Non-invasive electrocardiographic imaging to stratify risk of ventricular arrhythmia

Current tools for sudden cardiac death risk stratification have moderate accuracy. Indeed, two-third of the patients in primary prevention do not benefit from implantable cardioverter defibrillator (ICD). Non-invasive electrocardiographic imaging (ECGI) has emerged as a promising tool to assess ventricular deceleration zones in patients who have experienced ventricular arrhythmias (VAs). However, the ECGI properties of patients at risk of VAs have not yet been assessed.

To identify non-invasive ECGI parameters related with risk of suffering VAs in patients with ICD indication in primary prevention.

A case-control study was conducted comparing three groups of patients: those with ICDs who underwent ventricular tachycardia (VT) ablation (Group 1), those with ICDs implanted for primary prevention without VAs (Group 2), and a cohort of healthy subjects (Group 3) with normal QRS, normal MRI, and no cardiomyopathy. ECGI was performed on all patients to obtain ventricular activation maps. Group 1 patients were recorded before ablation during RV apical pacing. Groups 2 and 3 were recorded during their basal rhythm: Group 2 in sinus (n=4) and biventricular pacing (BiVP) (n=10), and Group 3 in sinus for all cases. Both left and right ventricles were segmented into 15 regions for ECGI analysis. Ventricular total activation time (TAT) and the mean regional TAT of the three regions with the largest activations (rTAT) were analysed, and these parameters were compared across the three groups.

Our primary finding is that non-invasive parameters measured by ECGI differentiates patients with a history of VAs from those without, see Figure 1. Overall, 43 patients were included in Group 1 (63.0±11.4 years; LVEF: 31±8.6%; 5 females; 10 non-ischemic; 100% with VAs), 14 patients in Group 2 (72.0±6.5 years; LVEF: 28.5±7.7%; 2 females; 10 non-ischemic; no VAs), and 26 subjects in Group 3 (58±8 years; LVEF: 60.6±4.7%; 5 females; no VAs). Patients with VAs had a higher rTAT (Group 1: 129.5±29.0 ms) compared to those at risk (Group 2: 69.2±25.2 ms) and healthy subjects (Group 3: 35.2±7.6 ms) (global p-value < 0.001). This suggests that higher rTAT values are associated with an increased risk of VAs, as shown in Figure 1. Representative ECGI cases of each cohort for paced rhythms (Group 1 and 2) and sinus (Group 3) are illustrated in Figure 2.

Non-invasive ECGI parameters, specifically regional activation times, effectively distinguish patients with a history of ventricular arrhythmias from those without, despite having an ICD indication in primary prevention. These findings support further prospective, multicentric studies to confirm ECGI’s predictive utility for predicting the risk of VAs in primary care.Figure 1  Figure 2