T-Wave Abnormality as Electrocardiographic Signature of Myocardial Edema in Non-ST-Elevation Acute Coronary Syndromes

ST segment and T wave abnormalities: A narrative review

INTRODUCTION

The electrocardiogram (ECG) is a valuable tool for interpreting ventricular repolarization. This article aims to broaden the diagnostic scope beyond the conventional ischemia-centric approach, integrating an understanding of pathophisiological influences on ST-T wave changes.

METHODS

A review was conducted on the physiological underpinnings of ventricular repolarization and the pathophisiological processes that can change ECG patterns. The research encompassed primary repolarization abnormalities due to uniform variations in ventricular action potential, secondary changes from electrical or mechanical alterations, and non-ischemic conditions influencing ST-T segments.

RESULTS

Primary T waves are characterized by symmetrical waves with broad bases and variable QT intervals, indicative of direct myocardial action potential modifications due to ischemia, electrolyte imbalances, and channelopathies. Secondary T waves are asymmetric and often unassociated with significant QT interval changes, suggesting depolarization alterations or changes in cardiac geometry and contractility.

CONCLUSION

We advocate for a unified ECG analysis, recognizing primary and secondary ST-T changes, and their clinical implications. Our proposed analytical framework enhances the clinician's ability to discern a wide array of cardiac conditions, extending diagnostic accuracy beyond myocardial ischemia.

Mechanisms of Myocardial Edema Development in CVD Pathophysiology

Myocardial edema is the excess accumulation of fluid in the myocardial interstitium or cardiac cells that develops due to changes in capillary permeability, loss of glycocalyx charge, imbalance in lymphatic drainage, or a combination of these factors. Today it is believed that this condition is not only a complication of cardiovascular diseases, but in itself causes aggravation of the disease and increases the risks of adverse outcomes. The study of molecular, genetic, and mechanical changes in the myocardium during edema may contribute to the development of new approaches to the diagnosis and treatment of this condition. This review was conducted to describe the main mechanisms of myocardial edema development at the molecular and cellular levels and to identify promising targets for the regulation of this condition based on articles cited in Pubmed up to January 2024.

Comparison of quantifiable electrocardiographic changes associated with severe hyperkalemia

BACKGROUND

Hyperkalemia (HK) is a life-threatening condition that is frequently evaluated by electrocardiogram (ECG). ECG changes in severe HK (≥ 6.3 mEq/L) are not well-characterized. This study sought to compare and correlate ECG metrics in severe HK to baseline normokalemic ECGs and serum potassium.

METHODS

A retrospective analysis of 340 severe HK encounters with corresponding normokalemic ECGs was performed.

RESULTS

Various ECG metrics were analyzed. P wave amplitude in lead II, QRS duration, T wave slope, ratio of T wave amplitude: duration, and ratios of T wave: QRS amplitudes were significantly different between normokalemic and HK ECGs. P wave amplitude attenuation in lead II correlated better with serum potassium than in V1. T wave metrics that incorporated both T wave and QRS amplitudes correlated better than metrics utilizing T wave metrics alone.

CONCLUSION

Multiple statistically significant and quantifiable differences among ECG metrics were observed between normokalemic and HK ECGs and correlated with increasing degrees of serum potassium and along the continuum of serum potassium. When incorporated into a logistic regression model, the ability to distinguish HK versus normokalemia on ECG improved significantly. These findings could be integrated into an ECG acquisition system that can more accurately identify severe HK.

The prognostic significance of Q waves and T wave inversions in the ECG of patients with STEMI: A substudy of the TOTAL trial

BACKGROUND

The prognostic significance of Q waves and T-wave inversions (TWI) combined and separately in STEMI patients undergoing primary PCI has not been well established in previous studies.

METHODS

We included 7,831 patients from the TOTAL trial and divided the patients into categories based on Q waves and TWIs in the presenting ECG. The primary outcome was a composite of cardiovascular death, recurrent myocardial infarction (MI), cardiogenic shock or new or worsening NYHA class IV heart failure within one year. The study evaluated the effect of Q waves and TWI on the risk of primary outcome and all-cause death, and whether patient benefit of aspiration thrombectomy differed between the ECG categories.

RESULTS

Patients with Q+TWI+ (Q wave and TWI) pattern had higher risk of primary outcome compared to patients with Q-TWI- pattern [33 (10.5%) vs. 221 (4.2%); adjusted hazard ratio (aHR) 2.10; 95% CI, 1.45-3.04; p<0.001] within 40-days' period. When analyzed separately, patients with Q waves had a higher risk for the primary outcome compared to patients with no Q waves in the first 40 days [aHR 1.80; 95% CI, 1.48-2.19; p<0.001] but there was no additive risk after 40 days. Patients with TWI had a higher risk for primary outcome only after 40 days when compared to patients with no TWI [aHR 1.63; 95% CI, 1.04-2.55; p=0.033]. There was a trend towards a benefit of thrombectomy in patients with the Q+TWI+ pattern.

