Electrocardiographic Z-axis QRS-T voltage-time-integral in patients with typical right bundle branch block - Correlation with echocardiographic right ventricular size and function.

BACKGROUND: Right bundle branch block (RBBB) can be benign or associated with right ventricular (RV) functional and structural abnormalities. Our aim was to evaluate QRS-T voltage-time-integral (VTI) compared to QRS duration and lead V1 R' as markers for RV abnormalities. METHODS: We included adults with an ECG demonstrating RBBB and echocardiogram obtained within 3 months of each other, between 2010 and 2020. VTIQRS and VTIQRST were obtained for 12 standard ECG leads, reconstructed vectorcardiographic X, Y, Z leads and root-mean-squared (3D) ECG. Age, sex and BSA-adjusted linear regressions were used to assess associations of QRS duration, amplitudes, VTIs and lead V1 R' duration/VTI with echocardiographic tricuspid annular plane systolic excursion (TAPSE), RV tissue Doppler imaging S', basal and mid diameter, and systolic pressure (RVSP). RESULTS: Among 782 patients (33% women, age 71 ± 14 years) with RBBB, R' duration in lead V1 was modestly associated with RV S', RV diameters and RVSP (all p ≤ 0.03). QRS duration was more strongly associated with RV diameters (both p < 0.0001). AmplitudeQRS-Z was modestly correlated with all 5 RV echocardiographic variables (all p ≤ 0.02). VTIR'-V1 was more strongly associated with TAPSE, RV S' and RVSP (all p ≤ 0.0003). VTIQRS-Z and VTIQRST-Z were among the strongest correlates of the 5 RV variables (all p < 0.0001). VTIQRST-Z.√BSA cutoff of ≥62 µVsm had sensitivity 62.7% and specificity 65.7% for predicting ≥3 of 5 abnormal RV variables (AUC 0.66; men 0.71, women 0.60). CONCLUSION: In patients with RBBB, VTIQRST-Z is a stronger predictor of RV dysfunction and adverse remodeling than QRS duration and lead V1 R'.

Electrocardiographic prediction of left ventricular hypertrophy in women and men with left bundle branch block - Comparison of QRS duration, amplitude and voltage-time-integral.

BACKGROUND: Standard ECG criteria for left ventricular (LV) hypertrophy rely on QRS amplitudes. However, in the setting of left bundle branch block (LBBB), ECG correlates of LV hypertrophy are not well established. We sought to evaluate quantitative ECG predictors of LV hypertrophy in the presence of LBBB. METHODS: We included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010-2020. Orthogonal X, Y, Z leads were reconstructed from digital 12­lead ECGs using Kors's matrix. In addition to QRS duration, we evaluated QRS amplitudes and voltage-time-integrals (VTIs) from all 12 leads, X, Y, Z leads and 3D (root-mean-squared) ECG. We used age, sex and BSA-adjusted linear regressions to predict echocardiographic LV calculations (mass, end-diastolic and end-systolic volumes, ejection fraction) from ECG, and separately generated ROC curves for predicting echocardiographic abnormalities. RESULTS: We included 413 patients (53% women, age 73 ± 12 years). All 4 echocardiographic LV calculations were most strongly correlated with QRS duration (all p < 0.00001). In women, QRS duration ≥ 150 ms had sensitivity/specificity 56.3%/64.4% for increased LV mass and 62.7%/67.8% for increased LV end-diastolic volume. In men, QRS duration ≥ 160 ms had a sensitivity/specificity 63.1%/72.1% for increased LV mass and 58.3%/74.5% for increased LV end-diastolic volume. QRS duration was best able to discriminate eccentric hypertrophy (area under ROC curve 0.701) and increased LV end-diastolic volume (0.681). CONCLUSIONS: In patients with LBBB, QRS duration (≥ 150 in women and ≥ 160 in men) is a superior predictor of LV remodeling esp. eccentric hypertrophy and dilation.

Reduction of left ventricular outflow tract obstruction with transcatheter mitral valve repair.

Many patients with severe mitral regurgitation cannot undergo conventional mitral valve surgery due to prohibitive surgical risk and are candidates for transcatheter repair with an edge-to-edge technique. Prior reports suggest efficacy with this approach for mitral regurgitation due to hypertrophic cardiomyopathy with left ventricular outflow obstruction. We present a case report of transcatheter mitral valve repair for posterior leaflet prolapse with concomitant left ventricular outflow tract obstruction due to systolic anterior motion of the mitral valve in the absence of hypertrophic cardiomyopathy.

