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?

AIM: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Maximizing the clinical benefit of high-pitch, single-heartbeat CT coronary angiography in clinical practice.

AIM: To prospectively analyse the occurrence of right coronary artery (RCA) artefact and assess its relationship with patient heart rate (HR) and HR variability (HRV) in order to determine the most appropriate parameters for high-pitch cardiovascular computed tomography (CT) acquisition, minimize the likelihood of artefact, and maximize the clinical benefit in consecutive clinical high-pitch CT coronary angiography (CA) examinations. MATERIALS AND METHODS: One hundred and seventy-three patients undergoing high-pitch CTCA were prospectively assessed for the presence of RCA artefact. Median and maximum HR and the difference in predicted and actual acquisition HR (HR difference, HRD) were correlated from the electrocardiograms recorded at the time of acquisition. RESULTS: Sixty-six percent of the cohort was male, with a median age of 54 (range 16-84 years). There were 53 cases of RCA artefact (30.6%); 26 (49.1%) of these required further imaging to fully delineate the RCA. Of the 53 cases with artefact, 81.1% affected the distal RCA and 18.9% were more proximal. Gender was not associated with an increased likelihood of the artefact (p = 0.14). RCA artefact decreased by 2% with each year of increasing age (p = 0.04). When compared with a reference HR of >70 beats/min, univariate analysis demonstrated RCA artefact significantly increased with both increasing median and maximum HR, whilst the incidence of RCA artefact increased for all HRD >1, with a greater likelihood of artefact with increasing HRD. CONCLUSION: The present results highlight the importance of optimizing patient HR in order to reduce the likelihood of RCA artefact. In addition to aggressive HR control to a median HR of ≤60 beats/min, the present results suggest limiting high-pitch acquisition to patients with HR variability of <3 beats/min. Therefore, use of beta-blockers is of crucial importance to both reduce HR and HR variability to optimize use of high-pitch single-heartbeat CTCA.