Low QRS voltage and its causes

Early detection of low QRS voltage and its association with mortality in patients with sepsis

Various electrocardiographic changes occur during sepsis, but data on the clinical importance of a low QRS voltage in sepsis are still limited. We aimed to evaluate the association between low QRS voltage identified early in sepsis and mortality in patients with sepsis. Between September 2019 and December 2020, all consecutive adult patients diagnosed with sepsis in the emergency room or general ward at Samsung Medical Center were enrolled. Patients without a 12-lead electrocardiogram recorded within 48 h of recognition of sepsis were excluded. In 432 eligible patients, 12-lead electrocardiogram was recorded within the median of 24 min from the first recognition of sepsis, and low QRS voltage was identified in 115 (26.6%) patients. The low QRS group showed more severe organ dysfunction and had higher levels of N-terminal pro-brain natriuretic peptide. The hospital mortality was significantly higher in the low QRS voltage group than in the normal QRS voltage group (49.6% vs. 28.1%, p < 0.001). Similarly, among the 160 patients who required intensive care unit admission, significantly more patients in the low QRS group died in the intensive care unit (35.9% vs. 18.2%, p = 0.021). Low QRS voltage was associated with increased hospital mortality in patients with sepsis.

Beating the heart failure odds: long-term survival after myocardial ischemia in juvenile rainbow trout

Salmonid fish include some of the most valued cultured fish species worldwide. Unlike most other fish, the hearts of salmonids, including Atlantic salmon and rainbow trout, have a well-developed coronary circulation. Consequently, their hearts' reliance on oxygenation through coronary arteries leaves them prone to coronary lesions, believed to precipitate myocardial ischemia. Here, we mimicked such coronary lesions by subjecting groups of juvenile rainbow trout to coronary ligation, assessing histomorphological myocardial changes associated with ischemia and scarring in the context of cardiac arrhythmias using electrocardiography (ECG). Notable ECG changes resembling myocardial ischemia-like ECG in humans, such as atrioventricular blocks and abnormal ventricular depolarization (prolonged and fragmented QRS complex), as well as repolarization (long QT interval) patterns, were observed during the acute phase of myocardial ischemia. A remarkable 100% survival rate was observed among juvenile trout subjected to coronary ligation after 24 wk. Recovery from coronary ligation occurred through adaptive ventricular remodeling, coupled with a fast cardiac revascularization response. These findings carry significant implications for understanding the mechanisms governing cardiac health in salmonid fish, a family particularly susceptible to cardiac diseases. Furthermore, our results provide valuable insights into comparative studies on the evolution, pathophysiology, and ontogeny of vertebrate cardiac repair and restoration.NEW & NOTEWORTHY Juvenile rainbow trout exhibit a remarkable capacity to recover from cardiac injury caused by myocardial ischemia. Recovery from cardiac damage occurs through adaptive ventricular remodeling, coupled with a rapid cardiac revascularization response. These findings carry significant implications for understanding the mechanisms governing cardiac health within salmonid fishes, which are particularly susceptible to cardiac diseases.

Electrocardiographic features and rhythm disorders in cardiac amyloidosis

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy caused by extracellular deposition of amyloid fibrils, mainly derived from transthyretin, either wild-type or hereditary variants, or immunoglobulin light chains misfolding. It is characterized by an increased left ventricular (LV) mass and diastolic dysfunction, which can lead to heart failure with preserved ejection fraction and/or conduction disturbances. The diagnosis is based on invasive pathology demonstration of amyloid deposits, or non-invasive criteria using advanced cardiovascular imaging techniques. Nevertheless, 12-lead electrocardiogram (ECG) remains of crucial importance in the assessment of patients with CA, since they can manifest peculiar features such as low QRS voltages, in discordance with the LV hypertrophy, but also pseudo-infarction patterns, sinus node dysfunction, atrioventricular blocks, premature supraventricular and ventricular beats, which support the presence of a myocardial disease. Great awareness of these common ECG characteristics of CA is needed to increase diagnostic performance and improve patient's outcome. In the present review, we discuss the current role of the ECG in the diagnosis and management of CA, focusing on the most common ECG abnormalities and rhythm disorders.

Should ECG criteria for Low QRS voltage (LQRSV) be specific for Sex?

INTRODUCTION

Low QRS peak-to-nadir voltage (LQRSV) is associated with arrhythmogenic right ventricular cardiomyopathy (ARVC) and other cardiomyopathies. Recent studies have proposed criteria for LQRSV when screening athletes for cardiovascular disease. These criteria have not yet been evaluated in a large population of healthy young athletes.

METHODS

The target population was 10,728 (42.5% female, 57.5% male, mean age 18.1 ± 4.3 years) athletes who participated in mass ECG screenings between 2014 and 2021 at multiple sites across the United States including grade schools (11%), high schools (32%), colleges (50%), and professional athletic teams (6%) with digitally recorded ECGs and a standardized protocol. Since by design, complete follow up for outcomes and the results of testing were not available. Including only ECGs from initial evaluation among athletes 14-35 years of age and excluding those with right bundle branch block, left bundle branch block, Wolf-Parkinson-White pattern, reversed leads and 3 clinically diagnosed cardiomyopathies at Stanford, 8,679 (58% males, 42% females) remained eligible for analysis. QRS voltage was analyzed for each ECG lead and LQRSV criteria were applied and stratified by sex.

RESULTS

QRS voltage was lower in all leads in female athletes compared to male athletes. Using traditional limb lead criteria or precordial lead criteria, the prevalence of LQRSV was significantly lower in males than females (P < .001). Strikingly, LQRSV using the Sokolow-Lyon Index was present in 1.9% of males and 9.8% of females (P < .001). Applying first percentile for LQRS amplitude criteria provided possible values for screening young athletes for LQRSV.

CONCLUSIONS

LQRSV is more common among female athletes than male athletes using established criteria. Using first percentile sex-specific cut points should be considered in future analyses. Proposed novel LQRSV criteria in young athletes should be specific for males and females.

The International Criteria for Electrocardiogram Interpretation in Athletes: Common Pitfalls and Future Directions

Preparticipation cardiovascular screening (PPCS) in young athletes is performed to detect conditions associated with sudden cardiac death. Many medical societies and sports governing bodies support the addition of a 12-lead electrocardiogram (ECG) to the history and physical to improve PPCS sensitivity. The current standard for ECG interpretation in athletes, the International Criteria, was developed to distinguish physiologic from pathologic ECG findings in athletes. Although application of the International Criteria has reduced the PPCS false-positive rate, interpretative challenges and potential areas of improvement remain. This review provides an overview of common pitfalls and future directions for ECG interpretation in athletes.

