Background Computed Tomography Coronary Angiography (CTCA) is sensitive and specific for ruling out coronary artery disease. Prerequisites in order to achieve optimum image quality include sinus rhythm and heart rate of 60–65 bpm. In the absence of contraindications beta-blockade is first-line treatment to reduce heart rate. Intravenous beta-blocker is frequently used, but this can, however, be time-consuming and may fail to achieve adequate heart rate control. Routine pre-treatment with oral beta-blocker prior to CTCA to reduce heart rate has not been fully evaluated in the literature. This observational study aimed to show that short term protocol guided pre-medication with oral beta-blocker is effective in optimising heart rates and is safe and tolerated by patients.

Methods We retrospectively and prospectively reviewed CTCA cases from a large single centre teaching hospital. Scanning was performed using a helical 80 detector row scanner with prospective gating (Aquilon Prime,Toshiba Medical System). Data collected included beta-blocker use, heart rate, scan time, total dose length product (DLP), adverse events and baseline patient characteristics. The first cohort of patients had CTCA prior to the introduction of a 5 day course of weight based dose Bisoprolol if resting heart rate >60 bpm. The second cohort of patients were followed prospectively after introduction of the protocol. Prior to the protocol routine beta-blocker prescription was at the discretion of the physician.

Results 204 CTCA studies were performed at Tallaght Hospital over an 8 month period. 100 cases took place before the protocol was released. 46 were prescribed oral beta-blocker prior to CTCA and 54 were not. Mean heart rate 64.71.9 bpm. Mean DLP 364.4 ±48 mGy.cm (mean effective dose 5.1±0.6 mSv). 104 cases took place after introduction of the protocol. Mean heart rate 57.8±1.2 bpm. Mean DLP 351.6±43 mGy.cm (mean effective dose 4.9±0.6 mSv). 67 patients (64%) were prescribed oral beta-blocker. Of these, 50 patients (75%) did not need IV metoprolol. Of the 37 patients not on oral beta-blocker, 21 (57%) did not need IV metoprolol. 14 of these patients did not meet criteria for oral beta-blocker as per protocol and none required IV metoprolol. Mean scanning time was significantly increased when IV metoprolol was used (table 1) (p=0.00001381). Mean DLP was 15.5 mGy.cm higher with IV metoprolol use (effective dose 0.22 mSv). 57% of patients had a family history of premature coronary artery disease, 47% dyslipidaemia, 31% hypertension and 24% active smokers. There were no adverse events associated with beta-blocker use and scan quality was similar when heart rate was controlled.

Conclusion Routine pre-treatment with a short course of oral beta-blocker prior to prospective ECG-gated CTCA reduces the requirement for IV beta-blocker peri-procedure, reduces effective radiation dose, significantly reduces scanning time, is safe, well tolerated and maintains diagnostic quality.