Impact of Asthma on sympathetic drive

<bold>Background:</bold> While sympathetic drive in pathophysiology and pharmacological therapy shapes our understanding of heart failure, it is still unclear whether Asthma is also associated with a potentially therapeutically targetable increase in sympathetic drive. The gold standard of sympathetic tone measurement, available only in a few centers worldwide, is invasive microneurographic measurement of muscle sympathetic activity. Burst rate (/minute) or incidence (adjusted for heart rate) then expresses sympathetic activity as the spontaneous discharge rate of sympathetic nerve fascicles measured with microneurographic electrodes as the gold standard. <bold>Methods:</bold> In12 Asthma patients without a secondary cardiovascular disease, external and intraneural microneurographic stimulation was used to find the peroneal nerve in the leg and then invasive microneurographic measurement of muscular sympathetic activity was performed via this nerve and compared with data from 6 healthy control subjects. <bold>Results:</bold> In 12 Asthma patients (age 46±15 years, BMI 29±6 kg/m², 3 male) there was no difference in heart rate compared to age, sex and BMI matched controls (HR 75±11 vs. 73±6 bpm, p=0.71). MSNA Burst rate was significantly increased in Asthma patients compared to controls (40±8 vs. 31±5 bursts/minute, p=0.03), indicating increased sympathetic drive. Burst incidence was significantly increased in Asthma patients compared to controls (54±11 vs. 43±8 bursts/100 bpm, p=0.05) as well. <bold>Conclusion:</bold> Sympathetic drive is increased in Asthma patients independent of secondary cardiovascular disease. This could be used therapeutically in the future to improve the prognosis of Asthma patients.