Pulse wave analysis during supine rest may identify subjects with recurrent vasovagal syncope

In the present study, we studied whether analysis of the FAP (finger arterial pressure) waveform during supine rest discriminates subjects with recurrent VVS (vasovagal syncope) from healthy controls. Signal-averaged FAP waveforms (Finapres) were obtained in 32 head-up tilt-test-positive subjects with recurrent VVS (35 +/- 13 years) and in 32 sex- and age-matched healthy controls. The DT (time delay) between the systolic and diastolic peaks of the FAP waveform was measured and large artery SI (stiffness index) was calculated as a ratio of body height and DT. VVS patients had significantly shorter DT compared with controls (303 +/- 31 compared with 329 +/- 18 ms; P < 0.001) and higher SI (5.79 +/- 0.70 compared with 5.20 +/- 0.36 m/s; P < 0.001). The differences were independent of heart rate and blood pressure. SI > 5.45 m/s identified subjects with syncope with a sensitivity of 72% and a specificity of 84%. Age-corrected DT (cDT = DT + age-350) identified subjects with syncope with a sensitivity of 75% and a specificity of 84%. Combined use of cDT <0 ms and SI > 5.45 m/s increased sensitivity and specificity to 81% and 96% respectively. The discriminative power of FAP descriptors improved further when younger subjects were excluded. In subjects aged >30 years (median age), the combination of cDT and SI identified subjects with syncope with a sensitivity of 93% and a specificity of 100%. These results suggest that FAP descriptors during supine rest might be useful in the diagnosis of VVS in middle-aged subjects.