Evaluation of the effectiveness of oral beta-blockade in patients for coronary computed tomographic angiography

OBJECTIVE: To determine the effectiveness of oral medications in lowering the resting heart rate (HR) for coronary computed tomographic angiography (CTA). BACKGROUND: The protocol of premedication for cardiac CTA is variable in terms of type, dose, route, and timing of administration. METHODS: Nursing records were retrospectively reviewed in 238 consecutive patients having coronary CTA and 217 patients evaluated for type and amount of oral medication administered. The HR on arrival to computed tomography (CT) and 30 and 60 minutes after medication was noted. RESULTS: One hundred twenty-three patients (56.6%) had a mean HR of 78.3 ± 9.4 beats per minute (bpm) on arrival and were given medication. One hundred fourteen patients (92.6%) were given 50 mg of oral metoprolol, with the remaining receiving 25 to 100 mg and 1 patient receiving 30 mg of oral diltiazem. Sixty-eight patients (55.2%) were monitored for less than 1 hour and had a mean HR of 73.1 ± 5.1 bpm on arrival, a 9.8 ± 4.7-bpm decrease in HR at 30 minutes, and an HR of 56.5 ± 7.2 bpm during CT. Thirty-nine patients (31.7%) had a mean HR of 81.3 ± 7.2 bpm on arrival, a 9.8 ± 7.4-bpm decrease in HR at 30 minutes, a 16.9 ± 6.3-bpm decrease in HR at 60 minutes, and an HR of 59.8 ± 4.8 bpm during CT. Sixteen patients were monitored for more than 1 hour, followed by intravenous metoprolol. These patients had a baseline HR of 93.5 ± 8.9 bpm, a 13.1 ± 6.4-bpm decrease in HR at 30 minutes, a 15.9 ± 6.8-bpm decrease in HR at 60 minutes, and an HR of 68.1 ± 7.9 bpm during CT. There were no complications due to metoprolol. CONCLUSION: Oral metoprolol given 1 hour before cardiac CT effectively and safely lowers the resting HR in most patients.