A novel method for the diagnosis of neurocardiogenic syncope: heart rate recovery index

Objectives: Neurocardiogenic syncope is a common and challenging problem in clinical practice. Heart rate recovery after the first minute of exercise is mainly controlled by the parasympathetic nervous system. The aim of the present study was to evaluate heart rate recovery as an index of parasympathetic tonus for the diagnosis of neurocardiogenic syncope.

Methods and results: Ninety five patients (mean age 36.5 +/- 11.8 years), who had vasovagal syncope episodes documented by tilt table testing and 70 healthy subjects (mean age 32.9 +/- 9.1 years) were included in this study. Maximal exercise stress testing was performed in both groups and heart rate recovery values were calculated. Heart rate recovery was calculated by subtracting recovery heart rate in the first minute after exercise from peak heart rate. Heart rate recovery was significantly higher in the vasovagal syncope group than the control group during the first minute (42.1 vs. 30.9, p < 0.001). When the cutoff point for heart rate recovery was taken as 35, the sensitivity for the diagnosis of vasovagal syncope was 81% and the specificity was 78%.

Conclusion: Results of our study show that heart rate recovery is greater in the first minute after exercise in vasovagal syncope patients and that it has a supportive role in the diagnosis of neurocardiogenic syncope.