Relevance of Electrical Remodeling in Human Atrial Fibrillation: Results of the ASSERT Mechanisms of Atrial Fibrillation Study

Background —In animal models of atrial fibrillation (AF), changes in atrial electrophysiologic (EP) properties are associated with the development of AF. Their relevance to human AF is unclear. Methods and Results —The ASSERT trial enrolled 2580 patients receiving a dual-chamber pacemaker, who were over the age of 65 years and had a history of hypertension, but no history of AF. Serial non-invasive EP testing was performed over 2 years, in a sub-group of 485 patients. There were no differences in clinical characteristics between patients with and without device-detected atrial tachyarrhythmias (AT) during the first year. Patients with AT had longer paced (153 ± 29 vs. 145 ± 28 msec, p=0.046) and sensed (128 ± 46 vs. 118 ± 25 msec, p=0.0 p=0.06) p-wave durations and were more likely to have AF induced during EP testing (23.5% vs. 13.6%, p=0.03). They had similar corrected sinus node recovery times (cSNRT) at 90 beats per minute (388 ± 554 vs. 376 ± 466 msec, p=0.86), atrial effective refractory periods (AERP) at 90 beats per minute (250 ± 32 vs. 248 ± 36 msec, p=0.70) and rate-adaptive shortening of the AERP (14 ± 13 vs. 12 ± 14 msec, p=0.11). There were no significant differences in the change in electrophysiologic properties over 2 years between patients with and without AT. Conclusions —Prolonged p-wave duration, but not differences in AERP was associated with the development of AT in pacemaker patients. Clinical Trial Registration Information —clinicaltrials.gov; Identifier: NCT00256152.