Quantification of the variability associated with repeat measurements of left ventricular two-dimensional global longitudinal strain in a real-world setting.

BACKGROUND: Global longitudinal strain (GLS) derived from two-dimensional speckle-tracking is an emerging technology, but lack of industry standards limits its application. Prior studies support using this tool to identify subclinical disease through serial changes, but the variability introduced by a change in vendor or reader is not well defined. METHODS: Fifty study subjects were prospectively identified to include four subgroups to ensure a broad range of GLS: normal (n = 20), left ventricular hypertrophy (n = 10), ST-segment elevation myocardial infarction (n = 10), and systolic heart failure (n = 10). Raw data were obtained using equipment from two vendors during the same session, and GLS was analyzed using an offline workstation. Intraobserver and interobserver variation was measured using correlation coefficients, intraclass correlation coefficients, and Bland-Altman plots. RESULTS: GLS measurements were highly reproducible by the same reader or a different reader using vendor 1 and vendor 2 or comparing vendors (correlation coefficients and intraclass correlation coefficients ≥ 0.95). However, the Bland-Altman plots suggested that the variation in repeat GLS measurements may range from ± 2% to ± 5% on the basis of a change in vendor, reader, or both. CONCLUSIONS: The expected variation in GLS measurements associated with a change in vendor, reader, or both should be considered when making conclusions about significant changes in serial measurements.

Two-dimensional longitudinal strain in patients with aortic stenosis can be reliably acquired at the bedside without additional benefit of offline analysis.

BACKGROUND: Two-dimensional strain echocardiography (2DS) has been used to assess ventricular function in several disease states. In previous studies of 2DS, strain analysis was usually performed offline by experienced echocardiographers. The applicability of 2DS in busy clinical labs would be enhanced if 2DS could be reproducibly measured by sonographers at the time of the echo exam. In this study we compared the reproducibility of strain measurements between sonographers at the time of the echo exam with those performed offline by an experienced echocardiographer. METHODS: Apical left ventricular (LV) B-mode images were acquired in 98 consecutive patients being evaluated for aortic stenosis. 2DS analysis was performed at the time of the exam by a sonographer. The same images were analyzed offline by an experienced echocardiographer. Global longitudinal strain (GLS) results were analyzed for interobserver reproducibility. Additionally, the regional longitudinal strain (RLS) of 20 randomly selected patients was analyzed for intraobserver reproducibility. RESULTS: Acceptable data quality was available in 97.8% of the segments measured at the time of the exam and in 96.9% at the workstation. Interobserver reproducibility of the global peak strain was high (r = 0.855, P < 0.001). Additionally, applying cutoffs for separating normal from abnormal GLS revealed good agreement between sonographer and experienced echocardiographer [kappa analysis (κ= 0.739, P < 0.001)]. Overall RLS intraobserver reproducibility was high (raw mean adjusted r = 0.915). CONCLUSION: The GLS in aortic stenosis patients can be reliably measured at the bedside by a sonographer without additional benefit of offline analysis.

Integrated backscatter during harmonic and fundamental frequency imaging--effect of depth, mechanical index, and tissue anisotropy: implications for myocardial tissue characterization.

OBJECTIVE: To explore the potential advantages of tissue harmonic imaging (THI) versus fundamental frequency imaging (FFI) when applied to tissue characterization. METHODS: A Philips Medical Systems Sonos 5500 echocardiograph equipped with a broadband transducer (S4) and an on-line quantitative analysis software package (Acoustic Densitometry) was used for imaging. The effect of mechanical index (MI), imaging depth, and anisotropy on relative backscatter amplitude was evaluated. RESULTS: This study demonstrated that imaging with tissue harmonics generated relatively greater backscatter values at clinically relevant imaging depths and instrument settings referenced to FFI. This effect was dependent on MI setting. A direct relationship between backscatter amplitude and MI was demonstrated. Additionally, tissue anisotropy had similar effects on integrated backscatter amplitude during both THI and FFI. However, relative backscatter values at each fiber orientation are greater during THI at similar instrument settings when referenced to FFI. CONCLUSION: Tissue harmonic imaging may offer advantages over FFI for myocardial tissue characterization.