Key result
The development of complete left bundle branch block frequently decreased QRS voltage while leaving AQRS unchanged in the majority of patients, complicating the diagnosis of left ventricular hypertrophy.
Why the study?
Does the development of complete left bundle branch block alter conventional ECG criteria (QRS voltage and AQRS) for left ventricular hypertrophy?
Observational (n=56)
Does the development of complete left bundle branch block alter conventional ECG criteria (QRS voltage and AQRS) for left ventricular hypertrophy?
The development of LBBB frequently decreases QRS voltage but leaves AQRS unchanged, indicating that LVH diagnosis in the presence of LBBB often relies on inference.
New LBBB may confound LVH diagnosis via reduced QRS voltage without AQRS shift; leaves open whether revised criteria improve accuracy.
In 56 patients, the QRS voltage and the AQRS were compared before and after the development of LBBB with particular reference to LVH. The QRS voltage was frequently de-creased, occasionally unchanged and rarely in-creased with the appearance of the conduction defect. The AQRS was unchanged in the majority of patients studied. The probable cause of these changes were discussed. Our results support the conclusion of others in that this diagnosis can be made in many only by inference. It was also re-emphasized that the significance of the AQRS deviation in LBBB in the same as that in normal conduction.
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Chung et al. (1969) conducted an observational in Left Ventricular Hypertrophy and Left Bundle Branch Block (n=56). Development of complete left bundle branch block vs. Before the development of left bundle branch block was evaluated on QRS voltage and AQRS changes. The development of complete left bundle branch block frequently decreased QRS voltage while leaving AQRS unchanged in the majority of patients, complicating the diagnosis of left ventricular hypertrophy.
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