The effect of conduction velocity slowing in left ventricular midwall on the QRS complex morphology: A simulation study

ISE/ISHNE expert consensus statement on the ECG diagnosis of left ventricular hypertrophy: The change of the paradigm

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria. The classical paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces, reflected in the augmented QRS amplitude. However, the low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm. The theoretical background for voltage measured at the body surface is defined by the solid angle theorem, which relates the measured voltage to spatial and non-spatial determinants. The spatial determinants are represented by the extent of the activation front and the distance of the recording electrodes. The non-spatial determinants comprise electrical characteristics of the myocardium, which are comparatively neglected in the interpretation of the QRS patterns. Various clinical conditions are associated with LVH. These conditions produce considerable diversity of electrical properties alterations thereby modifying the resultant QRS patterns. The spectrum of QRS patterns observed in LVH patients is quite broad, including also left axis deviation, left anterior fascicular block, incomplete and complete left bundle branch blocks, Q waves, and fragmented QRS. Importantly, the QRS complex can be within normal limits. The new paradigm stresses the electrophysiological background in interpreting QRS changes, i.e., the effect of the non-spatial determinants. This postulates that the role of ECG is not to estimate LV size in LVH, but to understand and decode the underlying electrical processes, which are crucial in relation to cardiovascular risk assessment.

ISE/ISHNE Expert Consensus Statement on ECG Diagnosis of Left Ventricular Hypertrophy: The Change of the Paradigm. The joint paper of the International Society of Electrocardiology and the International Society for Holter Monitoring and Noninvasive Electrocardiology

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria, i.e. the increased QRS complex amplitude in defined leads. The classical ECG diagnostic paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces. These increased forces are reflected in the augmented QRS amplitude in the corresponding leads. However, the clinical observations document increased QRS amplitude only in the minority of patients with LVH. The low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm.

The electrocardiogram: Still a useful marker for LV fibrosis in aortic stenosis

Left ventricular (LV) strain on the electrocardiogram (ECG) (down-sloping, convex ST-segment depression with asymmetric T-wave inversion in leads V5 and V6) reflects fibrosis as a result of subendocardial ischemia. It is associated with a significantly increased risk of cardiovascular events independent of the presence of LV hypertrophy on the echocardiogram or cardiac magnetic resonance (CMR) scan. Ongoing studies of early aortic valve replacement in asymptomatic patients with severe aortic stenosis are using ECG changes as a marker of possible fibrosis shown by midwall late gadolinium enhancement on CMR. However, until these studies report, it is still reasonable to respond to LV strain on the ECG by tightening control of systemic hypertension and consider intervention in cases where indications are otherwise in borderline.

Apparent electrocardiogram left ventricular hypertrophy during tachycardia

The electrocardiographic transient display of left ventricular hypertrophy (LVH), during rapid heart rates, in the setting of sinus/supraventricular tachycardias and atrial fibrillation, is illustrated via 3 case reports. This common occurrence is expressed by an increase in the S-waves in leads V2-V5, during tachycardias, rendering a false positive diagnosis of LVH by the frequently employed Cornell voltage LVH criteria. This tachycardia-mediated apparent LVH, is unrelated to the occasionally encountered stable, and unrelated to tachycardia, "false positive diagnosis of LVH", which could in reality occasionally reflect altered electrical properties of myocardium that could create a functional substrate for developing arrhythmias. The importance of awareness of this insight by all health professionals is immeasurable, considering that a false positive diagnosis of LVH has major consequences in the management, prognostication, resort to expensive unnecessary testing, and stress to the patients and their families.

Predictive value of electrocardiographic left ventricular hypertrophy in the general population: A meta-analysis

BACKGROUND

Conflicting results have been reported on the predictive value of the electrocardiographic left ventricular hypertrophy (LVH) in the general population. This meta-analysis sought to compare the predictive value of different electrocardiographic criteria of LVH in the general population.

METHODS

We comprehensively searched PubMed and Embase databases until May 9, 2020 to identify observational studies investigating the predictive value of different electrocardiographic criteria for LVH (Sokolow-Lyon voltage, Cornell voltage or Cornell product) in the general population. Outcome measures were major adverse cardiovascular events (MACEs), cardiovascular or all-cause mortality.

