The diagnostic value of coronary CT angiography (CTA) strongly depends on image quality, and radiation dose should be as low as reasonably achievable. Heart rate was identified as an independent predictor for coronary CTA image quality and radiation exposure (1,2). However, scanner and protocol improvements may bring to question the importance of heart rate control, and the optimal heart rate for patients undergoing coronary CTA is currently unclear. In this subanalysis of the Prospective Multicenter Registry on Radiation Dose Estimates of Cardiac CT Angiography in Daily Practice, or PROTECTION VI (3,4), we aimed to identify the optimal heart rate in coronary CTA allowing for best image quality and radiation dose reduction.