Clinical Outcomes of Computational Virtual Mapping-Guided Catheter Ablation in Patients With Persistent Atrial Fibrillation: A Multicenter Prospective Randomized Clinical Trial

Background: Clinical recurrence after atrial fibrillation catheter ablation (AFCA) still remains high in patients with persistent AF (PeAF). We investigated whether an extra-pulmonary vein (PV) ablation targeting the dominant frequency (DF) extracted from electroanatomical map–integrated AF computational modeling improves the AFCA rhythm outcome in patients with PeAF.Methods: In this open-label, randomized, multi-center, controlled trial, 170 patients with PeAF were randomized at a 1:1 ratio to the computational modeling-guided virtual DF (V-DF) ablation and empirical PV isolation (E-PVI) groups. We generated a virtual dominant frequency (DF) map based on the atrial substrate map obtained during the clinical AF ablation procedure using computational modeling. This simulation was possible within the time of the PVI procedure. V-DF group underwent extra-PV V-DF ablation in addition to PVI, but DF information was not notified to the operators from the core lab in the E-PVI group.Results: After a mean follow-up period of 16.3 ± 5.3 months, the clinical recurrence rate was significantly lower in the V-DF than with E-PVI group (P = 0.018, log-rank). Recurrences appearing as atrial tachycardias (P = 0.145) and the cardioversion rates (P = 0.362) did not significantly differ between the groups. At the final follow-up, sinus rhythm was maintained without any AADs in 74.7% in the V-DF group and 48.2% in the E-PVI group (P < 0.001). No significant difference was found in the major complication rates (P = 0.489) or total procedure time (P = 0.513) between the groups. The V-DF ablation was independently associated with a reduced AF recurrence after AFCA [hazard ratio: 0.51 (95% confidence interval: 0.30–0.88); P = 0.016].Conclusions: The computational modeling-guided V-DF ablation improved the rhythm outcome of AFCA in patients with PeAF.Clinical Trial Registration: Clinical Research Information Service, CRIS identifier: KCT0003613.

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Electrical posterior box isolation in persistent atrial fibrillation changed to paroxysmal atrial fibrillation: a multi-center, prospective, randomized study

European Heart Journal ◽

10.1093/ehjci/ehaa946.0614 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

H.N Pak ◽

J.B Park ◽

H.T Yu ◽

T.H Kim ◽

J.S Uhm ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Recurrence Rate ◽

Antiarrhythmic Drug ◽

Persistent Atrial Fibrillation ◽

Complication Rates ◽

Clinical Recurrence ◽

End Point ◽

Significant Difference

Abstract Background Persistent atrial fibrillation (PeAF) can change to paroxysmal AF (PAF) after antiarrhythmic drug medication and cardioversion. Purpose We investigated whether electrical posterior box isolation (POBI) may improve rhythm outcome of catheter ablation in those patient group. Methods We prospectively randomized 114 patients with PeAF to PAF (male 75%, 59.8±9.9 years old) to circumferential pulmonary vein isolation (CPVI) alone group (n=57) and additional POBI group (n=57). The primary end-point was AF recurrence after a single procedure, and the secondary end-point was a recurrence pattern, cardioversion rate, and the response to antiarrhythmic drugs (AADs). Results After a mean follow-up of 22.5±9.4 months, the clinical recurrence rate did not significantly differ between the two groups (29.8% vs. 28.1%, p=0.836; log rank p=0.815) The recurrence rate for atrial tachycardias (17.6% vs. 43.8%, p=0.141) was higher in POBI group, but the cardioversion rates (13.5% vs. 8.5%, p=0.434) were not significantly different between two groups. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drug in 52.6% in CPVI group and 59.7% of POBI group (p=0.452). No significant difference was found in the major complication rates between the two groups (5.3% vs. 1.8%, p=0.618), but the total ablation time was significantly longer in the POBI group (4397±842 sec vs. 5337±1517 sec, p<0.001). Conclusion In patients with persistent AF converted to paroxysmal AF by AAD, the addition of POBI to CPVI did not improve the rhythm outcome of catheter ablation nor influence overall safety. Funding Acknowledgement Type of funding source: None

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Electrical Posterior Box Isolation in Persistent Atrial Fibrillation Changed to Paroxysmal Atrial Fibrillation