Prevalence and clinical significance of low QRS voltages in healthy individuals, athletes and patients with cardiomyopathy: implications for sports preparticipation cardiovascular screening

Low QRS voltages (LQRSV), defined as a QRS amplitude from peak to nadir <0.5 mV in all limb leads, are an emerging diagnostic finding on the electrocardiogram (ECG). In healthy individuals and athletes, LQRSV are rare (2.2-4% of elite athletes, 0.5% of recreational athletes and 0.3% of sedentary individuals). LQRSV athletes commonly show ventricular arrhythmias (VAs) on exercise, and up to 40% of those with LQRSV and VAs have late gadolinium (LGE) on cardiac magnetic resonance (CMR). The prevalence of LQRSV in arrhythmogenic cardiomyopathy (ACM) ranges 17-40%, predicts left ventricular (LV) involvement, and is correlated with more extensive LGE replacement on CMR. In hypertrophic cardiomyopathy (HCM), LQRSV ranges 0.7% to 11%. LQRSV-HCM patients have more segments with LGE, despite relatively smaller LV mass, suggesting a more advanced clinical stage and a worse prognosis. In dilated cardiomyopathy (DCM), LQRSV range 6%-7%, but may be higher (36%) in certain genetic forms of DCM. On a follow-up, LQRSV are independently associated with incident cardiac events, such as sudden death, sustained ventricular arrhythmia, or appropriate internal cardioverter defibrillator discharge. In cardiac amyloid (CA), LQRSV range from 34% to 66% and demonstrate a negative prognostic value, with worse clinical outcomes regardless of underlying biologic, genetic, and clinical variables. In conclusion, LQRSV deserve careful consideration for exclusion of arrhythmogenic substrates in healthy individuals, athletes, and patients. While additional research is needed, it is reasonable that LQRSV should trigger clinical investigation to exclude underlying diseases at risk of life-threatening arrhythmias.

An unusual presentation of low QRS voltage in a patient with aortic aneurysm

There are many causes of low QRS voltage on the electrocardiogram (ECG). Although uncommon, there is evidence that an enlarged aorta can cause diminished QRS amplitude on ECG. In this case report, we describe an unusual presentation of low QRS voltage confined to the first three precordial leads (V1-V3) in a 77-year-old female with ascending aortic aneurysm. Analysis of the patient's medical history, echocardiogram and contrast-enhanced computed tomography indicates that the ECG pattern was caused by interposition of the aortic aneurysm between the heart and the skin electrodes (V1-V3), revealing a possible indirect sign for large aortic aneurysm on ECG.

Low QRS voltages and left ventricular hypertrophy: a risky association

AIMS

Low QRS voltages (LQRSV) are an unexpected finding in left ventricular hypertrophy, i.e. hypertrophic cardiomyopathy (HCM) or athlete's heart.

METHODS AND RESULTS

Prevalence and clinical correlates of LQRSV were investigated in 197 consecutive HCM patients, aged 58 ± 13 years and comparatively in 771 Olympic athletes, aged 23 ± 4. Clinical characterization included family/personal history, symptoms, New York Heart Association (NYHA) functional class, electrocardiographic pattern, ventricular arrhythmias, and cardiac magnetic resonance (CMR). Twenty-two (11%) of HCM and 18 (2.3%) of athletes presented LQRSV. At initial evaluation, in HCM, LQRSV showed no differences vs. non-LQRSV for functional class (90% vs. 91%, in Classes I and II; P = 0.983), symptoms (27% vs. 18%; P = 0.478), and ventricular arrhythmias (40% vs. 39%; P = 857) but showed larger extent of late gadolinium enhancement (LGE) at CMR (4.1 ± 1.5 vs. 1.5 ± 0.7 affected segments; P < 0.001). In athletes, LQRSV was associated with larger prevalence of inverted T-waves (22% vs. 9%; P < 0.001) and ventricular arrhythmias (28% vs. 8%; P = 0.005). In one LQRSV athlete, arrhythmogenic cardiomyopathy was identified. Over 4.5 ± 2.6-year follow-up, presence of LQRSV in HCM was associated with larger incidence of functional deterioration (31% vs. 14%; P = 0.038), stroke (22% vs. 6%; P = 0.008), and implantable cardioverter defibrillator (ICD) implant (27% vs. 10%; P = 0.015). No clinical events occurred in LQRSV athletes without initial evidence of cardiac disease.

CONCLUSION

LQRSV are relatively common (11%) in HCM and have clinical relevance, being predictive over a medium term for a worsening functional class, incidence of stroke, and ICD implant. Instead, LQRSV are rare (2.3%) in athletes but may occasionally be a marker that raises suspicion for underlying cardiac disease at risk.

The International Criteria for Electrocardiogram Interpretation in Athletes: Common Pitfalls and Future Directions

Preparticipation cardiovascular screening (PPCS) in young athletes is performed to detect conditions associated with sudden cardiac death. Many medical societies and sports governing bodies support the addition of a 12-lead electrocardiogram (ECG) to the history and physical to improve PPCS sensitivity. The current standard for ECG interpretation in athletes, the International Criteria, was developed to distinguish physiologic from pathologic ECG findings in athletes. Although application of the International Criteria has reduced the PPCS false-positive rate, interpretative challenges and potential areas of improvement remain. This review provides an overview of common pitfalls and future directions for ECG interpretation in athletes.

The juvenile ECG pattern in adolescent athletes and non-athletes in a national cardiac screening program (BEAT-IT)

BACKGROUND

Anterior T wave inversion (TWI) is frequent in healthy adolescent individuals (juvenile ECG pattern), normalising after puberty. Its clinical implications are uncertain.

AIM

This study assessed a) national prevalence of anterior TWI, b) ST segment morphology, c) proportion of individuals with a juvenile ECG pattern whose ECG normalises and d) factors predicting TWI persistence >16 years.

METHODS

Adolescents (mean 15y) in Malta were systematically invited to enrol in a cardiac screening program. Subjects completed a health questionnaire and an ECG at their school. Participants with TWI were labelled as TWI in V₁-V₂ or extended TWI (V₁-V₃/₄). The latter were followed at 1 year with a repeat ECG. Those with persistent extended anterior TWI were offered evaluation and surveillance.

RESULTS

The prevalence of isolated anterior TWI was 5.0%, commoner in females (6.3%) independent of athletic ability. Extended TWI was commoner in female athletes (4.2%, non-athletes 2.1%). Females often had shallow TWI without overt ST segment abnormalities. Deep TWI and ST segment changes were more frequent in males. Only 0.2% of cases persisted ≥16 years of age. ST segment characteristics were not able to predict T wave normalisation. No events took place during follow up (40 ± 9 months).

CONCLUSION

Anterior TWI is a frequent phenomenon in adolescents, especially in females. Female athletes are also more likely to have extended anterior TWI. Only 0.2% of cases have persistent anterior TWI at 16 years of age. Chest wall anatomy may explain this phenomenon in females. It is uncommon in males, hence why surveillance is more prudent.

