Anticoagulation in Heart Rhythm Control

This sections covers cardioversion and ablation in patients with AF, discussing the guideline recommendations and data from clinical studies

In this section:


Cardioversion aims to re-establish a normal sinus rhythm in patients with AF, either by:

  • 'Stunning' the left atrium using an electrical pulse (electrical cardioversion) or
  • Using rate-modifying drugs (pharmacological cardioversion)

Reported success rates of cardioversion vary:2

  • >90% for electrical cardioversion
  • 40–70% for pharmacological cardioversion

Evidence regarding the factors that predict successful cardioversion is limited:

  • A shorter versus longer duration of AF was independently associated with success in several studies
  • Lower body weight and pre-treatment with antiarrhythmic drugs may also be associated with successful cardioversion
  • Evidence on the influence of age is conflicting

AF recurs within 1 year in approximately half of patients who undergo successful cardioversion. Factors that have been identified as potentially predictive of AF recurrence include:

  • Decreased heart function
  • Increased CHA2DS2-VASc score
  • Age ≤65 years (rather than older)
  • Paroxysmal (rather than permanent) AF
  • Alcohol consumption


Ablation procedures are performed on patients with AF to attempt to restore a normal sinus rhythm by destroying the cardiac tissue responsible for the arrhythmia:

  • Traditional surgical ablation has reported efficacy rates of >90%; however, this procedure is technically difficult and involves open heart surgery
  • More recently, minimally invasive surgical procedures that make use of energy sources, such as cryoablation and radiofrequency ablation with pulmonary vein isolation, have yielded success rates of up to approximately 80%
  • Catheter ablation, another commonly employed and minimally invasive technique, is reported to be effective in approximately 80% of patients and is now the most popular method

Guideline recommendations

The ESC guidelines for the management of NVAF recommend:

  • Electrical cardioversion for patients who have recent-onset AF and are haemodynamically unstable
  • A choice between electrical and pharmacological cardioversion, based on patient and physician preference, in stable patients or those with persistent AF
European Society of Cardiology recommendations for cardioversion of recent-onset AF
European Society of Cardiology recommendations for cardioversion of recent-onset AF
ESC recommendations for left atrial ablation
Recommendation Grade of evidence
Catheter ablation is recommended in patients with symptomatic paroxysmal AF who experience symptomatic, recurrent AF on antiarrhythmic drug therapy and who instead prefer further rhythm-control therapy. This should be performed by an appropriately trained electrophysiologist at an experienced centre IA
Catheter ablation of AF should target isolation of the pulmonary veins IIA
Catheter ablation of AF should be considered as first-line therapy in selected patients with symptomatic paroxysmal AF as an alternative to antiarrhythmic drug therapy, taking into consideration patient choice, benefit and risk IIB
When AF recurs within the first 6 weeks after catheter ablation, a watch-and-wait rhythm-control therapy should be considered IIB

Catheter ablation is associated with an approximately 1% risk of stroke or TIA. Current guidelines recommend catheter ablation under low-level anticoagulation (INR ~2.0) with a VKA.

The electrical or pharmacological disruption of left atrium function during the cardioversion procedure is associated with a 5–7% incidence of thromboembolism, including stroke. By contrast, the risk is approximately 1% with adequate anticoagulation.

Current guidelines recommend ≥3 weeks of adequate anticoagulation before cardioversion:,

  • Either with a VKA, dosed to maintain an INR of 2.0–3.0, or a NOAC
  • Unless a TEE excludes left atrial or LAA thrombus, in which case cardioversion can be performed immediately with heparin anticoagulation

After cardioversion, anticoagulation with a VKA or a NOAC should be given for ≥4 weeks and may need to be continued indefinitely in some patients.

ESC recommendations for anticoagulation in patients with NVAF undergoing cardioversion
Recommendation Grade of evidence
For patients with AF of ≥48 h duration, or when the duration of AF is unknown, oral anticoagulant therapy (e.g. VKA with INR 2.0–3.0 or dabigatran) is recommended for ≥3 weeks prior to and for ≥4 weeks after cardioversion, regardless of the method (electrical or oral/intravenous pharmacological) IB
In patients with risk factors for stroke or AF recurrence, oral anticoagulant therapy, whether with dose-adjusted VKA (INR 2.0–3.0) or a NOAC, should be continued lifelong irrespective of the apparent maintenance of sinus rhythm following cardioversion IB

Result from studies

The ESC guidelines recommend dabigatran for pre-cardioversion anticoagulation based on a subanalysis of the RE-LY trial because a relatively large number of patients planned for cardioversion were included in the study:

  • Outcomes among the 1270 patients who underwent cardioversion were similar to the overall population, and were not significantly different between dabigatran and VKA

Subanalyses of the phase III studies of rivaroxaban (ROCKET AF) and apixaban (ARISTOTLE) also indicated similar outcomes to the overall populations in patients receiving cardioversion, but there were relatively few of these patients in these trials:

  • These analyses were limited by their retrospective nature and the lack of TEE data collected at baseline to exclude patients with left atrial/LAA thrombus, in whom cardioversion is contraindicated

To date, there have been few studies regarding the use of NOACs during AF ablation:

  • A single-centre retrospective study and a prospective registry found no difference between dabigatran and warfarin in terms of the periablative risk of bleeding or thromboembolic complications; however, patients receiving dabigatran took longer to reach the target activated clotting time compared with patients receiving uninterrupted warfarin
  • In a post hoc analysis of the phase III ROCKET AF study, outcomes associated with catheter ablation in 79 patients treated with warfarin and rivaroxaban were described; the authors noted that long-term outcomes (>30 days) were not statistically different between the treatment groups before and after ablation

Prospective clinical studies have been conducted to prospectively investigate NOAC use in patients undergoing cardioversion and catheter ablation.

The X-VeRT trial of rivaroxaban (NCT01674647) was the first prospective study of a NOAC to report results in the cardioversion setting (N=1504):

  • Following early cardioversion, four rivaroxaban (0.71%) and three VKA (1.08%) patients experienced a primary efficacy event; following delayed cardioversion the numbers were one (0.24%) and two (0.93%), respectively. There was a trend towards lower incidences of thromboembolic events and major bleeding events in favour of rivaroxaban compared with VKA

The ENSURE-AF study (NCT02072434) of edoxaban and the EMANATE trial of apixaban (NCT02100228) are due to report results in the near future. It is important to note that these studies, like X-VeRT, are not powered to show significant differences in either safety or efficacy.

The safety of rivaroxaban in patients with AF undergoing catheter ablation was investigated in the open-label VENTURE-AF study (NCT01729871), which was the first prospective, randomized study of a NOAC in this setting:

  • Patients (N=248) with paroxysmal or persistent NVAF received rivaroxaban 20 mg once daily or dose-adjusted VKA (INR 2.0–3.0) before and after ablation
  • During the catheter ablation procedure, patients received intravenous heparin
  • There was a low incidence of major bleeding and thromboembolic events in both treatment arms, indicating that rivaroxaban is a reasonable alternative to VKA in the setting of catheter ablation
  • Based on the design of VENTURE-AF, patients should either:
    • Have a TEE and, after confirmed absence of any thrombus, receive rivaroxaban for 1–7 days prior to ablation and for at least 4 weeks afterwards; or
    • Take rivaroxaban for at least 3 weeks prior to ablation and for at least 4 weeks afterwards

Next section: Other Options

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