Speeding up beta-blockade prior to coronary CT angiography: can we predict the dose of intravenous metoprolol required to achieve target heart rate in a given patient?

• Published in: Clinical radiology Vol. 76; no. 3; pp. 236.e21 - 236.e25
• Main Authors: Androshchuk, V., Sabharwal, N., St Noble, V., Kelion, A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2021
• ISSN: 0009-9260; 1365-229X
• DOI: 10.1016/j.crad.2020.09.026

To evaluate the use and safety of intravenous (IV) metoprolol in a cohort of patients undergoing coronary computed tomographic angiography (CCTA) at a university hospital, and in particular, to establish if the minimum dose required to achieve the target heart rate (HR) in a given patient can be predicted from the baseline HR. Patients undergoing CCTA at a tertiary centre between January 2015 and May 2018, with baseline HR ≥60 bpm requiring IV metoprolol, were identified retrospectively from the database. Patients with a contraindication to beta-blockade or an indication for CCTA other than coronary disease were excluded. HR at baseline and at the time of scanning were recorded, together with the total dose of IV metoprolol administered. Of 625 patients identified, 330 (52.8%) achieved HR ≤60 with IV metoprolol. Patients who achieved target HR had lower baseline HR. They received a lower radiation exposure due to tight prospective gating and a lower tube voltage. The lower quartile dose of metoprolol administered was 5 mg for patients with baseline HR <65 beats per minute (bpm), but 10 mg for HR 65–74 bpm, and ≥20 mg for higher HRs. There were no cases of symptomatic bradycardia/hypotension. Patients with a resting HR of ≥60 bpm can reasonably be given an initial minimum dose of 5–20 mg metoprolol IV before CCTA, with additional doses as required. •Baseline HR can predict IV metoprolol dose required for achieving CCTA target HR.•Starting dose in patients with resting HR ≥60 bpm should be 5 mg–20 mg IV metoprolol.•A maximum of 40 mg IV metoprolol can be given in appropriately screened patients.•Only 10% of patients requiring over 40 mg IV metoprolol achieve target HR for CCTA.•Giving higher off-label doses of IV metoprolol did not cause adverse side effects.