Cavotricuspid Isthmusblock and Circumferential Pulmonary Vein Isolation in Patients With Atrial Fibrillation

BACKGROUND:

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Medical treatment is often inefficient or associated with side effects. Pulmonary vein isolation (PVI) in the left atrium using radiofrequency energy is a new and promising non-medical treatment in patients with symptomatic AF with reported success rates of 65 % to 90 % depending on AF classification and ablation procedure (1).

Circumferential PVI appears to be the superior ablation technique in patients with AF (2). However, the risk of recurrence has led to suggestions of how to improve the clinical outcome by tailoring a more efficient ablation procedure. Patients with AF often have coexisting atrial flutter (3), but it is uncertain if patients referred for PVI can benefit from additional cavotricuspid isthmusblock (CTI) which is the traditional ablation treatment of atrial flutter. A recent study indicates that PVI reduces both AF and atrial flutter by eliminating sharing triggers in the pulmonary veins (4). Other investigators showed that patients with AF and atrial flutter prior or during PVI had high risk of recurrent atrial flutter during follow-up, and that successful PVI did not reduce the risk of recurrent atrial flutter (3). The current approach in our lab is to perform additional CTI in cases of documented atrial flutter, but CTI may potentially improve the overall outcome (freedom of symptomatic arrhythmia) in patients without documented atrial flutter, especially since most symptomatic periods are undocumented.

A prospective, randomised study with 150 patients with symptomatic AF referred for PVI has been initiated and patients are allocated to PVI alone (75 patients) or PVI with additional CTI (75 patients). Patients undergo extensive Holter monitoring during follow-up to document symptomatic or asymptomatic AF or atrial flutter. Patients with AF have a high incidence of asymptomatic AF which correlates to an increased risk of tromboembolic complications (5). The presence of aymptomatic AF after PVI could potentially affect the management of the anticoagulation therapy in these patients.

The structural and functional changes in the atria after PVI have been described in few studies. To our knowledge, Tissue Doppler Imaging (TDI) and neurohormones (NT-pro-BNP and ANP) have not previously been used in characterising the left atrial function after PVI. New echocardiographic modalities such as TDI have been introduced in the characterisation of the left ventricle systolic function in ischemic heart disease and congestive heart failure. TDI has been used for characterising the global and segmental atrial systolic function in healthy individuals (6), and TDI may be an effective tool for characterising changes in the left atrial function after PVI.