CONCLUSIONS

Q waves and TWI combined (Q+TWI+ pattern) in the presenting ECG is associated with unfavourable outcome within 40-days. Q waves tend to affect short-term outcome, while TWI has more effect on long-term outcome.

Temporal electrocardiographic changes in anterior ST elevation myocardial infarction versus the Takotsubo syndrome

Background

Electrocardiography (ECG) on admission is similar in ST elevation myocardial infarction (STEMI) and Takotsubo syndrome (TTS). ECG on admission has been extensively investigated and compared between STEMI and TTS, however, only a few studies have compared temporal ECG. Our aim was to compare ECG in anterior STEMI versus female TTS from admission to day 30.

Methods

Adult patients with anterior STEMI or TTS treated at Sahlgrenska University Hospital (Gothenburg, Sweden) from December 2019 to June 2022 were prospectively enrolled. Baseline characteristics, clinical variables and ECGs from admission to day 30 were analyzed. Using a mixed effects model, we compared temporal ECG between female patients with anterior STEMI or TTS, as well as between female and male patients with anterior STEMI.

Results

A total of 101 anterior STEMI patients (31 female, 70 male) and 34 TTS patients (29 female, 5 male) were included. The temporal pattern of T wave inversion was similar between female anterior STEMI and female TTS, as well as between female and male anterior STEMI. ST elevation was more common, whereas QT prolongation was less common, in anterior STEMI compared with TTS. Q wave pathology was more similar between female anterior STEMI and female TTS than between female and male anterior STEMI.

Conclusions

The pattern of T wave inversion and Q wave pathology from admission to day 30 was similar in female patients with anterior STEMI and female patients with TTS. Temporal ECG in female patients with TTS may be interpreted as following a "transient ischemic" pattern.

Twenty-four hour variability of inverted T-waves in patients with apical hypertrophic cardiomyopathy

Background

Patients with apical hypertrophic cardiomyopathy (ApHCM) have marked inverted T-waves that vary over several years. Inverted T-waves in ApHCM are unstable, but it is unclear whether this change is due to coronary artery disease (CAD) or if it is a characteristic of ApHCM itself. We aimed to study the characteristics of inverted T-waves in patients with ApHCM over the course of 24 h to improve the diagnostic indices of ApHCM.

Methods

We examined 83 patients with ApHCM and 89 patients with CAD (who served as the control group). All patients underwent a 24-h dynamic electrocardiogram (ECG). We analyzed the average depth of inverted T-waves per minute and sorted them from shallow to deep; the sorted ECG segments at the 10^th, 50^th, and 90^th positions of the T-wave were subsequently analyzed.

Results

The amplitudes of inverted T-waves in ApHCM corresponding to the 10^th, 50^th, and 90^th percentiles were −5.13 ± 4.11, −8.10 ± 4.55, and −10.9 ± 5.04 mm, respectively. Changes in the degree of inverted T-waves were greater in ApHCM than in CAD. T-wave amplitudes in ApHCM were strongly associated with heart rate and circadian rhythm and only weakly associated with CAD and posture. Maximum T-wave amplitudes in the CAD group were <10 mm, while 68% of patients with ApHCM had maximum T-wave amplitudes >10 mm, and all patients with ApHCM aged <50 years had maximum T-wave amplitudes >10 mm.

Conclusion

Notable variations in the T-waves of patients with ApHCM were observed over 24 h. ECG examinations during states of inactivity (comparable to sleep) improved the sensitivity of the diagnosis of ApHCM. Inverted T-wave amplitudes correlated with heart rate and circadian rhythm, where T-wave changes in ApHCM may be due to the normalization of abnormal T-waves effect. Identifying T-wave amplitudes >10 mm can effectively improve the diagnostic rate of ApHCM, especially in patients aged <50 years. The short-term change in T-waves in patients with ApHCM could serve as a novel index that will help in the diagnosis of ApHCM.

ECG Abnormalities in Patients with Acute Exacerbation of Bronchiectasis and Factors Associated with High Probability of Abnormality

BACKGROUND

Bronchiectasis is an important reason for morbidity and mortality according to the last records that referred to high incidence rate of disease. Cardiovascular problems are common in pulmonary diseases, in general, and it can symptom by ECG abnormalities. The objective of this study was to define the most ECG abnormalities in patients with acute exacerbation of bronchiectasis and to study the correlation between the cardiac disorder and the other risk factors of the exacerbation.

MATERIALS AND METHODS

A prospective single-center observational cohort study was done at Aleppo University Hospital for patients with AEB between October 2017 and September 2018. They were divided into 2 groups (normal ECG vs. abnormal). Patients with COPD, cystic fibrosis, new diagnosis of ischemic accident through the last 6 months of the study, and treatment with macrolides or fluoroquinolones through the last 3 months of the study were excluded. We study the percent of abnormalities through the AEB and the percentage of the most common abnormalities.

