Session PC1.7

Assessment of the Long-Duration Effect of Inhaled Long-Acting Bronchodilator Salmeterol on Cardiac Autonomic Control in Adult Asthma Patients

CH Tsou*, T Kao, JH Wang, CY Chung

National Yang-Ming University
Taipei, Taiwan

The asthma patients usually received regular use of inhaled corticosteroid combined with long-acting ß2 agonist (LABA) for their asthma control. The inhaled LABA achieved the bronchodilation effect through sympathetic activation in airways of asthma patients. These LABAs also have the cardiovascular effects such as palpitation, tachycardia and QTc prolongation. Besides, there are many studies to investigate the short-duration effect of LABA on cardiac autonomic control in asthma. However, the long-duration effect of inhaled LABA on cardiac autonomic control in adult asthma remains lack. In this study, we explored the long-duration effect of inhaled bronchodilator Salmeterol (one kind of LABA) during respiratory-sympathetic activation on cardiac autonomic control with heart rate variability (HRV) analysis in adult asthma patients. Serial resting, surface ECGs (at least 8 min length) were recorded at the different time intervals (baseline, 0th, 8th, 20th, 32th, 45th, 60th and 180th min after Salmeterol 25 µg 2 puffs inhalation) in eligible adult asthma patients. Mean heart rate (mean RR) and standard deviation of normal RR interval (SDNN) were obtained from analysis of heart rate variability (HRV) over these different intervals. Frequency domain analysis with fast Fourier transform of RR intervals was also performed to calculate normalized low frequency band power (LFn), normalized high frequency band power (HFn) and the ratio LF/HF over these time intervals. Wilcoxon signed-rank test was used to determine the statistical significance of difference of HRV parameters at different time intervals compared with baseline interval. P value less than 0.05 is considered as significant. Significant increase of LF/HF (60th min: 3.18±3.89 vs 2.06±2.65; p= 0.028) after inhalation of Salmeterol as compared with baseline time interval was noted. Significantly increased LFn (180th min: 59.23±10.81 vs 50.45±16.29; p= 0.046) and decreased HFn (180th min: 35.14±12.48 vs 41.92±18.22; p=0.046) without significant change of LF/HF were also noted as compared with baseline interval. Besides, significantly increased mean RR (32th min: 887.98±65.84 vs 845.05±108.33; p=0.017) and SDNN (32th min: 52.54± 32.15 vs 45.20±35.35; p= 0.037. 45th min 56.79±31.14 vs 45.20 ±35.35; p=0.028) were also noted. During the 3-hour duration after inhalation of Salmeterol in adult asthma patients, HRV analysis revealed that maximal cardiac-sympathetic activation occurred at the 60th min time interval, which may precede the maximal effect of bronchodilation occurred at around the 180th min time interval.

(Abstract Control Number: 170)