Pleomorphism during Ventricular Tachycardia: A Distinguishing Feature between Cardiac Sarcoidosis and Idiopathic VT

BACKGROUND: Ventricular tachycardia (VT), a common manifestation of cardiac sarcoidosis (CS), is associated with high morbidity and mortality. It could be mistaken for idiopathic VT (IVT) in the absence of systemic manifestations and overt cardiac structural abnormality. We studied the electrocardiogram (ECG) characteristics of VT in CS that may distinguish from IVT and also explored the relationship of the ECG characteristics with imaging findings in patients with CS. METHODS AND RESULTS: Twelve-lead ECG characteristics of VT in CS patients (Group I = 37) were compared with IVT (Group II = 49). QRS duration, axis, morphology, VT cycle length, and cycle length variation (CLV) were analyzed. In Group I, 18 (49%) had pleomorphic VT (PLVT) and none in Group II. CLV was seen only in Group I (24%). Mean QRS duration (milliseconds) and cycle length (milliseconds) were greater in Group I (QRSd 152.49 [39.3] vs 140.9 [19.2]) and (332.2 [136.5] vs 312.9 [56.2]), the differences not statistically significant. In Group I, myocardial scar was present in 22 of 25 patients and myocardial inflammation in 28 of 29 patients as assessed by cardiac magnetic resonance imaging (delayed enhancement) and 18-fluorodeoxyglucose positron emission computed tomography, respectively. PLVT was seen more commonly in patients with involvement of >1 myocardial region than focal involvement (58% and 30%, respectively, with myocardial scar and 50% and 40%, respectively, with myocardial inflammation). CONCLUSION: Pleomorphism and CLV during VT may be distinguishing features between IVT and VTs of CS origin.