Challenges in the classification of atrial fibrillation

Abstract

The incidence and prevalence of atrial fibrillation (AF) are increasing worldwide. AF is of public health importance because it accounts for substantial morbidity, mortality, and health-care costs. AF may be transient initially, but many patients have progressive disease marked by increasing frequency and duration of episodes. Various classification schemes for AF have been proposed, although current guidelines are based on temporal rhythm-based patterns. We discuss existing schemes for the classification of AF, focusing on the advantages and limitations of the pattern-based scheme, in the context of new knowledge about AF pathophysiology, AF patterns, and clinical outcomes. Furthermore, we address gaps in knowledge that present opportunities to re-examine the current pattern-based classification of AF. A future classification scheme should ideally combine elements such as the risk of stroke, an assessment of symptoms, and the degree of impairment of the atrial substrate.

Figure 1

Rhythm-based patterns of atrial fibrillation (AF), as defined in the 2006 AHA, ACC and European Society of Cardiology guidelines for the management of patients with AF. Paroxysmal AF is characterized by episodes that generally last 7 days or less, with most lasting less than 24 h. Persistent AF is characterized by episodes that usually last longer than 7 days. When cardioversion failed or is not attempted, AF is classified as permanent. Both paroxysmal and persistent AF may be recurrent. Permission obtained from the American Heart Association.

Figure 2

Proposed elements for inclusion in a unifying clinical classification scheme for AF. Elements with established or potential roles in guiding management of patients with AF are displayed. Examples of metrics that measure these elements are shown, along with potential management decisions that might depend on the degree of severity on each scale. Elements and decisions might be inter-related. Arrows indicate a proposed sequential flow of assessments. Abbreviations: AF, atrial fibrillation; AV, atrial-ventricular; CCF–SAF, Canadian Cardiovascular Society Severity of Atrial Fibrillation; CHADS2, where “C” denotes congestive heart failure, “H” denotes hypertension, “A” denotes age > 75 years, “D” denotes diabetes mellitus, and “S” denotes stroke or transient ischemic attack; SF-36, 36-item short-form survey for health and quality of life.