RESULTS

67 patients were included in the study (44 males and 23 females) with a mean age of 52.85 ± 21.456. ECG abnormalities were recorded in 43 patients, and it was more common in men (67.44% of cases). Advanced age and survival state had a statistical significance (p = 0.003, 0.023), respectively, between the 2 groups. Right axis deviation (RAD) is the most common abnormality (23.3%) followed by sinus tachycardia (20.9%), and it is close to T-depression (18.6%). AF was the most common arrhythmia from all recorded arrhythmias (6.98% from all cases). Positive sputum cultures were recorded in 55.8%, and the most common isolated pathogen factor was Pseudomonas aeruginosa. Recurrent pneumonia was seen in 30.2% of all patients with abnormal ECG. We find a high prevalence of ECG abnormalities in patients with Oximetry (90-95%, 39.5%), and the opportunity for abnormalities is equal in the 2 age groups (45-59 and more than 75) that reflexed the possibility of cardiac disorders in any age in patients with AEB.

CONCLUSIONS

ECG abnormalities are common in AEB, and it can happen in any age and any value of Oximetry. It needs more attention because of the prognosis of the cardiac morbidity.

The significance of upright T wave in lead V1 in predicting myocardial ischemia A literature review

Chest pain is still representing one of the most common and serious presentations to the emergency department worldwide. ECG is a crucial tool in evaluating patients with chest pain; however, only around 50% of patients with acute coronary syndrome (ACS) will have a diagnostic ECG upon their presentation; the rest may either have a completely normal ECG or what is called nonspecific ST segment and T wave (NSSTTW) changes, hence it is essential to recognize the subtle ECG changes and know its significance. One of the ECG changes that can be easily missed is when the T wave in V1 is upright, especially when it is either a Tall Upright T wave (TTV1) or a New Tall Upright T-wave (NTTV1). Although upright T wave in lead V1 can be a normal variant, it has been linked in a few studies and observations to cardiovascular disease, especially myocardial ischemia. In this article, we are trying to highlight the importance of this subtle ECG change in predicting cardiovascular disease through a concise review of the available evidence on this topic.

"Apical sparing" T-wave inversion in a case of mid-ventricular takotsubo syndrome

Previous studies showed that myocardial edema correlates with dynamic T-wave inversion and QTc prolongation in a variety of acute cardiovascular diseases including takotsubo syndrome (TTS). We reported the case of a patient with "atypical" (mid-ventricular) TTS showing a unique pattern of diffuse T-wave inversion that spared only the apical precordial leads V3-V4. Cardiac magnetic resonance (CMR) showed myocardial edema involving all mid-ventricular segments but not the apex. Both ECG and CMR normalized at follow-up evaluation. This case further reinforces the theory of an association between presence and regional distribution of acute myocardial inflammation and dynamic repolarization changes.

Prognostic value of admission electrocardiographic findings in non-ST-segment elevation myocardial infarction

BACKGROUND

Admission electrocardiographic (ECG) findings of non-ST-segment elevation myocardial infarction (NSTEMI) include transient ST-segment elevation (TSTE), ST-segment depression (STD), T-wave inversion (TWI), and no ischemic changes (NIC).

HYPOTHESIS

This study aimed to assess the prognostic value of qualitative ECG findings at presentation and to clarify the influence of invasive treatment on the prognostic value of admission ECG findings.

METHODS

We analyzed the Acute Coronary Syndrome Quality Improvement in Kerala (ACS QUIK) study post hoc. NSTEMI patients were included and classified into four groups per ECG findings. Study endpoints were in-hospital and 30-day mortality rates and major adverse events (MAE). We performed multivariate logistic regression, adjusting for covariates in the Global Registry of Acute Coronary Events risk model, with subset analyses of patients treated with or without invasive management.

RESULTS

STD patients had significantly higher in-hospital and 30-day mortality rates/MAE than TWI patients, which had lower in-hospital mortality rate/MAE than the NIC group. TSTE patients had intermediate outcomes. In multivariate logistic regression using the TWI group as the reference, STD and NIC remained independently associated with worse outcomes. Subset analysis showed prognostic value of admission ECG in non-invasively managed but not in invasively managed patients.

CONCLUSIONS

STD was associated with adverse outcomes, TWI with benign prognoses. NIC should not be taken to indicate low risk. Qualitative analysis of admission ECG is suitable for rapid risk stratification of NSTMI patients at presentation. However, it may not be predictive of short-term outcomes of NSTEMI patients after invasive management.

Wellen's Syndrome: Is One Electrocardiogram Good and Plenty?

The authors present a case of Wellen's syndrome, which has a characteristic T-wave on an electrocardiogram during a pain-free period in a patient with intermittent chest pain. The clinical presentation, pathophysiology, and management is discussed, and the importance of obtaining more than one electrocardiogram (ECG) is explained. 

What this case adds to the literature is the fact that Wellen’s syndrome patients may present atypically with active chest pain and, as such, should be managed similarly to acute myocardial infarction patients. However, because the diagnosis of Wellen’s syndrome depends on an ECG obtained during the ensuing pain-free period, serial ECGs are usually required to reveal T-wave abnormalities in this context and have been shown to be disposition-altering in the Emergency Department (ED). Support for the death-denying outcome preferred in Wellen’s syndrome by patients and providers alike depends on recognizing the diagnosis and consulting cardiology expediently.