Left ventricular hypertrophy: disagreements between increased left ventricular mass and ECG-LVH criteria: the effect of impaired electrical properties of myocardium

Predicting left ventricular hypertrophy from the 12-lead electrocardiogram in the UK Biobank imaging study using machine learning

Aims

Left ventricular hypertrophy (LVH) is an established, independent predictor of cardiovascular disease. Indices derived from the electrocardiogram (ECG) have been used to infer the presence of LVH with limited sensitivity. This study aimed to classify LVH defined by cardiovascular magnetic resonance (CMR) imaging using the 12-lead ECG for cost-effective patient stratification.

Methods and results

We extracted ECG biomarkers with a known physiological association with LVH from the 12-lead ECG of 37 534 participants in the UK Biobank imaging study. Classification models integrating ECG biomarkers and clinical variables were built using logistic regression, support vector machine (SVM) and random forest (RF). The dataset was split into 80% training and 20% test sets for performance evaluation. Ten-fold cross validation was applied with further validation testing performed by separating data based on UK Biobank imaging centres. QRS amplitude and blood pressure (P < 0.001) were the features most strongly associated with LVH. Classification with logistic regression had an accuracy of 81% [sensitivity 70%, specificity 81%, Area under the receiver operator curve (AUC) 0.86], SVM 81% accuracy (sensitivity 72%, specificity 81%, AUC 0.85) and RF 72% accuracy (sensitivity 74%, specificity 72%, AUC 0.83). ECG biomarkers enhanced model performance of all classifiers, compared to using clinical variables alone. Validation testing by UK Biobank imaging centres demonstrated robustness of our models.

Conclusion

A combination of ECG biomarkers and clinical variables were able to predict LVH defined by CMR. Our findings provide support for the ECG as an inexpensive screening tool to risk stratify patients with LVH as a prelude to advanced imaging.

Left Ventricular Hypertrophy and Ventricular Tachyarrhythmia: The Role of Biomarkers

Left ventricular hypertrophy (LVH) refers to a complex rebuilding of the left ventricle that can gradually lead to serious complications-heart failure and life-threatening ventricular arrhythmias. LVH is defined as an increase in the size of the left ventricle (i.e., anatomically), therefore the basic diagnosis detecting the increase in the LV size is the domain of imaging methods such as echocardiography and cardiac magnetic resonance. However, to evaluate the functional status indicating the gradual deterioration of the left ventricular myocardium, additional methods are available approaching the complex process of hypertrophic remodeling. The novel molecular and genetic biomarkers provide insights on the underlying processes, representing a potential basis for targeted therapy. This review summarizes the spectrum of the main biomarkers employed in the LVH valuation.

The Use of Romhilt-Estes Criteria in the Presumptive Electrocardiographic Diagnosis of Left Ventricular Hypertrophy in Comparison to Voltage-Based Criteria

Background

The ECG diagnosis of left ventricular hypertrophy (LVH) has been challenging for over a hundred years. ECG diagnosis of LVH has shown good specificity but lacks sensitivity. In addition, voltage-based criteria can be affected by multiple conditions such as obesity and chronic lung disease. Therefore, we sought to compare Romhilt-Estes (R-E) criteria with commonly used voltage-based criteria in presumptive ECG diagnosis of LVH. 

Methods

This is a retrospective electronic medical record study from September 1, 2017, to September 1, 2018, of 499 consecutive ECGs from Boca Raton Regional Hospital. Different ECG criteria were used to identify the presence of LVH, including the Cornell criteria, modified Cornell criteria, Sokolow-Lyon criteria, and Romhilt-Estes criteria. The main study outcome was to compare the R-E criteria in presumptive ECG diagnosis of LVH to the voltage-based criteria (Cornell, modified Cornell, and Sokolow-Lyon). 

