Progression of paroxysmal AF
MAASTRICHT, THE NETHERLANDS. Most afibbers begin their "career" with intermittent (paroxysmal) self-terminating episodes, although some are diagnosed with permanent asymptomatic atrial fibrillation (AF) during a routine visit to the doctor. Unfortunately, left to its own devices, AF tends to progress from paroxysmal to persistent episodes lasting longer than 7 days or requiring cardioversion for termination), and then to permanent (long-standing persistent) where the patient has been in AF for at least a year and cardioversion has proven ineffective. Several studies have been carried out to determine the factors that are associated with progression.

A 2010 study, involving 1219 initially paroxysmal afibbers, reported from the University of Maastricht concluded that hypertension, history of heart failure, chronic obstructive pulmonary disease (COPD), age above 75 years, and a history of stroke or transient ischemic attack (TIA) predicted progression of paroxysmal AF to persistent or permanent. Digoxin, ACE inhibitors, and diuretics speeded up progression, while angiotensin II receptor blockers slowed it down.[1,2]

A 2005 survey of 188 lone afibbers concluded that the risk of progression from paroxysmal to permanent was associated with a family history of AF, having undergone one or more cardioversion, having developed hypertension, and having an enlarged left atrium.[3]Now researchers from 532 centers in 21 countries weigh in with a major study to determine the factors involved in progression. The study followed 2137 initially paroxysmal afibbers having experienced a single first episode, or having experienced episodes for a year or less prior to enrolment. During the 12-month follow-up, 318 patients (15%) progressed to persistent (6%) or permanent (9%) AF. Advanced age, elevated diastolic blood pressure, coronary artery disease, a history of TIA or stroke, hypertension, and heart failure were all associated with increased risk of progression, as was a treatment strategy based on rate control only. Multivariable analysis showed that a history of heart failure (odds ratio=2.2), a history of hypertension (OR=1.5), and the use of rate control rather than rhythm control (OR=3.2) were the only independent variables significantly associated with progression.

The use of class 1C antiarrhythmics (flecainide, propafenone) for rhythm control was associated with a significantly lower risk of progression, whereas the use of digoxin almost tripled the risk. The risk among lone afibbers was significantly lower than average at 8%/year and very significantly lower than the risks associated with heart failure (24%) and hypertension (16%). The risk of progression was closely related to stroke risk as measured with the CHADS2 score. A score of 0 was associated with an average 9%/year progression, a score of 1 was associated with an average 14% progression, and a score of 2 with a 19%/year progression. The researchers suggest that an aggressive rhythm control strategy slows electrical remodelling and the resulting progression.

de Vos, CB, et al. Progression of atrial fibrillation in the Registry on Cardiac Rhythm Disorders assessing the control of atrial fibrillation cohort: clinical correlates and the effect of rhythm-control therapy. American Heart Journal, Vol. 163, May 2012, pp. 887-93

Editor's comment: An earlier study involving 330 paroxysmal afibbers who had a pacemaker implanted to deal with bradycardia concluded that an increasing AF burden (more frequent and/or longer episodes) was associated with a more rapid progression to persistent or permanent AF.[4,5] If increasing AF burden is indeed a universal sign of progression, then lone afibbers who experience such an increase may wish to consider medication with an angiotensin receptor blocker (losartan, valsartan, irbesartan) in order to slow down remodelling.

[1] de Vos, CB, et al. Progression from paroxysmal to persistent atrial fibrillation. Journal of the American College of Cardiology, Vol. 55, No. 8, February 23, 2010, pp. 725-31
[2] Jahangir, A and Murarka, S. Progression from paroxysmal to persistent atrial fibrillation. Journal of the American College of Cardiology, Vol. 55, No. 8, February 23, 2010, pp. 732-34 (editorial comment)
[3] Kerr, CR, et al. Progression to chronic atrial fibrillation after the initial diagnosis of paroxysmal atrial fibrillation. American Heart Journal, Vol. 149, March 2005, pp. 489-96
[4] Saksena, S, et al. Progression of paroxysmal atrial fibrillation to persistent atrial fibrillation in patients with bradyarrhythmias. American Heart Journal, Vol. 154, No. 5, November 2007, pp.884-92
[5] Homoud, MK and Estes, M. Shedding new light on the pathophysiology of conversion of paroxysmal atrial fibrillation into persistent atrial fibrillation. American Heart Journal, Vol. 154, No. 5, November 2007, pp.801-04