High-density mapping of His-ventricular intervals: impact of measurement location and sex-specific differences

Abstract Background A His-ventricle (HV) interval measurement is considered to be normal between 35 and 55 ms, and prolongation ≥70 ms has been proposed for risk stratification, e.g. in patients with left bundle branch block after transcatheter aortic valve replacement or in patients with bifascicular block and syncope. However, there is no clear consensus regarding the exact location to measure the HV interval and sparse data on sex-specific differences. Purpose To investigate the impact of the measurement location on HV interval as assessed using a high-density mapping catheter and to determine sex-specific differences. Methods Consecutive patients undergoing catheter ablation for atrial fibrillation were evaluated using the ablation catheter as well as with a multipolar high-density mapping catheter in conjunction with a 3D-electroanatomical mapping system. HV interval measurements were obtained in sinus rhythm in four positions: with the ablation catheter at the end of the procedure - clinical HV, with the high density mapping catheter proximal – HVprox, distal – HVdis and at the right bundle branch– HVRB). Differences in male and female patients were evaluated. Results 67 patients were included (mean age 64±10, 33% women). The distance in millimeters between HVprox and HVdis was 8±4 and between HVdis and HVRB 11±5. The median HV measurements at HVprox, HVdis and HVRB were 51±10 ms, 46±10ms and 37±10ms, respectively (p<0.001). The clinical HV was measured on average at 45±9 ms and was not significantly different compared to the HVdis (p=0.1, Figure 1). The difference in HV measurements between HVprox and HVdis were 6.3±6.3 ms and between HVdis and HVRB 7.2±7.8 ms. The HV-measurements were significantly shorter in women compared to men: HVprox (48±9 ms vs 53±10 ms, p=0.03), HVdis (42±8 ms vs 48±10 ms, p=0.005) and HVRB (33±8 vs 40±10 ms, p=0.002). An HV interval ≥55ms was identified in 19 patients (28%), 8 patients (12%) and 3 patients (4%) when measuring at the HVprox, HVdis and HVRB position, respectively. The conduction velocity from the HVprox, to the HVdis was 1.8±1 m/s and from the HVdis to the HVRB 1.4±1 m/s. While the distal conduction velocities were significantly slower than the proximal conduction velocities in men (1.4±0.6 m/s vs 1.8 ±1 m/s, p=0.03), they were similar in women (1.5±0.8 m/s vs 1.6±0.9 m/s, p=0.85). Conclusions Using high-density mapping, we found significant differences in the HV interval depending on the location of the measurement. Irrespective of the location, the HV interval is consistently shorter in women than men. This may have clinical implications for risk stratification.Figure 1- Comparison of HV Intervals Figure 2