Introduction:
In patients (pts) with right bundle branch block (RBBB) and heart failure, assessment of left ventricular (LV) function is vital to management, but echocardiograms (ECHO) may not always be readily available. We studied the utility of using the
Superimposed Median Format
(available on digital ECG systems) in assessing LV function. This format allows visual recognition of change in dV/dT when rapid initial impulse propagation over the left bundle branch (LBB) and LV Purkinje network transitions to slower muscle-to-muscle propagation to the right ventricle (RV) in the setting of RBBB.
Hypothesis:
With a normal LBB and healthy LV myocardium, the transition from rapid forces to slower depolarization would occur in the 1
st
half of the QRS complex (
Early Transition Group - ET)
whereas in patients with abnormal LV function, this transition would occur in the 2
nd
half
(Late Transition Group - LT)
of the QRS complex.
Methods:
Digital superimposed median format ECGs of 108 pts with RBBB were analyzed. Pts were divided into 2 groups: ET or LT. See figure. LVEFs were obtained from ECHO. LVEF ≥ 50% was considered normal.
Results:
ET: n = 69. LT: n = 39. Mean QRS durations were not different in the 2 groups. ET pts were more likely to have normal LVEF (p < 0.01). See figure. PPV of ET in predicting LVEF ≥50% = 90%; NPV = 71%. Accuracy = 82%.
Conclusions:
These data, if confirmed, suggest that in pts with RBBB, visual analysis of the QRS complex from the surface ECG using the superimposed median format may provide valuable clues about LV systolic function, and may be clinically useful when ECHO are not readily available.
The Apparent and the Effective PR Interval, Insights for Cardiac Pacing