Circulation Arrhythmia and Electrophysiology ◽

10.1161/circep.120.008531 ◽

2020 ◽

Vol 13 (9) ◽

Author(s):

Hui-Nam Pak ◽

Junbeom Park ◽

Je-Wook Park ◽

Song-Yi Yang ◽

Hee Tae Yu ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Antiarrhythmic Drug ◽

Persistent Atrial Fibrillation ◽

Complication Rates ◽

Unique Identifier ◽

Clinical Recurrence ◽

Ablation Time ◽

Significant Difference

Background: Persistent atrial fibrillation (AF) can change to paroxysmal AF after antiarrhythmic drug medication and cardioversion. We investigated whether electrical posterior box isolation (POBI) may improve rhythm outcome of catheter ablation in those patient groups. Methods: We prospectively randomized 114 patients with persistent AF to paroxysmal AF (men, 75%; 59.8±9.9 years old) to circumferential pulmonary vein isolation (CPVI) alone group (n=57) and additional POBI group (n=57). Primary end point was AF recurrence after a single procedure, and secondary end points were recurrence pattern, cardioversion rate, and response to antiarrhythmic drugs. Results: After a mean follow-up of 23.8±10.2 months, the clinical recurrence rate did not significantly differ between the CPVI alone and additional POBI group (31.6% versus 28.1%; P =0.682; log-rank P =0.729). The recurrences as atrial tachycardias (5.3% versus 12.3%; P =0.134) and cardioversion rates (5.3% versus 10.5%; P =0.250) were not significantly different between the CPVI and POBI groups. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drug in 52.6% of CPVI group and 59.6% of POBI group ( P =0.450). No significant difference was found in major complication rates between the two groups (5.3% versus 1.8%; P =0.618), but the total ablation time was significantly longer in the POBI group (4187±952 versus 5337±1517 s; P <0.001). Conclusions: In patients with persistent AF converted to paroxysmal AF by antiarrhythmic drug, the addition of POBI to CPVI did not improve the rhythm outcome of catheter ablation or influence overall safety, while leading to longer ablation time. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02176616.

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Radiofrequency Ablation versus Cryoablation in the Treatment of Paroxysmal Atrial Fibrillation: A Meta-Analysis

Cardiology Research and Practice ◽

10.1155/2018/6276241 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 10

Author(s):

Ali H. Hachem ◽

Joseph E. Marine ◽

Housam A. Tahboub ◽

Sana Kamdar ◽

Shaffi Kanjwal ◽

...

Keyword(s):

Atrial Fibrillation ◽

Radiofrequency Ablation ◽

Meta Analysis ◽

Fluoroscopy Time ◽

Radiofrequency Energy ◽

Cryoballoon Ablation ◽

Complication Rates ◽

Ablation Time ◽

Significant Difference

Background. Pulmonary vein isolation is commonly performed using radiofrequency energy with cryoablation gaining acceptance. We performed a meta-analysis of randomized controlled trials which compared radiofrequency versus cryoablation for patients with atrial fibrillation. Methods. A systematic search strategy identified both published and unpublished articles from inception to November 10, 2016, in multiple databases. The primary outcomes for this meta-analysis were long-term freedom from atrial fibrillation at 12-month follow-up and overall postoperative complication rates. For all included studies, the methodological quality was assessed through the Cochrane Collaboration’s tool for risk of bias. Results. A total of 247 articles were identified with eight being included in this review as they satisfied the prespecified inclusion criteria. Overall, there was no significant difference in freedom from atrial fibrillation at ≥12-month follow-up between those receiving cryoballoon and radiofrequency ablation, respectively (OR = 0.98, CI = 0.67–1.43, I2 = 56%, p=0.90). Additionally, the secondary outcomes of duration of ablation, fluoroscopy time, and ablation time failed to reach significance. Cryoballoon ablation had significantly greater odds of postoperative phrenic nerve injury at 12-month follow-up. Conclusions. Our meta-analysis suggests that cryoballoon ablation provides comparable benefits with regard to freedom from atrial fibrillation at medium-term follow-up, fluoroscopy time, ablation time, operative duration, and overall complication rate in comparison to radiofrequency ablation.

