Background - Recurrent paroxysmal atrial fibrillation (PAF) after catheter ablation is presumably caused by failure to achieve durable pulmonary vein isolation (PVI). The primary methods of PVI are radiofrequency (RF) and cryoballoon (CRYO) catheter ablation, but these methods have not been directly compared with respect to PVI durability and the effect thereof on AF burden (% of time in AF). Methods - Accordingly, we performed a randomized trial including 98 patients (68% male, 61 [55-67] years) with PAF assigned 1:1 to PVI by contact-force sensing, irrigated RF catheter or second-generation CRYO catheter. Implantable cardiac monitors were inserted ≥1 month before PVI for assessment of AF burden and recurrence, and all patients, irrespective of AF recurrence, underwent a second procedure 4-6 months after PVI to determine PVI durability. Results - In the second procedure, 152/199 (76%) pulmonary veins (PVs) were found durably isolated after RF and 161/200 (81%) after CRYO (NS), corresponding to durable isolation of all veins in 47% of patients in both groups (NS). Median AF burden before PVI was 5.4% (interquartile range: 0.5-13.0%) vs. 4.0% (0.6-18.1%), RF vs. CRYO, and reduced to 0.0% (0.0-0.1%) and 0.0% (0.0-0.5%), respectively - a reduction of 99.9% (92.9-100.0%) and 99.3% (85.9-100.0%) (all NS). AF burden after PVI significantly correlated to the number of durably isolated PVs (p < 0.01), but 9/45 (20%) patients with durable isolation of all veins had recurrence of AF within 4-6 months after PVI (excluding a 3-month blanking period). Conclusions - PVI by RF and CRYO catheter ablation produce similar moderate to high PVI durability. Both treatments lead to marked reductions in AF burden, which is related to the number of durably isolated PVs. However, for one fifth of PAF patients, complete and durable PVI was not sufficient to prevent even short-term AF recurrence.

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Background Insulin-treated patients with type 2 diabetes (T2D) are at risk of hypoglycemia, which is associated with an increased risk of cardiovascular disease and mortality. Using a long-term monitoring approach, we investigated the association between episodes of hypoglycemia, glycemic variability and cardiac arrhythmias in a real-life setting. Methods Insulin-treated patients with T2D (N = 21, [mean ± SD] age 66.8 ± 9.6 years, BMI 30.1 ± 4.5 kg/m2, HbA1c 6.8 ± 0.4% [51.0 ± 4.8 mmol/mol]) were included for a one-year observational study. Patients were monitored with continuous glucose monitoring ([mean ± SD] 118 ± 6 days) and an implantable cardiac monitor (ICM) during the study period. Results Time spend in hypoglycemia was higher during nighttime than during daytime ([median and interquartile range] 0.7% [0.7–2.7] vs. 0.4% [0.2–0.8]). The ICMs detected 724 episodes of potentially clinically significant arrhythmias in 12 (57%) participants, with atrial fibrillation and pauses accounting for 99% of the episodes. No association between hypoglycemia and cardiac arrhythmia was found during daytime. During nighttime, subject-specific hourly incidence of cardiac arrhythmias tended to increase with the occurrence of hypoglycemia (incident rate ratio [IRR] 1.70 [95% CI 0.36–8.01]) but only slightly with increasing time in hypoglycemia (IRR 1.04 [95% CI 0.89–1.22] per 5 min). Subject-specific incidence of cardiac arrhythmias during nighttime increased with increasing glycemic variability as estimated by coefficient of variation whereas it decreased during daytime (IRR 1.33 [95% CI 1.05–1.67] and IRR 0.77 [95% CI 0.59–0.99] per 5% absolute increase, respectively). Conclusions Cardiac arrhythmias were common in insulin-treated patients with T2D and were associated with glycemic variability, whereas arrhythmias were not strongly associated with hypoglycemia. Trial registration: NCT03150030, ClinicalTrials.gov, registered May 11, 2017. https://clinicaltrials.gov/ct2/show/NCT03150030