Aims Identifying patients who benefit from restored sinus rhythm (SR) would optimize the selection of candidates for ablation of long-standing persistent atrial fibrillation (LSPAF). This prospective study sought to identify the hitherto unknown factors associated with global functional improvement after successful radiofrequency catheter ablation of LSPAF. Methods and results In 171 LSPAF patients (84% of the total consecutive 203 patients) who were examined in SR 12 months after ablation, the individual per cent change from baseline value in maximum oxygen consumption at exercise test (VO₂ max), left ventricular ejection fraction (LVEF), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and five-dimensional descriptive system (EQ-5D) of quality-of-life questionnaire were classified in quartiles by 0 (worse) to 3 (best) grades. The individual grades were summed into a composite score (SCORE, 0 … 12) reflecting global functional improvement. Significant improvement in VO₂ max (3.4 ± 4.7 mL/kg/min), LVEF (7.5 ± 9.1%), NT-proBNP (−861 ± 809 pg/mL), and EQ-5D (0.7 ± 0.12) was observed (all P < 0.0001). On multivariable analysis, younger age (P = 0.001), male gender (P = 0.02), timely post-ablation left atrial appendage (LAA) outflow (P = 0.005) with improvement in outflow velocity (P = 0.0002), and withdrawal of Class I/III antiarrhythmic drugs (P < 0.05) were positively and independently correlated with the SCORE. Conclusions Younger male patients benefited most from catheter ablation of LSPAF. Delayed or non-improved LAA outflow and inability to discontinue Class I/III antiarrhythmic medication reduced the post-ablation functional improvement.

QT interval variability, mostly expressed by QT variability index (QTVi), has repeatedly been used in risk diagnostics. Physiologic correlates of QT variability expressions have been little researched especially when measured in short 10-second electrocardiograms (ECGs). This study investigated different QT variability indices, including QTVi and the standard deviation of QT interval durations (SDQT) in 657,287 10-second ECGs recorded in 523 healthy subjects (259 females). The indices were related to the underlying heart rate and to the 10-second standard deviation of RR intervals (SDRR). The analyses showed that both QTVi and SDQT (as well as other QT variability indices) were highly statistically significantly (p < 0.00001) influenced by heart rate and that QTVi showed poor intra-subject reproducibility (coefficient of variance approaching 200%). Furthermore, sequential analysis of regression variance showed that SDQT was more strongly related to the underlying heart rate than to SDRR, and that QTVi was influenced by the underlying heart rate and SDRR more strongly than by SDQT (p < 0.00001 for these comparisons of regression dependency). The study concludes that instead of QTVi, simpler expressions of QT interval variability, such as SDQT, appear preferable for future applications especially if multivariable combination with the underlying heart rate is used.

Purpose: To assess possible left ventricular (LV) structural changes that might be behind long-lasting arrhythmia-induced cardiomyopathy related to long-standing persistent atrial fibrillation (LSPAF), delayed-enhancement magnetic resonance imaging (DE-MRI) in detecting abnormal LV tissue was performed in LSPAF patients with severe depression of LV ejection fraction (LVEF). Methods: Of 210 consecutive patients with first LSPAF ablation in years 2006-12, 41 (20%) subjects (58 ± 9 years, 12% females) presented with consistent LVEF ≤40% for 23 ± 20 pre-ablation months. Resting/peak heart rates of 97 ± 18/152 ± 26 bpm were significantly higher for only resting heart rate as compared to LSPAF patients with normal LVEF. In years 2014-5, the patients were contacted to undergo DE-MRI. Results: At the end of 59 ± 18 month follow-up (1.6 ± 0.6 procedures/patient) 39 (95%) patients were in stable SR and LVEF was ≤40% in 7 (17%) patients. At 1 year post-ablation, LVEF improved from baseline by 22 ± 8% (increase to ≥50% in 85% patients), accompanied by improvement in NT-proBNP (-711 ± 562 pg/ml), VO2 max (+3.9 ± 5.1 mL/kg/min), and quality of life (all p < 0.00001). DE-MRI was not available in 18 patients (death 2, ICD 7, PM 2, claustrophobia 3, declined 3). DE-MRI performed 54 ± 17 (25-89) months after initial ablation in remaining 23 patients with SR proved durable ablation effect on LVEF (57 ± 9% by MRI vs. 59 ± 5% by echocardiography at 1 year) with LVEF impairment from ≥50 to ≤40% (54 to 29%) in 1 patient with no DE deposit. Discrete LV DE deposits were found in basal septum (n = 3), basal lateral wall (n = 1), and anterolateral papillary muscle (n = 1) in 3 patients (LVEF 62, 67, and 55%, respectively). Conclusion: Successful LSPAF ablation reversed related long-lasting LVEF depression in a majority of patients. The adverse LV response to arrhythmia was not related to concealed intramural structural (e.g. post-myocarditis) changes.

