Abstract Background In the PROTECT AF (Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation) trial that evaluated patients with nonvalvular ...atrial fibrillation (NVAF), left atrial appendage (LAA) occlusion was noninferior to warfarin for stroke prevention, but a periprocedural safety hazard was identified. Objectives The goal of this study was to assess the safety and efficacy of LAA occlusion for stroke prevention in patients with NVAF compared with long-term warfarin therapy. Methods This randomized trial further assessed the efficacy and safety of the Watchman device. Patients with NVAF who had a CHADS2 (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and previous stroke/transient ischemic attack) score ≥2 or 1 and another risk factor were eligible. Patients were randomly assigned (in a 2:1 ratio) to undergo LAA occlusion and subsequent discontinuation of warfarin (intervention group, n = 269) or receive chronic warfarin therapy (control group, n = 138). Two efficacy and 1 safety coprimary endpoints were assessed. Results At 18 months, the rate of the first coprimary efficacy endpoint (composite of stroke, systemic embolism SE, and cardiovascular/unexplained death) was 0.064 in the device group versus 0.063 in the control group (rate ratio 1.07 95% credible interval (CrI): 0.57 to 1.89) and did not achieve the prespecified criteria noninferiority (upper boundary of 95% CrI ≥1.75). The rate for the second coprimary efficacy endpoint (stroke or SE >7 days’ postrandomization) was 0.0253 versus 0.0200 (risk difference 0.0053 95% CrI: –0.0190 to 0.0273), achieving noninferiority. Early safety events occurred in 2.2% of the Watchman arm, significantly lower than in PROTECT AF, satisfying the pre-specified safety performance goal. Using a broader, more inclusive definition of adverse effects, these still were lower in PREVAIL (Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) trial than in PROTECT AF (4.2% vs. 8.7%; p = 0.004). Pericardial effusions requiring surgical repair decreased from 1.6% to 0.4% (p = 0.027), and those requiring pericardiocentesis decreased from 2.9% to 1.5% (p = 0.36), although the number of events was small. Conclusions In this trial, LAA occlusion was noninferior to warfarin for ischemic stroke prevention or SE >7 days’ post-procedure. Although noninferiority was not achieved for overall efficacy, event rates were low and numerically comparable in both arms. Procedural safety has significantly improved. This trial provides additional data that LAA occlusion is a reasonable alternative to warfarin therapy for stroke prevention in patients with NVAF who do not have an absolute contraindication to short-term warfarin therapy.
Long-term data on the safety and efficacy of left atrial appendage closure (LAAC) for stroke prevention in patients with nonvalvular atrial fibrillation remain limited.
The purpose of this study was ...to evaluate 4.5- to 5-year data in 2 U.S. Food and Drug Association LAAC mandated registries (CAP Continued Access to PROTECT-AF and CAP2 Continued Access to PREVAIL) for safety and efficacy.
Two registries of patients implanted with LAAC devices provide the largest source of follow-up data. Both accompanied their respective randomized clinical trials, PROTECT-AF (Watchman Left Atrial Appendage System for Embolic PROTECTion in Patients With Atrial Fibrillation) and PREVAIL (Prospective Randomized Evaluation of the WATCHMAN LAA Closure Device In Patients with Atrial Fibrillation versus Long Term Warfarin Therapy), which used the same endpoints (primary efficacy of composite of stroke, systemic embolism, cardiovascular/unexplained death, and safety).
CAP included 566 patients with an average follow-up of 50.1 months (2,293 patient-years), and CAP2 included 578 patients with an average follow-up of 50.3 months (2,227 patient-years). CAP2 patients were significantly older and had higher CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack, vascular disease, age 65 to 74 years, sex category) scores (4.51 vs. 3.88; p < 0.001). Procedural success was similar in both (94%). The primary composite endpoint occurred at a rate of 3.05 per 100 patient-years in CAP and 4.80 per 100 patient-years in CAP2; events contributing to this endpoint were most commonly cardiovascular/unexplained death (1.69 per 100 patient-years for CAP and 2.92 per 100 patient-years for CAP2). Hemorrhagic stroke was significantly less than ischemic stroke (0.17 per 100 patient-years in CAP and 0.09 per 100 patient-years in CAP2), and total stroke rates were significantly less than predicted by CHA2DS2-VASc score (78% reduction with CAP, 69% reduction with CAP2).
These registries, which contain the longest and largest follow-up data of patients with the Watchman device, support LAAC as a safe and effective therapy for long-term anticoagulation in patients with nonvalvular atrial fibrillation, and document the lowest rate of hemorrhagic stroke identified in this population.
