Safety and efficacy of a rate control protocol for cardiac CT

Abstract

The clinical application of cardiac CT is increasing, but heart rate control is often required to prevent motion artefact. Here, we describe a protocol for heart rate control in patients undergoing outpatient CT coronary angiography (CTCA). Among 121 consecutive patients, 75 (61.9%) with a resting heart rate >60 beats per minute (bpm) required rate control medication. Our protocol called for oral metoprolol 100 mg to be given 60 min before scanning, with patients for whom beta-blockers were contraindicated receiving 240 mg oral verapamil. Additional 5 mg intravenous boluses (maximum for both drugs, 15 mg) were given if the heart rate remained >60 bpm prior to scanning. Of 71 patients treated with oral metoprolol, 59 (83%) achieved a rate <or=65 bpm and 46 (65%) achieved a heart rate of <or=60 bpm during the CTCA scan. All four patients receiving verapamil had a poor rate response and had heart rates >70 bpm at the time of scanning. No adverse events resulted from rate control medication. Image quality was closely related to heart rate. Severe motion artefact (Grade 3) occurred in only 0.9% of patients with a rate <or=60 bpm compared with 50% of patients with a rate >70 bpm. In conclusion, the administration of oral metoprolol according to the described protocol is a safe and effective way of reducing heart rate and improving scan quality in the majority of patients undergoing CTCA.