Cardiovascular autonomic tests established the cause of syncope in 79% of patients, while absence of prodromes (+48% odds, P<0.001) and comorbidities predicted an unexplained aetiology.
Observational (n=2,663)
What are the predictors of unexplained syncope after cardiovascular autonomic tests in patients evaluated in a syncope unit?
Cardiovascular autonomic tests establish a diagnosis in 79% of syncope patients, but those with older age, absence of prodromes, and cardiovascular comorbidities are more likely to have inconclusive results requiring further investigation.
AIMS: Syncope is a common condition with many possible causes, ranging from benign to life-threatening aetiologies. Establishing a diagnosis can be difficult, and specialized syncope units, using cardiovascular autonomic tests (CATs), including a head-up tilt test, can increase the diagnostic yield. However, up to one-fifth of examined patients have inconclusive CAT results. The aim of the present study was to investigate the predictive value of history, and clinical findings for unexplained syncope after CAT and characterize the group with negative results. METHODS AND RESULTS: Consecutive syncope patients n = 2663, 61% women, median age 52 (32-69) years were evaluated and CAT explained aetiology of syncope in 79% of cases, whereas 21% remained unexplained. Predictors of negative CAT were older age at first syncope (+8% higher odds per 10-year increment, P = 0.042), higher supine heart rate (HR; +12% per 10 b.p.m.; P = 0.003), absence of prodromes (+48%; P < 0.001), hypertension (+45%; P = 0.003), diabetes (+82%; P < 0.001), heart failure (+98%; P = 0.014), and coronary artery disease (+51%; P = 0.027). Compared with vasovagal syncope, patients with negative CAT were older, reported more often the absence of prodromes, and had a higher burden of cardiovascular comorbidities. CONCLUSION: A cardiovascular autonomic test established the cause of syncope in 79% of patients evaluated in a syncope unit. Syncope without prodromes and cardiovascular comorbidities were significant predictors of failure to reveal an aetiology from assessment by CAT. These are known risk factors for cardiac syncope and patients with inconclusive CAT warrant further investigation.
Torabi et al. (Wed,) conducted a observational in Syncope (n=2,663). Cardiovascular autonomic tests (CATs) was evaluated on Aetiology of syncope explained by CAT. Cardiovascular autonomic tests established the cause of syncope in 79% of patients, while absence of prodromes (+48% odds, P<0.001) and comorbidities predicted an unexplained aetiology.