[Anticoagulation for Stroke Prevention in Atrial Fibrillation]. / Antikoagulation bei Vorhofflimmern.

Anticoagulation with oral antagonists without vitamin K (NOACs) is the preferred therapy for stroke prevention in atrial fibrillation. Vitamin K antagonists (VKA) should only be prescribed if there are contraindications to NOAC (e. g. mechanical heart valves, rheumatic mitral stenosis). The guideline recommendations are based on dedicated NOAC development programs with large randomized clinical phase III studies. Data from observational studies on the efficacy and safety of NOACs compared to VKA are in general complementary to data stemming from the phase III studies. Due to their pharmacokinetic and dynamic properties, NOACs are much easier to handle than VKA. Amongst other advantages, this implies that in case of short interruptions in anticoagulation therapy (e. g. for surgical procedures), bridging therapy with heparin is no longer required. This will reduce bleeding complications dramatically.

Changes in Oral Anticoagulation Therapy over One Year in 51,000 Atrial Fibrillation Patients at Risk for Stroke: A Practice-Derived Study.

BACKGROUND: This study assessed changes in anticoagulation therapy over time in patients with atrial fibrillation (AF). METHODS: Analyses were performed on a claims-based dataset of 4 million health-insured individuals. The study population consisted of patients newly initiating a non-vitamin-K oral anticoagulants (NOACs) or vitamin K antagonist (VKA) for AF between 2013 and 2016. The study outcomes consisted of the proportion of patients who had (1) discontinued OAC treatment, (2) switched from VKA to NOAC, (3) switched from NOAC to VKA or (4) switched from one NOAC to another. Predictors of discontinuation or switching of OAC treatment were determined by Cox proportional hazards regression models with time-independent and time-dependent covariates. RESULTS: The study population comprised 51,606 AF patients initiating VKA (n = 21,468, 41.6%), apixaban (n = 8,832, 17.1%), dabigatran (n = 3,973, 7.7%) or rivaroxaban (n = 17,333, 33.6%). After 1 year, 29.9% of VKA and 29.5% of NOAC patients had discontinued OAC treatment without switching to another anticoagulant. A total of 10.7% of VKA patients switched to NOACs within 1 year, whereas 4.9% NOAC patients had switched to VKA. Of AF patients who were initiated on a NOAC, 5.2% switched to another NOAC. Treatment changes among NOAC starters were strongly associated with occurrence of stroke, myocardial infarction and gastrointestinal bleeding after treatment initiation. For VKA starters switching to a NOAC, stroke and bleeding events were associated with an increased likelihood of switching. CONCLUSION: Overall discontinuation rates of VKA and NOACs are comparable over the first year of therapy, while switching from VKA to NOAC was more common than from NOAC to VKA. The majority of treatment changes were associated with clinical events.

Non-Vitamin K Oral Anticoagulants in Comparison to Phenprocoumon in Geriatric and Non-Geriatric Patients with Non-Valvular Atrial Fibrillation.