Metformin and Dapagliflozin Attenuate Doxorubicin-Induced Acute Cardiotoxicity in Wistar Rats: An Electrocardiographic, Biochemical, and Histopathological Approach

Doxorubicin is a widely used anticancer drug whose efficacy is limited due to its cardiotoxicity. There is no ideal cardioprotection available against doxorubicin-induced cardiotoxicity. This study aimed to investigate the anticipated cardioprotective potential of metformin and dapagliflozin against doxorubicin-induced acute cardiotoxicity in Wistar rats. At the beginning of the experiment, cardiac screening of experimental animals was done by recording an electrocardiogram (ECG) before allocating them into the groups. Thereafter, a total of thirty healthy adult Wistar rats (150-200 g) were randomly divided into five groups (n = 6) and treated for eight days as follows: group I (normal control), group II (doxorubicin control), group III (metformin 250 mg/kg/day), group IV (metformin 180 mg/kg/day), and group V (dapagliflozin 0.9 mg/kg/day). On the 7th day of the treatment phase, doxorubicin 20 mg/kg was administered intraperitoneal to groups II, III, IV, and V. On the 9th day (immediately after 48 h of doxorubicin administration), blood was collected from anesthetized animals for glucose, lipid profile, CK-MB & AST estimation, and ECG was recorded. Later, animals were sacrificed, and the heart was dissected for histopathological examination. We found that compared to normal control rats, CK-MB, AST, and glucose were significantly increased in doxorubicin control rats. There was a significant reversal of doxorubicin-induced hyperglycemia in the rats treated with metformin 250 mg/kg compared to doxorubicin control rats. Both metformin (180 mg/kg and 250 mg/kg) and dapagliflozin (0.9 mg/kg) significantly altered doxorubicin-induced ECG changes and reduced the levels of cardiac injury biomarkers CK-MB and AST compared to doxorubicin control rats. Metformin and dapagliflozin protected the cellular architecture of the myocardium from doxorubicin-induced myocardial injury. Current study revealed that both metformin and dapagliflozin at the FDA-recommended antidiabetic doses mitigated doxorubicin-induced acute cardiotoxicity in Wistar rats. The obtained data have opened the perspective to perform chronic studies and then to clinical studies to precisely consider metformin and dapagliflozin as potential chemoprotection in the combination of chemotherapy with doxorubicin to limit its cardiotoxicity, especially in patients with comorbid conditions like type II diabetes mellitus.

Electro- and echocardiographic features of left ventricle hypertrophy in patients with hypertrophic cardiomyopathy

Background

Standard 12‐lead electrocardiogram (ECG), next to medical history and physical examination, is a basic screening tool for hypertrophic cardiomyopathy in General practice. There are many electrocardiographic criteria of left ventricular hypertrophy, but their accuracy is usually weak in patients with systemic hypertension or aortic stenosis. Sensitivity of these criteria in patients with HCM has not been well described.

Aim

To assess the prevalence of electrocardiographic criteria for LVH in patients with HCM and their relationship with echocardiographic parameters.

Material and methods

A total of 49 patients with HCM (mean age 53.2 ± 15.4 years; men/women: 31/18) were enrolled to study. Eight electrocardiographic criteria for LVH were evaluated and correlated with echocardiographic parameters.

Results

The ECG features of LVH were found in 36 (73.5%) subjects. These patients had increased thickness of intraventricular septum (20.5 ± 4.7 vs. 17.3 ± 3.2 mm, p = .03), LVM (340.5 ± 104.8 vs. 264.0 ± 61.5 g; p = .02), and LVMI (178.9 ± 48.8 vs. 125.9 ± 22.5; p = .002). All of ECG criteria for LVH had low sensitivity (14.3%–40.8%) for LVH diagnosis confirmed by echocardiography. The most common positive criterion was Cornell Voltage (20 patients; 40.8%). A total of 41 (83.4%) patients had T‐wave inversion in limb and/or precordial leads. LVMI correlated positively with R‐wave amplitude in aVL (R = 0.34; p = .03), Gubner‐Ungerleider voltage (R = 0.4; p = .009), and Cornell Voltage (R = 0.31; p = .04).

Conclusion

ECG criteria for LVH are characterized by poor sensitivity in patients with HCM. Cornell Voltage and criteria based on limb leads correlate positively with LVMI.

Can the ECG be used to estimate age-related survival?

BACKGROUND

There are few reports of the relationship between electrocardiogram (ECG) findings and the age-related survival of acutely ill patients.

AIM

This study compared the 1-year survival curves of patients attending two Danish emergency departments (EDs) with normal and abnormal ECGs. Patients were divided into age groups from 20 to 90 years of age, and an abnormal ECG was defined as low QRS voltage (i.e. lead I + II <1.4 mV) or QTc interval prolongation >434 ms.

METHODS

A retrospective register-based observational study on 35 496 patients attending two Danish EDs, with 100% follow-up for 1 year.

RESULTS

ECG abnormality increases linearly with age, and between 30 and 70 years of age. Patients aged 20-29 years with ECG abnormalities are more than four times more likely to die within a year than patients of the same age with a normal ECG. An individual with an abnormal ECG has the same risk of dying within a year as an individual with a normal ECG who is 10 years older. After 70 years of age this tight relationship ends, but for younger individuals with an abnormal ECG the increase in mortality is even higher.

CONCLUSION

An ECG may be a simple practical estimate of age-related survival. For a patient under 70 years, an abnormal QRS voltage or a prolonged QTc interval may increase 1-year mortality to that of a patient ∼10 years older.

A deep learning approach identifies new ECG features in congenital long QT syndrome

BACKGROUND

Congenital long QT syndrome (LQTS) is a rare heart disease caused by various underlying mutations. Most general cardiologists do not routinely see patients with congenital LQTS and may not always recognize the accompanying ECG features. In addition, a proportion of disease carriers do not display obvious abnormalities on their ECG. Combined, this can cause underdiagnosing of this potentially life-threatening disease.

METHODS

This study presents 1D convolutional neural network models trained to identify genotype positive LQTS patients from electrocardiogram as input. The deep learning (DL) models were trained with a large 10-s 12-lead ECGs dataset provided by Amsterdam UMC and externally validated with a dataset provided by University Hospital Leuven. The Amsterdam dataset included ECGs from 10000 controls, 172 LQTS1, 214 LQTS2, and 72 LQTS3 patients. The Leuven dataset included ECGs from 2200 controls, 32 LQTS1, and 80 LQTS2 patients. The performance of the DL models was compared with conventional QTc measurement and with that of an international expert in congenital LQTS (A.A.M.W). Lastly, an explainable artificial intelligence (AI) technique was used to better understand the prediction models.

RESULTS

Overall, the best performing DL models, across 5-fold cross-validation, achieved on average a sensitivity of 84 ± 2%, 90 ± 2% and 87 ± 6%, specificity of 96 ± 2%, 95 ± 1%, and 92 ± 4%, and AUC of 0.90 ± 0.01, 0.92 ± 0.02, and 0.89 ± 0.03, for LQTS 1, 2, and 3 respectively. The DL models were also shown to perform better than conventional QTc measurements in detecting LQTS patients. Furthermore, the performances held up when the DL models were validated on a novel external cohort and outperformed the expert cardiologist in terms of specificity, while in terms of sensitivity, the DL models and the expert cardiologist in LQTS performed the same. Finally, the explainable AI technique identified the onset of the QRS complex as the most informative region to classify LQTS from non-LQTS patients, a feature previously not associated with this disease.

CONCLUSIONS

This study suggests that DL models can potentially be used to aid cardiologists in diagnosing LQTS. Furthermore, explainable DL models can be used to possibly identify new features for LQTS on the ECG, thus increasing our understanding of this syndrome.

