Intrinsic antitachycardia pacing (iATP) is a novel automated ventricular ATP algorithm that designs ATP sequences based on the analysis of prior failed ATP. Real‐world data on the efficacy and safety of iATP are lacking. Among 124 ventricular tachycardia (VT) episodes in 130 consecutive patients (mean age at implantation: 63.8 ± 14.9 years; sex, 95 male and 35 female) for whom implantable cardioverter defibrillator or cardiac resynchronization therapy defibrillator equipped with iATP algorithm was implanted, we investigated the efficacy and safety of iATP for VT refractory to conventional burst pacing. Eight patients had a total of 17 episodes of iATP therapy after failed conventional burst pacing within 11.2 ± 6.6 months of follow‐up. Eleven VT episodes (64.7%) in seven patients (87.5%) were successfully terminated by iATP, and only one patient (12.5%) experienced VT acceleration. iATP might be useful for VTs refractory to conventional burst pacing with a low risk of VT acceleration.

Introduction: Most of the early repolarization patterns (ERP) in electrocardiography (ECG) are benign but some of them are associated with ventricular fibrillation (VF). We evaluated whether or not a high spatio-temporal resolution magnetocardiography (MCG) could non-invasively detect malignant types of ERP. Methods: Sixty four-channel MCG, standard 12-lead ECG, and signal averaged ECG (SAECG) were recorded in 120 patients with inferolateral ERP in ECG without any major structural heart diseases; 13 of them had a history of VF (VF(+)-group) and the remaining 107 had no VF (VF(-)-group). We evaluated the following novel MCG indexes: MCG-QRS (msec), root mean square of terminal 40 msec magnetic field (MCG-RMS) (msec), and the duration under 10% of maximal amplitude (MCG-LAS) (msec) of the highest amplitude channel. Results: The amplitude and distribution of the J-wave, ST-T morphology in ECG, parameters of SAECG were not significantly different, whereas MCG-QRS and MCG-LAS were significantly longer and MCG-RMS was smaller in ERP-VF(+) compared with ERP-VF(-) group (107(SD=24) vs 84(13) msec, P<0.01, 8(22) vs 22(11) msec, P<0.01, 0.10(0.08) vs 0.28(0.19) msec, P<0.01, respectively). In the multivariate logistic regression model, only MCG-QRS remained significant among the MCG indexes and the existing predictors (odds ratio (OR) 1.08, 95%CI 1.01 to1.17). The predictive ability of VF was significantly higher using MCG-QRS when the c-statistic was compared with that of the existing ECG measure (0.82 vs 0.56, P<0.01, Figure). When cut-offs were set by the least squares method at MCG-QRS 100 msec, MCG-RMS 0.24 msec, MCG-LAS 27 msec, corresponding ORs were calculated as 12.7, 95%CI 3.6 to 45.0, 6.1, 95%CI 1.7 to 21.2, 6.2, 95%CI 1.8 to 20.8, respectively. Conclusions: MCG-QRS >100 msec was a simple and effective criterion for prediction of high risk ERP subjects, thus MCG analysis is an useful screening tool to detect malignant ERP out of the numerous benign ones.