RESUMEN
Objectives: To evaluate usefulness of the recovery time after a treadmill exercise ECG test for assessment of autonomic system function in hypertensive patients using Holter-based heart rate variability as a reference
Methods: Sixty untreated hypertensive patients were included in the study. Echocardiography was done to assess left ventricular mass index and function. Exercise ECG test was given for all patients. The heart rate recovery was calculated as reduction in heart rate from the peak to one minute of the recovery time and a cutoff value of 12 beats/minute or less was considered abnormal. The patients were classified into two groups: group I: included 40 patients with impaired heart rate recovery after exercise test and group II: included 20 patients with normal heart rate recovery. Holter 24-hour ECG monitoring was done for all patients for assessment of heart rate variability
Results: There was a significant impaired heart rate variability in the hypertensive patients with impaired heart rate recovery than those with normal heart rate recovery [p< 0.05]. Predictive indices of heart rate recovery after exercise ECG test for assessment of cardiac autonomic function revealed that sensitivity = 94%, specificity = 81%, positive predictive value = 90%, negative predictive value = 90% and accuracy = 90%. Stepwise logistic analysis revealed a significant relation between the maximal heart rate during exercise test, time-domain heart rate variability variables [r-MSSD and p-NN50] and impaired heart rate recovery after exercise ECG test in hypertensive patients [p< 0.05]. There was a significant correlation between Holier based vagal dependent r-MSSD and the heart rate recovery after exercise test [p <0.05]
Conclusion: Incorporation of heart rate recovery after exercise may eventually be considered the usefull diagnostic test for assessment of autonomic nervous system function in hypertensive patients