Main factors affecting ablation outcome

BAD KROZINGEN, GERMANY. Being able to predict whether a RF ablation for atrial fibrillation is likely to be successful or not – prior to the actual procedure – would clearly be of great benefit. There is considerable evidence that systemic inflammation and afib are associated, but it is not entirely clear whether inflammation causes afib or afib, particularly persistent and permanent, causes inflammation. A group of German researchers recently set out to determine whether being in an inflammatory state prior to a pulmonary vein isolation (PVI) procedure would affect the long-term outcome of the procedure.

The study involved 72 patients with paroxysmal (64%) or persistent (36%) afib who underwent an acutely successful circumferential PVI (no conduction between isolated area and the rest of the left atrium). The majority (81%) of the patients were male and the average age at ablation was 55 years (46-64 years). The patients had suffered from afib for an average of 5.5 years and only 14% had underlying heart disease, so 86% would be classified as having lone atrial fibrillation (LAF). However, 52% of the group had high cholesterol/triglyceride levels, 22% had diabetes, and 19% had hypertension.

All patients underwent a medical examination on the day prior to the ablation during which baseline blood samples were obtained. NOTE: Patients with left atrial diameters larger than 55 mm were excluded from the study. All patients underwent 24-hour Holter monitoring 1, 3, 6 and 12 months following the procedure and were also advised to report any afib symptoms during the average 12.5-month follow-up. Any symptomatic or asymptomatic afib episodes observed after the first month post-procedure were classified as a recurrence.

At the end of the study 44 patients (61%) were in normal sinus rhythm without the use of antiarrhythmic drugs. The remaining 28 patients had experienced one or more recurrences with the mean time to relapse being about 10 months. The following variables were found to increase the risk of recurrence:

  • Hypertension
  • Elevated body mass index
  • Diminished left ventricular ejection fraction
  • Low left ventricular end-diastolic diameter
  • Enlarged left atrium
  • High white blood cell (WBC) count
  • Elevated C-reactive protein (CRP) level

Age, afib type, years of afib, structural heart disease, medications, and fibrinogen level were not associated with relapse. A Cox multivariate analysis showed that only hypertension (Hazard ratio = 3.1), enlarged left atrium (HR = 1.08) and WBC count (HR = 1.42) were independent predictors of afib recurrence following an initially successful PVI. There was a trend for longer AF duration to be associated with greater risk of failure. The data showed that having a WBC count above about 6280/cubic millimeter (normal range of 4300 – 10800) was a fairly accurate predictor (70.4% sensitivity and 69.8% specificity) of AF recurrence after an initially successful circumferential PVI.

Letsas, KP, et al. Pre-ablative predictors of atrial fibrillation recurrence following pulmonary vein isolation: the potential role of inflammation. Europace, Vol. 11, 2009, pp. 158-63

Editor’s comment: WBC count is a common blood test and it is generally accepted that an elevated level indicates the presence of an infection or inflammation. In light of the above findings, it would seem prudent to have a WBC count, and a CRP level determination a month or two prior to a scheduled PVI. If they indicate the presence of an inflammation, it should be brought under control before the procedure. This can usually be accomplished by supplementing with a natural anti-inflammatory such as Zyflamend, ginger, curcumin, vitamin C, beta-sitosterol, boswellia, or Moducare.