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We assessed the presence of immortal time bias (ITB) in observational studies evaluating the effectiveness of radiofrequency catheter ablation for atrial fibrillation (AF) on reduction of stroke. Eligible studies were classified based on presence or absence of ITB. Hazard ratios (HRs) were pooled using the random-effects model. Eight of 10 (80%) studies were subject to ITB. Pooling studies without ITB indicated no statistically significant reduction in incident strokes (HR 0.75; 95% confidence interval [CI], 0.49-1.02]. In conclusion, the pervasiveness of ITB in observational studies precludes definitive conclusions regarding an effect of AF ablation on strokes. Further studies designed to avoid ITB are warranted., (Copyright © 2020 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Aims: The COLchicine Cardiovascular Outcomes Trial (COLCOT) demonstrated the benefits of targeting inflammation after myocardial infarction (MI). We aimed to determine whether time-to-treatment initiation (TTI) influences the beneficial impact of colchicine., Methods and Results: In COLCOT, patients were randomly assigned to receive colchicine or placebo within 30 days post-MI. Time-to-treatment initiation was defined as the length of time between the index MI and the initiation of study medication. The primary efficacy endpoint was a composite of cardiovascular death, resuscitated cardiac arrest, MI, stroke, or urgent hospitalization for angina requiring coronary revascularization. The relationship between endpoints and various TTI (<3, 4-7 and >8 days) was examined using multivariable Cox regression models. Amongst the 4661 patients included in this analysis, there were 1193, 720, and 2748 patients, respectively, in the three TTI strata. After a median follow-up of 22.7 months, there was a significant reduction in the incidence of the primary endpoint for patients in whom colchicine was initiated < Day 3 compared with placebo [hazard ratios (HR) = 0.52, 95% confidence intervals (CI) 0.32-0.84], in contrast to patients in whom colchicine was initiated between Days 4 and 7 (HR = 0.96, 95% CI 0.53-1.75) or > Day 8 (HR = 0.82, 95% CI 0.61-1.11). The beneficial effects of early initiation of colchicine were also demonstrated for urgent hospitalization for angina requiring revascularization (HR = 0.35), all coronary revascularization (HR = 0.63), and the composite of cardiovascular death, resuscitated cardiac arrest, MI, or stroke (HR = 0.55, all P < 0.05)., Conclusion: Patients benefit from early, in-hospital initiation of colchicine after MI., Trial Registration: COLCOT ClinicalTrials.gov number, NCT02551094., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Catheter ablation (CA) is an established therapy for atrial fibrillation (AF). Studies regarding long-term real-world outcomes post-CA have inconsistently accounted for oral anticoagulation (OAC)., Objectives: To describe patterns of OAC use post-CA and to compare the OAC-adjusted long-term risk of stroke and major bleeding in AF patients with and without CA., Methods: A population-based cohort of AF patients was constructed in Quebec and Ontario, Canada (1999-2014). Propensity score matching was performed to determine the incidence rates of stroke and major bleeding among those undergoing CA, adjusted for time-dependent OAC use., Results: From the entire cohort, 6391 patients were identified as having undergone CA as compared to 482 977 patients who did not. Of these, 1240 patients with government medical insurance undergoing CA were matched with 2427 patients without CA. Post-CA, 78%, 65%, and 61% remained on an OAC at 1, 2, and 5 years, while 75%, 71%, and 68% of patients not undergoing CA were on OACs at 1, 2, and 5 years. At follow-up, there was no statistically significant difference for stroke (adjusted hazard ratio [HR], 0.88; 95% CI, 0.63 to 1.21) or major bleeding (adjusted HR, 0.88; 95% CI, 0.73 to 1.06)., Conclusion: No evidence was found that CA significantly decreases the risk of stroke or major bleeding when adjusting for OAC use over time. It may be prudent to continue anticoagulation post-CA based on patient-risk profile until randomized trials demonstrate both reduced stroke rates with CA, and improved safety (balancing stroke and bleeding risk) with OAC discontinuation post-CA., (© 2018 Wiley Periodicals, Inc.)

Introduction: Catheter ablation (CA) has been increasingly used to treat atrial fibrillation (AF) in patients with heart failure (HF), however, its safety at the population‐level has not yet been evaluated. To assess the safety of CA in AF‐HF patients, the frequency and potential risk factors for adverse events (AEs) within 30 days post‐CA were determined. Methods: A population‐based cohort of AF‐HF patients who underwent CA in Quebec, Canada (2000‐2017) was constructed using administrative databases. Major AEs included all‐cause mortality, cerebrovascular accident (CVA), pericardial effusion requiring drainage (PERD), vascular AEs, hemorrhage/hematoma, and pulmonary embolism. Univariate logistic regression models were employed to assess potential risk factors for major AEs. Results: Of 700 AF‐HF patients who underwent CA (median age 64.5 years [interquartile range, IQR, 56.2‐71.0], 22.0% female, and median CHA2DS2‐Vasc 3 [IQR, 2‐4]), 14 (2.0%) patients developed 16 major AEs within 30 days of CA. Hemorrhage/hematoma was the most frequent major AE (four patients; 0.6%) followed by all‐cause mortality, CVA/TIA, PERD, and vascular AEs (three patients each; 0.4%). Coronary artery disease (odds ratio [OR], 3.9 [95% confidence interval, CI, 1.2‐12.3]) and age ≥65 years (OR, 3.1 [95% CI, 1.1‐9.8]) were identified predictors for the composite outcome of major AEs. More than half of the patients (57.2%) underwent a second CA within a median of 0.8 (IQR, 0.2‐2.2) years from the date of first CA. Conclusion: CA performed in the AF‐HF population portends a relatively low incidence of major AEs. A larger study is required to determine whether certain patient factors are independently associated with a higher risk of post‐CA AEs. [ABSTRACT FROM AUTHOR]