Entrainment of the natural pacemakers of the heart precedes atrial fibrillation.

A new measure of heart rate variability is proposed to investigate the interaction of the sino-atrial (SA) and atrio-ventricular (AV) pacemakers. Using electrocardiogram (ECG) fiduciary markers corresponding to the depolarization time of the SA and AV pacemakers, the variability of SA and AV depolarization rate is jointly analyzed by spectral analysis. The result of this joint analysis provides evidence of a distinct pattern of interaction between the SA and AV nodes prior to the onset of paroxysmal atrial fibrillation (PAF): frequency entrainment between the primary and secondary pacemakers of the heart, occurring at the respiratory frequency. We propose a measure of this entrainment as a diagnostic indicator for PAF, and compare it to standard diagnostic measures. The entrainment measure is found to have greater diagnostic power than five other common ECG-derived measures.