AF, atrial fibrillation; PWA, pulse wave alternans; Hz, hertz; LF/HF, low frequency/high frequency; F/M, female/male; IL, interleukin; TNF, tumor necrosis factor; CRP, c-reactive protein; LLTS, low-level transcutaneous vagus nerve stimulation; NA, not available; mo, months. The gene discussed is CRP; the disease is atrial fibrillation.