Overall, the presence of AF does not increase the probability of PE when this diagnosis is suspected. Nevertheless, when PE suspicion is based on new-onset dyspnea, AF significantly decreases the probability of PE, as AF may mimic its clinical presentation. However, in patients with chest pain alone, AF tends to increase PE probability.
Gex, G., Gerstel, E., Righini, M., LE Gal, G., Aujesky, D., Roy, P.-M., Sanchez, O., Verschuren, F., Rutschmann, O. T., Perneger, T., & Perrier, A. (2012). Is atrial fibrillation associated with pulmonary embolism? Journal of thrombosis and haemostasis : JTH, 10(3), 347-351. https://doi.org/10.1111/j.1538-7836.2011.04608.x (Original work published 2012)