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Paroxysmal to persistent AF transition 'due to structural changes'
MedWire News: Transition to persistent atrial fibrillation (AF) in patients with paroxysmal AF seems to depend on atrial structural changes, owing to heart disease and other factors, say researchers.
They found that atrial tachyarrythmia (AT)/AF burden increases progressively in patients who develop persistent AF, but is not elevated immediately before a sudden transition to persistent AF.
\"Our data would suggest that structural remodeling may be critical to this clinical transition,\" write Sanjeev Saksena (Electrophysiology Research Foundation, Warren, New Jersey, USA) and colleagues. \"This structural change may result in a substrate that can support a wider spectrum of re-entrant ATs, which may co-exist in the same period.\"
The authors say that therapies directed at the atrial substrate may therefore be needed to prevent persistent AF.
Writing in the American Heart Journal, the team explains that the experimentally derived concept \"AF begets AF\" implies that the AT/AF burden uniformly increases over time, but the temporal patterns of paroxysmal AT/AF burden progression, its conversion to persistent AF, and the relationship to underlying disease in humans are unknown.
To investigate, the team studied 330 patients with a history of paroxysmal AF (mean age 70 years) who were implanted with a pacemaker that automatically recorded the cumulative AT/AF burden.
Over an average follow-up period of 401 days, 78 (24%) patients progressed to persistent AF, defined as 7 or more consecutive days with > 23 hours of AT/AF, whereas the other patients remained classified as having paroxysmal AF.
Patients who progressed to persistent AF had a higher daily mean and median AT/AF burden (p<0.001) and a higher probability of experiencing AT/AF on any given day (p<0.001) than those remaining in paroxysmal AF.
Furthermore, the mean AT/AF burden increased significantly over time (p<0.001) in the persistent AF group but did not increase in the paroxysmal AF group.
\"Thus device data logs could potentially identify patients likely or unlikely to progress to persistent AF in the foreseeable future,\" Saksena et al note.
However, most patients were in sinus rhythm in the days immediately preceding transition, indicating a sudden transition to persistent AF. The authors say this suggests that \"the persistent AF event is triggered by a single or very low density triggering arrhythmia and may be maintained by a remodeled substrate.\"
Saksena and team say that this would explain the self-limited nature of AF in younger patients without structural heart disease.
They suggest that patients with increasing AT/AF burden who are likely to progress to persistent AF could be targeted for modification of structural remodeling, eg, with ACE inhibitors or angiotensin receptor blockers.
Am Heart J 2007; 154: 884-892
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发表于 2008-1-1 20:42:54