In patients with ventricular tachycardia, arrhythmogenic right ventricular cardiomyopathy (ARVC) may be mimicked in cardiac sarcoidosis (CS) with right ventricular (RV) involvement. The 12-lead electrocardiogram (ECG) may report specific RV activation patterns generated due to the histopathological differences of the diseases.
Terminal activation delay and occasionally an epsilon wave with small amplitude on the ECG arises due to delayed activation of areas with reduced voltages as the scar progresses from the epicardium to the endocardium in ARVC. Whereas preserved R'-waves in the right precordial leads, reflecting the late activated areas with preserved voltages, are observed due to the conduction block of patchy transmural RV scar in CS.
The study intended to establish whether CS with RV involvement can be distinguished from ARVC in ventricular tachycardia patients, using the terminal activation patterns in precordial leads V1-V3.
Patients with either 1) gene-positive ARVC referred for VT ablation or 2) CS with RV involvement were included in a retrospective multicenter study. Before the ablation, a non-ventricular-paced 12-lead surface ECG was taken. Leiden ECG Analysis and Decomposition Software (LEADS) was used for detailed analysis. The measurement tool in Adobe Pro DC was used to derive measurements per lead. After an S-wave, any positive deflection from baseline was defined as the R'-wave.
The study included 23 ARVC patients (78% male, 37 ± 15years) and 13 CS patients with RV involvement (62% male, 54 ± 8years).
All CS patients were found to have R'-wave in V1-V3, in contrast to the 11 (48%) ARVC patients.
The maximum R'-wave surface area in lead V1-V3 was noted as:
ARVC: 0.00 (IQR:0.00-0.43) mm2 (p < 0.001)
CS: 3.55 (IQR:2.18-5.81) mm2
Therefore, the presence of the R' wave and its cut-off surface area of ≥1.65mm2 served as an excellent discriminator between CS and ARVC.
The presence of an R'-wave in V1-V3 and its SA was used to develop an algorithm.
CS and ARVC can be distinguished with optimal specificity and sensitivity using an algorithm including the SA of the largest R'-wave in the lead V1-V3 ≥1.65mm2.