Elsevier

Journal of Electrocardiology

Volume 41, Issue 6, November–December 2008, Pages 662-664
Journal of Electrocardiology

Intermittent interatrial block after electrical cardioversion for atrial fibrillation

https://doi.org/10.1016/j.jelectrocard.2008.03.005Get rights and content

Abstract

A 67-year-old woman with persistent atrial fibrillation presented for elective electrical cardioversion. The patient was cardioverted to normal sinus rhythm with a synchronized 150 joules (J) biphasic shock. Varying P-wave morphology suggesting intermittent interatrial block (IAB) was noted after the cardioversion on the rhythm strip. Three minutes later the patient developed early recurrence of atrial fibrillation and a second successful 150 J biphasic shock was delivered; IAB was still evident on a single lead II monitoring. However, the patient remained in sinus rhythm. The patient was discharged in normal sinus rhythm with electrocardiographic evidence of intermittent interatrial block. This case report examines the occurrence of IAB postcardioversion for atrial fibrillation and speculates on its prognostic significance.

Section snippets

Case report

A 67-year-old woman with persistent atrial fibrillation (AF) presented for elective electrical cardioversion. Atrial fibrillation had been detected several months previously, and the patient had been optimally anticoagulated for 8 weeks before the procedure. The patient was treated with metoprolol 50 mg twice a day.

Transthoracic 2-dimensional echocardiogram revealed global left ventricular hypokinesis with an ejection fraction of 40%, normal right ventricular size, and mild tricuspid

Discussion

Interatrial block is caused by conduction delay between the right and left atria (P-wave duration >110 milliseconds) and has been found to be associated with development of atrial tachyarrhythmia.1 It is also associated with left atrial enlargement, and it could represent a risk factor for systemic thromboembolic events due to poorly contracting left atria.2 Intermittent interatrial block is caused by abnormal conduction over Bachmann's bundle, resulting in a delay of left atrial depolarization.

Conclusion

Intermittent interatrial block after electrical cardioversion of atrial fibrillation has not been previously described. It is an interesting finding that may represent an abnormal sequence of activation of the left atrium. The observation of intermittent IAB in this postcardioversion patient invites speculation about the mechanisms of reverse electrical remodeling in the just-cardioverted patient with AF, as well as the potential role of IAB in early recurrences of AF. Presence of IAB should be

References (13)

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Cited by (8)

  • Advanced interatrial block is an electrocardiographic marker for recurrence of atrial fibrillation after electrical cardioversion

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    This aIAB is also associated with a higher risk of AF recurrence at 1 year after pharmacological cardioversion [12]. In a case report, the presence of intermittent IAB after ECV of AF could be a predictor of early AF recurrence. [13] To date, aIAB has been found to exist in various conditions such as in older people, a male gender, the white race, dyslipidemia, a higher body mass index, and hypertension [14].

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