2179Influence of irregular heart rhythm on radiation exposure, image quality and diagnostic impact of cardiac computed tomography angiography in 4,767 patients

Abstract

Background: Coronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD). Purpose: To investigate whether irregular heart rhythm including atrial flutter, atrial fibrillation, and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA. Methods: Nine tertiary centres with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2015, 4767 coronary CTA examinations were analysed. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, the presence or absence of CAD, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed. Results: Of 4767 patients in total, 299 (6.3%) had irregular heart rhythm during coronary CTA, whereas the remaining 4468 (93.7%) had stable sinus rhythm without supraventricular or ventricular premature beats. Patients with irregular heart rhythm were older (64.2±12.3yrs. versus 59.1±11.5yrs., p<0.001) and more frequently had history of prior CAD (13.2% versus 8.8%, p=0.01), whereas the Agatston score was similar (77.6 versus 61.5, p=0.62). Patients with irregular heart rhythm had higher heart rates during scan compared to those with sinus rhythm (62.9±12.3bpm versus 59.0±8.5bpm, p<0.001). Both contrast media exposure and radiation exposure were higher in patients with irregular heart rhythm (90mL (95% CI=80-110mL) versus 80mL (95% CI=70-90mL) and 7.0mSv (95% CI=2.9-12.7) versus 3.5mSv (95% CI=1.7-7.2), p<0.001 for both). In addition, coronary CTA could exclude significant CAD less frequently in patients with irregular heart rhythm (29.6% versus 42.0%, p<0.001). This was partly explained by artefacts, since in patients with irregular heart rhythm 11.4% of the examinations included at least one non-diagnostic coronary segment, compared to 5.9% of the examinations in patients with sinus rhythm (p<0.001). Subsequent invasive angiography could be avoided in 47.3% of patients with irregular heart rhythm compared to 52.0% of patients with sinus rhythm (p=NS), whereas downstream stress testing was recommended in 6.2% of patients with irregular heart rhythm versus 6.7% of patients with sinus rhythm (p=NS). Conclusion: A significant number of patients scheduled for coronary CTA has irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent examinations with at least one nondiagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures.