A newly developed algorithm combining unipolar voltage and electrogram characteristics correctly identified epicardial scar with a sensitivity of 75% in patients with non-ischaemic cardiomyopathy.
Observational (n=10)
Can unipolar voltage, bipolar voltage, and electrogram characteristics distinguish fibrosis from viable myocardium and fat during epicardial EAM for VT ablation in patients with non-ischaemic cardiomyopathy?
A novel algorithm combining unipolar voltage and electrogram characteristics can differentiate between scar and viable myocardium during epicardial mapping, overcoming the confounding effect of epicardial fat.
p-value: p=<0.001
AIMS: During epicardial electroanatomical mapping (EAM), it is difficult to differentiate between fibrosis and fat, as both exhibit attenuated bipolar voltage (BV). The purpose of this study was to assess whether unipolar voltage (UV), BV, and electrogram characteristics (EC) can distinguish fibrosis from viable myocardium and fat during epicardial EAM for ventricular tachycardia (VT) ablation in non-ischaemic cardiomyopathy (NICM). METHODS AND RESULTS: Ten NICM patients (7 males, 56 ± 13 years) with VT underwent epicardial EAM with real-time integration of computed tomography-derived epicardial fat and contrast-enhanced MRI-derived scar. Bipolar voltage (filtered 30-400 Hz), UV (filtered 1-240 Hz), and EC (duration and morphology) were correlated with the presence of fat and scar. At sites devoid of fat, the optimal cutoff values to differentiate between scar and myocardium were 1.81 mV for BV and 7.95 mV for UV. Bipolar voltage, UV, and electrogram duration >50 ms distinguished scar from myocardium in areas covered with <2.8 mm fat (all P < 0.001), but not ≥ 2.8 mm fat. In contrast, electrogram morphology-characteristics could also detect scar covered with ≥ 2.8 mm fat (P = 0.001). A newly developed three-step algorithm combining electrogram morphology, duration, and UV could correctly identify scar with a sensitivity of 75%. Unipolar voltage but not BV could detect intramural scar in the absence of fat. CONCLUSIONS: Both BV ≤ 1.81 mV and UV ≤ 7.95 mV are useful for detection of scar during epicardial EAM, in the absence of ≥ 2.8 mm fat. However, EC can be used to detect scar covered with fat. A newly developed algorithm combining UV and EC can differentiate between scar and viable myocardium. Unipolar voltage but not BV could detect intramural scar.
Piers et al. (2012) conducted an observational in Ventricular tachycardia in non-ischaemic cardiomyopathy (n=10). Epicardial electroanatomical mapping with unipolar voltage, bipolar voltage, and electrogram characteristics was evaluated on Optimal cutoff values to differentiate between scar and myocardium at sites devoid of fat (p=<0.001). A newly developed algorithm combining unipolar voltage and electrogram characteristics correctly identified epicardial scar with a sensitivity of 75% in patients with non-ischaemic cardiomyopathy.