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Abstract 4104: Organization of Atrial Signals is Critical Prior to Cardioversion of Atrial Fibrillation with Intravenous Flecainide: Insight from Spectral Analysis of Intracardiac Electrograms

Circulation ◽

10.1161/circ.118.suppl_18.s_829-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Jiun Tuan ◽

Suman Kundu ◽

Mohamed Jeilan ◽

Faizel Osman ◽

Rajkumar Mantravadi ◽

...

Keyword(s):

Atrial Fibrillation ◽

Spectral Analysis ◽

Catheter Ablation ◽

Cycle Length ◽

Dominant Frequency ◽

Relative Increase ◽

Significant Difference ◽

Before And After ◽

Atrial Activation ◽

Relative Change

Introduction & Hypothesis: Studies in catheter ablation of atrial fibrillation (AF) show that an increase in cycle length (CL) and higher organization index (OI) is associated with termination of AF. We hypothesize that similar changes can be seen in chemical cardioversion with Flecainide Methods: Patients who were still in AF at the end of catheter ablation for AF were given intravenous flecainide. OI and dominant frequency (DF) were obtained by Fast Fourier Transform of coronary sinus electrograms over 10s in AF, before and after flecainide infusion. Mean CL was also calculated. Results: 28 patients were identified (18 paroxysmal AF and 10 persistent AF). 8 cardioverted to sinus rhythm (SR) with flecainide. In all patients, mean CL increased from 211 ± 44 ms to 321 ± 85 ms (p <0.001). Mean DF decreased from 5.2 ± 1.03 Hz to 3.6 ± 1.04 Hz (p <0.001). Mean OI was 0.33 ± 0.13 before and 0.32 ± 0.11 after flecainide (p = 0.90). Comparing patients who cardioverted to SR with those who did not, OI post-flecainide was 0.41 ± 0.12 vs 0.29 ± 0.10 (p=0.013) and relative change in OI was 29 ± 33% vs −3.9 ± 27% (p=0.016) respectively. No significant difference was noted in the change in CL and DF in the 2 groups. Logistic regression showed that a greater relative increase in OI (p=0.04), a higher OI post-flecainide (p=0.03) and SR at start of procedure (p=0.03) are independently associated with cardioversion to SR with flecainide. Conclusion: Increase in OI, independent of changes to the CL and DF, appears critical to AF termination with flecainide. The increase in OI may reflect an increase in size and reduction in the number of re-entrant circuits, which together with slowing of atrial activation, result in return to SR.

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Kolmogorov Complexity of Coronary Sinus Atrial Electrograms before Ablation Predicts Termination of Atrial Fibrillation after Pulmonary Vein Isolation

Entropy ◽

10.3390/e21100970 ◽

2019 ◽

Vol 21 (10) ◽

pp. 970 ◽

Cited By ~ 1

Author(s):

Stępień ◽

Kuklik ◽

Żebrowski ◽

Sanders ◽

Derejko ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Pulmonary Vein ◽

Pulmonary Vein Isolation ◽

Coronary Sinus ◽

Kolmogorov Complexity ◽

Similarity Index ◽

Dominant Frequency ◽

Significant Difference ◽

The Rich

Atrial fibrillation (AF) is related to a very complex local electrical activity reflected in the rich morphology of intracardiac electrograms. The link between electrogram complexity and efficacy of the catheter ablation is unclear. We test the hypothesis that the Kolmogorov complexity of a single atrial bipolar electrogram recorded during AF within the coronary sinus (CS) at the beginning of the catheter ablation may predict AF termination directly after pulmonary vein isolation (PVI). The study population consisted of 26 patients for whom 30 s baseline electrograms were recorded. In all cases PVI was performed. If AF persisted after PVI, ablation was extended beyond PVs. Kolmogorov complexity estimated by Lempel–Ziv complexity and the block decomposition method was calculated and compared with other measures: Shannon entropy, AF cycle length, dominant frequency, regularity, organization index, electrogram fractionation, sample entropy and wave morphology similarity index. A 5 s window length was chosen as optimal in calculations. There was a significant difference in Kolmogorov complexity between patients with AF termination directly after PVI compared to patients undergoing additional ablation (p < 0.01). No such difference was seen for remaining complexity parameters. Kolmogorov complexity of CS electrograms measured at baseline before PVI can predict self-termination of AF directly after PVI.

