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 30 min 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) (89 ± 11 vs 81 ± 10 bpm, p < 0.001), stroke index (SI) (40.2 ± 7.1 vs 35.5 ± 9.7 ml/m(2), p = 0.013), cardiac index (CI) (3.5 ± 0.6 vs 2.8 ± 0.8 l/(min·m(2)), p < 0.001) and decreased total peripheral resistance index (TPRI) (2230 ± 362 vs 2965 ± 725 dyne·s 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 dyne·s m(2)/cm(5) and CI >3 l/(min·m(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.