Heart Rate Variability to Assess Changes in Cardiac Vagal Modulation Prior to the Onset of Paroxysmal Atrial Fibrillation in Patients With and Without Structural Heart Disease

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Abstract
Background and Objectives: In patients with paroxysmal lone AF, clinical data indicate a predominance of vagal modulation preceding attacks of the arryhthmia. Systematic data derived from time‐domain analysis of HRV evaluating changes in autonomic modulation prior to AF onset are sparse, both in patients without and with evidence for structural heart disease. This study evaluated changes in autonomic modulation prior to the onset of AF in patients with and without structural heart disease.Methods and Results: In 26 consecutive patients with at least one episode of paroxysmal AF preceded by a period of sinus rhythm of at least 8 hours duration documented on Holter monitoring, the time‐domain parameters SDNN, rMSSD, and pNN5O were analyzed at different time points between 8 hours and 10 minutes prior to the onset of AF. Fourteen patients had AF associated with structural heart disease, whereas 12 patients had paroxysmal lone AF. Analysis of HRV changes before onset of AF revealed significant differences between the two patient groups: In patients without heart disease, pNN5O and rMSSD increased from 10 ± 3 to 15 ± 4% (P=0.003) and from 38 ± 7 to 53 ± 9 ms (P=0.035). No significant change in HRV was observed in patients with structural heart disease (pNN5O 5 ± 3 vs. 6 ± 2 % and rMSSD 25 ± 4 vs. 28 ± 6 ms).Conclusions: In patients with lone AF, there is a significant shift of autonomic modulation towards a vagal predominance prior to the onset of paroxysmal AF as compared to patients with structural heart disease. Analysis of HRV prior to attacks of AF is useful in determining these triggering mechanisms.