Abstract 10979: Late Gadolinium Enhancement on Cardiac MRI Depicts Spatial and Temporal Repolarization Abnormalities in Patients with Lethal Ventricular Arrhythmias
[Background]: The distribution of late gadolinium enhancement (LGE) on cardiac MRI (CMR) represents myocardial scar that produces abnormal repolarization as well as abnormal depolarization. Recently, great attention has been focused on the QT/RR relationship since it is a potential prognostic predictive factor in view of the arrhythmogenicity.
[Purpose]: To elucidate whether the LGE distribution correlates with the rate adaptation pattern and diurnal variability of the QT/RR in patients with lethal ventricular arrhythmias.
[Methods]: CMR and QT/RR analyses using Holter monitoring were performed in 34 patients (24 males, 59.7±10.5 years) with VT and/or VF. The LGE was classified into 17 left ventricular segments. The average transmural extent of the LGE was scored as 1 to 4 in each segment and the sum of the LGE scores (Total LGE score) was calculated in each patient. The QT/RR slope and day-time/night-time QT/RR ratio (Day/Night ratio) were calculated. The correlation of the slope or Day/Night QT/RR ratio and LGE findings were analyzed.
[Results]: All patients were divided into 23 LGE positive (LGE(+)) and 11 LGE negative (LGE(-)) patients. The slopes of the QTe (QRS onset to the end of the T wave)/RR and QTa (QRS onset to the apex of the T wave)/RR were significantly steeper in the LGE(+) than LGE(-) patients (0.212±0.026 vs. 0.128±0.021 (p<0.001), 0.187±0.032 vs. 0.130±0.024 (p<0.001), respectively), and both slopes correlated significantly with the Total LGE scores (r=0.83 (p<0.001), r=0.71 (p<0.001), respectively). In the LGE(+) patients, the QTe Day/Night (1.37±0.38 vs. 0.91±0.33 (p<0.01)), and QTa Day/Night ratios (1.33±0.26 vs. 1.06±0.31 (p<0.01)) were significantly greater than in the LGE(-) patients.
[Conclusions]: The transmural distribution of the LGEs was deeply related to the hyperadaptation of the QT dynamicity in addition to the diurnal QT/RR variability. These results indicate that myocardial scar demonstrated by LGE results in increases in the dispersion of the repolarization among healthy and damaged myocardium, which can also be enhanced by autonomic tone, causing severe ventricular arrhythmias in patients with organic heart disease.
- © 2011 by American Heart Association, Inc.