Medtronic
 
 

Insertable
Cardiac Monitor

Diagnostic Tools for Syncope

In an effort to make a diagnosis in patients with unexplained syncope, ECGs, ambulatory (Holter) monitors, external event recorders, insertable loop recorders (ILRs), tilt table tests, neurological tests, echocardiograms, and electrophysiology (EP) studies may be performed. With the array of tests available, it can be useful to consider the associated cost of testing, as well as the diagnostic yield, to select the most appropriate diagnostic pathway.

In patients with infrequent events, ECGs and 24-hour Holter monitoring proves diagnostic in only 2-11% of cases.1,2 Tilt table testing can help identify vasovagal syncope. However, effectiveness varies widely (11-87%) and depends on the use of provocative drugs, patient selection, and additional factors.3,4

Test/Procedure Yield
ECG 2-11%*
Holter Monitoring 2%*
External Loop Recorder 20%2
Tilt Table Test** 11-87%3,4
EP Study** without SHD*** 11%5
EP Study** with SHD*** 49%3
Neurological Testing (CT scan, carotid doppler) 0-4%3,4
Reveal® Plus ILR 43-88%6,7,8

*Based on mean diagnosis time of 5.1 mos.2
**Provocative test
***Structural heart disease (SHD)

EP studies can be quite useful in patients with organic heart disease. But in those without structural heart disease (SHD) diagnostic yield is reported at just 11%.5

According to Mark Linzer, et al., “The only means of diagnosing or excluding arrhythmia as the etiology of syncope is capturing the cardiac rhythm during symptoms.”9 Thus, ECG recordings from an external event recorder can provide help for patients who experience relatively frequent syncope. But when compliance is an issue and syncope episodes are infrequent, an ILR can significantly improve diagnosis – with a reported diagnostic yield of up to 88%.6

References
  1. Kapoor WN. Am J Med. 1991;90: 91-106.
  2. Krahn AD, et al. Cardiol Clinics. 1997;15(2):313-326.
  3. Kapoor WN. Medicine. 1990;69:160-175.
  4. Kapoor WN. JAMA. 1992;268:2553-2560.
  5. Linzer M, et al. Ann Int Med. 1997;127(1):76-86.
  6. Krahn AD, et al. Am J Cardiol. 1998;82(1):117-119.
  7. Krahn AD et. al. Circulation. 1999;99:406-410.
  8. Krahn, AD, et al. JACC. 2003;42(3):495-501.
  9. Linzer M, et al. Am J Cardiol. 1990;66:214-219

Additional Information