Key result
Peripheral unipolar low-voltage area surrounding bipolar scar was significantly larger in patients with VT recurrence compared to those without (57.0 vs. 17.2 cm2, P=0.01).
Why the study?
Does the size of peripheral unipolar low-voltage area (pUni-LVA) predict ventricular tachycardia recurrence after ablation in patients with structural heart disease?
Cohort (n=20)
Does the size of peripheral unipolar low-voltage area (pUni-LVA) predict ventricular tachycardia recurrence after ablation in patients with structural heart disease?
p-value: p=0.01
In patients with structural heart disease and unmappable VT, a larger peripheral unipolar low-voltage area surrounding bipolar scar predicts VT recurrence after ablation, highlighting the importance of intramural/epicardial substrate.
May support risk stratification by peripheral unipolar LVA after VT ablation; leaves open whether targeting this substrate improves outcomes.
AIMS: Scars causing ventricular tachycardia can extend deep to and beyond bipolar low-voltage areas (LVAs) and they may be a reason for endocardial ablation failure. Analysis of endocardial unipolar voltage maps has been used to detect scar transmurality and epicardial scar. We hypothesized that endocardial unipolar LVA around the overlying bipolar LVA may predict endocardial ablation recurrence in patients with structural heart disease undergoing substrate modification. METHODS AND RESULTS: Twenty consecutive patients with structural heart disease (11 ischaemic and 9 non-ischaemic cardiomyopathy) and undergoing substrate modification due to unmappable ventricular tachycardia (VT) (18 males, 51 ± 11 age, LVEF: 36 ± 7%) were retrospectively reviewed. Bipolar LVA defined as <1.5 mV and unipolar LVA defined as <8.3 mV, respectively, on electro-anatomic mapping system. Peripheral unipolar LVA (pUni-LVA) surrounding bipolar LVA was measured and compared patients with and without VT recurrence at 6-month follow-up period. : Mean unipolar voltage and mean bipolar voltage was 6.26 ± 4.99 and 1.90 ± 2.30 mV, respectively. Bipolar voltage and unipolar voltage in corresponding points were correlated (r = 0.652, P = 0.0001). In all patients, unipolar LVAs were larger than the bipolar LVAs. Bipolar LVA (91.1 ± 93.5 vs. 87.5 ± 47.5 cm(2), P = 0.91) and unipolar LVA (148.1 ± 96.3 vs. 104.7 ± 44.2 cm(2), P = 0.21) were similar in patients with and without VT recurrence, respectively. Peripheral unipolar LVA was significantly larger in patients with VT recurrence than without (57.0 ± 40.4 vs. 17.2 ± 12.9 cm(2), P = 0.01). CONCLUSION: In patients with structural heart disease and unmappable VT, pUni-LVA surrounding bipolar scar predicts recurrence of VT ablation. The results of this pilot study highlight the importance of intramural/epicardial substrate on endocardial VT ablation outcome.
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Yalın et al. (2015) conducted a cohort in Structural heart disease and unmappable ventricular tachycardia (n=20). Peripheral unipolar low-voltage area (pUni-LVA) vs. Patients without VT recurrence was evaluated on VT recurrence at 6-month follow-up (p=0.01). Peripheral unipolar low-voltage area surrounding bipolar scar was significantly larger in patients with VT recurrence compared to those without (57.0 vs. 17.2 cm2, P=0.01).
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