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Published on: October 28, 2020
Electrocardiographic markers of left ventricular systolic dysfunction in patients with left bundle branch block
Ali Deniz1, Çağlar Özmen, Halil Aktaş
1Çukurova University, Faculty of Medicine, Adana, Turkey. alideniz78@gmail.com.
Insights
Electrocardiography (ECG) can differentiate patients with left bundle branch block (LBBB) and reduced left ventricular ejection fraction (LVEF) from those with normal heart function. Key indicators include male gender, QRS duration over 140 ms, and specific ECG patterns.
Area of Science:
- Cardiology
- Medical Diagnostics
- Electrocardiography
Background:
- Left bundle branch block (LBBB) can occur in patients with and without structural heart disease.
- Electrocardiography (ECG) criteria for LBBB in patients with reduced left ventricular ejection fraction (LVEF) are not fully established.
Purpose of the Study:
- To distinguish between patients with LBBB and reduced LVEF versus those with normal left ventricular systolic function using only a 12-lead ECG.
- Identify simple ECG markers for assessing LVEF in LBBB patients.
Main Methods:
- Included 100 consecutive patients with LBBB.
- Categorized patients into two groups: LVEF ≥ 50% (normal function) and LVEF < 50% (reduced function).
- Analyzed QRS duration, residual left bundle branch conduction, and T wave concordance/discordance, comparing findings between groups.
Main Results:
- 65% of patients had reduced LVEF. Male patients were more likely to have reduced LVEF (80% vs. 45% in females).
- Mean QRS duration was significantly longer in the reduced LVEF group (152 ms vs. 132 ms).
- A QRS duration > 140 ms identified reduced LVEF with 72% sensitivity and 75% specificity. Discordant LBBB and residual left bundle branch conduction were more prevalent in the reduced LVEF group.
Conclusions:
- Male gender, QRS duration exceeding 140 ms, discordant LBBB patterns, and residual left bundle branch conduction are potential indicators of reduced LVEF in LBBB patients.
- These ECG findings may aid in non-invasively assessing left ventricular systolic function in LBBB patients.
Background:
Although some patients with left bundle branch block (LBBB) have structural heart diseases, some patients with LBBB have "normal hearts". The electrocardiography (ECG) criteria of LBBB in reduced left ventricular ejection fraction (LVEF) have not been defined completely.
Aim:
The main purpose of this study was to differentiate patients with reduced LVEF from patients with normal left ventricular systolic function simply by analysing 12-lead ECG.
Methods:
Subjects admitted to our hospital with LBBB in their ECG were included in the study. The patients were categorised according to their left ventricular systolic function as group 1 (LVEF ≥ 50%) and group 2 (LVEF < 50%). Duration of the QRS complex, residual conduction of left bundle branch, and concordance/discordance of T waves in leads V5, V6, or D1 were recorded. The ECG findings of the two groups were compared.
Results:
One hundred consecutive patients with LBBB were included in the study (male/female: 56/44, age: 66 ± 15 years). In the whole group, there were 35 patients with normal left ventricular systolic function (LVEF ≥ 50%), and 65 patients had LVEF below 50%. 80% of male patients with LBBB and 45% of female patients with LBBB had their LVEF below 50% (p < 0.001). Mean QRS durations of group 1 and group 2 were 132 ± 10 ms vs. 152 ± 22 ms, respectively (p < 0.001). The QRS duration of 140 ms was found to be the cut-off value to differentiate group 1 from group 2, with sensitivity and specificity of 72% and 75%, respectively. Twenty-one per cent of patients in group 1 and 69% in group 2 had discordant LBBB (p < 0.001). Residual conduction of left bundle branch was more frequent in group 2 (29% in group 1 vs. 52% in group 2, p = 0.03).
Conclusions:
Male gender, QRS duration greater than 140 ms, discordant LBBB, and residual conduction in the left bundle branch seem to be markers of reduced LVEF in patients with LBBB.
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