Long-term follow-up of patients with unexplained syncope and negative electrophysiologic study

Abstract

Fifty-eight patients (29 M, 29 F, mean age 60.8 +/- 16 years) with unexplained syncope at the end of a complete clinical and electrophysiological evaluation, were followed for a mean period of 36.6 +/- 20.5 months (median: 30.5 months). Structural heart disease was present in 32 patients (55.2%). The standard ECG was normal in 24 (41.4%) and showed sinus bradycardia (greater than 40 m-1) and/or first degree AV block and/or intraventricular conduction disturbances in 29 patients (50%). During follow-up, recurrences of syncope were observed in 11 of 43 untreated patients (25.6%), three of seven electrically treated patients (42.9%) and two of eight pharmacologically treated patients (25%). The cause of these recurrences was cardiac in one (1.7%), non-cardiac in 10 (17.2%) and remained undetermined in five (8.6%). Sudden death occurred in only one patient (1.7%), who was receiving chronic amiodarone therapy. These results indicate that (1) syncopal recurrences may occur in an appreciable percentage of patients with unexplained syncope and a negative electrophysiologic study during a relatively long-term follow-up, (2) syncopal recurrences, when they occur, are generally due to a non-cardiac cause, (3) sudden death is an occasional and rare event in this patient population and (4) empirical prophylactic treatment with a permanent pacemaker or antiarrhythmic drugs does not usually prevent complications during the follow-up.

Guidelines on management (diagnosis and treatment) of syncope

“…An approximately 5% first year mortality in patients with unexplained syncope has been a relatively consistent observation in the literature [19,20,27,28,37] . Although the mortality is largely due to underlying co-morbidity, such patients continue to be at risk for physical injury, and may encounter employment and life-style restrictions.…”

2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: Developed by the Task Force on cardiac pacing and cardiac resynchronization therapy of the European Society of Cardiology (ESC) With the special contribution of the European Heart Rhythm Association (EHRA)

“…In patients with unexplained syncope at the end of a complete workup and absence of any conduction disturbance, the lack of a rationale and the negative results of small studies 234,235 give sufficient evidence of inefficacy of cardiac pacing. Thus, cardiac pacing is not recommended until a diagnosis is made (Figure 8).…”

Guidelines on Management (diagnosis and treatment) of syncope ? update 2004

“…The definition of unexplained syncope largely depends on the diagnostic accuracy employed. An approximately 5% first year mortality in patients with unexplained syncope has been a relatively consistent observation in the literature [19,20,28,29,38]. As referred to earlier [17], the participants with syncope of unknown cause, compared with those who did not have syncope, had 1.31 increased risk of death.…”