Table 1.

Summary characteristics of the 10 studies included in the systematic review

PubMed ID	Year	First author	Title	Study design	Country	Length of follow up	Outcome measures	Method of cognitive impairment ascertainment	Total number of patients included in the study	Number with atrial fibrillation who received catheter ablation	Ablation procedure details	Number with atrial fibrillation treated with medical therapy	Medical therapy group details
30397930	2021	Wang	Radiofrequency and cryoballoon ablation improve cognitive function in patients with atrial fibrillation	Case–control	China	12 months	Telephone interview for cognitive status-modified (TICS-m) scores at baseline, 3 months and 12 months	Telephone interview for cognitive status-modified (TICS-m) scores ≤ 27 were defined as dementia and 28–31 were defined as mild cognitive impairment	139	98	Of the 98 patients treated with catheter ablation, 68 underwent radiofrequency catheter ablation with an irrigated contact force-sensing catheter whilst 30 underwent cryoballoon ablation using a double-walled balloon	41	The medical therapy group comprised patients who received conventional antiarrhythmic drug therapy. Patients in this group received antiarrhythmic drugs to lower ventricular rate below 110 beats/min and anticoagulant therapy according to CHA2DS2-VASc score Of the 41 patients treated with medical therapy, 21/41 (51.22%) were being treated with anticoagulant therapy
34261448	2021	Zhang	Incidence and risk factors of post-operative cognitive decline after ablation for atrial fibrillation	Case–control	China	6 months	Post operative cognitive decline at 48 h after ablation	Used a battery of 9 neuropsychological tests based on the Canadian Study of Health and Aging: (1) Consortium to establish a registry for Alzheimer’s disease (CERAD) auditory-verbal immediate, (2) CERAD auditory-verbal delayed, (3) & (4) trail making tasks A and B, (5) digit symbol substitution, (6) controlled oral word association, (7) CERAD semantic fluency, (8) and (9) grooved pegboard test-dominant hand and non-dominant hand Post operative cognitive decline was defined in an individual when the reliable change index score was less than − 1.96 on 2 tests and/or the combined z-score was less than − 1.96	287	190	Atrial fibrillation ablation procedures were performed under conscious sedation. For patients with paroxysmal atrial fibrillation, circumferential pulmonary vein isolation was utilised. Patients with persistent atrial fibrillation were treated with bilateral circumferential pulmonary vein antrum isolation and three linear ablation sets	87	Data were not available regarding the proportions of patients on rate and/or rhythm control therapy The medical therapy group comprised a similar proportion of patients taking oral anticoagulant therapy compared with the ablation group
31884008	2020	Hsieh	Catheter ablation of atrial fibrillation reduces the risk of dementia and hospitalization during a very long-term follow-up	Cohort	Taiwan	Mean follow up: 9.0 years	1. New onset of non-vascular dementia 2. Atrial fibrillation related hospitalisation	New onset of dementia of each subject was identified by International classification of disease (ICD-9-CM) codes	2344	787	Details about the catheter ablation procedure were not provided	787	In the group of patients treated with medical therapy, 459/787 (58.3%) were on anti-arrhythmic agents compared with 759/787 (96.4%) who underwent catheter ablation Warfarin was used in 448/787 (56.9%) of patients treated with medical therapy compared with 291/787 (37%) of patients who underwent catheter ablation
33022705	2020	Kim	Less dementia after catheter ablation for atrial fibrillation: a nationwide cohort study	Cohort	Korea	Median follow up: 52 months	1. Dementia 2. Dementia subtypes, including Alzheimer’s disease and vascular dementia	Diagnosis of dementia was defined using International classification of disease (ICD-10) codes	27097	9119	Details about the catheter ablation procedure were not provided	17978	Comparisons were made amongst groups propensity matched for anti-arrhythmic drug use and rate control therapy (comprising beta blocker, non-dihydropyridine calcium channel blockers and digoxin). The groups were also propensity matched for anticoagulant use (warfarin, non-vitamin K antagonist oral anticoagulant)
31299299	2020	Bunch	Stroke and dementia risk in patients with and without atrial fibrillation and carotid arterial disease	Cohort	USA	Mean follow up in atrial fibrillation, non-ablation group: 1459 days. Mean follow up in the atrial fibrillation, ablation group 2093 days	1. Long term dementia 2. 3-year dementia 3. 5-year dementia, 3-year stroke/transient ischaemic attack, 5-year stroke/transient ischaemic attack, long term stroke/transient ischaemic attack	Dementia was diagnosed using International classification of disease (ICD-9 and ICD-10) codes	11572	450	Details about the catheter ablation procedure were not provided	5336	Details about amiodarone, beta blocker, calcium channel blocker and anticoagulant therapy use are provided in supplementary table 2 of the article. Lower proportions of patients were treated with amiodarone (15.9% compared with 22.7%), beta blockers (46.8% compared with 60.9%), calcium channel blockers (32.4% compared with 36.7%) and anticoagulant therapy (34.7% compared with 56.0%) in the medical therapy arm