Geriatric characteristics such as high age, multi-morbidity, polypharmacy and frailty are common in patients with atrial fibrillation (AF). In a retrospective study using a German claims database, effectiveness (ischaemic stroke/systemic embolism) and safety (intracerebral, gastrointestinal and major extracranial bleeding) were compared in patients with non-valvular AF starting non-vitamin K oral antagonists (NOACs) (apixaban, dabigatran and rivaroxaban) and phenprocoumon. Cox proportional hazards models were used to calculate adjusted hazard ratios, and interaction terms of the treatment group and geriatric status (defined by age ≥75 years, frailty, ≥ 4 co-morbidities and polypharmacy) were entered into the model. A total of 42,562 and 27,939 patients initiated NOAC and phenprocoumon treatment (mean age 74 years ± 11, 51% male) with a follow-up time of 147,785 person-years. Note that 52.9% of patients were elderly, 50.8% were frail, 37.0% were co-morbid and 46.5% had polypharmacy. NOAC use was not associated with effectiveness and gastrointestinal bleeding, neither in geriatric nor in non-geriatric patients. The hazard of major extracranial and intracranial bleeding was significantly decreased for NOAC use, with similar risk reduction in geriatric and non-geriatric patients: major extracranial bleeding 0.70 (95% confidence interval [CI], 0.56-0.87) to 0.73 (95% CI, 0.60-0.89) for the geriatric groups and 0.71 (95% CI, 0.56-0.93) to 0.76 (0.59-0.98) for the non-geriatric groups (p-values for interaction > 0.6); and intracranial bleeding 0.52 (95% CI, 0.39-0.69) to 0.59 (95% CI, 0.47-0.73) for the geriatric groups and 0.54 (95% CI, 0.37-0.79) to 0.65 (95% CI, 0.49-0.86) for the non-geriatric groups (p-values for interaction > 0.2). Hence, NOACs showed similar effectiveness and superior safety in geriatric and non-geriatric patients.

Efficacy and safety of rivaroxaban compared with vitamin K antagonists for peri-procedural anticoagulation in catheter ablation of atrial fibrillation: a systematic review and meta-analysis.

Rivaroxaban is increasingly used in patients undergoing catheter ablation of atrial fibrillation (AF). In the absence of large controlled trials, a comprehensive meta-analysis of the literature appears to be the best way to obtain reliable evidence on rare peri-procedural outcomes such as thromboembolic or bleeding events. We aimed to provide a detailed analysis of currently available data on safety and efficacy of peri-procedural rivaroxaban in patients undergoing AF ablation. We performed a systematic search of the English language literature for studies comparing peri-procedural rivaroxaban therapy with vitamin K antagonists (VKAs) and reporting detailed data on bleeding and/or thromboembolic complications. The Peto odds ratio (POR) was used to pool data into a fixed-effect meta-analysis. A total of 7400 patients undergoing catheter ablation were included in 15 observational and 1 randomized studies of which 1994 were receiving rivaroxaban and 5406 VKA. The risk of thromboembolism trended to be lower in the rivaroxaban group [4/1954 vs. 19/5219, POR 0.40, 95% confidence interval (CI), 0.16-1.01, P = 0.052]. Major bleeding events occurred in 23 of 1994 cases (1.15%) in the rivaroxaban and 90 of 5406 (1.66%) in the VKA group (POR 0.74, 95% CI, 0.46-1.21, P = 0.23). A total of 87 minor bleeding events were reported in 1753 patients (4.96%) in the rivaroxaban group and in 165 of 4009 patients (4.12%) in the VKA group (POR 0.84, 95% CI 0.63-1.11, p = 0.22). In patients undergoing AF ablation, rivaroxaban appears to be an effective and safe alternative to VKA.

Patient-reported treatment satisfaction and budget impact with rivaroxaban vs. standard therapy in elective cardioversion of atrial fibrillation: a post hoc analysis of the X-VeRT trial.

AIMS: We compared patient-reported treatment satisfaction and the economic impact of anticoagulation therapy with rivaroxaban vs. vitamin K antagonists (VKAs) in patients with non-valvular atrial fibrillation undergoing elective cardioversion procedures. METHODS AND RESULTS: The current study is a post hoc analysis of the prospective, multicentre X-VeRT (EXplore the efficacy and safety of once-daily oral riVaroxaban for the prevention of caRdiovascular events in subjects with non-valvular aTrial fibrillation scheduled for cardioversion) trial. Patient-reported treatment satisfaction with anticoagulation therapy was assessed using the Treatment Satisfaction Questionnaire for Medication version II in seven countries (US, UK, Canada, Germany, France, Italy, and the Netherlands). An economic model was also developed to estimate the impact of postponed cardioversions for two countries (UK and Italy). This model estimated the total costs of cardioversion, taking into consideration the costs for drug therapy (including extended treatment duration due to cardioversion postponement), international normalized ratio monitoring of VKAs, the cardioversion procedure, and rescheduling the procedure. These costs were linked to the respective X-VeRT study data to estimate the total costs. Patients receiving rivaroxaban in the delayed cardioversion group had significantly higher scores for Convenience, Effectiveness, and Global satisfaction (81.74 vs. 65.78; 39.41 vs. 32.95; and 82.07 vs. 66.74, respectively; P < 0.0001). Based on the total patient population included in the treatment satisfaction substudy (n = 632) in the delayed cardioversion group in X-VeRT, the use of rivaroxaban was estimated to result in a saving of £421 and €360 per patient in UK and Italian settings, respectively. CONCLUSION: The use of rivaroxaban in the setting of cardioversion resulted in greater patient satisfaction and cost savings, compared with that of VKA.

