Evaluation of QT dispersion and T-peak to T-end interval in patients with early-stage sarcoidosis

A Comprehensive Review on the Electrocardiographic Manifestations of Cardiac Sarcoidosis: Patterns and Prognosis

PURPOSE OF REVIEW

Cardiac sarcoidosis (CS) refers to cardiac involvement in sarcoidosis and is usually associated with worse outcomes. This comprehensive review aims to elucidate the electrocardiographic (ECG) signs and features associated with CS, as well as examine modern techniques and their importance in CS evaluation.

RECENT FINDINGS

The exact pathogenesis of CS is still unclear, but it stems from an abnormal immunological response triggered by environmental factors in individuals with genetic predisposition. CS presents with non-cardiac symptoms; however, conduction system abnormalities are common in patients with CS. The most common electrocardiographic (ECG) signs include atrioventricular blocks and ventricular tachyarrhythmia. Distinct patterns, such as fragmented QRS complexes, T-wave alternans, and bundle branch blocks, are critical indicators of myocardial involvement. The application of advanced ECG techniques such as signal-averaged ECG, Holter monitoring, wavelet-transformed ECG, microvolt T-wave alternans, and artificial intelligence-supported analysis holds promising outcomes for opportune detection and monitoring of CS. Timely utilisation of inexpensive and readily available ECG possesses the potential to allow early detection and intervention for CS. The integration of artificial intelligence models into ECG analysis is a promising approach for improving the ECG diagnostic accuracy and further risk stratification of patients with CS.

The pivotal role of ECG in cardiomyopathies

Cardiomyopathies are a heterogeneous group of pathologies characterized by structural and functional alterations of the heart. Recent technological advances in cardiovascular imaging offer an opportunity for deep phenotypic and etiological definition. Electrocardiogram (ECG) is the first-line diagnostic tool in the evaluation of both asymptomatic and symptomatic individuals. Some electrocardiographic signs are pathognomonic or fall within validated diagnostic criteria of individual cardiomyopathy such as the inverted T waves in right precordial leads (V1-V3) or beyond in individuals with complete pubertal development in the absence of complete right bundle branch block for the diagnosis of arrhythmogenic cardiomyopathy of the right ventricle (ARVC) or the presence of low voltages typically seen in more than 60% of patients with amyloidosis. Most other electrocardiographic findings such as the presence of depolarization changes including QRS fragmentation, the presence of epsilon wave, the presence of reduced or increased voltages as well as alterations in the repolarization phase including the negative T waves in the lateral leads, or the profound inversion of the T waves or downsloping of the ST tract are more non-specific signs which can however raise the clinical suspicion of cardiomyopathy in order to initiate a diagnostic procedure especially using imaging techniques for diagnostic confirmation. Such electrocardiographic alterations not only have a counterpart in imaging investigations such as evidence of late gadolinium enhancement on magnetic resonance imaging, but may also have an important prognostic value once a definite diagnosis has been made. In addition, the presence of electrical stimulus conduction disturbances or advanced atrioventricular blocks that can be seen especially in conditions such as cardiac amyloidosis or sarcoidosis, or the presence of left bundle branch block or posterior fascicular block in dilated or arrhythmogenic left ventricular cardiomyopathies are recognized as a possible expression of advanced pathology. Similarly, the presence of ventricular arrhythmias with typical patterns such as non-sustained or sustained ventricular tachycardia of LBBB morphology in ARVC or non-sustained or sustained ventricular tachycardia with an RBBB morphology (excluding the "fascicular pattern") in arrhythmogenic left ventricle cardiomyopathy could have a significant impact on the course of each disease. It is therefore clear that a learned and careful interpretation of ECG features can raise suspicion of the presence of a cardiomyopathy, identify diagnostic "red flags" useful for orienting the diagnosis toward specific forms, and provide useful tools for risk stratification. The purpose of this review is to emphasize the important role of the ECG in the diagnostic workup, describing the main ECG findings of different cardiomyopathies.