Results

After analyzing the ECGs using the different ECG criteria, R-E criteria were positive with LVH present (score ≥ 5 points) in 162 patients. In contrast, Cornell criteria were positive in 42 patients (8.4%), modified Cornell criteria in 50 patients (10%), and Sokolow-Lyon criteria in 13 patients (2.6%). In addition, R-E criteria showed higher positivity of LVH diagnosis compared to the sum of three voltage-based criteria (32.7% versus 21% respectively, p<0.001).

Conclusion

We presume that R-E criteria can help better diagnose LVH by ECG compared to other commonly-used voltage-based criteria. However, further studies are needed using confirmatory imaging to confirm the accuracy of R-E criteria and compare it with other voltage based-criteria.

Complementary value of ECG and echocardiographic left ventricular hypertrophy for prediction of adverse outcomes in the general population

OBJECTIVE

To investigate whether ECG left ventricular hypertrophy (ECG-LVH) has prognostic value independent of echocardiography LVH (Echo-LVH).

METHODS

Participants (N = 9744, mean age, 53.81 ± 10.49 years and 45.5% male) from the Northeast China Rural Cardiovascular Health Study were included. Associations between Echo-LVH (sex-specific left ventricular mass normalized to BSA) and ECG-LVH (diagnosed using the Cornell-voltage duration product) and adverse outcomes were evaluated using Cox regression. The value of ECG-LVH for predicting adverse events was evaluated by reclassification and discrimination analyses.

RESULTS

Median follow-up was 4.65 years; 563 participants developed incident stroke or coronary heart disease (CHD) and 402 died. Compared with participants without either condition, those with both Echo-LVH and ECG-LVH had a significantly increased risk of incident stroke or CHD (hazard ratio, 2.42; 95% confidence interval, 1.82-3.22) and mortality (2.58; 1.85-3.60). ECG-LVH remained an independent risk factors for both outcomes when ECG-LVH and Echo-LVH were included in the model as separate variables [incident stroke or CHD (1.43; 1.14-1.79); mortality (1.41; 1.08-1.84)]. Reclassification and discrimination analyses indicated ECG-LVH addition could improve the conventional model for predicting adverse outcomes within 4 years. These relationships persisted after excluding participants with cardiovascular disease history or taking antihypertension drugs or upon applying other ECG-LVH and Echo-LVH diagnostic criteria.

CONCLUSION

Our study provides strong evidence that ECG-LVH is associated with adverse outcomes, independent of Echo-LVH. Clinically, ECG-LVH could be considered as a consequential factor, especially in those with Echo-LVH. These findings have potential clinical relevance for risk stratification.

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.

Additional prognostic value of electrocardiographic left ventricular hypertrophy in traditional cardiovascular risk assessments in chronic kidney disease

BACKGROUND

Left ventricular hypertrophy (LVH) is a common predictor of the cardiovascular prognosis in chronic kidney disease (CKD). However, whether or not electrocardiography-derived LVH (ECG-LVH) has prognostic value in patients with various degrees of CKD and improves the cardiovascular risk stratification based on traditional risk factors remains unclear.

METHODS

A total of 7206 participants at least 40 years of age who were free from cardiovascular events in a general population were followed for the incidence of cardiovascular events. CKD was confirmed by either the presence of a reduced estimated glomerular filtration rate (eGFR) (<60 ml/min per 1.73 m) or albuminuria, defined as a urinary albumin-to-creatinine ratio (UACR) of at least 30 mg/g Cr.

RESULTS

A total of 1886 (26.2%) had CKD, of which 1471 (78.0%) had a preserved eGFR (CKD stage 1-2). After an average 11.3 years of follow-up, the adjusted hazard ratio for the incidence of cardiovascular events significantly increased for ECG-LVH according to the Sokolow--Lyon voltage, Cornell voltage, or Cornell voltage product among participants with CKD (hazard ratio 1.47, P = 0.002), in contrast to those without CKD (hazard ratio 1.15, P = 0.210). The inclusion of any ECG-LVH parameters improved the accuracy of reclassification in any risk prediction model based on the eGFR, UACR, or Framingham 10-year risk score in the CKD participants (net reclassification improvement = 0.13-0.32, all P values <0.040).

