OBJECTIVES: This study sought to evaluate the effects of autonomic stimulation and blockade on the signal-averaged P wave duration. BACKGROUND: Signal-averaged P wave duration has been shown to have prognostic implications for patients prone to develop atrial fibrillation, but autonomic influences on the signal-averaged P wave duration have not been studied. METHODS: In 14 healthy volunteers (8 men, 6 women; mean [ +/- SD] age 28.5 +/- 4.8 years, range 22 to 38), signal-averaged P wave duration was measured on day 1 at baseline, during sympathetic stimulation with infusions of epinephrine (50 ng/kg body weight per min) and isoproterenol (50 ng/kg per min), beta-blockade with propranolol (0.2 mg/kg) and autonomic blockade with propranolol followed by atropine (0.04 mg/kg). On a second day, 10 of the 14 subjects returned for repeat baseline recordings and recordings during parasympathetic blockade with atropine (0.04 mg/kg). Signal averaging was performed using a P wave template. Both unfiltered and filtered (least-squares fit filter with 100-ms window) P wave durations were measured. Day to day and interobserver variability were assessed by calculation of intraclass correlation coefficients. RESULTS: The mean ( +/- SD) baseline filtered P wave duration on day 1 was 141 +/- 10 ms. Isoproterenol infusion significantly shortened the P wave duration to 110 +/- 16 ms (p < 0.001), and epinephrine resulted in significant prolongation to 150 +/- 10 ms (p < 0.05). Beta-adrenergic blockade increased the P wave duration to 153 +/- 10 ms (p < 0.005). Autonomic blockade shortened the P wave duration to 143 +/- 16 ms (p < 0.05 vs. beta-blockade). On the second day, the mean baseline P wave duration was slightly longer (144 +/- 10 ms, p < 0.02). Parasympathetic blockade with atropine resulted in mild shortening of the P wave duration to 136 +/- 15 ms (p < 0.1). Interobserver reproducibility was excellent (intraclass correlation coefficient 0.99). Day to day reproducibility was good (intraclass correlation coefficient 0.56). CONCLUSIONS: The signal-averaged P wave duration is not a fixed variable because it may change significantly under different autonomic conditions. This has important implications for the application of this test to the heterogeneous population susceptible to atrial fibrillation.
OBJECTIVES: This study sought to evaluate the effects of autonomic stimulation and blockade on the signal-averaged P wave duration. BACKGROUND: Signal-averaged P wave duration has been shown to have prognostic implications for patients prone to develop atrial fibrillation, but autonomic influences on the signal-averaged P wave duration have not been studied. METHODS: In 14 healthy volunteers (8 men, 6 women; mean [ +/- SD] age 28.5 +/- 4.8 years, range 22 to 38), signal-averaged P wave duration was measured on day 1 at baseline, during sympathetic stimulation with infusions of epinephrine (50 ng/kg body weight per min) and isoproterenol (50 ng/kg per min), beta-blockade with propranolol (0.2 mg/kg) and autonomic blockade with propranolol followed by atropine (0.04 mg/kg). On a second day, 10 of the 14 subjects returned for repeat baseline recordings and recordings during parasympathetic blockade with atropine (0.04 mg/kg). Signal averaging was performed using a P wave template. Both unfiltered and filtered (least-squares fit filter with 100-ms window) P wave durations were measured. Day to day and interobserver variability were assessed by calculation of intraclass correlation coefficients. RESULTS: The mean ( +/- SD) baseline filtered P wave duration on day 1 was 141 +/- 10 ms. Isoproterenol infusion significantly shortened the P wave duration to 110 +/- 16 ms (p < 0.001), and epinephrine resulted in significant prolongation to 150 +/- 10 ms (p < 0.05). Beta-adrenergic blockade increased the P wave duration to 153 +/- 10 ms (p < 0.005). Autonomic blockade shortened the P wave duration to 143 +/- 16 ms (p < 0.05 vs. beta-blockade). On the second day, the mean baseline P wave duration was slightly longer (144 +/- 10 ms, p < 0.02). Parasympathetic blockade with atropine resulted in mild shortening of the P wave duration to 136 +/- 15 ms (p < 0.1). Interobserver reproducibility was excellent (intraclass correlation coefficient 0.99). Day to day reproducibility was good (intraclass correlation coefficient 0.56). CONCLUSIONS: The signal-averaged P wave duration is not a fixed variable because it may change significantly under different autonomic conditions. This has important implications for the application of this test to the heterogeneous population susceptible to atrial fibrillation.
Authors: Wesley T O'Neal; Muhammad Hammadah; Pratik B Sandesara; Zakaria Almuwaqqat; Ayman Samman-Tahhan; Mohamad M Gafeer; Naser Abdelhadi; Kobina Wilmot; Ibhar Al Mheid; Douglas J Bremner; Michael Kutner; Elsayed Z Soliman; Amit J Shah; Arshed A Quyyumi; Viola Vaccarino Journal: J Cardiovasc Electrophysiol Date: 2017-08-22
Authors: Martina Nassif; Sébastien P J Krul; Antoine H G Driessen; Thomas Deneke; Arthur A M Wilde; Jacques M T de Bakker; Joris R de Groot Journal: J Interv Card Electrophysiol Date: 2013-04-16 Impact factor: 1.900