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The Watchman Left Atrial Appendage System for Embolic Protection in Patients With AF (PROTECT AF) randomized trial compared left atrial appendage closure against warfarin in atrial fibrillation (AF) ...patients with CHADS₂ ≥1. Although the study met the primary efficacy end point of being noninferior to warfarin therapy for the prevention of stroke/systemic embolism/cardiovascular death, there was a significantly higher risk of complications, predominantly pericardial effusion and procedural stroke related to air embolism. Here, we report the influence of experience on the safety of percutaneous left atrial appendage closure.
The study cohort for this analysis included patients in the PROTECT AF trial who underwent attempted device left atrial appendage closure (n=542 patients) and those from a subsequent nonrandomized registry of patients undergoing Watchman implantation (Continued Access Protocol CAP Registry; n=460 patients). The safety end point included bleeding- and procedure-related events (pericardial effusion, stroke, device embolization). There was a significant decline in the rate of procedure- or device-related safety events within 7 days of the procedure across the 2 studies, with 7.7% and 3.7% of patients, respectively, experiencing events (P=0.007), and between the first and second halves of PROTECT AF and CAP, with 10.0%, 5.5%, and 3.7% of patients, respectively, experiencing events (P=0.006). The rate of serious pericardial effusion within 7 days of implantation, which had made up >50% of the safety events in PROTECT AF, was lower in the CAP Registry (5.0% versus 2.2%, respectively; P=0.019). There was a similar experience-related improvement in procedure-related stroke (0.9% versus 0%, respectively; P=0.039). Finally, the functional impact of these safety events, as defined by significant disability or death, was statistically superior in the Watchman group compared with the warfarin group in PROTECT AF. This remained true whether significance was defined as a change in the modified Rankin score of ≥1, ≥2, or ≥3 (1.8 versus 4.3 events per 100 patient-years; relative risk, 0.43; 95% confidence interval, 0.24 to 0.82; 1.5 versus 3.7 events per 100 patient-years; relative risk, 0.41; 95% confidence interval, 0.22 to 0.82; and 1.4 versus 3.3 events per 100 patient-years; relative risk, 0.43; 95% confidence interval, 0.22 to 0.88, respectively).
As with all interventional procedures, there is a significant improvement in the safety of Watchman left atrial appendage closure with increased operator experience. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00129545.
In the PROTECT AF (Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation) trial that evaluated patients with nonvalvular atrial fibrillation ...(NVAF), left atrial appendage (LAA) occlusion was noninferior to warfarin for stroke prevention, but a periprocedural safety hazard was identified.
The goal of this study was to assess the safety and efficacy of LAA occlusion for stroke prevention in patients with NVAF compared with long-term warfarin therapy.
This randomized trial further assessed the efficacy and safety of the Watchman device. Patients with NVAF who had a CHADS2 (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and previous stroke/transient ischemic attack) score ≥2 or 1 and another risk factor were eligible. Patients were randomly assigned (in a 2:1 ratio) to undergo LAA occlusion and subsequent discontinuation of warfarin (intervention group, n = 269) or receive chronic warfarin therapy (control group, n = 138). Two efficacy and 1 safety coprimary endpoints were assessed.
At 18 months, the rate of the first coprimary efficacy endpoint (composite of stroke, systemic embolism SE, and cardiovascular/unexplained death) was 0.064 in the device group versus 0.063 in the control group (rate ratio 1.07 95% credible interval (CrI): 0.57 to 1.89) and did not achieve the prespecified criteria noninferiority (upper boundary of 95% CrI ≥1.75). The rate for the second coprimary efficacy endpoint (stroke or SE >7 days' postrandomization) was 0.0253 versus 0.0200 (risk difference 0.0053 95% CrI: -0.0190 to 0.0273), achieving noninferiority. Early safety events occurred in 2.2% of the Watchman arm, significantly lower than in PROTECT AF, satisfying the pre-specified safety performance goal. Using a broader, more inclusive definition of adverse effects, these still were lower in PREVAIL (Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) trial than in PROTECT AF (4.2% vs. 8.7%; p = 0.004). Pericardial effusions requiring surgical repair decreased from 1.6% to 0.4% (p = 0.027), and those requiring pericardiocentesis decreased from 2.9% to 1.5% (p = 0.36), although the number of events was small.
