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[Complete left branch block and electrocardiographic diagnosis of left ventricular hypertrophy]
Insights
Diagnosing left ventricular hypertrophy (LVH) with left bundle branch block (LBBB) is possible using specific ECG criteria. Certain QRS amplitude indices in precordial leads remain reliable for accurate LVH detection, even with LBBB present.
Area of Science:
- Cardiology
- Electrocardiography
- Diagnostic Imaging
Background:
- Transient or intermittent complete left bundle branch block (LBBB) presents diagnostic challenges for left ventricular hypertrophy (LVH).
- Accurate LVH diagnosis is crucial for patient management and risk stratification.
Purpose of the Study:
- To assess the sensitivity and specificity of various electrocardiogram (ECG) criteria for diagnosing LVH in patients with intermittent LBBB.
- To identify the most reliable ECG indices for LVH detection in the presence of LBBB.
Main Methods:
- Analysis of ECGs from 71 patients with and without LBBB, recorded within 90 days.
- Evaluation of classical ECG criteria and index associations for LVH using LBBB-present tracings.
Main Results:
- Several ECG criteria demonstrated good diagnostic performance for LVH with LBBB.
- The criteria SV2 + RV6 ≥ 32 mm (80% sensitivity, 81% specificity) and Sokolow's index ≥ 33 mm (78% sensitivity, 81% specificity) were most effective.
- Indices based on QRS amplitude in precordial leads, particularly SV1 + SV2 + RV6 + RV7 ≥ 65 mm, showed high stability and reproducibility.
Conclusions:
- ECG indices based on QRS amplitude in precordial leads are valid and clinically useful for diagnosing LVH, even in the presence of LBBB.
- Specific criteria offer reliable LVH detection, aiding clinical decision-making in challenging ECG presentations.
Abstract:
The electrocardiogrammes of 71 patients (39 men and 32 women) with transient or intermittent complete left bundle branch block (LBBB) were studied. Two tracings, one with and the other without LBBB were analysed in each case. The interval between the two recordings was less than 90 days in all cases (average 10 days). The diagnosis of left ventricular hypertrophy (LVH) was established from the ECG without LBBB. The sensitivity and specificity of the classical criteria or indices of LVA and of different associations of indices of LVH were assessed on the ECGs with LBBB. The best criteria of LVH in the presence of LBBB were the SV2 + RV6 greater than or equal to 32 mm (sensitivity 80%; specificity 81%), Sokolow's index greater than or equal to 33 mm (sensitivity 78%, specificity 81%); followed by SV1 greater than or equal to 23 mm (sensitivity 73%, specificity 86%), SV1 + SV2 + RV6 + RV7 greater than or equal to 65 mm (sensitivity 88%, specificity 63%), SV1 + SV2 greater than or equal to 54 mm (sensitivity 73%, specificity 74%). These six parameters allow correct diagnosis of LVH in 81%, 79%, 78%, 79% and 73% of cases, respectively. The SV1 + SV2 + RV5 + RV7 and the SV1 + SV2 + RV6 + RV7 greater than or equal to 65 mm indices are the most stable (same sensitivity and specificity for several consecutive threshold values, i.e. 62 to 67 mm and 64 to 66 mm respectively); the results obtained with these two indices are therefore more likely to be reproducible than those of the other indices as they seem less dependent on the sampling. The indices of LVH based on the QRS amplitude in the precordial leads remain valid in the presence of LBBB and are sufficiently reliable for the diagnosis of LVH to be clinically useful.