Classifications of Atrial Fibrillation and Temporal Persistence
Classifications of Atrial Fibrillation and Temporal Persistence
Objectives This study aimed to identify how accurately the current clinical atrial fibrillation (AF) classifications reflect its temporal persistence.
Background Clinical classification of AF is employed to communicate its persistence, to select appropriate therapies, and as inclusion criterion for clinical trials.
Methods Cardiac rhythm histories of 1,195 patients (age 73.0 ± 10.1 years, follow-up: 349 ± 40 days) with implantable devices were reconstructed and analyzed. Patients were classified as having paroxysmal or persistent AF by physicians at baseline in accordance with current guidelines. AF burden, measured as the proportion of time spent in AF, was obtained from the device. Additionally we evaluated the agreement between clinical and device-derived AF classifications.
Results Patients within the same clinical class were highly heterogeneous with regards to AF temporal persistence. Agreement between the clinical AF classification and the objective device-derived assessments of AF temporal persistence was poor (Cohen's kappa: 0.12 [95% CI: 0.05 to 0.18]). Patient characteristics influenced the clinical decision to classify AF as paroxysmal or persistent. Higher ejection fraction (odds ratio: 0.97/per unit [95% CI: 0.95 to 0.98/per unit]; p < 0.0001) and presence of coronary artery disease (odds ratio: 0.53 [95% CI: 0.32 to 0.88]; p = 0.01) were independently associated with a lower probability of being classified as persistent AF for the same AF burden level.
Conclusions The currently used clinical AF classifications poorly reflect AF temporal persistence. Patient characteristics significantly influence the physician's classification of AF. Patients classified in identical clinical categories may be inherently heterogeneous with regard to AF temporal persistence. Further study is required to determine if patient selection on the basis of objective criteria derived from rigorous AF monitoring can improve reported outcomes and better identify responders and non-responders to treatments. (OMNI Study–Assessing Therapies in Medtronic Pacemaker, Defibrillator, and Cardiac Resynchronization Therapy Devices; NCT00277524; TRENDS: A Prospective Study of the Clinical Significance of Atrial Arrhythmias Detected by Implanted Device Diagnostics; NCT00279981)
The clinical classifications of atrial fibrillation (AF) are employed to communicate the persistence of AF, to select appropriate candidates for therapies, and as inclusion criterion for patients in clinical trials. Therefore it is important for these classifications to accurately characterize the magnitude and scale of the arrhythmia.
The 2006 American Heart Association (AHA) guidelines classify AF as first detected episode of AF, paroxysmal (spontaneously terminating AF sustained for <7 days), persistent (when episodes are sustained for >7 days), and permanent (when cardioversion attempts have failed or have been foregone). In a manner similar to the AHA guidelines, the European Society of Cardiology guidelines distinguish between first diagnosed AF, paroxysmal (self-terminating AF lasting no longer than 7 days), persistent (AF episode lasting >7 days or requiring some form of pharmacological or electrical cardioversion), long-standing persistent (AF lasting ≥1 year and a rhythm control strategy is decided), and permanent (when the arrhythmia is accepted and rhythm control is no longer pursued). Both statements recognize the high uncertainty in diagnosing AF on the basis of symptoms or intermittent rhythm monitoring.
These clinical classifications are used to individualize the choice of rate or rhythm control strategies and to select appropriate medical or interventional therapies for each AF patient. For example, although patients classified as having paroxysmal or persistent AF are generally indicated for rhythm control, patients with permanent AF are usually treated with rate control strategies. Additionally, the success of cardioversion efforts has been shown to be related to the duration of AF, which is partly communicated through the AF classification.
The clinical AF classifications are also employed to select patients for inclusion in clinical trials with the primary intention to build groups of patients with similar arrhythmia magnitude and persistence in order to draw valid inferences regarding the effect of a treatment between the control and the treatment group.
The aim of the present study was 2-fold. First, we sought to assess how accurately the clinical AF classifications ("paroxysmal," "persistent") reflect the temporal persistence of AF (i.e., how much time a patient is in AF). Second, we assessed the homogeneity of patients classified in the same clinical AF classification. To accurately evaluate the temporal persistence of AF, we analyzed patients who were continuously monitored via implantable devices.
