Europace Advance Access originally published online on October 31, 2009
Europace 2009 11(12):1696-1701; doi:10.1093/europace/eup338
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Syncope and implantable loop
Blood pressure oscillations during tilt testing as a predictive marker of vasovagal syncope
1 The Hatter Cardiovascular Institute, University College London Hospital and Medical School, 67 Chenies Mews, London WC1E 6HX, UK; 2 Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK; 3 King's College Hospital, Denmark Hill, London SE5 9RS, UK; 4 Imperial College Healthcare NHS Trust, St Mary's Hospital, Praed Street, London W2 1NY, UK
Aims: During head-up tilt (HUT) testing, a period of haemodynamic instability, marked by oscillations in blood pressure, often precedes vasovagal syncope. We hypothesized that the presence of oscillations in blood pressure during HUT testing predicts a positive diagnosis for vasovagal syncope.
Methods and results: The haemodynamic profiles of 42 consecutive patients non-responsive to passive HUT and glyceryl trinitrate (GTN) provocation (‘non-responders’) and, contemporaneously, 41 consecutive patients responsive to passive HUT and GTN provocation (‘responders’) were assigned oscillation-positive or oscillation-negative depending on the presence or absence of a characteristic oscillation in systolic blood pressure which varied by 
30 mmHg (peak-to-trough). All the non-responders proceeded to an isoprenaline (Iso) challenge test. Of the 42 non-responders, 27 patients were Iso tilt-positive; all of these patients were assigned oscillation-positive. The other 15 non-responders were Iso tilt-negative; of these 9 were assigned oscillation-positive and 6 were assigned oscillation-negative. Of the 41 responder patients, 33 were assigned oscillation-positive, whereas 8 were assigned oscillation-negative. Overall, the presence of oscillations as a diagnostic predictor for vasovagal syncope had a sensitivity of 88% (positive predictive value of 87%) and a specificity of 40% (negative predictive value of 43%).
Conclusion: In patients non-responsive to passive HUT and GTN provocation, the presence of an oscillating systolic blood pressure varying 30 mmHg may still indicate a diagnosis of vasovagal syncope, possibly obviating the need for Iso testing.
Key Words: Head-up tilt, Vasovagal syncope, Blood pressure, Oscillations
* Corresponding author. Tel: +44 207 380 9776, Fax: +44 207 388 5095, Email: d.hausenloy{at}ucl.ac.uk
Manuscript submitted 18 June 2009. Accepted after revision 3 October 2009.