Safety, Efficacy and Indications of β-Blockers to Reduce Heart Rate prior to Coronary CT Angiography-An Overview

WA Jahan, A Azam, S Deena, W Begum, M Rahman
<span title="2012-10-19">2012</span> <i title="Bangladesh Journals Online (JOL)"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/fbs5tmf73zdi3cwimln2jmjgam" style="color: black;">Cardiovascular Journal</a> </i> &nbsp;
Coronary computed tomographic (CT) angiography is an established clinical technology for the evaluation of coronary artery disease, with high sensitivity and high negative predictive value in selected patients. Furthermore, it has potential for the detection of coronary plaque burden. 1 Over the past decade, advances in scanner and post processing technology have led to substantial improvements in temporal and spatial resolution and hence image quality. Yet image quality remains highly
more &raquo; ... on both the regularity of the cardiac rhythm and the heart rate, especially when single-source CT scanners are used, which to date represent the vast majority of scanners in clinical practice. Current publications recommend a heart rate of ideally less than 60 beats per minute both for optimal image quality and for reduction of radiation exposure. 2 However, most patients seen in clinical practice have heart rates often much above 75 beats per minute at presentation. 3 Therefore, in the absence of contraindications, âblockers should be routinely administered prior to coronary CT angiography to achieve sufficient reduction of heart rate prior to data acquisition. There many clinical trials support the need for more effective heart rate reduction in clinical practice. In this article, we provide an overview of indications, safety, and efficacy of â-blockade prior to coronary CT angiography. Pharmacologic Properties of â-Blockers To reduce heart rate during coronary CT angiography, cardio selective β 1 -blockers are the predominantly used agents. β-adrenergic antagonists reduce the heart rate by decreasing the frequency of the sinus node, by decreasing the spontaneous rate of depolarization of ectopic pacemakers, by slowing conduction in the atria and in the atrioventricular node, and by increasing the functional refractory period of the atrioventricular node. Pharmacologic properties of short-term â-blockers, such as decreasing cardiac output and peripheral resistance, differ substantially from long-acting βblockers, when total peripheral resistance returns to initial values, effects mediated by âadrenoreceptors. 4 β -Blockers as a daily medicationfor example, for heart failure-have only mild influence on resting heart rates and mainly reduce maximum heart rates achieved during exercise. 5 However, when administered as short-term medication in high doses, they also allow reduction of heart rate at rest, as desired for cardiac CT. As a trade-off, β-blockers can then cause substantial Abstract: For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. â-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple âblocker administration protocols with oral and/or intravenous application have been proposed. This review article provides an overview of the indications, efficacy, and safety of â-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover, implications for radiation exposure and left ventricular function analysis are discussed. (Cardiovasc. j. 2012; 5(1): 100-106)
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