None listed
Conditions
Brief summary
Before some patients have a CT scan of the heart's arteries (called a CT coronary angiogram), they are given medication to slow their heart rate down. A slower, steadier heart rate produces clearer pictures and helps the scan work well. The medication used is a type called a beta-blocker. At present, this medication is usually given as a tablet taken by mouth. Tablets take time to work, and some patients' heart rates do not slow down enough, which can delay the scan or mean it has to be postponed. Another option is to give the same type of medication through a drip into a vein, which may work more quickly. This study aims to find out whether giving the heart-rate medication through a drip, rather than by tablet, gets patients ready for their scan sooner. We will compare the two approaches in patients coming in for a CT scan of the heart's arteries. Everyone taking part will be randomly placed into one of two groups: one group will receive the tablet approach currently used, and the other will receive the medication through a drip. We will mainly measure the time it takes each patient to be ready for their scan, and we will also look at how well each approach controls the heart rate, the quality of the scan pictures, the dose of medication needed, and whether any side effects occur. We think that giving the medication through a drip will prepare patients for their scan more quickly than tablets, without affecting their safety or the quality of the scan. If this is correct, it could mean shorter waits, fewer cancelled scans, and a smoother experience for patients.
Interventions
Intravenous metoprolol protocol for pre-scan heart rate control (Group 2, intervention arm)
Participants allocated to Group 2 receive intravenous metoprolol tartrate for heart rate control immediately prior to CTCA. The protocol is adapted from the Barts Heart Centre intravenous beta-blockade protocol.
Metoprolol tartrate is administered intravenously in 5 mg increments. Each 5 mg dose is administered as a slow intravenous bolus, with heart rate and blood pressure reassessed 2 minutes after ea
Intravenous metoprolol protocol for pre-scan heart rate control (Group 2, intervention arm) Participants allocated to Group 2 receive intravenous metoprolol tartrate for heart rate control immediately prior to CTCA. The protocol is adapted from the Barts Heart Centre intravenous beta-blockade protocol. Metoprolol tartrate is administered intravenously in 5 mg increments. Each 5 mg dose is administered as a slow intravenous bolus, with heart rate and blood pressure reassessed 2 minutes after each dose before any further dose is given; the complete titration typically takes 10 to 15 minutes. Dosing is titrated to a target heart rate of 65 beats per minute or lower, up to a maximum cumulative dose of 30 mg (a maximum of six 5 mg doses). Heart rate, non-invasive blood pressure (NIBP) and mean arterial pressure (MAP) are recorded at baseline and after each incremental dose. Further doses are withheld once the target heart rate is achieved, the maximum 30 mg cumulative dose is reached, or a pre-specified safety threshold is met (systolic NIBP less than or equal to 89 mmHg or MAP less than or equal to 59 mmHg), consistent with the thresholds applied in Group 1. The intervention is delivered by a trained cardiac imaging nurse, credentialed in intravenous beta-blocker administration, under the supervision of the cardiologist or radiologist sub-investigator, with continuous cardiac monitoring in place. Both groups additionally receive sublingual glyceryl trinitrate 300–600 micrograms immediately prior to image acquisition for coronary vasodilation, in accordance with standard CTCA practice, provided systolic blood pressure remains above the safety threshold described above and no contraindication exists. Glyceryl trinitrate is administered identically in both arms and does not form part of the randomised comparison. Mode of administration: Intravenous. Timing and duration: Administered on the day of the scan. Intravenous administration commences approximately 15 to 30 minutes prior to planned image acquisition, in the period immediately preceding the scan; administration concludes when the target heart rate is achieved, the maximum cumulative dose is reached, or a safety threshold is met (as described above). Tailoring: Dosing is titrated to each participant's heart rate response, as described above, rather than fixed. Adherence and fidelity: As administration is clinician-delivered and directly observed, each incremental dose and its corresponding heart rate and blood pressure, together with the total dose administered, are recorded contemporaneously on the study data collection sheet, allowing protocol fidelity to be verified.
Sponsors
Rebecca Woodley - Monash Health
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Diagnosis
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Adult outpatients aged 18 years or older Presenting for computed tomography coronary angiography (CTCA) In sinus rhythm Resting heart rate greater than 60 beats per minute (bpm) Systolic non-invasive blood pressure (NIBP) of 100 mmHg or greater Able to lie supine and raise both arms above the head Able to understand and follow instructions, including lying motionless and performing a breath-hold when requested
Exclusion criteria
Regular pharmacological treatment including beta-blockers or verapamil, or self-administration of beta-blockers as premedication prior to arrival Resting heart rate of 100 bpm or greater Marked bradycardia, or heart rate already within the range for diagnostic imaging (less than 60 bpm) Systolic non-invasive blood pressure (NIBP) of 100 mmHg or less at baseline Arrhythmia - current or history of atrioventricular block, sinus bradycardia, or atrial fibrillation (unless a permanent pacemaker is in situ) Permanent pacemaker in situ Aged under 18 years Pregnant or breastfeeding Allergy to contrast media Known allergy or hypersensitivity to beta-blockers, including bronchospasm Contraindication to nitroglycerin (glyceryl trinitrate) Claustrophobia or anxiety requiring anxiolytic Obesity: girth 80 cm or greater, or weight 135 kg or greater Renal insufficiency: eGFR 60 mL/min/1.73m² or less Previous percutaneous coronary intervention or coronary artery bypass grafting Unstable angina Poorly controlled or brittle asthma (refer to cardiologist; documented hospital admission in the preceding 6–12 months by record or patient report) History of severe asthma, chronic obstructive pulmonary disease (COPD), severe aortic valve stenosis, restrictive cardiomyopathy, or severe hepatic impairment Severe left ventricular dysfunction, ejection fraction 35% or less History of cardiomyopathy with no echocardiogram in the previous 2 years Use of phosphodiesterase inhibitors (e.g. sildenafil) in the previous 24 hours
Outcome results
None listed