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Evaluation of proarrythmogenic effects after different techniques of radiofrequency catheter ablation of atrial fibrillation

Patologiya krovoobrashcheniya i kardiokhirurgiya ◽

10.21688/1681-3472-2013-1-33-37 ◽

2015 ◽

Vol 17 (1) ◽

pp. 33 ◽

Cited By ~ 1

Author(s):

S. N. Artemenko ◽

A. B. Romanov ◽

V. V. Shabanov ◽

I. G. Stenin ◽

D. A. Yelesin ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Left Atrium ◽

Radiofrequency Catheter Ablation ◽

Persistent Atrial Fibrillation ◽

Linear Lesions ◽

Group I ◽

Significant Difference ◽

Group Ii

To assess proarrythmogenic effects after different techniques of radiofrequency catheter ablation, 427 patients with paroxysmal, persistent, and long-standing persistent atrial fibrillation (AF) were examined. The patients were randomized into four groups: antral pulmonary vein isolation (PVI) (Group I), PVI plus roof line and mitral isthmus ablation (Group II), anatomic ablation of ganglionated plexuses (GP) of the left atrium (Group III) and GP plus PVI (Group IV). At the end of follow up (34,43,2 months) the largest number of proarrythmogenic effects was observed in Group II, 24,8% (26 patients). In the remaining groups the percentage of proarrythmogenic effects did not exceed 11%, neither was there any significant difference among Groups I, III and IV. Thus, the creation of additional linear lesions in the left atrium is a predictor of proarrythmogenic effects during follow up.

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The impact of catheter ablation for patients with asymptomatic atrial fibrillation: subanalysis of kansai plus atrial fibrillation (kpaf) registry

European Heart Journal ◽

10.1093/ehjci/ehaa946.0442 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

M Pak ◽

A Kobori ◽

S Shizuta ◽

Y Sasaki ◽

T Toyota ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Primary Endpoint ◽

Hazard Analysis ◽

Secondary Endpoint ◽

Asymptomatic Patients ◽

Significant Difference ◽

Secondary Endpoints ◽

The Impact

Abstract Background Catheter ablation (CA) of atrial fibrillation (AF) for symptomatic patients improves the quality of life and prognosis of patients with heart failure. However, the impact of CA for asymptomatic patients is still controversial. Purpose We aimed to investigate the clinical outcomes of CA of AF for asymptomatic patients compared to those for symptomatic patients. Methods A total of 5,013 patients from the Kansai Plus Atrial Fibrillation (KPAF) Registry who underwent CA were screened. The patients were divided into three groups by type of AF; paroxysmal (PAF), persistent (PEAF) and long standing (LSAF) and the patients in each type of AF were divided into two groups: asymptomatic and symptomatic. The primary endpoint was recurrent supraventricular tachyarrhythmias lasting for more than 30 seconds during follow-up 4 years after CA. The secondary endpoint was a composite of cardiovascular, cerebral, and gastrointestinal events during follow-up 4 years after CA. The incidence of complications related to CA between asymptomatic and symptomatic patients was also evaluated. Kaplan–Meier analysis was employed to estimate the primary and secondary endpoints. The statistical differences in primary and secondary endpoints between asymptomatic and symptomatic patients were evaluated using a log–rank test. The impact of symptom due to AF on the primary and secondary endpoint was evaluated using a Cox hazard analysis. The difference in incidence of complications between asymptomatic and symptomatic patients was evaluated using a chi–square test. Results In this study population, PAF was the most frequent at 64.4%, followed by PEAF (22.7%) and LSAF (13.0%). There were some significant differences in the baseline characteristics between asymptomatic and symptomatic patients in each type of AF. The proportion of male was significantly higher in asymptomatic patients than symptomatic patients in PAF (81.2% versus 67.2%, p<0.001) and PEAF (86.4% versus 74.3%, p<0.001). Left atrial diameter was larger in asymptomatic patients than symptomatic patients only in PAF (40±6mm versus 38±6mm, p<0.001). In all types of AF, there was no significant difference in primary endpoint between asymptomatic and symptomatic patients as follows: 37.5% versus 40.6% (p=0.6) in PAF, 45.2% versus 55.1% (p=0.09) in PEAF and 59.3% versus 63.6% (p=1.0) in LSAF. There was also no significant difference in secondary endpoint between asymptomatic and symptomatic patients: 7.1% versus 6.8% (p=0.7) in PAF, 5.4% versus 8.7% (p=0.3) in PEAF and 4.4% versus 5.1% (p=0.5) in LSAF. In a Cox hazard analysis, the symptom did not affect both of the primary and secondary endpoints in each type of AF. In regard to the incidence of complications related to CA, there was no significant difference between asymptomatic and symptomatic patients in each type of AF. Conclusion CA of AF for asymptomatic patients can be safe and can lead to equivalent outcomes as well as symptomatic patients. Funding Acknowledgement Type of funding source: None

