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Introduction: The utility of ablation index (AI) to guide ventricular tachycardia (VT) ablation in patients with structural heart disease is unknown. The aim of this study was to assess procedural characteristics and clinical outcomes achieved using AI‐guided strategy (target value 550) or conventional non‐AI‐guided parameters in patients undergoing scar‐related VT ablation. Methods: Consecutive patients (n = 103) undergoing initial VT ablation at a single center from 2017 to 2022 were evaluated. Patient groups were 1:1 propensity‐matched for baseline characteristics. Single lesion characteristics for all 4707 lesions in the matched cohort (n = 74) were analyzed. The impact of ablation characteristics was assessed by linear regression and clinical outcomes were evaluated by Cox proportional hazard model. Results: After propensity‐matching, baseline characteristics were well‐balanced between AI (n = 37) and non‐AI (n = 37) groups. Lesion sets were similar (scar homogenization [41% vs. 27%; p =.34], scar dechanneling [19% vs. 8%; p =.18], core isolation [5% vs. 11%; p =.4], linear and elimination late potentials/local abnormal ventricular activities [35% vs. 44%; p =.48], epicardial mapping/ablation [11% vs. 14%; p =.73]). AI‐guided strategy had 21% lower procedure duration (−47.27 min, 95% confidence interval [CI] [−81.613, −12.928]; p =.008), 49% lower radiofrequency time per lesion (−13.707 s, 95% CI [−17.86, −9.555]; p <.001), 21% lower volume of fluid administered (1664 cc [1127, 2209] vs. 2126 cc [1750, 2593]; p =.005). Total radiofrequency duration (−339 s [−24%], 95%CI [−776, 62]; p =.09) and steam pops (−155.6%, 95% CI [19.8%, −330.9%]; p =.08) were nonsignificantly lower in the AI group. Acute procedural success (95% vs. 89%; p =.7) and VT recurrence (0.97, 95% CI [0.42–2.2]; p =.93) were similar for both groups. Lesion analysis (n = 4707) demonstrated a plateau in the magnitude of impedance drops once reaching an AI of 550–600. Conclusion: In this pilot study, an AI‐guided ablation strategy for scar‐related VT resulted in shorter procedure time and average radiofrequency time per lesion with similar acute procedural and intermediate‐term clinical outcomes to a non‐AI‐guided approach utilizing traditional ablation parameters. [ABSTRACT FROM AUTHOR]

Background: Current American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) and European Society of Cardiology (ESC) guidelines recommend different strategies to avoid low-yield admissions in patients with syncope., Objective: The purpose of this study was to directly compare the safety and efficacy of applying admission criteria of both guidelines to patients presenting with syncope to the emergency department in 2 multicenter studies., Methods: The international BASEL IX (BAsel Syncope EvaLuation) study (median age 71 years) and the U.S. SRS (Improving Syncope Risk Stratification in Older Adults) study (median age 72 years) were investigated. Primary endpoints were sensitivity/specificity for the adjudicated diagnosis of cardiac syncope (BASEL IX only) and 30-day major adverse cardiovascular events (30d-MACE)., Results: Among 2560 patients in the BASEL IX and 2085 in SRS studies, ACC/AHA/HRS and ESC criteria recommended admission for a comparable number of patients in BASEL IX (27% vs 28%), but ACC/AHA/HRS criteria less often in SRS (19% vs 32%; P <.01). Recommendations were discordant in ∼25% of patients. In BASEL IX, sensitivity for cardiac syncope and 30d-MACE among patients without admission criteria was comparable for ACC/AHA/HRS and ESC criteria (64% vs 65%, P = .86; and 67% vs 71%, P = .15, respectively). In SRS, sensitivity for 30d-MACE was lower with ACC/AHA/HRS (54%) vs ESC criteria (88%; P <.001). Similarly, specificity for cardiac syncope and 30d-MACE in BASEL IX was comparable for both guidelines, but in SRS the ACC/AHA/HRS guidelines showed a higher specificity for 30d-MACE than the ESC guidelines., Conclusion: ACC/AHA/HRS and ESC guidelines showed disagreement regarding admission for 1 in 4 patients and had only modest sensitivity, all indicating possible opportunities for improvements., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: It is unknown whether cardiac syncope, and possibly also other syncope aetiologies exhibit circadian, weekly, seasonal, and temperature-dependent patterns., Methods and Results: We prospectively recorded the exact time, date, and outside temperature of syncope of patients >40 years old presenting with syncope to the emergency department in a diagnostic multicentre study. Two independent cardiologists/emergency physicians adjudicated the final diagnosis based on all information becoming available during clinical work-up including 1-year follow-up. Among 1230 patients, the adjudicated aetiology was cardiac in 14.6%, reflex in 39.2%, orthostatic in 25.7%, other non-cardiac in 9.7%, and unknown in 10.8% of patients. All syncope aetiologies occurred much more frequently during the day when compared with the night (P < 0.01). While reflex and orthostatic syncope showed a broad peak of prevalence with 80.9% of these events occurring between 4 am and 4 pm, cardiac syncope showed a narrow peak of prevalence with 70.1% of all events occurring between 8 am and 2 pm. A weekly pattern was present for most syncope aetiologies, with events occurring mainly from Monday to Friday (P < 0.01). Reflex syncope displayed a seasonal rhythm and was more common in winter (P < 0.01), while cardiac syncope stayed constant over the year. Syncope occurred most often when the outside temperature was coldest. Overall the patterns observed for cardiac syncope were similar to the patterns observed for its differential diagnosis., Conclusion: Syncope aetiologies in patients >40 years old display circadian, weekly, seasonal, and temperature-dependent patterns. Unfortunately, these patterns do not allow to reliably differentiate cardiac syncope from other aetiologies., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.)