Background: Cardiac sarcoidosis (CS) with right ventricular (RV) involvement may mimic ARVC.
Objective: To determine if the 12-lead ECG can distinguish CS from ARVC.
Methods: This is a multicenter retrospective study including patients (pts) with 1) CS with RV involvement or 2) ARVC fulfilling TFC plus pathogenic mutation referred for VT ablation with a non-ventricular paced 12-lead surface ECG available. We hypothesized that patchy transmural RV scar in CS may lead to conduction block, resulting in late activated areas with preserved voltages, whilst scar in ARVC progresses from epi- to endocardium and may lead to delayed activation of areas with reduced voltages. Thus, the surface area (SA) of the R’-wave (any positive deflection from baseline after an S-wave) in V1-V3 was measured.
Results: 13 CS pts with RV involvement (53±9yrs, 62% male) and 23 ARVC pts (36±16yrs, 78% male) were included. A terminal S-wave in V1-V3 was present in 57% ARVC pts vs. 0% CS pts. The maximum R’-wave SA in V1-V3 was significantly larger in CS vs. ARVC (Figure A). The maximum R’-wave SA in V1-V3 was an excellent discriminator (AUC 0.980). A cutoff of >1.65mm2 had 85% sens and 96% spec for CS. An algorithm including the presence of an R’-wave in V1-V3 and the SA of this R’-wave (Figure B) was validated in a separate cohort (CS(n=13), ARVC(n=16)) with 92% sens and 88% spec.
Conclusion: Transmural RV scars in CS may cause local conduction block, leading to late activated areas with preserved voltages, reflected as large R’-wave on the ECG. An easily applicable algorithm including the presence and surface area of the largest R’-wave in V1-V3 distinguishes CS from ARVC with excellent sensitivity and specificity (examples: Figure C).$$graphic_{3890347A-761E-4AD1-BF19-348E0EFF6666}$$
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