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P1373Assessment of atrial fibrillation cryoablation outcomes in patients with diabetes

EP Europace ◽

10.1093/europace/euaa162.358 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

Y Z Sener ◽

M Oksul ◽

F Akkaya ◽

A H Ates ◽

U Canpolat ◽

...

Keyword(s):

Catheter Ablation ◽

Phrenic Nerve ◽

Nerve Damage ◽

Diabetic Group ◽

P Value ◽

Diabetic Patients ◽

Complication Rates ◽

Significant Difference ◽

Patients With Diabetes

Abstract Background Diabetes is related with both AF occurence and increased thromboembolic risk. There is scarce data about the outcomes of AF catheter ablation in patients with diabetes. Purpose We aimed to evaluate outcomes of AF catheter ablation in patients with diabetes. Methods All patients underwent AF cryoablation between January 2013 and January 2018 were included . Results A total of 493 patients were enrolled. Mean age was 59.6 ± 11.8 years and 253 (51.3 %) patients were female. Median follow up time was 28 (6-59) months. Recurrence occured in 61 (12.4%) patients. Diabetes was present in 78 (16%) cases. Mean HbA1c value of the diabetic patients was 6.79 ± 1.02 %. 50 (64.1 %) patients was under treatment with only oral antidiabetics while others were using insulin. Diabetic group was older (p < 0.001) and hypertension prevalance was significantly higher in diabetics(p < 0.001). Complication and recurrence rates were similar between the two groups (Table-1). Subgroup analysis revealed that there was not significant difference by AF recurrence between not only patients treated with OAD alone and treated with insulin but also patients with HbA1c value <7 and HbA1c value ≥7 (p = 0.064). Conclusion Recurrence and complication rates were similar between diabetic and non-diabetic patients. Despite neuropathy is a well known manifestation of diabetes; phrenic nerve damage rate is similar in diabetic patients with non-diabetic counterparts. Table-1 Diabetic group (n = 78) Non-diabetic group (n = 415) p value Age, (years) 64.38 ±10.12 58.91 ±11.84 <0.001* Gender, female (%) 45 (57 %) 207 (49.8 %) 0.267 Follow up, (months) 29.5 (6-59) 28 (6-58) 0.987 Hypertension, n (%) 57 (73%) 191 (46 %) <0.001 StrokeTIA, n(%) 4 (5.1 %) 8 (1.9 %) 0.104 Coronary artery disease, n (%) 39 (50 %) 176 (42.4 %) 0.242 AF type, Paroxysmal, (%) 65.7 % 71% 0.367 LV EF, % 59.81 ± 8.44 61.82 ± 6.89 0.027* LV end diastolic diameter, cm 4.90 ± 0.49 4.82 ± 0.46 0.160 LA diameter, cm 3.88 ± 0.51 3.81± 0.58 0.361 Recurrence 8 (10.2 %) 53 (12.7 %) 0.708 Phrenic nerve damage, n (%) 0 (0 %) 17 (4.1 %) 0.088 Inguinal hematoma, n (%) 7 (8.9%) 44 (10.6 %) 0.647 Pseudoaneurysm, n(%) 1 ( 1.2%) 3 ( 0.7 %) 0.502 Comparison of diabetic and non-diabetic patients

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Tapered, Double-Lead Threads Single Implants Placed in Fresh Extraction Sockets and Healed Sites of the Posterior Jaws: A Multicenter Randomized Controlled Trial with 1 to 3 Years of Follow-Up

BioMed Research International ◽

10.1155/2017/8017175 ◽

2017 ◽

Vol 2017 ◽

pp. 1-16 ◽

Cited By ~ 3

Author(s):

Alessandro Cucchi ◽

Elisabetta Vignudelli ◽

Simonetta Franco ◽

Luca Levrini ◽

Dario Castellani ◽

...