The Abnormal Sinus Rhythm: Myxedema Coma Complicated by Subacute Cardiac Tamponade

Subacute cardiac tamponade (SCT) is a potentially life-threatening condition that requires immediate medical attention. Combining careful history taking, focused physical exam, and the use of point of care ultrasound (POCUS) for early diagnosis with aggressive management can minimize potential complications. In patients with severe hypothyroidism and myxedema coma, clinical signs of cardiac tamponade may be masked and lead to delayed diagnosis. We present a case of a 67-year-old female with SCT secondary to myxedema coma, necessitating emergent pericardiocentesis following the identification of a large pericardial effusion with tamponade physiology. This case highlights the importance of thorough history taking with focused diagnostic workup, including POCUS in patients with an insidious presentation of SCT.

Low QRS Voltage in Limb Leads Indicates Accompanying Precordial Voltage Attenuation Resulting in Underestimation of Left Ventricular Hypertrophy

Low QRS voltage (LQRSV) in electrocardiography (ECG) often occurs in limb leads without apparent cause. However, its clinical significance is obscure in healthy populations. We reviewed patients aged over 60 who were scheduled for non-cardiac surgery in two hospitals. Patients underwent pre-operative ECG, echocardiography, pulmonary function test, and chest X-ray. Patients with LQRSV isolated to limb leads and patients without LQRSV were selected from separate hospitals. Among the 9832 patients screened in one hospital, 292 (3.0%) showed LQRSV in limb leads. One-hundred and ninety-four without LQRSV were selected as the control from the 216 patients screened at the other hospital. For primary analysis, patients with structural heart disease or classic etiologies of LQRSV were excluded. Patients with LQRSV had a higher proportion of male and a greater body mass index. Precordial QRS voltages were smaller, whereas left ventricular mass index and the prevalence of echocardiographic left ventricular hypertrophy (LVH) was higher in patients with LQRSV than in those without. Consequentially, diagnostic performance of precordial voltage criteria for LVH was particularly poor in patients with LQRSV in limb leads. LQRSV in limb leads frequently occurs without apparent etiologies. ECG voltage criteria may underestimate LVH in a relatively healthy population with LQRSV in limb leads.

Late cardiac toxicity of neo-adjuvant chemoradiation in esophageal cancer survivors: A prospective cross-sectional pilot study

PURPOSE

Although cure rates in esophageal cancer (EC) have improved since the introduction of neoadjuvant chemoradiation (nCRT), evidence for treatment-related cardiac toxicity is growing, of which the exact mechanisms remain unknown. The primary objective of this study was to identify (subclinical) cardiac dysfunction in EC patients after nCRT followed by surgical resection as compared to surgery alone.

MATERIALS AND METHODS

EC survivors followed for 5-15 years after curative resection with (n = 20) or without (n = 20) nCRT were enrolled in this prospective cross-sectional pilot study. All patients underwent several clinical and diagnostic tests in order to objectify (sub)clinical cardiac toxicity including cardiac CT and MRI, echocardiography, ECG, 6-minutes walking test, physical examination and EORTC questionnaires.

RESULTS

We found an increased rate of myocardial fibrosis (Linear late gadolinium enhancement (LGE) 4 vs. 1; p = 0.13; mean extracellular volume (ECV) 28.4 vs. 24.0; p < 0.01), atrial fibrillation (AF) (6 vs. 2; p = 0.07) and conduction changes in ECG among patients treated with nCRT as compared to those treated with surgery alone. The results suggested an impact on quality of life in terms of worse role functioning for this patient group (95.0 vs. 88.8; p = 0.03).

CONCLUSION

Based on our analyses we hypothesize that in EC patients, radiation-induced myocardial fibrosis plays a central role in cardiac toxicity leading to AF, conduction changes and ultimately to decreased role functioning. The results emphasize the need to verify these findings in larger cohorts of patients.

Prognostic Value of Electrocardiographic QRS Diminution in Patients Hospitalized With COVID-19 or Influenza

During the clinical care of hospitalized patients with COVID-19, diminished QRS amplitude on the surface electrocardiogram (ECG) was observed to precede clinical decompensation, culminating in death. This prompted investigation into the prognostic utility and specificity of low QRS complex amplitude (LoQRS) in COVID-19. We retrospectively analyzed consecutive adults admitted to a telemetry service with SARS-CoV-2 (n = 140) or influenza (n = 281) infection with a final disposition-death or discharge. LoQRS was defined as a composite of QRS amplitude <5 mm or <10 mm in the limb or precordial leads, respectively, or a ≥50% decrease in QRS amplitude on follow-up ECG during hospitalization. LoQRS was more prevalent in patients with COVID-19 than influenza (24.3% vs 11.7%, p = 0.001), and in patients who died than survived with either COVID-19 (48.1% vs 10.2%, p <0.001) or influenza (38.9% vs 9.9%, p <0.001). LoQRS was independently associated with mortality in patients with COVID-19 when adjusted for baseline clinical variables (odds ratio [OR] 11.5, 95% confidence interval [CI] 3.9 to 33.8, p <0.001), presenting and peak troponin, D-dimer, C-reactive protein, albumin, intubation, and vasopressor requirement (OR 13.8, 95% CI 1.3 to 145.5, p = 0.029). The median time to death in COVID-19 from the first ECG with LoQRS was 52 hours (interquartile range 18 to 130). Dynamic QRS amplitude diminution is a strong independent predictor of death over not only the course of COVID-19 infection, but also influenza infection. In conclusion, this finding may serve as a pragmatic prognostication tool reflecting evolving clinical changes during hospitalization, over a potentially actionable time interval for clinical reassessment.

Discrepancy between left ventricular hypertrophy by echocardiography and electrocardiographic hypertrophy: clinical characteristics and outcomes

Background

The clinical significance of the discrepancy between left ventricular hypertrophy (LVH) by echocardiography and ECG remains to be elucidated.

Methods

After excluding patients who presented with pacemaker placement, QRS duration ≥120 ms and cardiomyopathy and moderate to severe valvular disease, we retrospectively analysed 3212 patients who had undergone both scheduled transthoracic echocardiography (echo) and ECG in a hospital-based population. Cornell product >2440 mm · ms was defined as ECG-based LVH; left ventricular mass index >115 g/m² for men and >95 g/m² for women was defined as echo-based LVH. The study population was categorised into four groups: patients with both ECG-based and echo-based LVH (N=131, 4.1%), those with only echo-based LVH (N=156, 4.9%), those with only ECG-based LVH (N=409, 12.7%) and those with no LVH (N=2516, 78.3%).

Results

The cumulative 3-year incidences of a composite of all-cause death and major adverse cardiovascular events were 32.0%, 33.8%, 19.2% and 15.7%, respectively. After adjusting for confounders, the HRs relative to that in no LVH were 1.63 (95% CI 1.16 to 2.28), 1.68 (95% CI 1.23 to 2.30) and 1.09 (95% CI 0.85 to 1.41) in patients with both ECG-based and echo-based LVH, those with only echo-based LVH, and those with only ECG-based LVH, respectively.

Conclusions

Echo-based LVH without ECG-based LVH was associated with a significant risk of adverse clinical events, and the risk was comparable to that in patients with both echo-based and ECG-based LVH.

