How much does elective cardioversion increase the risk of ischaemic stroke compared to the baseline risk in atrial...

Area of Science:

• Cardiology
• Neurology
• Public Health

Background:

• Atrial fibrillation (AF) patients undergoing cardioversion (CV) have an increased risk of ischaemic stroke (IS).
• The precise magnitude of this post-CV IS risk compared to long-term risk is not well-defined.
• Guideline-recommended anticoagulation therapy is standard for AF patients.

Purpose of the Study:

• To compare IS rates in the immediate post-CV period with the long-term risk in AF patients.
• To quantify the excess IS risk within the first two weeks after elective CV.
• To assess the influence of anticoagulation type and conventional risk factors on this early post-CV IS risk.

Main Methods:

• Nationwide register-based study of all AF patients undergoing first-ever elective CV in Finland (2012-2018).
• Follow-up divided into immediate (0-2 weeks) and subsequent (2 weeks to 360 days) post-CV periods.
• Breakpoint analysis and Poisson regression used to estimate incidence rate ratios and assess interactions.

Main Results:

• A total of 9625 AF patients were included; 64.9% used warfarin, 35.1% used non-vitamin K oral anticoagulants.
• Overall, 1.0% of patients experienced IS within one year post-CV.
• The adjusted IS rate in the first 2 weeks post-CV was 7.5-fold higher than in the subsequent period, independent of anticoagulation or risk factors.

Conclusions:

• The incidence of IS is substantially elevated in the first two weeks following elective CV for AF.
• This early excess IS risk is approximately seven times higher than the risk observed in the subsequent 360 days.
• The heightened risk during the initial post-CV period is not influenced by the type of anticoagulation used or conventional stroke risk factors.