Statistical Analysis
Values were analyzed using standard statistical methods. T-tests were used for continuous variables. All statistical analyses were done using Microsoft Excel.
Results
A total of 50 consecutive CCTAs were included in this study, 30 men and 20 women. The average age was 55.4 ± 14.1 years. Medical history included hypertension (64%), diabetes (50%) and CAD (10%). LVH was present in 9 patients (18%) but was mild in all cases. Heart failure was present in 9 patients (18%), 4 of whom had systolic dysfunction with an average EF for the study being 57.0 ± 8.6 % determined by echocardiography. The mean left ventricular internal diameter at end diastole (LVIDd) and interventricular septum thickness (IVS) were 46.7 mm and 10.2 mm, respectively. The mean distance from the His Bundle to the first septal perforator (His-SP) along the line connecting the His bundle to the RV apex (His-RV apex) was 27.17 ± 7.7 mm, median 26.9 mm, range 13.0 to 44.7 mm. There was no significant difference by gender for mean distance (28.1 mm in men vs 25.6 mm in women, p=0.26). Given the variability in cardiac structure among patients, this ratio between the His-SP distance and the His-RV Apex distance was also measured. The mean His-SP:His-RV Apex was 0.302 and the median was 0.298. The relationship between the His-SP and the His-RV Apex distances are shown inFigure 2 . The percentage of patients who met certain distance and ratio cutoffs between the His Bundle and the first septal perforator are shown in Table 1 .