Electrocardiographic Patterns in Patients with Neurally Mediated Syncope

The baseline electrocardiogram (ECG) is less informative in neurally mediated syncope (NMS) than in arrhythmic syncope. However, some of the ECG patterns present in NMS can have diagnostic and prognostic value in such patients. Electrocardiographic documentation of a syncopal spell and thus identification of the ECG changes can be performed during tilt table test (TTT) or during prolonged ECG monitoring. This work reviews the specific ECG patterns in NMS, which are primarily related to the cardioinhibitory reflex. In addition, there are other ECG findings present in patients with NMS that are being analyzed, such as increased heart rate variability as well as specific QRS voltage patterns. In addition to the diagnostic and prognostic value, these ECG patterns in NMS may help improving the selection of patients for pacemaker implant.

Methyl Gallate Attenuates Doxorubicin-Induced Cardiotoxicity in Rats by Suppressing Oxidative Stress

Doxorubicin-induced cardiotoxicity is the leading cause of morbidity and mortality among cancer survivors. The present study was aimed to investigate the cardioprotective potential of methyl gallate; an active polyphenolic nutraceutical, against doxorubicin-induced cardiotoxicity in Wistar rats. Twenty-four female Wistar rats (150-200 g) were divided into four groups (n = 6) which consist of normal control (group I), doxorubicin control (group II), test-A (group III), and test-B (group IV). Group III and group IV animals were prophylactically treated with methyl gallate 150 mg/kg/day and 300 mg/kg/day orally, respectively, for seven days. Doxorubicin (25 mg/kg; single dose) was administered through an intraperitoneal route to group II, III, and IV animals on the seventh day to induce acute cardiotoxicity. On the 8^th day, besides ECG analysis, serum CK, CK-MB, LDH, AST, MDA, and GSH were assayed. Following gross examination of isolated hearts, histopathological evaluation was performed by light microscopy. A significant (p < 0.05) cardiac injury, as well as oxidative stress, was observed in doxorubicin control rats in comparison to normal control rats. Methyl gallate at both the doses significantly (p < 0.05) reduced doxorubicin-induced ECG changes, dyslipidaemia, and elevation of CK, CK-MB, LDH, AST, MDA and increased GSH level. Methyl gallate reversed the doxorubicin-induced histopathological changes in the heart. The present study revealed that methyl gallate exerts cardioprotection against doxorubicin-induced cardiotoxicity in female Wistar rats by suppressing oxidative stress. Our study opens the perspective to clinical studies for consideration of methyl gallate as a potential chemoprotectant nutraceutical in the combination chemotherapy with doxorubicin to limit its cardiotoxicity.

[CME-ECG 70: Chest Pain in a Young Patient - Differential Diagnoses beyond the Acute Coronary Syndrome]

CME-ECG 70: Chest Pain in a Young Patient - Differential Diagnoses beyond the Acute Coronary Syndrome Abstract. Older patients with chest pain and typical ECG changes are most likely to be diagnosed with cardiovascular diseases. However, younger patients with similar symptoms may reveal different disease patterns. In this case report, differential diagnoses and diagnostic steps, with particular attention to the ECG, will be discussed.

Cardiac biomarkers of disordered eating as a function of diagnostic subtypes

OBJECTIVE

The purpose of this study was to identify cardiac biomarkers of disordered eating as a function of diagnostic subtype as assessed via self-report inventory.

METHOD

Mean heart rate (HR), systolic and diastolic blood pressure, mean R wave amplitude (mV), mean T wave amplitude (mV), QTc interval (sec), Tpeak-Tend interval prolongation (sec), QTc interval prolongation (sec), QRS prolongation (sec), and spectral indicators of cardiac dysfunction (LF/HF spectral ratio, HF spectral power) were assessed via electrocardiography among women with no eating disorder symptoms (n = 32), subclinical eating disorder symptoms (n = 92), anorexia nervosa (n = 7), bulimia nervosa (n = 89), binge eating disorder (BED: n = 20), and other specified feeding and eating disorders (OSFED: n = 19).

RESULTS

MANOVA results showed statistically significant group differences. Follow-up tests revealed significantly decreased mean R wave amplitude among participants with self-indicated clinical (bulimia nervosa, binge eating disorder) and subclinical forms of disordered eating compared to asymptomatic controls.

DISCUSSION

Results suggest decreased mean R wave amplitude is a promising cardiac biomarker of disordered eating.

Prognostic value of Goldberger's electrocardiographic criteria for left ventricular dysfunction

BACKGROUND

The ability of the Goldberger electrocardiographic (ECG) triad criteria to detect left ventricular dysfunction (LVD) is well-established. However, the prognostic significance of this triad as a predictor of poor outcomes is not known.

OBJECTIVE

We explored the association between the Goldberger ECG-LVD triad with all-cause mortality and cardiovascular mortality in the general population.

METHODS

This analysis included 8426 participants (60.5 ± 13.6 years, 51.5% women, 50% non-Hispanic white) from the Third National Health and Nutrition Examination Survey. The Goldberger ECG-LVD triad was defined as follows: high precordial QRS voltage (SV1 or SV2 + RV5 or RV6 ≥ 3500 μV); low limb lead QRS voltage (mean QRS amplitude in each of the limb leads ≤800 μV); and poor R wave progression (RV4/SV4 < 1). Mortality was ascertained using the National Death Index.

RESULTS

At baseline, 1384 (47.3%) of the participants had at least one of the criteria of Goldberger triad (1193 had only one and 191 participants had 2 or more). During a median follow up of 13.8 years, 3184 deaths occurred, of which 1405 were cardiovascular. In multivariable-adjusted Cox proportional hazards models, presence of at least one of the Goldberger triad criteria (vs. none) was associated with increased risk of all-cause (HR 1.17, 95% CI 1.08-1.26, p ≤0.0001) and cardiovascular mortality (1.19, 1.06-1.33, p = 0.003).

CONCLUSION

The Goldberger ECG-LVD triad for left ventricular dysfunction may offer prognostic value in addition to its reported diagnostic utility.

Electrocardiographic Findings in Bitches Affected by Closed Cervix Pyometra

Pyometra is considered the most common disease in intact bitches, being associated with potentially life-threatening disorders. Myocardial damage is a potentially life-threatening consequence of pyometra. The aim of this study was to describe the electrocardiographic patterns in bitches affected by closed cervix pyometra, to assess the clinical relevance of electrocardiographic changes with the occurrence of pyometra, and to relate their severity with laboratory and clinical findings. A total of 39 bitches with closed cervix pyometra and 10 healthy female dogs were included in this study. During the hospitalization, bitches underwent a complete physical examination. An electrocardiographic examination before the ovariohysterectomy was performed. Blood samples for biochemical and hematological analysis were also evaluated. Bitches suffering pyometra at least one arrhythmia 31/39 (79.4%), sinus tachycardia (22/39, 56.4%), ventricular premature complexes (9/39, 23%), increased amplitude of T wave (7/39, 17.9%), ST depression (4/39, 10.2%), second-degree atrioventricular block (2/39, 5.1%), increase of QT interval (2/39, 5.1%), sinus bradycardia (2/39, 5.1%), and first-degree atrioventricular block (1/39, 2.5%). Some bitches were also detected with low wave amplitude (17/39, 43.5%). Cardiac arrhythmias associated with canine pyometra are frequent events. These data suggest that arrhythmias may be the consequence of one or more factors that can occur during pyometra, such as myocardial damage, electrolyte/metabolic disorders, and/or sepsis.