In this trial, LAA occlusion was noninferior to warfarin for ischemic stroke prevention or SE >7 days' post-procedure. Although noninferiority was not achieved for overall efficacy, event rates were low and numerically comparable in both arms. Procedural safety has significantly improved. This trial provides additional data that LAA occlusion is a reasonable alternative to warfarin therapy for stroke prevention in patients with NVAF who do not have an absolute contraindication to short-term warfarin therapy.
The multicenter PROTECT AF study (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) was conducted to determine whether percutaneous left atrial ...appendage closure with a filter device (Watchman) was noninferior to warfarin for stroke prevention in atrial fibrillation.
Patients (n=707) with nonvalvular atrial fibrillation and at least 1 risk factor (age >75 years, hypertension, heart failure, diabetes, or prior stroke/transient ischemic attack) were randomized to either the Watchman device (n=463) or continued warfarin (n=244) in a 2:1 ratio. After device implantation, warfarin was continued for ≈45 days, followed by clopidogrel for 4.5 months and lifelong aspirin. Study discontinuation rates were 15.3% (71/463) and 22.5% (55/244) for the Watchman and warfarin groups, respectively. The time in therapeutic range for the warfarin group was 66%. The composite primary efficacy end point included stroke, systemic embolism, and cardiovascular death, and the primary analysis was by intention to treat. After 1588 patient-years of follow-up (mean 2.3±1.1 years), the primary efficacy event rates were 3.0% and 4.3% (percent per 100 patient-years) in the Watchman and warfarin groups, respectively (relative risk, 0.71; 95% confidence interval, 0.44%-1.30% per year), which met the criteria for noninferiority (probability of noninferiority >0.999). There were more primary safety events in the Watchman group (5.5% per year; 95% confidence interval, 4.2%-7.1% per year) than in the control group (3.6% per year; 95% confidence interval, 2.2%-5.3% per year; relative risk, 1.53; 95% confidence interval, 0.95-2.70).
The "local" strategy of left atrial appendage closure is noninferior to "systemic" anticoagulation with warfarin. PROTECT AF has, for the first time, implicated the left atrial appendage in the pathogenesis of stroke in atrial fibrillation.
: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00129545.
The risk-benefit ratio of left atrial appendage closure (LAAC) versus systemic therapy (warfarin) for prevention of stroke, systemic embolism, and cardiovascular death in nonvalvular atrial ...fibrillation (NVAF) requires continued evaluation.
This study sought to assess composite data regarding left atrial appendage closure (LAAC) in 2 randomized trials compared to warfarin for prevention of stroke, systemic embolism, and cardiovascular death in patients with nonvalvular AF.
Our meta-analysis included 2,406 patients with 5,931 patient-years (PY) of follow-up from the PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) and PREVAIL (Prospective Randomized Evaluation of the Watchman LAA Closure Device In Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) trials, and their respective registries (Continued Access to PROTECT AF registry and Continued Access to PREVAIL registry).
With mean follow-up of 2.69 years, patients receiving LAAC with the Watchman device had significantly fewer hemorrhagic strokes (0.15 vs. 0.96 events/100 patient-years PY; hazard ratio HR: 0.22; p = 0.004), cardiovascular/unexplained death (1.1 vs. 2.3 events/100 PY; HR: 0.48; p = 0.006), and nonprocedural bleeding (6.0% vs. 11.3%; HR: 0.51; p = 0.006) compared with warfarin. All-cause stroke or systemic embolism was similar between both strategies (1.75 vs. 1.87 events/100 PY; HR: 1.02; 95% CI: 0.62 to 1.7; p = 0.94). There were more ischemic strokes in the device group (1.6 vs. 0.9 and 0.2 vs. 1.0 events/100 PY; HR: 1.95 and 0.22, respectively; p = 0.05 and 0.004, respectively). Both trials and registries identified similar event rates and consistent device effect in multiple subsets.
In patients with NVAF at increased risk for stroke or bleeding who are candidates for chronic anticoagulation, LAAC resulted in improved rates of hemorrhagic stroke, cardiovascular/unexplained death, and nonprocedural bleeding compared to warfarin.
The PROTECT AF (WATCHMAN Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) trial demonstrated that left atrial appendage closure (LAAC) with the Watchman ...device (Boston Scientific, St. Paul, Minnesota) was equivalent to warfarin for preventing stroke in atrial fibrillation, but had a high rate of complications. In a second randomized trial, PREVAIL (Evaluation of the WATCHMAN LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy), the complication rate was low. The warfarin cohort experienced an unexpectedly low ischemic stroke rate, rendering the efficacy endpoints inconclusive. However, these outcomes were based on relatively few patients followed for a relatively short time.