Association of Tp-e/QT ratio with SYNTAX score II in patients with coronary artery disease

Background. The SYNTAX score II (SS) is an angiographic tool, which grades the complexity of coronary artery lesions and predicts short- and long-term events. Tp-e/QT ratio is a novel electrocardiographic marker for the risk of ventricular arrhythmias. We aimed to investigate whether there was a correlation between SS and Tp-e/QT ratio.Methods. A total of 227 consecutive patients who underwent elective coronary angiography were enrolled in this study. Patients who had a lumen diameter >1.5 mm and at least % 50 diameter stenosis on coronary angiogram were determined as coronary artery disease (CAD) group, and others were identified as a control group. The SS was calculated for the CAD group, and SS ≥23 was defined as a high SS group, and SS < 23 was identified as a low SS group. Electrocardiographic indices, such as Tp-e and Tp-e/QT, were measured for all patients. A multivariable logistic regression analysis was performed with variables age, interventricular septum thickness (IVS), hypertension, and Tp-e/QT. Results. Tp-e interval and Tp-e/QT ratio were higher in the CAD group compared with the control group. Tp-e, corrected Tp-e (cTP-e) and Tp-e/QT were higher in the high SS group than in the low SS group. The cTp-e and Tp-e/QT were correlated with SS score. Age, IVS and Tp-e/QT ratio were independent predictors of high SS in the logistic regression analysis. Conclusions. Tp-e/QT ratio was an independent predictor of high SS and might be used for risk stratification in CAD patients.

The ECG in sarcoidosis - a marker of cardiac involvement? Current evidence and clinical implications

Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by noncaseating granulomas. Cardiac involvement is often limiting patients' prognosis. Cardiac sarcoidosis can manifest with variant cardiac arrhythmias, of which atrioventricular (AV)-block-related bradycardia and ventricular tachycardias are the most common. Although cardiac sarcoidosis remains a histopathological diagnosis, the significance of imaging modalities, especially cardiac magnetic resonance imaging is increasing rapidly but mainly remains reserved for patients with a high suspicion due to a previous arrhythmia or unknown cardiomyopathy. Thus, there is a need for screening in daily clinical practice so that possible characteristic electrocardiographic (ECG) findings may guide the way to detect the disease. We therefore evaluated the ECG as a potential tool for screening of cardiac sarcoidosis and present different electrophysiological manifestations of cardiac sarcoidosis based on a literature review. The ECG is a valuable tool for screening of cardiac involvement in patients with sarcoidosis. Several parameters have been shown to be associated with cardiac involvement in sarcoidosis such as higher-degree AV-block, QRS complex fragmentation and widening, as well as certain T wave abnormalities that may indicate cardiac involvement, of which the latter two are most promising and specific. However, prospective studies examining a large number of trials are desirable.

T-Wave Indices and Atherosclerosis

Tpeak-Tend interval, the time difference between the peak and the end of the T-wave, reflects the degree of dispersion of repolarization. Its prolongation has been associated with higher risks of developing ventricular arrhythmias and sudden cardiac death in different pro-arrhythmic conditions such as Brugada and long QT syndromes. In this review, we will provide a comprehensive overview on how Tpeak-Tend is altered in different atherosclerotic conditions such as hypertension, stable coronary artery disease, acute coronary obstruction, and coronary slow flow as well as inflammatory diseases affecting the arterial tree. We will explore its relationship with arterial function and dysfunction, ventricular remodeling, and arrhythmic and mortality outcomes. The published literature shows that patients with coronary atherosclerosis, whether in the form of stable coronary artery disease, chronic total occlusion, slow flow, or acute coronary obstruction, have prolonged Tpeak-Tend intervals and Tpeak-Tend/QT ratios. These can be used to predict the occurrence of ventricular arrhythmias and sudden cardiac death. They also correlate with the extent and severity of arterial stenosis and structural remodeling of the ventricles as well as arterial function and dysfunction. Finally, they can be normalized following revascularization and may therefore be used as a surrogate measure of treatment success.