Keyword(s):

Controlled Trial ◽

Survival Rates ◽

Test Group ◽

Primary Stability ◽

Control Group ◽

Complication Rates ◽

Significant Difference ◽

Multicenter Randomized Controlled Trial ◽

Implant Crown

Purpose. To evaluate the survival, success, and complication rates of tapered double-lead threads single implants, placed in fresh extraction sockets and healed sites of the posterior jaws. Methods. The enrolled patients were randomly divided into 2 groups: in the test group (TG), all implants were inserted at the time of tooth extraction; in the control group (CG), all implants were placed 3 months after extraction. The implants were followed for a period of 1 to 3 years after loading. The main outcomes were implant survival, complications, and implant-crown success. Results. Ninety-two patients had 97 installed implants (49 in the TG, 48 in the CG). Only two implants failed, in the TG; the survival rates were therefore 95.9% (47/49) and 100% (48/48) for TG and CG, respectively. In the surviving implants, no complications were reported, for an implant-crown success of 100%. Conclusions. Although a significant difference was found in the levels of primary stability between TG and CG, single implants placed in fresh extraction sockets and healed sites of the posterior jaws had similar survival and complication rates. Crestal bone levels and peri-implant bone resorption showed similar values. A longer follow-up period is however required, to confirm these positive outcomes.

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Effect of immortal time bias on the association between atrial fibrillation ablation and incident stroke: a meta-analysis

European Heart Journal ◽

10.1093/ehjci/ehaa946.3551 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

M Samuel ◽

P Khairy

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Observational Studies ◽

Controlled Trial ◽

Methodological Issue ◽

Careful Consideration ◽

Randomized Controlled ◽

Immortal Time Bias ◽

Pubmed Database

Abstract Background/Introduction In the era of big data and large observational studies, identification and prevention of immortal time bias (ITB) is essential to attain unbiased effect estimates. Immortal time refers to a period of follow-up in a cohort when the outcome cannot occur. Typically, it results when the exposure is initiated after the start of follow-up. The misclassification of person-time results in a systematic overestimation of the treatment effect. ITB is a common methodological issue in epidemiology studies. We sought to assess the presence and magnitude of bias due to ITB in observational studies evaluating the effectiveness of catheter ablation (CA) for atrial fibrillation. Purpose To compare the association between CA and stroke in 1) observational studies that controlled for ITB, 2) observational studies that did not address ITB, and 3) randomized controlled trials (RCT). Methods The PUBMED database was screened from inception to January 15, 2020 for publications with the following string of search terms: (“ablation” or “catheter ablation” or “pulmonary vein isolation”) and “atrial fibrillation” and (“stroke” or “thromboembolism”). Observational studies and RCTs comparing CA to medical therapy were eligible. Studies were excluded if: 1) evaluation of the association was limited to a subgroup of AF patients, 2) cryoablation was performed, 3) strokes were not reported, and 4) HRs or 95% CI were not presented. Information on study characteristics, HRs, and the potential for ITB was extracted. Subsequently, articles were classified based on the type of study and whether ITB was addressed. For each group of articles, HRs were logarithmically transformed and pooled using the random effects model. Results A total of 10 observational studies and 1 randomized controlled trial were included in the present analysis. Of the 10 observational studies, only 2 studies were designed to prevent ITB. The pooled HR for observational studies without ITB prevention showed a statistically significant reduction in risk of stroke (HR 0.66 (95% CI 0.58–0.74); I2=27.3%) in CA patients compared to non-CA patients. However, pooling the two observational studies that prevented ITB indicated no difference in the incidence of stroke [HR 0.75 (95% CI 0.49–1.02); I2=4.5%] among patients with and without CA, a finding similar to CABANA trial [HR 0.42 (95% CI 0.11–1.21)]. Conclusion It is important to evaluate the effectiveness of procedures and medications using observational data to determine if the results from RCTs translate to the real-world. However, careful consideration needs to be taken in the design phase to avoid ITB and produce effect estimates that more accurately represent the true association between treatment and outcomes. Examples of design methods to prevent ITB include the use of a time-varying covariate or matching on pre-treatment exposure time. Funding Acknowledgement Type of funding source: None

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