RESULTS

Ten studies enrolling 58,400 individuals were included. Comparison with and without electrocardiographic LVH, the pooled risk ratio (RR) of MACEs was 1.62 (95% confidence interval [CI] 1.40-1.89) for the Sokolow-Lyon voltage criteria, 1.70 (95% CI 1.27-2.29) for the Cornell voltage criteria, and 1.56 (95% CI 1.17-2) for the Cornell product criteria. The pooled RR of all-cause mortality was 1.47 (95% CI 1.10-1.97) for the Sokolow-Lyon voltage criteria and 1.87 (95% CI 1.29-2.71) for the Cornell voltage criteria. Furthermore, the pooled RR of cardiovascular mortality was 1.38 (95% CI 1.19-1.60) for the Sokolow-Lyon criteria, 1.66 (95% CI 1.24-2.33) for the Cornell voltage criteria, and 1.82 (95% CI 0.65-5.09) for the Cornell product criteria.

CONCLUSIONS

Different electrocardiographic criteria for evaluating LVH had a similar value in predicting MACEs among the general population. LVH detected by the Cornell voltage appeared to have a stronger predictive value in prediction of cardiovascular or all-cause mortality.

Missing Link between Molecular Aspects of Ventricular Arrhythmias and QRS Complex Morphology in Left Ventricular Hypertrophy

The aim of this opinion paper is to point out the knowledge gap between evidence on the molecular level and clinical diagnostic possibilities in left ventricular hypertrophy (LVH) regarding the prediction of ventricular arrhythmias and monitoring the effect of therapy. LVH is defined as an increase in left ventricular size and is associated with increased occurrence of ventricular arrhythmia. Hypertrophic rebuilding of myocardium comprises interrelated processes on molecular, subcellular, cellular, tissue, and organ levels affecting electrogenesis, creating a substrate for triggering and maintaining arrhythmias. The knowledge of these processes serves as a basis for developing targeted therapy to prevent and treat arrhythmias. In the clinical practice, the method for recording electrical phenomena of the heart is electrocardiography. The recognized clinical electrocardiogram (ECG) predictors of ventricular arrhythmias are related to alterations in electrical impulse propagation, such as QRS complex duration, QT interval, early repolarization, late potentials, and fragmented QRS, and they are not specific for LVH. However, the simulation studies have shown that the QRS complex patterns documented in patients with LVH are also conditioned remarkably by the alterations in impulse propagation. These QRS complex patterns in LVH could be potentially recognized for predicting ventricular arrhythmia and for monitoring the effect of therapy.

Electrocardiogram (ECG) patterns of left anterior fascicular block and conduction impairment in ventricular myocardium: a whole-heart model-based simulation study

Left anterior fascicular block (LAFB) is a heart disease identifiable from an abnormal electrocardiogram (ECG). It has been reported that LAFB is associated with an increased risk of heart failure. Non-specific intraventricular conduction delay due to the lesions of the conduction bundles and slow cell to cell conduction has also been considered as another cause of heart failure. Since the location and mechanism of conduction delay have notable variability between individual patients, we hypothesized that the impaired conduction in the ventricular myocardium may lead to abnormal ECGs similar to LAFB ECG patterns. To test this hypothesis, based on a computer model with a three dimensional whole-heart anatomical structure, we simulated the cardiac exciting sequence map and 12-lead ECG caused by the block in the left anterior fascicle and by the slowed conduction velocity in the ventricular myocardium. The simulation results showed that the typical LAFB ECG patterns can also be observed from cases with slowed conduction velocity in the ventricular myocardium. The main differences were the duration of QRS and wave amplitude. In conclusion, our simulations provide a promising starting point to further investigate the underlying mechanism of heart failure with LAFB, which would provide a potential reference for LAFB diagnosis.

Relationship between QRS measurements and left ventricular morphology and function in asymptomatic individuals

BACKGROUND AND AIM

QRS amplitude and duration are associated with increased left ventricular (LV) volume, mass and dysfunction. However, the diagnostic concordance between QRS measurements and LV morphology and function, as shown by Doppler echocardiography, is not well established. We investigated the relationships of QRS duration and amplitude with echocardiographic measurements of LV morphology and systolic and diastolic function in normal individuals.

METHODS

Individuals without signs or symptoms of coronary artery disease or heart failure, who underwent clinical examination as a part of a cross-sectional survey for the prevalence of coronary risk factors, randomly selected from the population list in Caltanissetta, Italy, were included in the study. QRS duration and amplitude were automatically measured using inbuilt software. LV ejection and filling patterns were studied using Doppler echocardiography.

