Accuracy of standard bipolar amplitude voltage thresholds to identify late potential channels in ventricular tachycardia ablation

Abstract

Background Ventricular tachycardia (VT) is caused by the presence of a slow conduction channel (CC) of border zone (BZ) tissue inside the scar-core tissue. Electroanatomic mapping can depict this tissue by voltage mapping. Areas of slow conduction can be detected as late potentials (LPs) and their abolition is the most accepted ablation endpoint. In the current guidelines, bipolar voltage thresholds for BZ and core scar are 1.5 and 0.5 mV respectively. The performance of these values is controversial. The aim of the study is to analyze the diagnostic yield of current amplitude thresholds in voltage map to define VT substrate in terms of CCs of LPs. Predictors of usefulness of current thresholds will be analyzed. Methods All patients with structural heart disease who underwent VT ablation in Hospital Clinic in 2016–2017 were included. Maps with delineation of CCs based on LPs were created with contact force sensor catheter. Thresholds were adjusted for every patient based on CCs. Diagnostic yield and predictors of performance of conventional thresholds were analyzed. Results During study period, 57 consecutive patients were included (age: 60.4 ± 8.5; 50.2% ischemic cardiomyopathy, LVEF 39.8 ± 13.5%). Cutoff voltages that better identified the scar and BZ according to the LP channels were 0.32 (0.02–2 mV) and 1.84 (0.3–6 mV) respectively. Current voltage thresholds identified correctly core and BZ in 87.7% and 42.1% of the patients respectively. Accuracy was worse in non-ischemic cardiomyopathy (NICM) especially for BZ (28.6% vs 55.2%, p = 0.042). Conclusions Accuracy of standard voltage thresholds for scar and BZ is poor in terms of LPs detection. Diagnostic yield is worse in NICM patients specially for border zone.

Autonomic neuro-cardiac profile of electrical, structural and neuronal remodeling in myocardial infarction-induced heart failure

“…Of note, VNS protocol was different with Vaseghi et al performing pulsed VNS (15 s on, 15 s off) as compared to steady-state VNS protocol used in this study. Interestingly in that study, scar borders were defined with conventional bipolar voltages of 0.5–1.5 mV and scars being 0.05–0.5 mV although MRI revealed areas of normal myocardium recording <0.5 mV, supporting the notion of variable (often lower) bipolar voltages in border zones [ 18 ]. This may confound the regional electrophysiologic effects of VNS observed in the border zones defined by conventional bipolar voltage definition.…”

Solving the Reach Problem: A Review of Present and Future Approaches for Addressing Ventricular Arrhythmias Arising from Deep Substrate

“…29 EAM with a bipolar voltage cut off <1.5 mV showed a good correlation with transmural scar but not with non-transmural heterogenous scar. 29,34 Histological studies have also shown that EAM (bipolar and unipolar) did not demonstrate a good correlation when identifying fibrosis in patients with NICM. 35 The importance of scar location was highlighted in another study, which showed just a 2 mm rim of viable endocardium overlying otherwise transmural scarring could result in a falsely normal bipolar voltage map, although a unipolar map can sometimes overcome this limitation.…”

Advancements in management of ventricular arrhythmias

“…However, these thresholds cut-offs were found mainly in studies of patients with ischemic heart disease and have not been well validated in patients with NICM. In a cross-sectional study, Roca-Luque et al examined the performance of conventional voltage thresholds and found only moderate diagnostic yield in identification of scars and delineation of border zone tissue, with worse performance in patients with NICM [2], In ICM pts, they found mean voltages that better identified the conduction channels in core tissue and border zone were 0.32 (0.02-2 mV) and 1.84 (0.3-6 mV). These values did not differ significantly between ICM and NICM pts (p = 0.09).…”