Predicting Onset of Atrial Fibrillation

The general objective of the Computers in Cardiology Challenge 2001 is to characterize changes in the surface electrocardiogram immediately prior to the onset of paroxysmal atrial fibrillation (PAF), in an effort to develop a reliable prediction algorithm for the arrhythmia.

Currently, no reliable validated methods exist to predict the onset of PAF. Twelve-lead electrocardiograms [1], signal-averaged P-wave morphology [2,3], R-R interval dynamics [4,5], and atrial ectopy [5-7] have all been studied as possible predictors of the onset of PAF. Sensitive and specific non-invasive markers predicting the onset of PAF have not been determined or independently validated, however. Given recent advances in clinical electrophysiology, a prediction tool that would allow for detection of imminent atrial fibrillation may have future therapeutic ramifications.

Atrial fibrillation (AF) is the most common major cardiac arrhythmia. In the United States alone, it affects an estimated 2.2 million people, with an increasing prevalence in the elderly [8]. As the population ages, the prevalence is expected to rise; currently approximately 6% of the US population over the age of 65 are diagnosed with this arrhythmia. Management consists of heart rate control and/or prevention of recurrent fibrillation, as well as prevention of secondary complications (most often thromboembolism). Paroxysms of atrial fibrillation often precede the onset of more sustained atrial fibrillation. A Japanese study of 234 patients with atrial fibrillation found that 94 (40%) had PAF, and that sustained atrial fibrillation developed within one year in approximately one fourth of patients with PAF [9].

The development of accurate predictors of the acute onset of PAF is clinically important because of the increasing possibility of electrically stabilizing and preventing the onset of atrial arrhythmias with different atrial pacing techniques. Dual chamber atrial pacing may reduce the heterogeneity of atrial refractoriness manifested by P-wave duration changes on the surface electrocardiogram recording. Preliminary studies by Prakash and colleagues [10] have indicated that acute suppression of PAF is possible in selected patients with dual-site right atrial pacing from the coronary sinus ostium and high right atrium. The advances in anti-tachycardia pacing, drug management, and defibrillation may be applied to prevent the acute onset of PAF prior to the loss of sinus rhythm. The maintenance of sinus rhythm can lead to decreased symptoms, improved hemodynamics, and possibly a decrease in the atrial remodeling that causes increased susceptibility to future episodes of PAF [11]. In addition, there may be a reduction in the risk of thromboembolic events.

References

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2. Ishimoto N, Ito M, Kinoshita M. Signal-averaged P-wave abnormalities and atrial size in patients with and without idiopathic paroxysmal atrial fibrillation. Am Heart J 2000;139:684-689.
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