Application of the Bogossian formula for evaluation of the QT interval in pacemaker patients with stimulated left
K F Weipert1, H Bogossian2,3, P Conzen1
1Department of Cardiology and Angiology, Medical Clinic I, University Clinic of Gießen, Gießen, Germany.
Background:
The presence of left bundle branch block (LBBB) represents a particular challenge in properly measuring the QT interval. Here we demonstrate the applicability of the "Bogossian formula" in pacemaker patients with LBBB due to apical or nonapical right ventricular (RV) pacing and preserved left ventricular function.
Methods:
A total of 163 patients with a cardiac one- or two-chamber pacemaker were included in this prospective, multicentre observational study. Twelve-lead ECG recordings were obtained during both intrinsic rhythm and RV pacing with induced LBBB. The QT interval measured during LBBB was corrected using the Bogossian formula to obtain the "modified QT" (QTm). The QTmc interval was calculated with the Bazett formula, and this was compared with the QTc interval during intrinsic rhythm.
Results:
Eighty-three patients (78 ± 9 years; male n = 83) with apical and eighty patients (71 ± 13 years; male n = 80) with non-apical RV pacing were included in this study. In the apical group the QTmc was determined to be 444 ± 39 ms in paced rhythm and the QTc interval 413 ± 36 ms in intrinsic rhythm. In the non-apical group these values were 430 ± 34 ms in paced and 416 ± 32 ms in intrinsic rhythm.
Conclusion:
The Bogossian formula is a reliable tool for QTc interval evaluation in pacemaker patients with LBBB due to apical or non-apical RV pacing. However, an overestimation of 30 ms should be included in the calculation.
Related Concept Videos
02:52Chemical Formulas
03:10Molecular Compounds: Formulas and Nomenclature
03:34Ionic Compounds: Formulas and Nomenclature
02:37Experimental Determination of Chemical Formula
01:03Prediction Intervals
However, the point estimate is most likely not the exact value of the population parameter, but close to it. After calculating point estimates, we construct interval estimates, called confidence intervals or prediction intervals. This prediction interval comprises a range of values unlike the point estimate and is a better predictor of the observed sample value, y.
02:56Formula Mass and Mole Concepts of Compounds