Safety of intravenous β‐adrenoceptor blockers for computed tomographic coronary angiography

Abstract

Keywordsadrenergic β-adrenoceptor antagonists, coronary angiography, drug-related side effects and adverse reactions, metoprolol, tomography, X-ray computed AIMSTo assess the safety of our clinical practice using off-label intravenous metoprolol to facilitate computed tomographic (CT) coronary angiography. METHODSA retrospective analysis of scan reports and hospital admissions data was conducted to identify adverse events occurring following CT coronary angiography in patients who had received intravenous metoprolol prior to the scan. RESULTSA total of 3098 patients were included, of whom 1871 received intravenous metoprolol. Nine hundred and one patients received more than 15 mg and 129 patients received metoprolol despite a resting heart rate <65 beats min −1 . There was a single adverse incident, comprising transient loss of consciousness. CONCLUSIONSThe use of intravenous metoprolol to facilitate cardiac CT scanning appears safe. Dose limits recommended for other indications, generally in acutely unwell patients, may not need to be as stringent in this population.

Safety of intravenous metoprolol use in unmonitored wards: a single‐centre observational study

“…As far as we are aware, the safety of administering IV beta‐blockers to acutely unwell inpatients in unmonitored wards has not been previously reported. Populations receiving IV beta‐blockers who have been heavily investigated and reported on include acute myocardial infarction (AMI) and those undergoing CT coronary angiography . Both of these groups differ from our study in several ways.…”

“…However, despite these differences, the overall results are not dissimilar to ours. In the radiology group, the use of IV beta‐blockers was deemed safe in populations without contraindication, with one large trial only reporting 1 SAE out of 1871 patients . The most common complications in the AMI group were hypotension, bradycardia and heart block; however, the absolute numbers were low, the mortality was not increased and all were easily treatable with atropine or inotropes .…”

“…Intravenous (IV) administration is a proposed solution; however, the safety of this is not well described . Concerns include the potential for hypotension, bradycardia and A‐V nodal conduction delay .…”

CT coronary angiography in atrial fibrillation: a comparison of radiation dose and diagnostic confidence with retrospective gatingvsprospective gating with systolic acquisition

“…Patients with a minimum heart rate of .50 beats per minute and a maximum heart rate of .60 beats per minute received intravenous metoprolol, titrated in 5 mg aliquots. 7 Imaging was performed on a 64-detector row CT scanner (Discovery TM CT750 HD, GE Healthcare, Milwaukee, WI), with either prospective or retrospective gating. For prospective ECG gating with systolic triggering (45% R-R interval), 100 milliseconds of padding (additional tube-on time either side of the R-R interval) was applied, as per standard departmental protocol when imaging patients with heart rate variability.…”

“…End systole (or more precisely, the period of isovolumetric relaxation which immediately follows) offers a small window of relative cardiac and coronary stability, which has been exploited to image both the aorta 4 and the coronary arteries in patients with AF. 5,6 This seems intuitive, owing to the reduced time from detection of the R wave to scanning which, in combination with aggressive heart rate control, 7 would minimize the opportunity for interruption by the next ventricular contraction. Studies of "systolic triggering" have been limited, demonstrating improvement in both image quality and radiation dose but still with only moderate image quality in more than one-third of patients.…”