Last update: April 2020

  Sarcoidosis is a multisystem disease characterized by the presence of non-caseating granulomas in the involved organs.

  Sarcoidosis may affect heart in two ways: 1. Right ventricular remodeling due to pulmonary hypertension (which is due to progresive lung disease). 2. Direct involvement of the heart by sarcoid granulomas: Cardiac Sarcoidosis (CS).

  CS occurs in a focal manner, not in a diffuse manner as in viral myocarditis.

  Focal granulomas destruct the myocardial tissue by causing both inflammation and scar formation (fibrosis). This, in turn, may result in arrhythmias, heart failure and sudden death.

  Clinical manifestations of CS depend on the areas involved by the granulomas.

  CS generally involves
myocardium and the conduction system of heart which explains the abnormal ECG findings.

  Because CS has a predilection for involvement of the basal septum, the conduction system gets involved relatively early, resulting in fascicular blocks or bundle branch blocks.

  It has been reported that sudden death due to cardiac arrest may be caused by granulomatous lesions in the sinus node.

  CS has no diagnostic ECG finding.

  The presence of a normal ECG is not enough to exclude the diagnosis of cardiac sarcoidosis.




ECG abnormalities that may be observed in Cardiac Sarcoidosis

  Atrioventricular (AV) blocks: at rest or during exercise.

  Bundle branch blocks (BBB)

  Fragmented QRS (in absence of BBB). This is a marker of slow conduction and scarring.

  Atrial arrhythmias: atrial fibrillation, atrial flutter, atrial tachycardia. Atrial flutter may be followed by a long pause in the cardiac cycle (probably due to fibrosis in the atria).

  Ventricular arrhythmias: frequent VPCs, episodes of ventricular tachycardia (VT). In patients with VT of left bundle branch block (LBBB) morphology and nonischemic cardiomyopathy with prominent right ventricular (RV) involvement, it is important to consider sarcoidosis, arrhythmogenic right ventricular cardiomyopathy (ARVC), and idiopathic giant cell myocarditis in the differential diagnosis.

  Low QRS voltage (less than 0.5 mV for limb and 1 mV for precordial leads). Especially in aVF and lead II.

  Abnormal (pathological) Q waves.

  Epsilon wave (rarely). A giant epsilon wave may be seen as a bizarre "double QRS" pattern.




References and links to sample ECGs

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