An example of a system may include a sensing circuit and an atrial fibrillation (AF) detection circuit. The sensing circuit may be configured to sense a cardiac signal indicative of atrial and ventricular depolarizations. The AF detection circuit may be configured to detect AF using the cardiac signal and may include a detector and a detection enhancer. The detector may be configured to detect the ventricular depolarizations using the cardiac signal, to measure ventricular intervals each between two successively detected ventricular depolarizations, and to detect the AF using the ventricular intervals. The detection enhancer may include a respiratory sinus arrhythmia (RSA) detector configured to detect RSA using the cardiac signal and may be configured to verify each detection of the AF based on whether the RSA is detected.
