The precordial R-prime wave: a novel discriminator between cardiac sarcoidosis and arrhythmogenic right ventricular cardiomyopathy in patients presenting with ventricular tachycardia
Authors: Hoogendoorn J , Venlet J , Man S , Kumar S , Sramko M , Dechering DG , Nakajima I , Siontis KC , Watanabe M , Tedrow U , Bogun F , Eckardt L , Peichl P , Stevenson WG , Zeppenfeld K 
Published: May 2021

Abstract

Funding Acknowledgements
Type of funding sources: Other. Main funding source(s): The department of cardiology from Leiden University Medical Center receives unrestricted grants from Edwards Lifesciences, Biotronik, Medtronik, Boston Scientific and BioSense Webster. MS was supported by the Research Fellowship of the European Society of Cardiology 2017/2018.
Background Cardiac sarcoidosis (CS) with right ventricular (RV) involvement may mimic ARVC. Histopathological differences may result in disease specific RV activation patterns, detectable on the 12-lead electrocardiogram (ECG). Scar in ARVC progresses from epicardium to endocardium and may lead to delayed activation of areas with reduced voltages, translating into terminal activation delay and occasionally an (epsilon) wave with small amplitude on the ECG. On the contrary, patchy transmural RV scar in CS may lead to conduction block, and therefore late activated areas with preserved voltages, reflected as preserved R’-waves in the right precordial leads.
Purpose To determine whether the terminal activation patterns in precordial leads V1-V3 distinguish CS with RV involvement from ARVC.
Methods This is a multicenter retrospective study including patients with either 1) CS with RV involvement or 2) gene-positive ARVC referred for VT ablation. A non-ventricular paced 12-lead surface ECG prior to ablation was obtained (25mm/s and 10mm/mV). For detailed analysis, Leiden ECG Analysis and Decomposition Software (LEADS) was used. After detection of QRST complexes in the spatial velocity signal, LEADS generates a representative and low-noise averaged beat. Then, measurements per lead were performed using the measurement tool in Adobe Pro DC. Based on the hypothesis that conduction block in CS will lead to late activated areas with preserved voltages, we measured the surface area (SA) of the R’-wave in V1-V3. An R’-wave was defined as any positive deflection from baseline after an S-wave.
Results 13 CS patients with RV involvement (54 ± 8years, 62% male) and 23 ARVC patients (37 ± 15years, 78% male) were included. A R’-wave in V1-V3 was present in all CS patients, compared to 11 (48%) of ARVC patients (p = 0.002). The maximum R’-wave SA in lead V1-V3 was 3.55 (IQR:2.18-5.81) mm2 in CS vs. 0.00 (IQR:0.00-0.43) mm2 in ARVC (p &lt; 0.001; Figure A). By ROC-analysis, the maximum R’-wave SA in lead V1-V3 was an excellent discriminator (area under the curve 0.980 [95%CI: 0.945-1.000]). A cutoff of ≥1.65mm2 had a sensitivity of 85% and specificity of 96% for diagnosing CS. An algorithm was created including the presence of an R’-wave in V1-V3 and the SA of this R’-wave (Figure B). This was validated in a second cohort (18 CS and 40 ARVC) with 72% sensitivity and 88% specificity.
Conclusion Transmural RV scars in CS may cause localized conduction block, leading to late activated areas with preserved voltages, reflected as large R’-wave on the 12-lead surface ECG. An easily applicable algorithm including the surface area of the largest R’-wave in lead V1-V3 ≥1.65mm2 distinguishes CS from ARVC with good sensitivity and specificity. The QRS terminal activation in precordial leads V1-V2 may reflect disease specific scar patterns (for examples: Figure C). Abstract Figure