Relation of QRS Voltage and Prolonged QTc Interval to One-Year Mortality

The association between QRS voltage and QTc interval prolongation with mortality for up to 1 year after recording an ECG on patients attending emergency departments (EDs) was examined in a retrospective register-based observational study on 37,473 patients attending 2 Danish EDs. Of 37,473 patients who had an ECG performed on their first ED presentation 2,164 (5.8%) died within 30 days of presentation and 6,395 (17.1%) died within a year. Compared with survivors, patients who died had significantly longer QRS intervals and lower QRS voltages. A combined lead I and II QRS voltage <=1.4 mV was consistently associated with approximately twice the risk of mortality for up to at least 1 year after the ECG recording and this risk was not influenced by the length of the QTc interval. The increased mortality risk of a low QRS voltage remained even after adjustment for age, gender, Charlson co-morbidity index, and abnormal sodium and urea levels. In conclusion, low QRS voltage is a simple measurement that could potentially be used as an objective prognostic marker.

Diagnostic and prognostic value of low QRS voltages in cardiomyopathies: old but gold

The interpretation of 12-lead resting electrocardiogram (ECG) in patients with a definitive diagnosis or with the suspicion of a cardiomyopathy represents a cornerstone for the diagnostic work up and management of patients. Although low electrocardiographic QRS voltages (LQRSV) detected by 12-lead resting ECG have historically been acknowledged by physicians, in view of recent evidence on the demonstration of myocardial scar by cardiac magnetic resonance and its relevance as a cause of sudden cardiac death even in young individuals, a new interest has been raised about the utility of LQRSV in the clinical practice. Beyond their diagnostic value, LQRSV have also demonstrated a prognostic role in different cardiomyopathies. The present review summarizes the diagnostic and prognostic value of LQRSV in cardiomyopathies, reporting the new evidence, primarily based on advanced imaging studies, supporting the clinical utility of this parameter.

Indexed left ventricular mass to QRS voltage ratio is associated with heart failure hospitalizations in patients with cardiac amyloidosis

In cardiac amyloidosis (CA), amyloid infiltration results in increased left ventricular (LV) mass disproportionate to electrocardiographic (EKG) voltage. We assessed the relationship between LV mass-voltage ratio with subsequent heart failure hospitalization (HHF) and mortality in CA. Patients with confirmed CA and comprehensive cardiovascular magnetic resonance (CMR) and EKG exams were included. CMR-derived LV mass was indexed to body surface area. EKG voltage was assessed using Sokolow, Cornell, and Limb-voltage criteria. The optimal LV mass-voltage ratio for predicting outcomes was determined using receiver operating characteristic curve analysis. The relationship between LV mass-voltage ratio and HHF was assessed using Cox proportional hazards analysis adjusting for significant covariates. A total of 85 patients (mean 69 ± 11 years, 22% female) were included, 42 with transthyretin and 43 with light chain CA. At a median of 3.4-year follow-up, 49% of patients experienced HHF and 60% had died. In unadjusted analysis, Cornell LV mass-voltage ratio was significantly associated with HHF (HR, 1.05; 95% CI 1.02-1.09, p = 0.001) and mortality (HR, 1.05; 95% CI 1.02-1.07, p = 0.001). Using ROC curve analysis, the optimal cutoff value for Cornell LV mass-voltage ratio to predict HHF was 6.7 gm/m2/mV. After adjusting for age, NYHA class, BNP, ECV, and LVEF, a Cornell LV mass-voltage ratio > 6.7 gm/m2/mV was significantly associated with HHF (HR 2.25, 95% CI 1.09-4.61; p = 0.03) but not mortality. Indexed LV mass-voltage ratio is associated with subsequent HHF and may be a useful prognostic marker in cardiac amyloidosis.

Electrocardiographic voltage criteria in patients with hypertrophic cardiomyopathy

BACKGROUND

Several ECG voltage criteria have been proposed for the diagnosis of left ventricular hypertrophy (LVH). Notably, ECG criteria have been historically validated in concentric LVH but not in hypertrophic cardiomyopathy (HCM), wherein the hypertrophy pattern is typically asymmetric.

OBJECTIVES

The aim of our study was to evaluate the performance of ECG voltage criteria for LVH diagnosis in the HCM population.

MATERIAL AND METHODS

The electrocardiograms of 92 HCM patients and 41 sex- and age-matched controls were evaluated with the most frequently used ECG voltage criteria for LVH diagnosis. Cardiac magnetic resonance (MRI) was performed in HCM and controls in order to quantify LVH and its distribution.

RESULTS

In the HCM population, the maximal diagnostic accuracy was achieved by Amplitude total and Amplitude total product criteria (58% for both), while the Cornell Voltage best performed in septal HCM (62%), the Sokolov in aVL and Gubner criteria in apical HCM (79% for both) and the Cornell Voltage and Product in anterior HCM (86% for both). All the ECG voltage criteria showed a poor correlation with left ventricular mass and maximal thickness measured by cardiac MRI.

CONCLUSIONS

In our study, only a few ECG voltage criteria used for the detection of LVH in clinical practice showed an acceptable performance in the HCM population. Further studies are needed to clarify the role of ECG for LVH detection in HCM patients.

Low QRS voltages in Olympic athletes: Prevalence and clinical correlates

BACKGROUND

Recently, novel interest in low QRS voltages was prompted by the observation that low QRS voltages are present in arrhythmogenic cardiomyopathy patients, even before occurrence of symptoms/events.

AIM

The purpose of this study was to assess prevalence and clinical correlates of low QRS voltages in Olympic athletes, evaluated and followed-up within our cardiovascular screening programme.

METHODS

Five hundred and sixteen athletes consecutively examined (2010-2011) were included in this study. A low QRS voltage was defined as amplitude of QRS <0.5 mV in limb and/or <1.0 mV in precordial leads. Cardiovascular evaluation included 12-lead and exercise electrocardiogram, echocardiography and, selectively, additional tests to confirm diagnosis. Athletes were followed-up for 5 ± 2 (1-9) years.

RESULTS

The majority of athletes (493; 96%) showed normal/increased R/S-wave voltages, but 23 (4%) had low QRS voltages. No differences were observed in low QRS voltage athletes compared to normal/increased QRS voltages for QRS duration, QTc and PR intervals, left ventricular cavity size and mass, or gender and sport participated. However, premature ventricular beats, occurred more frequently in low QRS voltages (39% vs 7%; p < 0.001), with patterns suggesting origin from left or right free wall. No diseases or events were registered in low QRS voltage athletes over the follow-up.

CONCLUSIONS

In Olympic athletes, the prevalence of low QRS voltages was 4%. Athletes with low QRS voltages did not differ from other athletes according to sport participated in or cardiac dimensions. However, more frequently (39% vs 7%) they showed premature ventricular beats, originating from either the left or right free ventricular wall. Therefore, long-term follow-up with serial clinical evaluations is needed in low QRS voltage athletes, in order to definitely clarify the clinical significance.

