Is it possible to predict heart rate and range during enhanced cardiac CT scan from previous non-enhanced cardiac CT?

The effect of heart rate and variation during cardiac computed tomography (CT) on the examination quality. The purpose of this study is to investigate whether it is possible to predict heart rate and range during enhanced cardiac computed CT scan from previous non-enhanced cardiac CT scan. Electrocardiograph (ECG) files from 112 patients on three types of cardiac 64-slice CT (non-enhanced, prospective ECG-triggered and retrospective ECG-gated enhanced scans) were recorded. The mean heart rate, range (defined as difference between maximal and minimal heart rates) and the range ratio (defined as maximal heart rate divided by minimal heart rate) during the scans were compared. Scan time was 4.8, 4.6, and 7.3 s on non-enhanced, prospective ECG-triggered and retrospective ECG-gated scans, respectively (p < 0.0001). The heart rates were not significantly different (60 ± 9 beats per minute (bpm), 60 ± 9 and 61 ± 10 bpm; p = 0.64). Heart rate on the enhanced scan markedly correlated with that of the non-enhanced scan (r = 0.78 and 0.74). In contrast, the ranges of heart rate were 2 ± 5, 4 ± 8, and 8 ± 21 bpm, with different range ratios (1.04, 1.07, and 1.14; p < 0.0001). Correlation of heart rate ranges between non-enhanced scan versus prospective ECG-triggered scan was low (r = 0.27) and that between non-enhanced scan versus retrospective ECG-gated scan negligible (r = -0.027).Heart rate on enhanced cardiac CT, in most cases, can be predicted from a non-enhanced scan. Heart rate range on enhanced cardiac CT, however, is hard to predict from the non-enhanced scan.