31624507	2019	Hyogo	One-year clinical outcomes of anticoagulation therapy among Japanese patients with atrial fibrillation: The Hyogo AF Network (HAF-NET) Registry	Cohort	Japan	Mean follow up: 355 days	1. Cerebral infarctions 2. Composite of new onset dementia, cardiac event requiring hospitalisation and all cause death	Mini‐Mental State Examination and/or Hasegawa dementia rating scales were used to define a diagnosis of dementia. Cut-off scores not mentioned	2113	614	Details about the catheter ablation procedure were not provided	1499	Details about the proportions of patients receiving rate and/or rhythm control therapy were not provided In total, 1842/2113 (87%) of the study participants were treated with anticoagulation therapy. In the catheter ablation arm, 439/614 (71.5%) patients were treated with anticoagulation therapy compared with 1403/1499 (93.6%) in the medical therapy group
31442075	2019	Jin	Atrial fibrillation catheter ablation improves 1-year follow-up cognitive function, especially in patients with impaired cognitive function	Case–control	Korea	1 year	Montreal cognitive assessment score at 3 months and 1 year	Used Reliable Change Index adjusted for practice effects to measure cognitive changes as described by Chelune et al. (1993). Cognitive improvement defined as a Reliable Change Index > 1.645 and deterioration as a Reliable Change Index ≤ 1.645	358	308	An open-irrigated tip catheter was used to deliver radiofrequency energy for ablation. Patients underwent pulmonary vein isolation and bidirectional block of the cavotricuspid isthmus. For patients with persistent atrial fibrillation, a roofline, posterior inferior line and anterior line were added	50	Details about the proportions of patients receiving rate and/or rhythm control therapy were not provided Details about anticoagulation therapy use were not provided
31915546	2019	Tischer	Prevalence and progression of cognitive impairment in atrial fibrillation patients after treatment with catheter ablation or drug therapy	Case–control study with patients recruited from 2 × randomised control trials	Germany	16.8 (11) months	Montreal cognitive assessment score and Mini mental state examination	Participants were classified as cognitively impaired if their cognitive function test scores were < 24 by Montreal cognitive assessment and/or < 27 by Mini mental state examination	46	18	Details about the catheter ablation procedure were not provided	28	Details about the proportions of patients receiving rate and/or rhythm control therapy were not provided Details about anticoagulation therapy use were not provided
23684686	2013	Medi	Subtle post-procedural cognitive dysfunction after atrial fibrillation ablation	Case–control	Australia	90 days after the procedure	Post operative cognitive decline at 2 days and 90 days	Assessed cognitive function using 8 neuropsychological tests, mini mental state examination, National Adult Reading Test and visual analogue scales. Post operative cognitive decline was identified using the reliable change index [14]. Post operative cognitive decline was defined in an individual when the reliable change index score was less than − 1.96 on 2 tests and/or the combined z-score was less than − 1.96	150	90	Patients with paroxysmal atrial fibrillation had an ablation strategy consisting of wide encirclement of the pulmonary vein antra. Patients with persistent atrial fibrillation had adjunctive ablation at the discretion of the treating electrophysiologist	30	Table 2 of the study provides details about the proportions of patients treated with calcium channel blockers, beta blockers, antiarrhythmic drug therapy and warfarin. The group of patients treated with medical therapy comprised 15/30 (50%) who had been treated with antiarrhythmic drug therapy and 9/30 (30%) of patients had been treated with warfarin
1410581	2011	Bunch	Patients treated with catheter ablation for atrial fibrillation have long-term rates of death, stroke, and dementia similar to patients without atrial fibrillation	Cohort	USA	Mean follow up in atrial fibrillation, no ablation group: 5.1 years. Mean follow up in atrial fibrillation, ablation group: 3.1 years	1. Total mortality, 1 year mortality, 3-year mortality, long-term mortality 2. Heart failure (1, 3 year long term) 3. Cerebrovascular accident (1, 3-year long term) 4. Dementia (1, 3-year long term) 5. Alzheimer’s (1, 3-year long term) 6. Senile dementia (1, 3-year long term) 7. Vascular dementia (1, 3-year long term)	International classification of disease codes were used to determine the diagnosis and subtype dementia into Alzheimer's disease, vascular dementia, senile dementia and non-specified dementia	37908	4212	Details about the  catheter ablation procedure were not provided	16848	Details about the proportions of patients receiving rate and/or rhythm control therapy were not provided Details about anticoagulation therapy use were not provided