CALCULATION OF QTC DURATION AND VARIABILITY IN THE PRESENCE OF SINES ARRHYTHMIA

In summary, this study proposes guidelines for calculation of the QTc in the presence of SA to help identify patients with true LQTS: (1) The QT interval immediately following the shortest RR interval should be used (with Bazett's formula) to calculate the QTc in patients with SA. (2) It is rare to have LQTS with a QTc <0.46 with SA using the shortest RR interval. (3) Varying absolute QT intervals (>0.04 second) with changing RR intervals also are suggestive of LQTS. © 1995 Excerpta Medica, Inc. All rights reserved under the United States, International, and Pan-American Copyright Conventions.