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Assessment of left ventricular function from the electrocardiogram in left bundle branch block
S H Recke1, H D Esperer, U Eberlein
1University Heart Centre, Erlangen, F.R.G.
Insights
QRS duration on ECG effectively predicts left ventricular function in patients with left bundle branch block. Shorter durations suggest normal function, while longer durations indicate impaired ejection fraction.
Area of Science:
- Cardiology
- Electrocardiography
- Cardiac Electrophysiology
Background:
- Left bundle branch block (LBBB) complicates the assessment of left ventricular (LV) function using standard electrocardiography.
- Identifying non-invasive predictors of LV end-diastolic volume index (LVEDVI) and ejection fraction (LVEF) in LBBB patients is clinically significant.
Purpose of the Study:
- To identify electrocardiographic predictors of LVEDVI and LVEF in patients with complete LBBB.
- To evaluate the diagnostic accuracy of specific ECG parameters for assessing LV dimensions and systolic function.
Main Methods:
- Analysis of QRS duration, S wave amplitude, S-T wave sum, and T wave polarity in 165 LBBB patients.
- Multivariate analysis to determine the discriminatory power of ECG parameters.
- Correlation analysis between ECG parameters and LVEDVI/LVEF measurements.
Main Results:
- QRS duration, maximal S wave amplitude, and T wave polarity were selected by multivariate analysis.
- QRS duration showed the best single correlations with LVEDVI (r=0.57) and LVEF (r=-0.63).
- QRS duration < 140 ms predicted normal LVEDVI/LVEF (sensitivity 100%); QRS duration > 170 ms predicted depressed LVEF < 55% (specificity 98%).
Conclusions:
- QRS duration is a valuable electrocardiographic predictor for evaluating LV function in LBBB.
- ECG parameters, particularly QRS duration, can guide the assessment of LVEDVI and LVEF in LBBB patients.
- QRS duration alone offers a reliable reference for LV function assessment in the presence of LBBB.
Abstract:
The QRS duration, maximum right precordial S amplitude, sum of amplitudes of the maximum right precordial S and T wave and T wave polarity in lead I have been analyzed in order to identify electrocardiographic predictors of left ventricular end-diastolic volume index and ejection fraction in 165 patients with complete left bundle branch block and various forms of heart disease. Multivariate analysis selected the duration, maximal amplitude of the S wave and polarity of the T wave in decreasing order of discriminatory power, which correctly identify 76.6% of the patients with a normal end-diastolic volume index less than or equal to 90 ml/m2 and a normal ejection fraction greater than or equal to 60% (n = 64) and 73.3% of those with an end-diastolic volume index greater than 90 ml/m2 or an ejection fraction less than 60% (n = 101). The comparisons of the QRS duration with the end-diastolic volume index and the ejection fraction give the best single correlations: r = 0.57 and -0.63, respectively. Multiple correlations lead to no substantial improvement of the r values: 0.06 and -0.65, respectively. A QRS duration less than 140 msec is almost always predictive of the presence of a normal end-diastolic volume index and a normal ejection fraction (sensitivity 100%, specificity 91.9%, positive predictive value 73.3%). A QRS duration greater than 170 msec is most accurate in predicting depressed left ventricular ejection fraction less than 55% (sensitivity 36.5%, specificity 98%, positive predictive value 92%). Thus, only the QRS duration provides a useful reference and guide for the evaluation of left ventricular function in the presence of left bundle branch block.