Atrial fibrillation (AF) is associated with a high risk of stroke. The contribution of arrhythmia to events is clear in sustained forms of AF, but in paroxysmal AF, presently available data have yet to identify what proportion of time spent in AF (ie, arrhythmia burden [AFB]) is of clinical relevance. We aimed to assess this relationship using surrogate blood markers for the hypercoagulable state associated with AF.
One hundred twenty-one consecutive outpatients (mean age 74.7 ± 7.8 years; 73 [60.3%] men) with pacemakers capable of arrhythmia detection were recruited. AFB was assessed over a 1-month period and classified as AFB = 0%, 0.1% to 10%, 10.1% to 50%, or > 50%.
Baseline characteristics and comorbidities were comparable between groups. There were no significant differences in levels of soluble E-selectin (sE-selectin), von Willebrand factor (vWf), high-sensitivity C-reactive protein, interleukin-6, soluble P-selectin (sP-selectin), or tissue factor (TF) across the four patient groups. Levels of plasma brain natriuretic peptide (BNP) were approximately twofold greater in the group with the highest AFB (P < .001). Following a stepwise multiple linear regression analysis, age was a significant predictor of vWf (P = .010), sP-selectin (P = .042), and BNP (P = .012). Left ventricular fractional shortening was predictive of BNP (P = .001) and sE-selectin (P = .012). Anticoagulation was a predictor of vWf levels (P = .005), and hypertension was predictive of TF (P < .001).
Given no appreciable difference in levels of prothrombotic markers in relation to AFB in this study, it is plausible that these abnormalities do, in fact, relate to underlying risk factors, and that such patients should be anticoagulated if risk factors dictate. Thus, AFB per se should probably not influence the decision to anticoagulate, but rather the presence of AF combined with clinical risk scoring should remain the predominant tool for stroke risk assessment.