A combined anatomic and electrophysiologic substrate based approach for sudden cardiac death risk stratification.

BACKGROUND: Although left ventricular ejection fraction (LVEF) is the primary determinant for sudden cardiac death (SCD) risk stratification, in isolation, LVEF is a sub-optimal risk stratifier. We assessed whether a multi-marker strategy would provide more robust SCD risk stratification than LVEF alone. METHODS: We collected patient-level data (n = 3355) from 6 studies assessing the prognostic utility of microvolt T-wave alternans (MTWA) testing. Two thirds of the group was used for derivation (n = 2242) and one-third for validation (n = 1113). The discriminative capacity of the multivariable model was assessed using the area under the receiver-operating characteristic curve (c-index). The primary endpoint was SCD at 24 months. RESULTS: In the derivation cohort, 59 patients experienced SCD by 24 months. Stepwise selection suggested that a model based on 3 parameters (LVEF, coronary artery disease and MTWA status) provided optimal SCD risk prediction. In the derivation cohort, the c-index of the model was 0.817, which was significantly better than LVEF used as a single variable (0.637, P < .001). In the validation cohort, 36 patients experienced SCD by 24 months. The c-index of the model for predicting the primary endpoint was again significantly better than LVEF alone (0.774 vs 0.671, P = .020). CONCLUSIONS: A multivariable model based on presence of coronary artery disease, LVEF and MTWA status provides significantly more robust SCD risk prediction than LVEF as a single risk marker. These findings suggest that multi-marker strategies based on different aspects of the electro-anatomic substrate may be capable of improving primary prevention implantable cardioverter-defibrillator treatment algorithms.

Relevance of electrical remodeling in human atrial fibrillation: results of the Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial mechanisms of atrial fibrillation study.

BACKGROUND: In animal models of atrial fibrillation (AF), changes in atrial electrophysiological properties are associated with the development of AF. Their relevance to human AF is unclear. METHODS AND RESULTS: The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial enrolled 2580 patients receiving a dual-chamber pacemaker, who were older than the age of 65 and had a history of hypertension, but no history of AF. Serial noninvasive electrophysiological testing was performed over 2 years in a subgroup of 485 patients. There were no differences in the clinical characteristics between patients with and those without device-detected atrial tachyarrhythmias during the first year. Patients with atrial tachyarrhythmias had longer paced (153±29 versus 145±28 ms; P=0.046) and sensed (128±46 versus 118±25 ms; P=0.06) P-wave durations and were more likely to have AF induced during electrophysiological testing (23.5% versus 13.6%; P=0.03). They had similar corrected sinus node recovery times at 90 bpm (388±554 versus 376 ± 466 ms; P=0.86), atrial effective refractory periods at 90 bpm (250±32 versus 248±36 ms; P=0.70), and rate-adaptive shortening of the atrial effective refractory periods (14±13 versus 12±14 ms; P=0.11). There were no significant differences in the change in electrophysiological properties over 2 years between patients with and those without atrial tachyarrhythmias. CONCLUSIONS: Prolonged P-wave duration, but not differences in atrial effective refractory periods, was associated with the development of atrial tachyarrhythmias in pacemaker patients.

