Appropriate indications for computed tomography coronary angiography.

Computed tomography coronary angiography (CTCA) has been shown in multicentre trials to be reliable in ruling out significant coronary artery disease (CAD). It is used most appropriately in symptomatic patients with low to intermediate pretest probability of CAD. It should not be used in asymptomatic subjects, patients with known significant CAD or patients with a high pretest probability of CAD. The radiation dose of CTCA was previously two to three times that of invasive coronary angiography but with modern protocols, it is similar or lower. Patients generally need to be in sinus rhythm, tolerate Β-blockers and nitrates, have a heart rate < 65 beats per minute, be able to hold their breath for 10 seconds, and have normal renal function.