Clinical Classifications of Atrial Fibrillation Poorly Reflect its Temporal Persistence: Insights From 1195 Patients Continuously Monitored With Implantable Devices
How does a clinical atrial fibrillation (AF) classification scheme reflect objectively determined arrhythmia burden in patients with implantable devices?
AF burden among 1,195 patients who underwent implantation of a pacemaker, defibrillator, or biventricular defibrillator was determined. AF was classified at the time of implantation according to the 2006 guidelines: paroxysmal (self terminating within 7 days) or persistent (sustained for >7 days). The clinical classification was compared with duration of AF as detected by the device (no AF during the study duration), paroxysmal AF (<7 consecutive days of AF), persistent AF (>7 consecutive days with AF), and permanent AF (continuous AF or >95% AF burden).
Among 1,091 patients who were diagnosed with paroxysmal AF clinically, 377 experienced no AF; and 509, 183, and 22 patients were designated as having paroxysmal, persistent, and permanent AF based on device-based arrhythmia burden, respectively. There was poor agreement between the two methods (Cohen’s kappa: 0.12). Patient characteristics, as opposed to arrhythmia duration, influenced the clinical decision to classify AF as paroxysmal or persistent.
The authors concluded that the 2006 AF classification scheme poorly reflects objectively determined AF burden.
There may be several reasons that help explain the discordance between clinical and device-based AF behavior. For example, after an initial episode of AF, patients may go several years without recurrence. In this study, one-third of the patients experienced no AF during the follow-up period, making it impossible to assess the validity of the clinical classification. The authors also report that a patient’s comorbidities often influenced the clinician’s adjudication, as opposed to the actual arrhythmia duration. Also, many patients in the current study had advanced heart disease, which makes it difficult to generalize the results to patients with AF at large. Last, little information is available regarding antiarrhythmic usage, which obviously impacts AF burden. To be sure, continuous monitoring is the ideal method to assess arrhythmia burden and follow response to intervention. Nevertheless, the current clinical classification scheme distinguishing paroxysmal from persistent and longstanding persistent AF is simple, clinically useful, and has been shown to be prognostically important.
Keywords: Defibrillators, Follow-Up Studies, Pacemaker, Artificial, Cost of Illness
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