Duration of warfarin sodium therapy prior to electrical cardioversion of atrial fibrillation

Real-life experience with non-vitamin K antagonist oral anticoagulants versus warfarin in patients undergoing elective cardioversion of atrial fibrillation

Background

Nonvitamin K antagonist oral anticoagulants (NOACs) are increasingly used in patients with atrial fibrillation (AF) undergoing elective cardioversion (ECV). The aim was to investigate the use of NOACs and warfarin in ECV in a real‐life setting and to assess how the chosen regimen affected the delay to ECV and rate of complications.

Methods

Consecutive AF patients undergoing ECVs in the city hospitals of Helsinki between January 2015 and December 2016 were studied. Data on patient characteristics, delays to cardioversion, anticoagulation treatment, acute (<30 days) complications, and regimen changes within one year were evaluated.

Results

Nine hundred patients (59.2% men; mean age, 68.0 ± 10.0) underwent 992 ECVs, of which 596 (60.0%) were performed using NOACs and 396 (40.0%) using warfarin. The mean CHA₂DS₂‐VASc score was 2.5 (±1.6). In patients without previous anticoagulation treatment, NOACs were associated with a shorter mean time to cardioversion than warfarin (51 versus. 68 days, respectively; p < .001). Six thromboembolic events (0.6%) occurred: 4 (0.7%) in NOAC‐treated patients and 2 (0.5%) in warfarin‐treated patients. Clinically relevant bleeding events occurred in seven patients (1.8%) receiving warfarin and three patients (0.5%) receiving NOACs. Anticoagulation treatment was altered for 99 patients (11.0%) during the study period, with the majority (88.2%) of changes from warfarin to NOACs.

Conclusions

In this real‐life study, the rates of thromboembolic and bleeding complications were low in AF patients undergoing ECV. Patients receiving NOAC therapy had a shorter time to cardioversion and continued their anticoagulation therapy more often than patients on warfarin.

Anticoagulation in the cardiac patient: A concise review

Anticoagulation has multiple roles in the treatment of cardiovascular disease, including in management of acute myocardial infarction, during percutaneous coronary intervention, as stroke prophylaxis in patients with atrial arrhythmias, and in patients with mechanical heart valves. Clinical anticoagulation choices in the aforementioned diseases vary widely, due to conflicting data to support established agents and the rapid evolution of evidence-based practice that parallels more widespread use of novel oral anticoagulants. This review concisely summarizes evidence-based guidelines for anticoagulant use in cardiovascular disease, and highlights new data specific to direct oral anticoagulants.

Cardioversion for atrial fibrillation - how to prevent thromboembolic complications?

Cardioversion is an essential component of rhythm control strategy for atrial fibrillation. The thromboembolic risk of cardioversion is well established and the mechanisms behind the phenomenon have been comprehensively described. There are several clinical aspects that are important to take into consideration when assessing the safety of cardioversion. Before proceeding to cardioversion, the probability of early treatment failure and antiarrhythmic treatment options to prevent recurrences should be carefully evaluated to avoid the risks of repeated futile cardioversions. Effective periprocedural anticoagulation is the mainstay in thromboembolic complication prevention and the first week after rhythm conversion is the most vulnerable period in this respect. Early timing of cardioversion appears to be another important measure to decrease the risk of thromboembolic complications. Transoesophageal echocardiography is useful in clinical scenarios where early cardioversion is desirable due to debilitating clinical symptoms and a short duration of arrhythmia or the adequacy of preceding anticoagulation is uncertain. However, it does not lessen the need for effective anticoagulation after cardioversion. This review summarizes the recent scientific discoveries to improve the safety of cardioversion for atrial fibrillation. Key messages Cardioversion for atrial fibrillation entails a significant risk of thromboembolic complications, especially during the first week after the procedure. The intensity of periprocedural anticoagulation and the timing of cardioversion appear to be significant determinants of the risk of thromboembolism. Awareness of the clinical aspects influencing cardioversion safety should be raised.