Purpose: Retrospective analysis of freedom from recurrent atrial fibrillation (AF) or atrial tachycardia (AT) after single catheter ablation for paroxysmal AF (PAF) in relation to procedural endpoint Methods: At first ablation in consecutive 946 patients (32% females, age 57 ± 10 years) it was at discretion of 4 involved operators whether they pursued AF/AT noninducibility following simple pulmonary vein isolation (PVI) performed during sinus rhythm (SR), or following termination of ongoing/induced AF/intermediate AT by simple PVI, or following termination of AF/AT continuing after completing PVI by ablation outside PVs. Noniducibility was tested by atrial pacing, isoproterenol and adenosine. Non-termination might be accepted after simple PVI or after PVI with extra-PV ablation. Three patients were excluded from analysis (ablation not performed: n = 2, no follow-up: n = 1). Results: PVI was completed in all patients. At the end of 69 ± 42 month follow-up after 1.36 procedures/patient stable SR was present in 85% patients (71% patients off drugs). No AF/AT recurrence vs. AF/AT recurrence after single ablation occurred in 71 vs. 29% of patients (p < 0.00001) in the group with proved noninducibility (n = 303), in 51 vs. 49% patients (p = 0.75) in the group of patients with non-tested/non-proved noninducibilty (n = 537), and in 31 vs. 69% patients (p = 0.001) in the group of non-terminated ongoing/induced AF/AT (n = 103) (Table). Conclusion: Noniducibility endpoint at first PAF ablation was associated with better single procedure arrhythmia-free outcome disregard presence or absence of AF during procedure. AF/AT non-termination was associated with the worst outcome.

Funding Acknowledgements: Type of funding sources: None. Background: Benefits of pulsed field ablation (PFA) compared to radiofrequency ablation (RFA) are not known in patients with longstanding persistent atrial fibrillation (LSPAF). Purpose: To present interim procedural and short-term clinical results of an ongoing prospective randomized comparison of PFA vs. RFA in patients with LSPAF. Methods: In 9/2021-10/2022, 125 patients underwent catheter ablation for LSPAF using PFA (n=64, 69±8 years, 11 F, continuous AF 32±20 months) vs. RFA (n=61, 68±8 years, 17 F, continuous AF 29±23 months). PFA included pulmonary vein isolation (PVI) and extra-PV left atrial (LA) ablation. RFA included stepwise PVI, electrogram-guided LA ablation, CS isolation, and electrogram-guided right atrial ablation. Intermediate endpoints were PVI, mitral isthmus, LA roof and CTI blocks); sinus rhythm (SR) restoration by ablation was the desired procedural endpoint. Follow-up included 7-day ECG monitoring every 3 months during the first year, and every 6 months afterwards. Results: In groups PFA vs. RFA, procedure and fluoroscopy times were 116±32 vs. 204±44 minutes, and 17±5 vs. 8±2 minutes, respectively (both p30 s) was achieved in 38 (79%) vs. 23 (46%) patients. Conclusion: Interim results of ongoing comparison suggest procedure time reduction and improved AF/AT free survival after PFA as compared to RFA in patients with LSPAF.