Electrocardiographic Changes in Liver Cirrhosis-Clues for Cirrhotic Cardiomyopathy

Background and Objectives: Cirrhotic cardiomyopathy is a chronic cardiac dysfunction associated with liver cirrhosis, in patients without previous heart disease, irrespective of the etiology of cirrhosis. Electrocardiography (ECG) is an important way to evaluate patients with cirrhosis and may reveal significant changes associated with liver disease. Our study aimed to evaluate ECG changes in patients with diagnosed liver cirrhosis and compare them to patients with chronic hepatitis. Materials and Methods: We evaluated laboratory findings and ECG tracings in 63 patients with cirrhosis and 54 patients with chronic hepatitis of viral etiology. The end points of the study were prolonged QT interval, QRS hypovoltage and T-peak-to-T-end decrease. We confirmed the diagnosis of cirrhotic cardiomyopathy using echocardiography data. Results: Advanced liver disease was associated with prolonged QT intervals. Also, QRS amplitude was lower in patients with decompensated cirrhosis than in patients with compensated liver disease. We found an accentuated deceleration of the T wave in patients with cirrhosis. These findings correlated to serum levels of albumin, cholesterol and ammonia. Conclusions: ECG changes in liver cirrhosis are frequently encountered and are important noninvasive markers for the presence of cirrhotic cardiomyopathy.

Isolated very low QRS voltage predicts response to tilt-table testing in patients with neurally mediated syncope

BACKGROUND

A number of patients with neurally mediated syncope (NMS) have isolated QRS complexes of very low voltage (≤0.3 mV) in the frontal plane leads on the 12-lead electrocardiogram (ECG).

HYPOTHESIS

The aim of this study was to assess the importance of QRS voltage in predicting response to tilt-table testing (TTT) in patients with suspected NMS.

METHODS

We included 216 patients (age: 49 ± 20 years, 103 men) with suspected NMS who had either a positive or negative response to TTT (n = 91 TTT+, and n = 125 TTT-). The QRS voltage was measured in mV on 12-lead ECGs performed within 3 days of the TTT. The lowest QRS voltage (QRSmin), as well as the voltage in each of the 12 leads was also determined.

RESULTS

Very low voltage (QRSmin  ≤ 0.3 mV) in the frontal leads was significantly more prevalent in the TTT+ group than in the TTT- group (74 vs 22%, respectively; P  < .001). Patients in the TTT+ group had significantly lower QRSmin when compared to patients in the TTT- group. QRSmin predicted a positive tilt-table test in a multivariate model that also included patient gender, height, history of presyncope, QRS duration, and left ventricular end-diastolic diameter indexed to height. ROC analysis showed that QRSmin of ≥0.3 mV discriminated between TTT+ and TTT- patients with a sensitivity of 78% and specificity of 68%.

CONCLUSION

Isolated very low QRS voltage in the frontal leads predicts a positive response to TTT in patients with suspected NMS.

Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Ischaemic-Reperfused Hearts in Adult Rats with Established Chronic Kidney Disease

Background and Objectives

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are adult multipotent non-haematopoietic stem cells that have regeneration potential. The current study aimed to detect the ability of BM-MSCs to improve kidney and cardiac functions in adult rats with established chronic kidney disease.

Methods

Rats were divided into sham-operated control, untreated sub totally nephrectomised and treated sub totally nephrectomised groups. Body weight, kidney and cardiac tissue weights, plasma creatinine and urea levels and arterial blood pressure were measured. ECG was recorded, and an in vitro isolated heart study was performed.

Results

Stem cell treatment decreased the elevated plasma creatinine and urea levels and decreased systolic, diastolic and mean arterial blood pressure values. These changes were accompanied by a decrease in glomerular hypertrophy with apparent normal renal parenchyma. Additionally, BM-MSCs shortened Q-To and Q-Tc intervals, all time to peak tension values, the half relaxation value at 30 min of reperfusion and the contraction time at 15 and 30 min of reperfusion. Moreover, stem cell treatment significantly increased the heart rate, QRS voltage, the peak tension at the 15- and 30-min reperfusion time points and the peak tension per left ventricle at the 30-min reperfusion time point compared to the pre-ischaemia baseline. BM-MSCs resolve inter muscular oedema and lead to the re-appearance of normal cardiomyocytes. This improvement occurs with the observations of BM-MSCs in renal and heart tissues.

Conclusions

BM-MSCs can attenuate chronic kidney disease progression and the associated cardiac electrophysiological and inotropic dysfunction.

Isolated very low QRS voltage in the frontal leads predicts recurrence of neurally mediated syncope

BACKGROUND

The study was prompted by our observation that some patients with neurally mediated syncope (NMS) have an isolated QRS complex, of very low voltage (≤0.3 mV cutoff), in 1 of the frontal leads on the 12-lead electrocardiogram.

OBJECTIVE

To prospectively evaluate whether the presence of isolated very low voltage (VLV) predicts recurrence of NMS.

METHODS

We included 205 patients (aged 50 ± 17 years) with a median of 3 syncopal episodes. Tilt testing was performed in all patients and was positive in 87 (42%). The patients were followed for a median of 14 months.

RESULTS

VLV in frontal leads was present in 92 patients (45%). During the follow-up period 60 patients experienced recurrence of syncope. The actuarial total syncope recurrence rate at 1 year was 32% (95% confidence interval [CI 23%-44%) in patients with isolated VLV in frontal plane leads, and 14% (95% CI 8%-24%) in patients without VLV (log-rank test P < .0001). The significant relationship between the presence of isolated VLV in the frontal leads and syncope recurrence was retained in Cox multivariate analysis that included the history of presyncope and syncope as well as the left ventricular end-diastolic diameter. The presence of isolated VLV in frontal leads was associated with a 3-fold increase of the risk of recurrent syncope.

CONCLUSIONS

Isolated very low QRS voltage in the frontal leads predicts recurrence of NMS independent of clinical factors that predict recurrence of syncope in such patients. This phenomenon may help generate new diagnostic tools and insights into the pathogenesis of NMS.

Development and assessment of a novel precordial lead system for accurate detection of right atrial and ventricular depolarization in dogs with various thoracic conformations

OBJECTIVE

To assess recording accuracy of right atrial and ventricular depolarization during 12-lead ECG when precordial lead V₁ was positioned at each of 5 locations on the thorax of dogs with various thoracic conformations.

ANIMALS

60 healthy client-owned dogs.

PROCEDURES

20 dogs were allocated to each of 3 groups (brachymorphic, mesomorphic, or dolichomorphic) on the basis of thoracic conformation. Each dog remained unsedated and was positioned in right lateral recumbency for a series of five 12-lead surface ECGs, with V₁ located adjacent to the sternum in the fifth intercostal space (ICS; control), at the costochondral junction (CCJ) of the right first ICS (1st-R), at the CCJ of the right third ICS, at the right third ICS where the thorax was the widest, and at the CCJ of the left first ICS. Electrocardiographic variables were compared among the 5 ECG tracings.

RESULTS

When V₁ was at the control location, the P wave was positive for all dogs; however, consistent recording of right atrial and ventricular depolarization (ie, R wave-to-S wave ratio [R/S] < 1) occurred more frequently for brachymorphic dogs (16/20) than for dolichomorphic (7/20) and mesomorphic (6/20) dogs. When V₁ was at the 1st-R location, the P wave was negative for most dogs, and R/S was < 1 for the majority of dogs in the brachymorphic (19/20), mesomorphic (17/20), and dolichomorphic (16/20) groups. The median R/S for V₁ at the 1st-R location was significantly lower than that for the other 4 V₁ locations.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that placement of V₁ at the 1st-R location provided correct evaluation of right atrial and ventricular depolarization in most dogs regardless of thoracic conformation.

