Abstract 1973: Positive Delayed Enhancement of Cardiac MR Imaging and Negative Uptake of 18F-FDG PET Indicates Damaged Myocardial Substrate of Ventricular Tachycardia in Cardiac Sarcoidosis
[Background]: Magnitude of delayed enhancement (DE) of cardiac magnetic resonance imaging (CMR) and uptake of 18F-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET) may represent damaged myocardial lesions in myocardial diseases. However, particularly in the case of cardiac sarcoidosis, it is unclear whether the myocardium at the site of DE positive (DE (+)) or 18F-FDG PET positive (PET (+)) demonstrates an abnormal electric activity playing a causal role of ventricular tachycardia (VT).
[Purpose]: To depict the characteristics of endocardial electrogram on DE (+) and PET (+) sites and clarify its nature as a VT substrate in patients with cardiac sarcoidosis.
[Methods]: A Gadolinium-enhanced CMR, 18F-FDG PET and endocardial catheter mapping were performed in 10 patients with cardiac sarcoidosis experienced VT episodes. Electrograms were recorded from 12 different sites of left ventricular endocardial surface (Basal - Middle - Apical × Anterior - Lateral -Posterior - Septal). In each 12 sites, existence of DE and PET was investigated, and area of DE on the short-axis left ventricular MRI view was calculated. Two parameters measured (amplitude and duration) of the electrogram were compared among groups of the sites with a combination of DE (+) or DE (−) vs. PET (+) or PET (−).
[Results]: Amplitude and duration of the electrogram were 7.7 ± 3.7 mV and 41.5 ± 6.9 ms in DE(−)PET(−), 7.6 ± 2.4 mV and 43.7 ± 5.1 ms in DE(−)PET(+), 5.5 ± 3.9 mV and 50.9 ± 13.3 ms in DE(+)PET(+) and 2.9 ± 1.6 mV and 53.6 ± 16.5 ms in DE(+)PET(−) sites, indicating the diminishment of amplitude and the prolongation of duration in this order. DE area showed a negative correlation (r=−0.60, p<0.001) with the amplitude and a positive correlation (r=0.53, p<0.001) with the duration. Surprisingly, all VTs were originated from DE(+)PET(−) sites.
[Conclusions]: The magnitude of localized DE significantly correlates with the corresponding myocardial electrical damage. In contrast, 18F-FDG PET findings have a less concern with the electrical damage. Positive DE with negative PET sites, probably representing myocardial scar without active inflammation, indicates the substrate of VTs in cardiac sarcoidosis.