The final results of the PREVAIL trial, both alone and as part of a patient-level meta-analysis with the PROTECT AF trial, are reported with patients in both trials followed for 5 years.
PREVAIL and PROTECT AF are prospective randomized clinical trials with patients randomized 2:1 to LAAC or warfarin; together, they enrolled 1,114 patients for 4,343 patient-years. Analyses are by intention-to-treat, and rates are events per 100 patient-years.
For the PREVAIL trial, the first composite coprimary endpoint of stroke, systemic embolism (SE), or cardiovascular/unexplained death did not achieve noninferiority (posterior probability for noninferiority = 88.4%), whereas the second coprimary endpoint of post-procedure ischemic stroke/SE did achieve noninferiority (posterior probability for noninferiority = 97.5%); the warfarin arm maintained an unusually low ischemic stroke rate (0.73%). In the meta-analysis, the composite endpoint was similar between groups (hazard ratio HR: 0.820; p = 0.27), as were all-stroke/SE (HR: 0.961; p = 0.87). The ischemic stroke/SE rate was numerically higher with LAAC, but this difference did not reach statistical significance (HR: 1.71; p = 0.080). However, differences in hemorrhagic stroke, disabling/fatal stroke, cardiovascular/unexplained death, all-cause death, and post-procedure bleeding favored LAAC (HR: 0.20; p = 0.0022; HR: 0.45; p = 0.03; HR: 0.59; p = 0.027; HR: 0.73; p = 0.035; HR: 0.48; p = 0.0003, respectively).
These 5-year outcomes of the PREVAIL trial, combined with the 5-year outcomes of the PROTECT AF trial, demonstrate that LAAC with Watchman provides stroke prevention in nonvalvular atrial fibrillation comparable to warfarin, with additional reductions in major bleeding, particularly hemorrhagic stroke, and mortality. (WATCHMAN Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation; NCT00129545; and Evaluation of the WATCHMAN LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy; NCT01182441).
Summary Background In patients with non-valvular atrial fibrillation, embolic stroke is thought to be associated with left atrial appendage (LAA) thrombi. We assessed the efficacy and safety of ...percutaneous closure of the LAA for prevention of stroke compared with warfarin treatment in patients with atrial fibrillation. Methods Adult patients with non-valvular atrial fibrillation were eligible for inclusion in this multicentre, randomised non-inferiority trial if they had at least one of the following: previous stroke or transient ischaemic attack, congestive heart failure, diabetes, hypertension, or were 75 years or older. 707 eligible patients were randomly assigned in a 2:1 ratio by computer-generated randomisation sequence to percutaneous closure of the LAA and subsequent discontinuation of warfarin (intervention; n=463) or to warfarin treatment with a target international normalised ratio between 2·0 and 3·0 (control; n=244). Efficacy was assessed by a primary composite endpoint of stroke, cardiovascular death, and systemic embolism. We selected a one-sided probability criterion of non-inferiority for the intervention of at least 97·5%, by use of a two-fold non-inferiority margin. Serious adverse events that constituted the primary endpoint for safety included major bleeding, pericardial effusion, and device embolisation. Analysis was by intention to treat. This study is registered with Clinicaltrials.gov , number NCT00129545. Findings At 1065 patient-years of follow-up, the primary efficacy event rate was 3·0 per 100 patient-years (95% credible interval CrI 1·9–4·5) in the intervention group and 4·9 per 100 patient-years (2·8–7·1) in the control group (rate ratio RR 0·62, 95% CrI 0·35–1·25). The probability of non-inferiority of the intervention was more than 99·9%. Primary safety events were more frequent in the intervention group than in the control group (7·4 per 100 patient-years, 95% CrI 5·5–9·7, vs 4·4 per 100 patient-years, 95% CrI 2·5–6·7; RR 1·69, 1·01–3·19). Interpretation The efficacy of percutaneous closure of the LAA with this device was non-inferior to that of warfarin therapy. Although there was a higher rate of adverse safety events in the intervention group than in the control group, events in the intervention group were mainly a result of periprocedural complications. Closure of the LAA might provide an alternative strategy to chronic warfarin therapy for stroke prophylaxis in patients with non-valvular atrial fibrillation. Funding Atritech.
BACKGROUND:In patients with atrial fibrillation, left atrial appendage closure with the Watchman device prevents thromboembolism from the left atrial appendage; however, thrombus may form on the left ...atrial face of the device, and then potentially embolize. Herein, we studied the incidence, predictors, and clinical outcome of device-related thrombus (DRT) using a large series of clinical trial cohorts of patients undergoing Watchman implantation.
