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.

Safety and efficacy of oral ivabradine as a heart rate-reducing agent in patients undergoing CT coronary angiography

“…An essential part of performing a successful CT CA examination is to optimise the patient's heart rate using b-blockers to limit motion artefacts in the coronary arteries. However, despite the routine use of b-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm, despite using oral as well as iv b-blockers [9][10][11]15].…”

“…There also exists a subset of patients in whom both b-blockers and calcium channel-blockers would be inadvisable, namely those with low baseline blood pressure (,100-110 mmHg), severe left ventricular dysfunction, severe aortic stenosis, etc. [15]. Moreover, patient response to b-blockers is often inadequate, which may be due to presence of polymorphisms in the b1-adrenoceptor or excessive adrenergic stimulation caused by anxiety, leading to persistent tachycardia [16].…”

Lowering of Heart Rate before Computed Tomographic Coronary Angiography: Improvement in Image Quality and Role of Ivabradine

“…Graaf et al 23 (n=537) administered oral metoprolol and/or lorazepam 60 min before coronary CTA in patients with HR >65 bpm. In 16% of the patients with HR above the goal there was some contraindication to the use of β-blockers.…”

Lowering heart rate with an optimised breathing protocol for prospectively ECG-triggered CT coronary angiography

“…Furthermore, when low-dose CTCA with prospective ECG triggering is performed with the smallest possible acquisition window to achieve the lowest possible radiation dose, it does not permit image reconstruction in other phases of the cardiac cycle to compensate for a possible reduction in image quality. An aggressive reduction in heart rate with b-blockers below a target heart rate of 63 bpm appears to be a prerequisite for lowdose CTCA [2,10].CTCA is generally performed during the patient's breath-hold to avoid motion artefacts caused by movement of the thorax during image acquisition. However, the breath-hold and, particularly, the level (or depth) of breath-hold can affect heart rate [11].…”

“…Furthermore, when low-dose CTCA with prospective ECG triggering is performed with the smallest possible acquisition window to achieve the lowest possible radiation dose, it does not permit image reconstruction in other phases of the cardiac cycle to compensate for a possible reduction in image quality. An aggressive reduction in heart rate with b-blockers below a target heart rate of 63 bpm appears to be a prerequisite for lowdose CTCA [2,10].…”