High-dose intravenous metoprolol usage for reducing heart rate at CT coronary angiography: efficacy and safety.

To evaluate the usage, safety, and efficacy of high-dose intravenous metoprolol for heart rate reduction in computer tomographic (CT) coronary angiography. As this was retrospective analysis of anonymous data, medical ethics committee approval was waived by the regional health research authority. Patients, who had known iodinated contrast medium allergy, contraindications to β-blockers, atrial fibrillation, and indications other than suspected coronary artery disease, were excluded from analysis. The ultimate study population of 662 were analysed with details of intravenous metoprolol doses, complications, heart rate before administration of intravenous metoprolol (resting heart rate, RHR), heart rate at acquisition of scan (acquisition heart rate, AHR), and usage of low radiation dose protocols. Of the ultimate study population of 662 patients, 183 had no intravenous metoprolol with mean acquisition heart rate (AHR) of 58 beats per minute (bpm), 257 had 1-15 mg intravenous metoprolol with mean AHR of 57 bpm, 114 had 16-29 mg intravenous metoprolol with mean AHR of 62 bpm and 108 had ≥30 mg intravenous metoprolol with mean AHR of 66 bpm. In the group receiving intravenous metoprolol, average usage was 19 mg (maximum 67 mg) with average reduction in HR of 15 bpm. There were no clinical incidents in relation to the use of high-dose intravenous metoprolol. Higher doses of intravenous metoprolol are beneficial in achieving target heart rates to facilitate usage of low radiation dose protocols. With appropriate exclusion criteria, higher doses of intravenous metoprolol, well in excess of 15 mg, can be safely administered when carefully titrated.