Background: Atrial tachycardia (AT) is a commonly encountered rhythm disorder in patients with underlying atrial scar. The role of atrial late activation mapping during sinus rhythm to predict the critical isthmus (CI) of AT has yet to be systematically evaluated. We aimed to investigate the relationship between the functional substrate mapping (FSM) characteristics and the CI of reentrant ATs in patients with underlying atrial low‐voltage areas.Methods: Patients with history of left AT who underwent catheter ablation with 3D mapping using high‐density mapping were enrolled. Voltage map and isochronal late activation mapping were created during sinus/paced rhythm to detect deceleration zones (DZ). Electrograms with continuous‐fragmented morphology were also tagged. After induction of AT, activation mapping was performed to detect CI of the tachycardia. Atrial tachyarrhythmia (ATa) recurrence was defined as detection of atrial fibrillation or AT (≥30 s) during the follow‐up.Results: Among 35 patients [mean age: 62 ± 9, gender: 25 (71.5%) female] with left AT, a total of 42 reentrant ATs induced. Voltage mapping during sinus rhythm revealed low‐voltage area of 37.1 ± 23.8% of the left atrium. The mean value of bipolar voltage, EGM duration, and conduction velocity during sinus rhythm corresponding to CI of ATs were 0.18 ± 0.12 mV, 133 ± 47 ms, and 0.12 ± 0.09 m/s, respectively. Total number of DZs per chamber was 1.5 ± 0.6, which were located in the low‐voltage zone (<0.5 mV) detected by high‐density mapping. All CIs of reentry were colocalized with DZs detected during FSM. The positive predictive value of DZs to detect CI of inducible ATs is 80.4%. Freedom from ATa after the index procedure was 74.3% during a mean follow‐up of 12.2 ± 7.5 months.Conclusion: Our findings demonstrated the utility of FSM during sinus rhythm to predict the CI of AT. DZs displayed continuous‐fragmented signal morphology with slow conduction which may guide to tailor ablation strategy in case of underlying atrial scar.

Introduction: We aimed to investigate the impact of the 2021 European Society of Cardiology (ESC) guideline changes in left bundle branch block (LBBB) definition on cardiac resynchronization therapy (CRT) patient selection and outcomes.Methods: The MUG (Maastricht, Utrecht, Groningen) registry, consisting of consecutive patients implanted with a CRT device between 2001 and 2015 was studied. For this study, patients with baseline sinus rhythm and QRS duration ≥ 130ms were eligible. Patients were classified according to ESC 2013 and 2021 guideline LBBB definitions and QRS duration. Endpoints were heart transplantation, LVAD implantation or mortality (HTx/LVAD/mortality) and echocardiographic response (LVESV reduction ≥15%).Results: The analyses included 1.202, typical CRT patients. The ESC 2021 definition resulted in considerably less LBBB diagnoses compared to the 2013 definition (31.6% vs. 80.9%, respectively). Applying the 2013 definition resulted in significant separation of the Kaplan–Meier curves of HTx/LVAD/mortality (p < .0001). A significantly higher echocardiographic response rate was found in the LBBB compared to the non‐LBBB group using the 2013 definition. These differences in HTx/LVAD/mortality and echocardiographic response were not found when applying the 2021 definition.Conclusion: The ESC 2021 LBBB definition leads to a considerably lower percentage of patients with baseline LBBB then the ESC 2013 definition. This does not lead to better differentiation of CRT responders, nor does this lead to a stronger association with clinical outcomes after CRT. In fact, stratification according to the 2021 definition is not associated with a difference in clinical or echocardiographic outcome, implying that the guideline changes may negatively influence CRT implantation practice with a weakened recommendation in patients that will benefit from CRT.

Aim: In the present study, the relationship between D-dimer/fibrinogen ratio (DFR) and in-hospital outcomes was evaluated in patients with COVID-19 and a diagnosis of heart failure (HF). Materials ...