Abstract and Introduction
Abstract
Objectives This study aimed to identify how accurately the current clinical atrial fibrillation (AF) classifications reflect its temporal persistence.
Background Clinical classification of AF is employed to communicate its persistence, to select appropriate therapies, and as inclusion criterion for clinical trials.
Methods Cardiac rhythm histories of 1,195 patients (age 73.0 ± 10.1 years, follow-up: 349 ± 40 days) with implantable devices were reconstructed and analyzed. Patients were classified as having paroxysmal or persistent AF by physicians at baseline in accordance with current guidelines. AF burden, measured as the proportion of time spent in AF, was obtained from the device. Additionally we evaluated the agreement between clinical and device-derived AF classifications.
Results Patients within the same clinical class were highly heterogeneous with regards to AF temporal persistence. Agreement between the clinical AF classification and the objective device-derived assessments of AF temporal persistence was poor (Cohen's kappa: 0.12 [95% CI: 0.05 to 0.18]). Patient characteristics influenced the clinical decision to classify AF as paroxysmal or persistent. Higher ejection fraction (odds ratio: 0.97/per unit [95% CI: 0.95 to 0.98/per unit]; p < 0.0001) and presence of coronary artery disease (odds ratio: 0.53 [95% CI: 0.32 to 0.88]; p = 0.01) were independently associated with a lower probability of being classified as persistent AF for the same AF burden level.
Conclusions The currently used clinical AF classifications poorly reflect AF temporal persistence. Patient characteristics significantly influence the physician's classification of AF. Patients classified in identical clinical categories may be inherently heterogeneous with regard to AF temporal persistence. Further study is required to determine if patient selection on the basis of objective criteria derived from rigorous AF monitoring can improve reported outcomes and better identify responders and non-responders to treatments. (OMNI Study–Assessing Therapies in Medtronic Pacemaker, Defibrillator, and Cardiac Resynchronization Therapy Devices; NCT00277524; TRENDS: A Prospective Study of the Clinical Significance of Atrial Arrhythmias Detected by Implanted Device Diagnostics; NCT00279981)
Introduction
The clinical classifications of atrial fibrillation (AF) are employed to communicate the persistence of AF, to select appropriate candidates for therapies, and as inclusion criterion for patients in clinical trials. Therefore it is important for these classifications to accurately characterize the magnitude and scale of the arrhythmia.
The 2006 American Heart Association (AHA) guidelines classify AF as first detected episode of AF, paroxysmal (spontaneously terminating AF sustained for <7 days), persistent (when episodes are sustained for >7 days), and permanent (when cardioversion attempts have failed or have been foregone). In a manner similar to the AHA guidelines, the European Society of Cardiology guidelines distinguish between first diagnosed AF, paroxysmal (self-terminating AF lasting no longer than 7 days), persistent (AF episode lasting >7 days or requiring some form of pharmacological or electrical cardioversion), long-standing persistent (AF lasting ≥1 year and a rhythm control strategy is decided), and permanent (when the arrhythmia is accepted and rhythm control is no longer pursued). Both statements recognize the high uncertainty in diagnosing AF on the basis of symptoms or intermittent rhythm monitoring.
These clinical classifications are used to individualize the choice of rate or rhythm control strategies and to select appropriate medical or interventional therapies for each AF patient. For example, although patients classified as having paroxysmal or persistent AF are generally indicated for rhythm control, patients with permanent AF are usually treated with rate control strategies. Additionally, the success of cardioversion efforts has been shown to be related to the duration of AF, which is partly communicated through the AF classification.
The clinical AF classifications are also employed to select patients for inclusion in clinical trials with the primary intention to build groups of patients with similar arrhythmia magnitude and persistence in order to draw valid inferences regarding the effect of a treatment between the control and the treatment group.
The aim of the present study was 2-fold. First, we sought to assess how accurately the clinical AF classifications ("paroxysmal," "persistent") reflect the temporal persistence of AF (i.e., how much time a patient is in AF). Second, we assessed the homogeneity of patients classified in the same clinical AF classification. To accurately evaluate the temporal persistence of AF, we analyzed patients who were continuously monitored via implantable devices.
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