From the Guidelines
Approximately 50-75% of patients with cardiac sarcoidosis have abnormal electrocardiograms (ECGs), with the most common abnormalities including conduction disturbances, ventricular arrhythmias, and ST-segment and T-wave changes. The ECG abnormalities occur because sarcoid granulomas infiltrate the myocardium and conduction system, causing inflammation, fibrosis, and scarring that disrupt normal electrical pathways 1.
Common ECG Abnormalities
- Conduction disturbances such as atrioventricular blocks (first-degree, second-degree, or complete heart block)
- Bundle branch blocks (particularly right bundle branch block)
- Fascicular blocks
- Ventricular arrhythmias
- Atrial arrhythmias
- ST-segment and T-wave changes
- Pathological Q waves mimicking myocardial infarction
- QT interval prolongation These abnormalities are associated with an increased risk of cardiac events, including atrioventricular block, ventricular tachycardia, and systolic dysfunction 1.
Diagnostic Considerations
The presence and severity of ECG abnormalities often correlate with the extent of cardiac involvement, though some patients with significant cardiac sarcoidosis may have normal ECGs, particularly in early disease 1.
Additional Diagnostic Testing
Therefore, while an abnormal ECG should raise suspicion for cardiac sarcoidosis in patients with known or suspected sarcoidosis, a normal ECG does not exclude the diagnosis, and additional cardiac imaging, such as cardiac MRI or PET, may be necessary to confirm the diagnosis and assess the extent of cardiac involvement 1.
From the Research
Patients with Cardiac Sarcoidosis and Abnormal EKG
Patients with cardiac sarcoidosis often present with abnormal electrocardiograms (ECGs) due to the disease's impact on the heart's electrical conduction system. The following are some key points regarding patients with cardiac sarcoidosis and abnormal EKGs:
- Cardiac sarcoidosis can present with conduction abnormalities, ventricular arrhythmias, and heart failure, which can be detected on an EKG 2, 3.
- Approximately 5% of sarcoidosis patients develop clinically manifest cardiac features, and about 25% have asymptomatic cardiac involvement verified by autopsy or imaging studies 4.
- Patients with cardiac sarcoidosis are at elevated risk for arrhythmias, including ventricular tachycardia, and may require implantable cardioverter-defibrillator therapy 5.
- The diagnosis of cardiac sarcoidosis can be challenging, and a substantial degree of clinical suspicion as well as expertise in advanced cardiac imaging is required 2.
- Corticosteroid therapy may be effective for ventricular arrhythmias in the early stage of cardiac sarcoidosis, but less effective in the late stage 6.
- Patients with cardiac sarcoidosis and symptoms such as syncope need an aggressive workup for a potentially life-threatening etiology, and often require implantable cardioverter-defibrillator therapy 3.
Abnormal EKG Findings
Abnormal EKG findings in patients with cardiac sarcoidosis may include:
- Conduction abnormalities, such as high degree atrioventricular (AV) block 4.
- Ventricular arrhythmias, such as premature ventricular contractions (PVCs) and nonsustained ventricular tachycardia (NSVT) 6.
- Late potentials on signal-averaged electrocardiography (SAECG) 6.
- Reduced ejection fraction, which may indicate heart failure 5.