CONCLUSION

In patients with CKD stage 1-5, ECG-LVH is useful for predicting the risk of future cardiovascular events and adds prognostic information to traditional cardiovascular risk assessments.

Influence of relative wall thickness on electrocardiographic voltage measures in left ventricular hypertrophy: a novel factor contributing to poor diagnostic accuracy

Objective: To characterize the influence of relative wall thickness (RWT) on Cornell, Sokolow-Lyon and Peguero-Lo Presti voltages and elucidate its potential impacts on their diagnostic accuracy for LVH in a large general Chinese population.Methods: A total of 10,614 permanent residents aged ≥ 35 years were recruited for this study. All the participants were subjected to ECG and echocardiogram during the same visit. Multivariate linear and logistic regression analyzes were conducted to assess the influence of RWT on the voltages and their diagnostic performance for LVH detection.Results: A distinct correlation was identified between RWT and Cornell and Peguero-Lo Presti voltages following adjustments for age, gender and left ventricular mass (LVM) (β = 0.675 and 1.342, respectively; Ps < 0.001). Besides, subjects with RWT > 0.42 exhibited higher rates of LVH diagnosed by Cornell (OR = 1.78, 95% CI: 1.45-2.20), Sokolow-Lyon (OR = 1.30, 95% CI: 1.08-1.56), and Peguero-Lo Presti voltage (OR = 1.48, 95% CI: 1.29-1.70) after adjustments for age, gender and echocardiographic LVH. Furthermore, concentric remodeling or concentric hypertrophy displayed higher rates of LVH diagnoses via Cornell and Peguero-Lo Presti voltage criteria, as compared with normal geometry or eccentric hypertrophy, respectively (all Ps < 0.05), findings of which were independent of age, gender and LVMI.Conclusion: Echocardiographic RWT was independently correlated with electrocardiographic voltage measures of LVH, which influenced their positive rates and contributed to poor diagnostic performance.

Left Ventricular Hypertrophy by the Surface ECG

Left ventricular hypertrophy (LVH) is defined as an increase in left ventricular mass (LVM) associated with structural changes of myocardium. The increase in LVM and associated changes are associated with changes in depolarization and repolarization, manifested as a variety of altered QRS and T patterns. Increased QRS voltage has been considered to be a specific ECG finding in LVH, and ECG criteria based on this increased QRS voltage are generally recommended. These ECG changes are also predictive of adverse cardiovascular outcomes. However, it must also be noted that the majority of patients with increased LVM do not have increased QRS voltage. While this is often considered a limitation of ECG in LVH diagnosis, the authors of this minireview consider it more likely that the electrical effects, represented in the altered ECG, and the increased LVM are independent effects, associated by virtue of their common relationship with an underlying pathologic state. This revised view challenges cardiologists and electrocardiologists to explore the interrelationships between electrical, biochemical, and mechanical alterations of myocardial remodeling seen with heart disease, to advance our understanding of this process and its effects, including the evolution of the ECG changes known as "LVH".

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.

Can we protect from malignant arrhythmias by modulation of cardiac cell-to-cell coupling?

Defects in intercellular coupling in the heart play a key role in the initiation and persistence of malignant arrhythmias. Such disorders result from abnormal expression and distribution of connexins, the major constituents of cardiac gap junction channels. The alterations of myocardial connexin are well established as a consistent feature of both human and animal heart disease and aging. Following these facts, the modulation of connexin mediated intercellular coupling is suggested as a new antiarrhythmic approach. This review provides recent data supporting this concept. It can be challenging for the development of new antiarrhythmic drugs. Moreover, findings point out the implication of some endogenous compounds in protection from life-threatening arrhythmias via preservation of myocardial connexin.