Findings of transoesophageal echocardiogram in appropriately anticoagulated patients with persistent atrial fibrillation prior to planned cardioversion

Background

To evaluate a diagnostic value of transoesophageal echocardiogram (TEE) in appropriately anticoagulated patients with a non-valvular atrial fibrillation (AF) and to establish possible additional indications for TEE; to evaluate the incidence of left atrial (LA) thrombi in appropriately anticoagulated patients in daily clinical practice.

Methods

This retrospective study analyses data of 432 patients who had been anticoagulated by means of oral anticoagulants (OACs) prior to planned cardioversion during the period from 2012 to 2015. Thromboembolic (TE) and bleeding risks were assessed using CHA2DS2-VASc and HAS-BLED scores. Transthoracic and transoesophageal echocardiograms were evaluated. TE complications during 30 days after discharge were assessed.

Results

432 patients were selected, aged from 22 to 89 years (mean 65.0 ±11.5), 277 (64.1%) males and 155 (35.9%) females, 306 (70.8%) on warfarin and 126 (29.2%) on non-vitamin K antagonist oral anticoagulants (NOAC). Mean CHA2DS2-VASc score was 3.5 ±1.5. TEE was performed for 120 (27.8%) patients, more frequently for patients on NOACs and for ones with III° LA enlargement.

TEE revealed LA thrombi in seven (5.8%) of the patients. In warfarin and NOACs groups thrombi were revealed in five (7.0%) and two (4.1%) patients, respectively. TEE did not reveal any thrombi in patients with normal left ventricular (LV) function; however, thrombi were found in two (6.1%) patients with slightly decreased LV function, and in five (17.9%) patients with markedly decreased LV function.

In patients with decreased left ventricular ejection fraction (LVEF) thrombi in LA were found more frequently than in patients with normal and slightly decreased LVEF (17.9% vs 2.2%, p=0.008). CHA2DS2-VASc score of all 7 patients was ≥5. None of the patients after cardioversion had TE complications 30 days after discharge.

Conclusions

The risk of LA thrombi in patients prepared for scheduled cardioversion in line with the guidelines is low. Higher risk of thrombi was present in patients with decreased LVEF (≤40%), CHA2DS2-VASc ≥5. In order to assess more accurately indications to perform TEE for appropriately anticoagulated patients prior to scheduled cardioversion a study with larger number of patients is required.

Practical Implementation of Anticoagulation Strategy for Patients Undergoing Cardioversion of Atrial Fibrillation

Anticoagulation is routinely prescribed to patients with persistent AF before cardioversion to reduce the risk of thromboembolic events. As direct oral anticoagulants (DOACs) have a rapid onset of action, a consistent anticoagulant effect, if taken correctly, and do not need monitoring or dose adjustments, there is considerable interest in their use for patients with AF undergoing cardioversion. Post-hoc analyses show that DOACs are safe to use prior to and following cardioversion. In addition, two randomised controlled trials, X-VeRT and ENSURE-AF, have demonstrated the efficacy and safety of the DOACs rivaroxaban and edoxaban, respectively, in this setting. The use of DOACs allows cardioversions to be performed promptly and reduces the number of cancelled procedures compared with the use of warfarin.

Poor anticoagulation relates to extended access times for cardioversion and is associated with long-term major cardiac and cerebrovascular events

BACKGROUND

Patients undergoing elective electrical cardioversion (ECV) for atrial fibrillation have a temporarily increased risk of thromboembolism. Current guidelines recommend adequate anticoagulation for ≥3 consecutive weeks precardioversion, i.e. consecutive INR values 2.0-3.0 in patients with vitamin K antagonists (VKA). We aimed to evaluate the occurrence and impact of subtherapeutic INRs precardioversion and to study factors associated with these unwanted fluctuations.

METHODS

We recruited 346 consecutive patients undergoing elective ECV in the Maastricht University Medical Centre between 2008 and 2013. Predictors of subtherapeutic INR values were identified and incorporated into a logistic regression model.