Clinical utility of microvolt T-wave alternans testing in identifying patients at high or low risk of sudden cardiac death.

BACKGROUND: Previous studies have demonstrated that microvolt T-wave alternans (MTWA) testing is a robust predictor of ventricular tachyarrhythmias and sudden cardiac death (SCD) in at-risk patients. However, recent studies have suggested that MTWA testing is not as good a predictor of "appropriate" implantable cardioverter-defibrillator (ICD) therapy as it is a predictor of SCD in patients without ICDs. OBJECTIVE: To evaluate the utility of MTWA testing for SCD risk stratification in patients without ICDs. METHODS: Patient-level data were obtained from 5 prospective studies of MTWA testing in patients with no history of ventricular arrhythmia or SCD. In these studies, ICDs were implanted in only a minority of patients and patients with ICDs were excluded from the analysis. We conducted a pooled analysis and examined the 2-year risk for SCD based on the MTWA test result. RESULTS: The pooled cohort included 2883 patients. MTWA testing was positive in 856 (30%), negative in 1627 (56%), and indeterminate in 400 (14%) patients. Among patients with a left ventricular ejection fraction (LVEF) of ≤35%, annual SCD event rates were 4.0%, 0.9%, and 4.6% among groups with MTWA positive, negative, and indeterminate test results. The SCD rate was significantly lower among patients with a negative MTWA test result than in patients with either positive or indeterminate MTWA test results (P <.001 for both comparisons). In patients with an LVEF of >35%, annual SCD event rates were 3.0%, 0.3%, and 0.3% among the groups with MTWA positive, negative, and indeterminate test results. The SCD rate associated with a positive MTWA test result was significantly higher than that associated with either negative (P <.001) or indeterminate MTWA test results (P = .003). CONCLUSIONS: In patients without ICDs, MTWA testing is a powerful predictor of SCD. Among patients with an LVEF of ≤35%, a negative MTWA test result is associated with a low risk for SCD. Conversely, among patients with an LVEF of >35%, a positive MTWA test result identifies patients at significantly heightened SCD risk. These findings may have important implications for refining primary prevention ICD treatment algorithms.

Rationale and design of AVERROES: apixaban versus acetylsalicylic acid to prevent stroke in atrial fibrillation patients who have failed or are unsuitable for vitamin K antagonist treatment.

BACKGROUND: Many patients with atrial fibrillation (AF) at moderate or high risk for stroke are not treated with a vitamin K antagonist (VKA). Presently, the only alternative to a VKA with a labeled indication for AF is antiplatelet therapy with acetylsalicylic acid (ASA), which is much less effective than a VKA for prevention of stroke. The novel oral factor Xa inhibitor, apixaban, is being developed for prevention of stroke in AF. A noninferiority trial of apixaban versus a VKA (warfarin) is being conducted but does not address the large unmet need of AF patients at risk of stroke who are unsuitable for or unwilling to take a VKA. Apixaban may be an attractive alternative to ASA for prevention of stroke in patients with AF who cannot or will not take a VKA. DESIGN: AVERROES is a double-blind, double-dummy superiority trial of apixaban 5 mg twice daily (2.5 mg twice daily in selected patients) compared with ASA 81 to 324 mg once daily in patients with AF and at least 1 risk factor for stroke who have failed or are unsuitable for VKA therapy. The primary outcome is stroke or systemic embolism, and the primary safety outcome is major bleeding. The trial is event driven and is expected to enroll at least 5,600 patients. CONCLUSIONS: By evaluating the use of apixaban as a replacement for ASA in AF patients who are not treated with a VKA, the AVERROES study is addressing an important unmet clinical need. The results of AVERROES will be complementary to those of a parallel noninferiority trial comparing apixaban with VKA therapy in patients with AF who are able to receive a VKA.

