Electrocardiograms transmitted via facsimile may not allow accurate interval interpretation.

BACKGROUND: Electrocardiograms (ECGs) are sent via facsimile by pediatricians and psychiatrists to cardiologists for assessment. The validity of this method of transmission has not been established.
METHODS: ECGs were collected from 100 consecutive patients from the cardiology clinic of the Children's Hospital at Montefiore. The ECGs were faxed and also electronically faxed (efax) and printed. Two electrophysiologists (EP1 and EP2) interpreted the intervals on original, faxed, and efaxed ECGs and intervals (RR, PR, and QT) were compared. A three-way analysis of variance to examine differences between raters, among ECG intervals, and among methods (repeated factor) was performed. Because no interaction terms were significant, a Duncan's multiple range test was used to evaluate where differences occurred among the three intervals and three methods, given these main effects were significant.
RESULTS: The difference between raters EP1 and EP2 was not significant (P = 0.6681). Although the interval measurements of the faxed and efaxed ECGs were not significantly different from each other (P > 0.05), each was significantly different from the original across all three ECG intervals and both raters (P = 0.0138). The RR interval yielded mean (SD) values for the original, faxed, and efaxed methods of 0.6986 seconds (0.2074), 0.6646 seconds (0.1938), and 0.6838 seconds (0.1935), respectively. For the QT interval, the mean (SD) values for the original, faxed, and efaxed methods were 0.3370 seconds (0.0524), 0.32134 seconds (0.0466), and 0.3284 seconds (0.0515), respectively.
CONCLUSIONS: ECG transmission via facsimile or efax may introduce significant distortion of the intervals. Alternative means of sending ECGs for interpretation should be considered. ©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.