RESULTS

A subtherapeutic INR precardioversion occurred in 55.2% of patients. The only statistically significant predictor was VKA-naivety (Odds Ratio (OR) 4.78, 95% Confidence Interval (CI) 2.67-8.58, p<0.001). In patients with ≥1 subtherapeutic INR precardioversion, time from referral until cardioversion was 91.1±42.8days, compared to 41.7±26.6days (p<0.001) in patients without subtherapeutic INRs. No thromboembolic events occurred <30days after the ECV. Independent predictors for the combined endpoint of cardiovascular death, ischemic stroke and the need of blood transfusion (n=30, median follow-up of 374days) were coronary artery disease in the history (OR 3.35, 95%CI 1.54-7.25, p=0.002) and subtherapeutic INR precardioversion (OR 3.64, 95%CI 1.43-9.24, p=0.007).

CONCLUSIONS

The use of VKA often results in subtherapeutic INRs precardioversion and is associated with a significant delay until cardioversion, especially in patients with recent initiation of VKA therapy. Furthermore, subtherapeutic INR levels prior to ECV are associated with the combined endpoint of cardiovascular death, ischemic stroke and the need of blood transfusion.

Contemporary approach to electrical and pharmacological cardioversion of atrial fibrillation

In patients with atrial fibrillation (AF), a rhythm-control strategy may be adopted when there are unacceptable symptoms from AF, failure of rate control, and/or the presence of comorbidities, such as heart failure, that may improve with restoration of sinus rhythm. When a rhythm-control strategy is chosen and the patient is in persistent AF, cardioversion will be necessary to convert the rhythm to sinus. Patients with AF present for > 48 hours must be effectively anticoagulated both prior to and after cardioversion. With newer oral anticoagulants, achieving effective anticoagulation is faster and more reliable, with no requirement for blood test monitoring. Cardioversion can be accomplished either electrically or pharmacologically, and in some cases, electrical cardioversion may be facilitated pharmacologically. Electrical cardioversion has a higher success rate compared with pharmacological cardioversion in the short-term. Pharmacological cardioversion is usually accomplished with intravenous ibutilide, oral flecainide or propafenone, or intravenous amiodarone. Oral amiodarone and dofetilide also result in chemical cardioversion in some patients over a longer period of time. Long-term success in the maintenance of sinus rhythm post-cardioversion can be increased with the use of antiarrhythmic drugs. Alternatively, when AF is recurrent and symptomatic despite the use of antiarrhythmic drugs, catheter ablation is a reasonable option for many patients. Cardioversion may be incorporated into the management approach of persistent AF when the primary therapeutic option chosen is catheter ablation.

[TEE-guided cardioversion in patients with atrial fibrillation without previous anticoagulation]

A total of 332 patients (mean age 65+/-10 years, 86 female) with nonvalvular atrial fibrillation (AF) of more than 48 hours duration and lack of a sufficient anticoagulation were included. After exclusion of thrombotic material in the left atrium using transesophageal echocardiography (TEE) cardioversion (CV) was performed within 24 hours. At the same time oral anticoagulation (AC) (overlapping with PTT-affecting heparinisation) was started. If thrombi were found by TEE, the examination was repeated after at least four weeks of anticoagulation. If thrombi were absent at this time, CV was performed. Periprocedural embolism was defined as primary endpoint, whereas the detection of atrial thrombi before CV was defined as secondary endpoint. In 33 of the 332 Patients (9.9%) the TEE showed a thrombus in the left atrium respectively the left atrial appendage (n=22) or thrombi could not be excluded (n=11). 383 TEEs were performed without complications in an overall of 332 patients.A total of 305 CV were performed (electrical n=300, pharmacological n=5) and during periprocedural monitoring and in the time of four weeks after CV no thromboembolic complications were observed.TEE-guided CV in patients with AF persisting for more than 48 hours and without previous AC can be considered as a method that is both safe and effective.