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

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.

Diagnostic and management strategies in cardiac sarcoidosis

Cardiac sarcoidosis (CS) is increasingly recognized in the context of with otherwise unexplained electrical or structural heart disease due to improved diagnostic tools and awareness. Therefore, clinicians require improved understanding of this rare but fatal disease to care for these patients. The cardinal features of CS, include arrhythmias, atrio-ventricular conduction delay and cardiomyopathy. In addition to treatments tailored to these cardiac manifestations, immunosuppression plays a key role in active CS management. However, clinical trial and consensus guidelines are limited to guide the use of immunosuppression in these patients. This review aims to provide a practical overview to the current diagnostic challenges, treatment approach, and future opportunities in the field of CS.

Relationship of Mild to Moderate Impairment of Left Ventricular Ejection Fraction With Fatal Ventricular Arrhythmic Events in Cardiac Sarcoidosis

BACKGROUND

Current guidelines recommend placing an implantable cardiac defibrillator for patients with cardiac sarcoidosis and a severely impaired left ventricular ejection fraction (LVEF) of ≤35%. In this study, we determined the association between mild or moderate LVEF impairment and fatal ventricular arrhythmic event (FVAE).

METHODS AND RESULTS

We retrospectively analyzed 401 patients with cardiac sarcoidosis without sustained ventricular arrhythmia at diagnosis. The primary end point was an FVAE, defined as the combined endpoint of documented ventricular tachycardia or ventricular fibrillation and sudden cardiac death. Two cutoff points for LVEF were used: a sex-specific lower threshold of normal range of LVEF (52% for men and 54% for women) and an LVEF of 35%, which is used in the current guidelines. During a median follow-up of 3.2 years, 58 FVAEs were observed, and the 5- and 10-year estimated incidences of FVAEs were 16.8% and 23.0%, respectively. All patients were classified into 3 groups according to LVEF: impaired LVEF group, mild to moderate impairment of LVEF group, and maintained LVEF group. Multivariable competing risk analysis showed that both the impaired LVEF group (hazard ratio [HR], 3.24 [95% CI, 1.49-7.04]) and the mild to moderate impairment of LVEF group (HR, 2.16 [95% CI, 1.04-4.46]) were associated with a higher incidence of FVAEs than the maintained LVEF group after adjustment for covariates.

CONCLUSIONS

Patients with cardiac sarcoidosis are at a high risk of FVAEs, regardless of documented ventricular arrhythmia at the time of diagnosis. In patients with cardiac sarcoidosis, mild to moderate impairment of LVEF is associated with FVAEs.

The new European Society of Cardiology guideline for the management of cardiomyopathies: key messages for cardiac electrophysiologists

Electrocardiographic findings and arrhythmias are common in cardiomyopathies. Both may be an early indication of a specific diagnosis or may occur due to myocardial fibrosis and/or reduced contractility. Brady- and tachyarrhythmias significantly contribute to increased morbidity and mortality in patients with cardiomyopathies. Antiarrhythmic therapy including risk stratification is often challenging and plays a major role for these patients. Thus, an "electrophysiological" perspective on guidelines on cardiomyopathies may be warranted. As the European Society of Cardiology (ESC) has recently published a new guideline for the management of cardiomyopathies, this overview aims to present key messages of these guidelines. Innovations include a new phenotype-based classification system with emphasis on a multimodal imaging approach for diagnosis and risk stratification. The guideline includes detailed chapters on dilated and hypertrophic cardiomyopathy and their phenocopies, arrhythmogenic right ventricular cardiomyopathy, and restrictive cardiomyopathy as well as syndromic and metabolic cardiomyopathies. Patient pathways guide clinicians from the initial presentation to diagnosis. The role of cardiovascular magnetic resonance imaging and genetic testing during diagnostic work-up is stressed. Concepts of rhythm and rate control for atrial fibrillation have led to new recommendations, and the role of defibrillator therapy in primary prevention is discussed in detail. Whilst providing general guidelines for management, the primary objective of the guideline is to ascertain the disease etiology and disease-specific, individualized management.

Effects of Valvular Heart Disease on Clinical Outcomes in Sarcoidosis

Systemic sarcoidosis can lead to heart failure, conduction abnormalities and ventricular arrhythmias although data on concomitant valvular heart disease (VHD) is limited. We reported the prevalence and outcomes of VHD in systemic sarcoidosis. A retrospective cohort study was conducted using National Inpatient Sample between 2016 and 2020 with respective ICD-10-CM codes. 406,315 patients were hospitalized with sarcoidosis, out of which 20,570 had comorbid VHD (5.1%). Mitral disease was most common (2.5%), followed by aortic, and tricuspid disease. Tricuspid disease was associated with increased mortality in sarcoidosis (OR 1.6, 95% CI, 1.1-2.6, P = 0.04), while aortic disease was associated with higher mortality in only 31-50 years age cohort. Patients with sarcoidosis and VHD have higher hospitalization charges and lower or similar valvular intervention rates than those without sarcoidosis. VHD has a prevalence of 5% in sarcoidosis, predominantly affecting mitral and aortic valves. Underlying VHD is associated with worse outcomes in sarcoidosis.