Prevention of immediate reinitiation of atrial tachyarrhythmias by high-rate overdrive pacing: results from a prospective randomized trial.

INTRODUCTION: Immediate reinitiation of atrial tachyarrhythmia (IRAT) is an important cause of failure to maintain sinus rhythm. IRAT prevention by overdrive pacing has not been evaluated in a prospective randomized trial. METHODS AND RESULTS: Patients with a DDDRP pacemaker offering temporary atrial overdrive pacing after AT termination (Post Mode Switching Overdrive Pacing [PMOP]) were enrolled into the prospective PIRAT (Prevention of IRAT) trial if paroxysmal AT episodes occurred after implantation. PMOP was randomly activated (120 beats/min for 2 min) or inactive. After 3 months, device memory was interrogated, symptoms and quality of life assessed, and patients crossed over to the alternative treatment arm for another 3 months. Primary study endpoint was the number of AT episodes; secondary endpoints were the cumulative time in AT (AT burden), percentage of AT episodes with IRAT, symptoms, and quality of life with PMOP active versus inactive. In 37 patients (21 men; 69 +/- 9 years), there was no difference in the median number of AT episodes (0.37 vs 0.34 per day), AT burden (both 1%), percentage of episodes with IRAT (30%vs 28%), symptoms, and quality of life during PMOP off versus on. With PMOP active, 29% of 439 ATs restarted during and 18% before PMOP intervention. The PMOP-induced rate increase appeared to be associated with IRAT in 9% of AT episodes. CONCLUSION: Automatic overdrive pacing after AT termination did not prevent IRAT, mainly due to insufficient overdrive suppression even at 120 beats/min and the delay between AT termination and PMOP intervention.

Usefulness of atrial pacing for prevention and termination of atrial tachyarrhythmias in a patient with persistent atrial fibrillation.

Atrial pacing with dedicated algorithms for prevention and termination of atrial tachyarrhythmias is under clinical evaluation. A patient is described with persistent symptomatic AF. After cardioversion and implantation of a DDDRP pacemaker before planned AVN ablation, the patient was free of symptoms. Early after implant, one cardioversion of AF was necessary. Over the course of 12 months, only five episodes of atrial tachyarrhythmia occurred, all automatically pace terminated within 24 hours. Thus, selected patients with persistent AF may benefit from preventive atrial pacing since the tachyarrhythmia can organize intermittently to a degree sufficient for pace termination.

Analysis during sinus rhythm of critical sites in reentry circuits of postinfarction ventricular tachycardia.

BACKGROUND: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites. METHODS: In 33 patients (mean age 67 +/- 11 yrs) with prior infarction, mapping and radiofrequency (RF) catheter ablation of 57 hemodynamically-tolerated VT's (cycle length 478 +/- 96) were performed. The morphologies of electrograms (EGM) at sites of concealed entrainment (CE) were compared during SR and VT. RF energy was delivered at 94 sites (51 successful and 43 unsuccessful ablation sites). RESULTS: During SR, isolated potentials (IP), but not late potentials (LP) recorded via the mapping catheter, were associated with successful ablation. At 29/39 sites with an IP during sinus rhythm, an isolated diastolic potential (IDP) also was present during VT, whereas at 4 sites IP's were present only during SR (p < 0.001). At 11/29 sites where isolated potentials were present during SR and VT, the morphology of the isolated potential during VT and SR was similar; and all but one of these sites were successful ablation sites (p = 0.01). The EGM amplitude during VT correlated with the amplitude during SR (R = 0.9, p < 0.001). An identical pacemap was present during SR at 33/94 sites; this was not associated with successful ablation. CONCLUSION: SR mapping may be helpful in identifying critical sites of reentry in postinfarction VT. At sites within the reentry circuit, characteristics of sinus rhythm EGM's that are associated with successful ablation include the presence of IP's, but not the presence of LP's.