Persistent atrial fibrillation and inflammation

GRONINGEN, THE NETHERLANDS. Persistent atrial fibrillation (AF) is defined as AF lasting longer than 7 days, but amenable to cardioversion (chemical or electrical). Unfortunately, approximately 50% of afibbers undergoing electrical cardioversion experience recurrence within the first month following the procedure. It is believed that electrical and structural remodelling of the left atrium is at least partly responsible for the high recurrence rate. There is also evidence that C-reactive protein is associated with an increased risk of recurrence after electrical cardioversion.

A group of researchers at Groningen University recently completed a study aimed at determining the variables affecting recurrence rate in a group of 100 afibbers with recent onset (median 4 months since diagnosis) persistent AF. All study participants had suffered from AF for less than a year and thus presumably had experienced minimal electrical and structural remodelling. The average age of the patients was 65 years, 74% were male, 67% had hypertension, 18% had coronary artery disease, and 20% had been treated for heart failure. Immediately prior to cardioversion, 99% of participants were on warfarin, 89% were on beta-blockers, and 74% were taking an ACE inhibitor or ARB (angiotensin receptor blocker). At cardioversion patients had been in AF for an average (median) of 3 months.

Eighty-six patients underwent electrical cardioversion which was successful in 88% of cases. Four patients underwent chemical conversion, 3 had a pulmonary vein ablation, and 7 converted spontaneously during treatment with antiarrhythmic drugs. During the following year, AF recurred in 59 patients (59%) with 30 patients experiencing early recurrence (within an average of one week from cardioversion). AF became permanent, i.e. not amenable to cardioversion, in 29 patients during the first year of follow-up.

An elevated baseline level of interleukin-6 (IL-6), an important marker of inflammation, and previous or present smoking were associated with an increased incidence of early recurrence. An elevated level of transforming growth factor-Beta1 (TGF-Beta1), an important signalling molecule involved in structural remodelling and fibrosis, and early AF recurrence predicted progression to permanent AF. Somewhat surprisingly, and unexplained, a higher left ventricular ejection fraction was also associated with a greater risk of progression to permanent AF.

The researchers point out that it is still not clear whether inflammation causes AF or AF causes inflammation, but nevertheless conclude that anti-inflammatory treatment may help prevent early recurrence of recent onset persistent AF after cardioversion.
Smit, MD, et al. Role of inflammation in early atrial fibrillation recurrence. Europace, Vol. 14, 2012, pp. 810-17

Editorís comment: Although the authors did not comment on this, there would appear to be a significant benefit associated with being on ACE inhibitors or ARBs prior to cardioversion. Only 57% of patients experiencing early recurrence were on these drugs, whilst 81% of patients not experiencing early recurrence were on them. Thus it is possible that taking these drugs as well as a natural anti-inflammatory prior to cardioversion may help prevent early recurrence. It is also very important to be replete in potassium and magnesium prior to the procedure.