RESULTS

We studied 184 individuals (96 men and 88 women), mean age 55.9 (11.3). QRS duration increased by 5.4 ms for every 100 g increase in LV mass, and by 4.6 ms for each 10 mm increase in LV end-diastolic diameter. The amplitude increased by 0.8 mm for every 100 g increase in LV mass. There was no relationship with LV dimensions. A nonlinear correlation was found between QRS amplitude and indexes of global dyssynchrony. The time-voltage QRS area correlated with LV mass, dimensions and indexes of dyssynchrony. There was no relationship between QRS measurements and ejection fraction.

CONCLUSIONS

QRS prolongation and increase in amplitude are strongly influenced by LV increased mass and volume, as well as by dyssynchrony, independently of ejection fraction.

Central aortic systolic blood pressure can predict prolonged QTc duration better than brachial artery systolic blood pressure in rural community residents

OBJECTIVES

Previous studies have suggested that prolonged electrocardiogram QTc duration was independent risk factor for both increased cardiovascular and all-cause mortality, but there was no dating about the relationship between central aortic systolic blood pressure (CASP) and QTc duration. The aim of this study was to analyze the relationship between CASP and QTc duration, and assess whether CASP can predict prolonged QTc duration more than BSBP.

METHODS

A total of 500 patients were enrolled in this study, central and brachial aortic blood pressure and electrocardiogram QTc duration were measured. Pearson correlation was assessed for determining the associations of QTc duration with clinical conditions. Multivariate logistic regression analyses were performed to determine the independent predictor of prolonged QTc duration. Receiver operating characteristic (ROC) curve was used to evaluate the utility of blood pressure for prolonged QTc duration.

RESULTS

We found QTc durations were significantly positive with CASP (r = 0.308, p < 0.001), BSBP (r = 0.227, p < 0.001), and age (r = 0.154, p = 0.010), but negatively related to heart rate (r = -440, p < 0.001). A multiple logistic regression analysis demonstrated that the CASP was an independent determinant of prolonged QTc (OR = 1.648; 95%CI: 1.032, 2.101; p < 0.001). CASP had a better predictive value for prolonged QTc duration than (AUC: 0.771 vs. 0.646, p < 0.001) BSBP.

CONCLUSION

Our results suggested that the non-invasive CASP is independently correlated with QTc duration, and CASP can predict prolonged QTc duration more than BSBP.

Systolic blood pressure but not electrocardiogram QRS duration is associated with heart rate variability (HRV): a cross-sectional study in rural Australian non-diabetics

BACKGROUND

A positive correlation between ECG derived QRS duration and heart rate variability (HRV) parameters had previously been reported in young healthy adults. We note this study used a narrow QRS duration range, and did not adjust for systolic blood pressure. Our aims are to investigate associations between systolic blood pressure (SBP), QRS duration and HRV in a rural aging population.

METHODS

A retrospective cross sectional population was obtained from the CSU Diabetes Screening Research Initiative data base where 200 participants had no diabetes or pre-diabetes. SBP data were matched with ECG derived QRS duration and HRV parameters. HRV parameters were calculated from R-R intervals. Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system.

RESULTS

Pearson correlation analysis revealed no statistically significant associations between HRV parameters and QRS duration. No significant mean differences in HRV parameter subgroups across defined QRS cut-offs were found. SBP > 146 mmHg was associated with increasing QRS durations, however this association disappeared once models were adjusted for age and gender. SBP was also significantly associated with a number of HRV parameters using Pearson correlation analysis, including high frequency (HF) (p < 0.05), HFln (p < 0.02), RMSDD (p < 0.02) and non-linear parameters; ApEN (p < 0.001) were negatively correlated with increasing SBP while the low frequency to high frequency ratio (LF/HF) increased with increasing SBP (p < 0.03).

CONCLUSIONS

Our results do not support associations between ECG derived R-R derived HRV parameters and QRS duration in aging populations. We suggest that ventricular conduction as determined by QRS duration is independent of variations in SA-node heart rate variability.

The 4th Report of the Working Group on ECG diagnosis of Left Ventricular Hypertrophy

The 4th Report provides a brief review of publications focused on the electrocardiographic diagnosis of left ventricular hypertrophy published during the period of 2010 to 2016 by the members of the Working Group on ECG diagnosis of Left Ventricular Hypertrophy. The Working Group recommended that ECG research and clinical attention be redirected from the estimation of LVM to the identification of electrical remodeling, to better understanding the sequence of events connecting electrical remodeling to outcomes. The need for a re-definition of terms and for a new paradigm is also stressed.