Measurement of the AH and HV interval and His bundle duration: interobserver and intraobserver variation.

Conduction system intervals measured during intracardiac electrophysiologic testing influence clinical decisions. To evaluate measurement reliability, interobserver and intraobserver variation for AH, HV, and His bundle duration measurements from 50 patients were evaluated. The square of the correlation coefficient (r2) was used as the index for measurement reliability. Three investigators performed the measurements. The r2 for interobserver variation of the AH interval ranged from 0.55 to 0.68 and for intraobserver variability from 0.60 to 0.88. The standard error of measurement based on intraobserver measurements ranged from 10.2 to 18.0 ms. The r2 for interobserver variation of the HV interval ranged from 0.42 to 0.63 and for intraobserver variation from 0.489 to 0.73. The standard error of measurement was 6.2 to 9.9 ms. For the His bundle duration, the r2 for interobserver variation ranged from 0.42 to 0.52 and for intraobserver variation from 0.19 to 0.52. The standard error of measurement was 3.1 to 5.2 ms. Although there is measurement variation for AH and HV intervals, their use in conjunction with the history and the surface electrocardiogram to make clinical decisions is appropriate. His bundle duration cannot be measured reliably using the standard recording technique and should not be used for clinical decision making.