocker and dose and the fastest dose of ivabradine from the dose-finding phase.

Inclusion Criteria:

• Individuals who are to undergo Cardiac CT
• Sinus rhythm with heart rate > 65 bpm on ECG
• Competent patients who have given written informed consent

Exclusion Criteria:

• Age > 80 years
• Age < 30 years
• Heart rate > 100 bpm
• BMI > 35
• Previous percutaneous coronary intervention (with or without stent)
• Previous CABG
• Known ischemic heart disease
• Pacemaker
• Acute coronary syndrome
• Known allergy to beta-blockers
• Known allergy to ivabradine
• Known allergy to used radiographic contrast agents
• Pregnant, including potentially pregnant, or breastfeeding (potentially pregnant patients will undergo pregnancy testing)
• Heart failure with systolic left ventricular ejection fraction < 45%
• Reduced kidney function with estimated glomerular filtration rate (eGFR) < 40 ml/min
• Regular treatment with beta-blockers
• Regular treatment with ivabradine
• Regular treatment with non-dihydropyridine calcium antagonists (Verapamil and Diltiazem)
• Regular treatment with Cordarone
• Contraindications for beta-blockers or ivabradine:
• Severe asthma
• Severe COPD
• Sick sinus syndrome
• Sinoatrial block (1st degree AV block)
• Advanced AV block (2nd or 3rd degree)
• Hypotension (systolic blood pressure < 110 mmHg)
• Severe heart failure
• Severe restrictive cardiomyopathy
• Severe aortic stenosis
• Severe circulatory disturbances
• Severe metabolic conditions
• Untreated pheochromocytoma
• Concurrent treatment with potent inhibitors of CYP3A4
• Concurrent treatment with potent inhibitors of MAO inhibitors,
• Concurrent treatment with potent inhibitors of CYP2D6 inhibitors
• Concurrent treatment with potent inhibitors of intravenous calcium antagonists type I or III

Individual participant data (IPD) will not be shared with other researchers. All data will be analyzed and managed locally at our site, and we do not plan to share IPD.