Sex differences in clinical characteristics and prognosis of patients with cardiac sarcoidosis

OBJECTIVE

Owing to the paucity of data, this study aimed to investigate sex differences in clinical features and prognosis of patients with cardiac sarcoidosis (CS).

METHODS

This study was a secondary analysis of the ILLUstration of the Management and prognosIs of JapaNese PATiEnts with Cardiac Sarcoidosis registry-a retrospective multicentre registry that enrolled patients with CS between 2001 and 2017. The primary outcome was potentially fatal ventricular arrhythmia events (pFVAEs)-a composite of sudden cardiac death, sustained ventricular tachycardia lasting >30 s, ventricular fibrillation or the requirement for implantable cardioverter defibrillator therapy.

RESULTS

Of the 512 participants (mean age±SD 61.6±11.4 years), 329 (64.2%) were females. Both sexes had peak ages of 60-64 years at diagnosis. Male patients were younger and had a higher prevalence of coronary artery disease and lower left ventricular ejection fraction than female patients. During a median follow-up of 3 years (IQR 1.6-5.6), pFVAEs were observed in 99 patients, with males having a significantly higher risk than females (p=0.002). This association was retained even after adjustment for other risk factors for pFVAEs, including left ventricular ejection fraction (adjusted HR 1.80; 95% CI 1.08 to 3.01, p=0.025).

CONCLUSION

Approximately two-thirds of patients with CS were females, with a peak age of approximately 60 years at clinical diagnosis in both sexes; male patients were younger than female patients. Male patients had a significantly higher risk of pFVAEs than female patients.

TRIAL REGISTRATION NUMBER

UMIN000034974.

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.

Pragmatic electrocardiogram tracings in non-ischaemic dilated cardiomyopathy: diagnostic and prognostic role

Dilated cardiomyopathy (DCM) is a primitive heart muscle disease characterized by a great heterogeneous aetiology and prognostic outcome. Dilated cardiomyopathy is an umbrella term encompassing different aetiologies that might require specific treatments. It principally affects young and male adults, with high-risk arrhythmic competitive risk. Unfortunately, the prevention of major ventricular arrhythmic events remains a clinical challenge. In the era of advanced multimodality imaging and widely available genetic testing, electrocardiogram (ECG) continues to represent a reliable diagnostic tool, for specific work up of every single patient. However, approaching DCM patients, only a cardiomyopathy-oriented reading makes the role of ECG central in the management of DCM, both for diagnosis, prognosis, and therapeutic management. In this paper, we present four ECGs of four different DCM patients, in order to guide a cardiomyopathy-oriented ECG reading, emphasizing its impact in an early, cost-effective, and personalized diagnostic and prognostic work up in this specific setting.

Fragmented QRS as a predictor of cardiac events in patients with cardiac sarcoidosis

BACKGROUND

Multiple spikes within the QRS complex, known as fragmented QRS (fQRS), are associated with the occurrences of ventricular arrhythmic events (VAEs) in patients with Brugada syndrome and hypertrophic cardiomyopathy. However, the association between fQRS and occurrence of VAEs in patients with cardiac sarcoidosis (CS) has not been elucidated.

METHODS

We evaluated the associations between fQRS and cardiac events including VAEs [non-sustained ventricular tachycardia (NSVT), sustained ventricular tachycardia (VT), and ventricular fibrillation (VF)], hospitalization for heart failure, and all-cause death in 68 patients with CS (30 patients with fQRS vs. 38 patients without fQRS) over a 5-year period.

RESULTS

Cardiac events occurred in 22 patients with fQRS and 18 patients without fQRS (73% vs. 47%, p=0.009). Of the cardiac events that occurred in CS patients, VAEs occurred more frequently in patients with fQRS than in patients without fQRS (VAEs: 70% vs. 45%, p=0.017; NSVT: 70% vs. 45%, p=0.010; VT: 43% vs. 18%, p=0.011, and VF: 6.7% vs. 2.6%, p=0.34), whereas there was no significant difference in hospitalization for heart failure or all-cause death between patients with and those without fQRS (hospitalization for heart failure: 6.7% vs. 5.3%, p=0.75; all-cause death: 6.7% vs. 5.3%, p=0.64). Multivariate analysis showed that fQRS in the baseline electrocardiogram was independently associated with VAEs (hazard ratio: 2.21, 95% confidence interval: 1.15-4.25, p=0.017).

CONCLUSION

fQRS is a predictor of VAEs in patients with CS.