Late gadolinium-enhanced cardiac magnetic resonance in repaired tetralogy of Fallot: characterization of the right ventricular arrhythmogenic substrate

Abstract Introduction Ventricular arrhythmias are one of the main causes of morbidity and mortality in patients with repaired tetralogy of fallot (rTF). These life-threatening arrhythmias are related to specific isthmuses of viable tissue between areas of scar and/or valve rings of the right ventricle (RV) that have been already described in the literature. Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) has proven useful in characterizing the arrhythmogenic substrate in several heart diseases. Nevertheless, LGE-CMR evidence in patients with rTF is scarce. Purpose To compare the characterization of the ventricular arrhythmogenic substrate by means of LGE-CMR and electroanatomic mapping (EAM) of the right ventricle (RV) in patients with rTF. Methods Unicentric and observational study of consecutive patients with rTF who underwent LGE-CMR performed with 1.5T equipment and RV high-density voltage map, performed with multipolar catheter and completed with contact force-sensing catheter. The LGE-CMR segmentation was performed with dedicated software. The extent (area and percentage) and location of the dense scar (defined as <0.5 mV in EAM and <40% of the maximum intensity pixel in LGE-CMR) were compared, as well as the location of the isthmuses of viable tissue. Results Eight patients were included (45.7±10.4 years; 50% male). The extent of the scar was 20.7±13.6 cm2 (15.1±9.3%) by EAM and 21.7±8.8 cm2 (11.8±7.6%) by LGE-CMR. There was an absolute correlation regarding the location of the dense scar and the distribution of the isthmuses of viable tissue. The quantification of the dense scar evidenced a positive linear correlation between both techniques (area correlation: ρ = 0.71, p=0.047; percentage correlation: ρ = 0.88; p=0.004). The average time spent for the segmentation of the LGE-CMR with the dedicated software was 19.9±3.0 minutes. Conclusions Characterization of the RV arrhythmogenic substrate in patients with rTF with LGE-CMR is feasible. An absolute association regarding the location of the dense scar and the distribution of the isthmuses of viable tissue was observed when compared to the RV high-density EAM. In the same way, a statistically significant linear correlation in the quantification of the dense scar between both techniques was documented. LGE-CMR and EAM of two patients with rTF Funding Acknowledgement Type of funding source: None