METHODS:We studied the device arms of 4 prospective Food and Drug Administration trialsPROTECT-AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) (n=463); PREVAIL (Evaluation of the Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy) (n=269); CAP (Continued Access to PROTECT AF registry) (n=566); and CAP2 (Continued Access to PREVAIL registry) (n=578). Surveillance transesophageal echocardiographs were performed at 45 days and 12 months in all patients, and also at 6 months in the randomized control trials. We assessed both the incidence of DRT during these transesophageal echocardiographs (and other unscheduled transesophageal echocardiographs), and clinical outcomes of postprocedure stroke or systemic embolism (SSE) and adjusted for CHA2DS2-VASC and HAS-BLED scores.
RESULTS:Of 1739 patients who received an implant (7159 patient-years follow-up; CHA2DS2-VASc=4.0), DRT was seen in 65 patients (3.74%). The rates of SSE with and without DRT were 7.46 and 1.78 per 100 patient-years (adjusted rate ratio, 3.55; 95% confidence interval CI, 2.18–5.79; P<0.001), and ischemic SSE rates were 6.28 and 1.65 per 100 patient-years (adjusted rate ratio, 3.22; 95% CI, 1.90–5.45, P<0.001). On multivariable modeling analysis, the predictors of DRT were as followshistory of transient ischemic attack or stroke (odds ratio OR, 2.31; 95% CI, 1.26–4.25; P=0.007), permanent atrial fibrillation (OR, 2.24; 95% CI, 1.19–4.20; P=0.012); vascular disease (OR, 2.06; 95% CI, 1.08–3.91; P=0.028); left atrial appendage diameter (OR, 1.06 per mm increase; 95% CI, 1.01–1.12; P=0.019); left ventricular ejection fraction (OR, 0.96 per 1% increase; 95% CI, 0.94–0.99; P=0.009). DRT and SSE both occurred in 17 of 65 patients (26.2%). Of the 19 SSE events in these patients with DRT, 9 of 19 (47.4%) and 12 of 19 (63.2%) occurred within 1 and 6 months of DRT detection. Conversely, after left atrial appendage closure, most SSEs (123/142, 86.62%) occurred in patients without DRT.
CONCLUSIONS:After left atrial appendage closure with Watchman, DRT (≈3.7%) is not frequent but, when present, is associated with a higher rate of stroke and systemic embolism.
Introduction
Pulsed electric field (PEF) ablation relies on the intersection of a critical voltage gradient with tissue to cause cell death. Field‐based lesion formation with PEF technologies may ...still depend on catheter–tissue contact (CTC). The purpose of this study was to assess the impact of CTC on PEF lesion formation with an investigational large area focal (LAF) catheter in a preclinical model.
Methods
PEF ablation via a 10‐spline LAF catheter was used to create discrete right ventricle (RV) lesions and atrial lesion sets in 10 swine (eight acute, two chronic). Local impedance (LI) was used to assess CTC. Lesions were assigned to three cohorts using LI above baseline: no tissue contact (NTC: ≤∆10 Ω, close proximity to tissue), low tissue contact (LTC: ∆11–29 Ω), and high tissue contact (HTC: ≥∆30 Ω). Acute animals were infused with triphenyl tetrazolium chloride (TTC) and killed ≥2 h post‐treatment. Chronic animals were remapped 30 days post‐index procedure and stained with infused TTC.
Results
Mean (± SD) RV treatment sizes between LTC (n = 14) and HTC (n = 17) lesions were not significantly different (depth: 5.65 ± 1.96 vs. 5.68 ± 2.05 mm, p = .999; width: 15.68 ± 5.22 vs. 16.98 ± 4.45 mm, p = .737), while mean treatment size for NTC lesions (n = 6) was significantly smaller (1.67 ± 1.16 mm depth, 5.97 ± 4.48 mm width, p < .05). For atrial lesion sets, acute and chronic conduction block were achieved with both LTC (N = 7) and HTC (N = 6), and NTC resulted in gaps.
Conclusions
PEF ablation with a specialized LAF catheter in a swine model is dependent on CTC. LI as an indicator of CTC may aid in the creation of consistent transmural lesions in PEF ablation.
Pulsed electric field (PEF) ablation with a specialized large area focal catheter in a swine model is dependent on catheter–tissue contact. Local impedance can be used as an indicator of catheter–tissue contact and aid in the creation of consistent transmural lesions in PEF ablation.
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