A novel strategy for evaluating tilt test in athletes with syncope.

Background The tilt test is used for the diagnosis of reflex syncope (RS) and is characterized by low sensitivity, especially in athletes. The objective of the study was the implementation of a novel diagnostic strategy for the tilt test without pharmacologic provocation in athletes based on haemodynamic criteria. Methods A passive tilt test for 30min was performed in 132 athletes (53 with a history of RS, 79 without RS). Measurement of haemodynamic, heart rate variability (HRV) and baroreflex sensitivity parameters was performed. Results Tilt testing yielded 34% sensitivity and 94% specificity. Among negative tilt test responders, the ones with RS had increased heart rate (HR) (8911 vs 81 +/- 10 bpm, p<0.001), stroke index (SI) (40.2 +/- 7.1 vs 35.5 +/- 9.7ml/m(2), p=0.013), cardiac index (CI) (3.5 +/- 0.6 vs 2.8 +/- 0.8l/(minm(2)), p<0.001) and decreased total peripheral resistance index (TPRI) (2230 +/- 362 vs 2965 +/- 725 dynes m(2)/cm(5), p<0.001), low frequency component of HRV (76.2% (49.0-88.4) vs 79.7% (10.2-91.1), p=0.045) during head-up tilt, compared with those without RS. Receiver-operating characteristic (ROC) curve analysis showed that among athletes with a negative tilt test the area under the curve (AUC) values were 0.727 (0.626-0.828) for HR (p<0.001), 0.707 (0.611-0.804) for SI (p=0.001), 0.847 (0.774-0.920) for CI (p<0.001), 0.830 (0.754-0.905) for TPRI (p<0.001). Further stratification of negative tilt test responders, characterizing their results as positive when TPRI <2800 dynes m(2)/cm(5) and CI >3l/(minm(2)), resulted in 85% sensitivity and 76% specificity. Conclusion Our results provide supportive evidence that a novel stratification based on haemodynamic criteria can improve the sensitivity of the tilt test for the diagnosis of RS in athletes.