Cardiac biomarkers of disordered eating: A case for decreased mean R wave amplitude

The purpose of this study was to identify cardiac biomarkers of disordered eating. Mean R wave amplitude (mV), mean T wave amplitude (mV), QRS interval (sec), QTc interval (sec), and Tpeak-Tend interval (sec) were assessed via electrocardiography among women with clinical (n = 53) and subclinical (n = 56) eating disorder symptoms versus asymptomatic controls (n = 32). QRS and QTc intervals were significantly longer and mean T and R wave amplitudes significantly lower among women with clinical symptoms compared to asymptomatic controls. QTc interval length was significantly longer and mean R wave amplitude was significantly lower among women with subclinical symptoms versus asymptomatic controls. Decreased mean R wave amplitude yielded a comparable effect size as QTc when differentiating between asymptomatic and subclinical groups and a larger effect size than QTc when differentiating between asymptomatic and clinical groups, representing a promising clinical biomarker.

Absence of electrocardiographic left ventricular hypertrophy is associated with increased mortality after transcatheter aortic valve replacement

BACKGROUND

Electrocardiographic (ECG) left ventricular hypertrophy (LVH) has been associated with increased mortality in patients with asymptomatic aortic stenosis (AS) and hypertension. However, patients with symptomatic AS undergoing transcatheter aortic valve replacement (TAVR) have higher percentages of myocardial fibrosis or amyloidosis that have been associated with decreased ECG voltage and worse outcomes.

HYPOTHESIS

We tested the hypothesis that baseline ECG LVH is independently associated with increased all-cause mortality after TAVR.

METHODS

A total of 231 patients (96 men; mean age 84.7 ± 7.8 years) that underwent TAVR at our institution were included. Cornell voltage, defined as S_V3 + R_aVL, was used to assess for presence of ECG LVH using gender-specific cut-off values. We used the Kaplan-Meier estimator to derive survival curves. Multivariate Cox regression analysis was used to compare mortality between patients without vs with ECG LVH and adjust for echocardiographic LVH and predictors of mortality in this cohort.

RESULTS

Over a follow-up time of 16.3 ± 10.4 months, the absence of ECG LVH was significantly associated with increased mortality (40.4% vs 23.6% at 2-years, log rank P = 0.003). After adjusting for echocardiographic LVH and predictors of mortality in our cohort, the absence of ECG LVH remained a predictor of increased mortality (HR = 1.79, CI 95% 1.02-3.14, P = 0.042).

CONCLUSIONS

The absence of ECG LVH was independently associated with increased mortality in patients undergoing TAVR. Baseline ECG may have an important prognostic role in these patients and could lead to further testing to evaluate for myocardial fibrosis or amyloidosis.

QRS voltage is a predictor of in-hospital mortality of acutely ill medical patients

BACKGROUND

Low QRS voltage has been shown to be associated with increased mortality in the general population and in a small pilot study the combined QRS voltage of ECG leads I and II was found to be associated with in-hospital mortality.

HYPOTHESIS

Confirm that low QRS voltage predicts the in-hospital mortality of acutely ill patients, and compare QRS voltage with other predictors of mortality that can be easily, quickly and cheaply obtained at the bedside.

METHODS

Prospective observational study of vital signs, QRS voltage and simple tools used to assess mental, functional and nutritional status at the bedside in unselected acutely ill patients admitted to a resource-poor hospital in sub-Saharan Africa.

RESULTS

Out of 1486 patients, 77 died (5.2%) in hospital. A combined lead I + II voltage <1.8 mV was present in 789 (53.1%) of patients, and significantly associated with in-hospital mortality (odds ratio 3.6, 95% CI 2.0-6.5, χ² 21.2, P < 0.00001). On logistic regression impaired mobility, the National Early Warning Score, male gender and lead I + II voltage were the only independent predictors of mortality. None of the 445 patients who were mobile on admission with a lead I + II voltage ≥ 1.8 mV died in hospital.

CONCLUSIONS

Low QRS voltage, male gender, NEWS, and impaired mobility were independent predictors of in-hospital mortality in the study population. These four variables, which are easily obtained at the bedside, could potentially provide a rapid, easy, and cheap risk stratification system.

Electrocardiogram voltage discordance: Interpretation of low QRS voltage only in the precordial leads

OBJECTIVES

To define clinical correlates of low voltage isolated to precordial leads on the surface electrocardiogram (ECG).

INTRODUCTION

Low voltage (V) on the ECG is defined as QRS V<5mm in all limb leads and <10mm in all precordial leads. The diagnostic use of ECGs with low voltage isolated to the precordial leads with normal limb lead voltages is unclear.

METHODS

Twelve-lead ECGs with QRS V>5mm in one or more limb leads and <10mm in all precordial leads were collected. Associated clinical conditions were determined from clinical data, echocardiograms, and chest radiographs.

RESULTS

Low precordial voltage was found in 256 of 150,000 ECGs (~0.2%). 50.4% of patients had discordant ECGs that correlated with classic etiologies, with a higher incidence of LV dilation in those with classic etiologies than those without.

CONCLUSION

Low precordial voltage is associated with classic etiologies and LV dilation.

Diffuse Myocardial Fibrosis Reduces Electrocardiographic Voltage Measures of Left Ventricular Hypertrophy Independent of Left Ventricular Mass

Background

Myocardial fibrosis quantified by myocardial extracellular volume fraction (ECV) and left ventricular mass (LVM) index (LVMI) measured by cardiovascular magnetic resonance might represent independent and opposing contributors to ECG voltage measures of left ventricular hypertrophy (LVH). Diffuse myocardial fibrosis can occur in LVH and interfere with ECG voltage measures. This phenomenon could explain the decreased sensitivity of LVH detectable by ECG, a fundamental diagnostic tool in cardiology.

Methods and Results

We identified 77 patients (median age, 53 [interquartile range, 26–60] years; 49% female) referred for contrast‐enhanced cardiovascular magnetic resonance with ECV measures and 12‐lead ECG. Exclusion criteria included clinical confounders that might influence ECG measures of LVH. We evaluated ECG voltage‐based LVH measures, including Sokolow‐Lyon index, Cornell voltage, 12‐lead voltage, and the vectorcardiogram spatial QRS voltage, with respect to LVMI and ECV. ECV and LVMI were not correlated (R²=0.02; P=0.25). For all voltage‐related parameters, higher LVMI resulted in greater voltage (r=0.33–0.49; P<0.05 for all), whereas increased ECV resulted in lower voltage (r=−0.32 to −0.57; P<0.05 for all). When accounting for body fat, LV end‐diastolic volume, and mass‐to‐volume ratio, both LVMI (β=0.58, P=0.03) and ECV (β=−0.46, P<0.001) were independent predictors of QRS voltage (multivariate adjusted R²=0.39; P<0.001).

Conclusions

Myocardial mass and diffuse myocardial fibrosis have independent and opposing effects upon ECG voltage measures of LVH. Diffuse myocardial fibrosis quantified by ECV can obscure the ECG manifestations of increased LVM. This provides mechanistic insight, which can explain the limited sensitivity of the ECG for detecting increased LVM.