Can sarcoidosis cause arrhythmias?

Can Sarcoidosis Cause Arrhythmia?

Yes, sarcoidosis definitively causes arrhythmias—both life-threatening ventricular arrhythmias and conduction abnormalities are hallmark cardiac manifestations of this disease. 1

Mechanisms of Arrhythmogenesis

Cardiac sarcoidosis produces arrhythmias through noncaseating granulomas that infiltrate the myocardium with a particular predilection for the AV conduction system. 1 This inflammatory process creates both:

• Conduction system damage leading to bradyarrhythmias
• Myocardial scar substrate generating ventricular tachyarrhythmias 1

The granulomatous inflammation and subsequent fibrosis create the anatomic substrate for re-entrant circuits, making these patients vulnerable to sustained ventricular tachycardia. 1

Specific Arrhythmic Manifestations

Bradyarrhythmias and Conduction Disease

Complete heart block develops in approximately 25-30% of patients with cardiac sarcoidosis. 1 The ACC/AHA/HRS guidelines emphasize that:

• Various degrees of AV conduction block occur due to granulomatous involvement of the AV conduction system 1
• Pacemaker implantation is recommended even if high-grade or complete AV block reverses transiently because disease progression is unpredictable 1
• Patients with cardiac sarcoidosis and conduction abnormalities have worse prognosis than those with idiopathic AV block 1
• Immunosuppression can cause transient reversal of AV block, but this reversibility is unpredictable and should not delay pacing 1

Ventricular Arrhythmias

Cardiac sarcoidosis causes life-threatening ventricular arrhythmias including sustained monomorphic VT and ventricular fibrillation. 1 Critical points include:

• Sudden cardiac arrest may be the initial manifestation of cardiac sarcoidosis, occurring in patients with few or no manifestations of extracardiac disease 1
• Ventricular tachycardia results from myocardial granulomatous involvement creating scar substrate 1
• In a multicenter study of 235 cardiac sarcoidosis patients with ICDs, 36% received appropriate ICD therapy for ventricular arrhythmias 1
• Patients with mild-to-moderate LV dysfunction have substantial risk of developing ventricular arrhythmias 1

Supraventricular Arrhythmias

While less emphasized in guidelines, atrial fibrillation can occur as a manifestation of cardiac sarcoidosis. 2 Paroxysmal supraventricular tachycardia has been reported as an initial presentation. 2

Clinical Presentation Patterns

Arrhythmias may present across a spectrum from asymptomatic ECG changes to sudden cardiac death. 3, 4, 5 The ACC/AHA guidelines note:

• Palpitations, dizziness, and syncope are common presenting symptoms that significantly increase likelihood of cardiac sarcoidosis 6
• More than 100 ventricular ectopic beats in 24 hours has been proposed as a diagnostic criterion 6
• Sudden cardiac death can be the first manifestation without prior cardiac symptoms 1

Prognostic Implications

Cardiac sarcoidosis with arrhythmias carries a poor prognosis. 1 The guidelines emphasize:

• Cardiac involvement is the second leading cause of death in sarcoidosis after pulmonary disease 6, 7
• Patients with heart block, ventricular arrhythmias, or LV dysfunction have particularly poor outcomes 1
• History of syncope, lower LVEF, and ventricular pacing on baseline ECG predict higher likelihood of appropriate ICD therapies 1

Risk Stratification for Sudden Cardiac Death

The ACC/AHA/HRS guidelines acknowledge that sufficient clinical data are not available to stratify SCD risk among cardiac sarcoidosis patients definitively. 1 However, clinicians should consider:

• Syncope of suspected arrhythmic origin 1
• Heart failure status and LV function 1
• Spontaneous or induced ventricular arrhythmias at electrophysiological study 1
• Electrophysiological study is reasonable in patients with syncope of suspected arrhythmic etiology, as inducible sustained VA predicts future events 1

Device Therapy Recommendations

ICD implantation is reasonable in cardiac sarcoidosis patients with syncope of suspected arrhythmic origin, particularly with LV dysfunction or pacing indication. 1 The rationale:

• Myocardial granulomas and inflammation create substrate for both AV block and ventricular arrhythmias 1
• Pacemakers treat bradyarrhythmias but are not effective in preventing or treating life-threatening ventricular arrhythmias 1
• ICD therapy should be individualized based on symptoms, LV function, and arrhythmia burden 1

Critical Pitfalls

• Do not assume arrhythmia risk is low if AV block reverses with steroids—permanent pacing is still indicated due to unpredictable disease progression 1
• Do not overlook cardiac sarcoidosis in young patients (20-40 years) presenting with unexplained VT or heart block 1
• Sudden death can occur without extracardiac manifestations—isolated cardiac sarcoidosis occurs in approximately 5% of cases 8
• Ventricular arrhythmias can occur even with preserved LVEF 6