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T1 Mapping in NICM Patients Undergoing VT Ablation
Quick Takes
- T1 mapping on CMR correlates with the burden of diffuse interstitial fibrosis, and correlates with the extent of voltage abnormalities detected during ventricular tachycardia (VT) ablation procedures.
- T1 mapping is a marker of diffuse fibrosis and is associated with adverse outcomes in VT patients.
Study Questions:
What is the relationship between diffuse fibrosis (DF) detected on T1 mapping, the electroanatomic mapping (EAM) substrate, and outcomes of catheter ablation of ventricular tachycardia (VT) in patients with nonischemic cardiomyopathy (NICM)?
Methods:
The authors analyzed data on 51 patients with NICM and VT, who had no late gadolinium enhancement (LGE) on preprocedural cardiac magnetic resonance (CMR) imaging before VT ablation. Post-contrast T1 relaxation time was assessed on the septum. The extent of endocardial low-voltage areas (LVAs) at EAM was correlated with T1 mapping data.
Results:
Bipolar LVAs were present in 22 (43%) patients (median extent 15 cm2) and unipolar LVA in all patients (median extent 48 cm2). A significant inverse correlation was found between T1 values and both unipolar-LVA (R2 = 0.64; p < 0.01) and bipolar-LVA (R2 = 0.16; p < 0.01). After a median follow-up of 45 months, two (4%) patients died, three (6%) underwent heart transplantation, and eight (16%) experienced VT recurrence. Shorter post-contrast T1 time was associated with an increased risk of VT recurrence (hazard ratio, 1.16; 95% confidence interval, 1.03-1.33 per 10 ms decrease; p = 0.02).
Conclusions:
In patients with NICM and no evidence of LGE on CMR undergoing catheter ablation of VT, DF estimated by using T1 mapping correlates with the voltage abnormality at EAM and appears to affect clinical outcomes.
Perspective:
In patients with VT and prior myocardial infarction, VT circuits are related to the areas of dense scar, which correlate with LGE. In contrast, most patients with NICM scheduled for VT ablation do not have LGE on CMR due to more DF with a reticular pattern. Prior studies have shown that T1 relaxation time from the septum is a marker of the burden of DF throughout the ventricles, and it is an independent predictor of ventricular arrhythmia in patients with NICM. In the present study, the authors show that there is a significant association between the burden of DF assessed by T1 mapping and the extent of abnormal electrical substrate determined during the ablation procedure and between the extent of DF on T1 mapping and outcomes in patients. Future studies are needed to test the role of preablation T1 mapping to guide ablation in a larger cohort of patients.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Acute Heart Failure, Heart Transplant, Interventions and Imaging, Magnetic Resonance Imaging
Keywords: Arrhythmias, Cardiac, Cardiomyopathies, Catheter Ablation, Contrast Media, Diagnostic Imaging, Fibrosis, Gadolinium, Heart Failure, Heart Transplantation, Magnetic Resonance Imaging, Myocardial Infarction, Tachycardia, Ventricular
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