Induction of neurally mediated syncope with adenosine

Area of Science:

• Cardiology
• Neurology
• Clinical Diagnostics

Background:

• Neurally mediated syncope diagnosis relies on tilt testing.
• Current tilt testing methods have limitations in sensitivity and duration.
• Adenosine's sympathomimetic effects may aid syncope induction.

Purpose of the Study:

• To evaluate adenosine as a potential alternative to routine tilt testing for diagnosing neurally mediated syncope.
• To compare the diagnostic yield of adenosine tilt testing with standard tilt testing protocols.

Main Methods:

• Two protocols compared adenosine tilt testing with isoproterenol tilt testing and routine tilt testing.
• Microneurography assessed sympathetic activation during adenosine and isoproterenol administration.

Main Results:

• Adenosine tilt testing showed comparable diagnostic yields to isoproterenol and routine tilt testing (10% vs 8% and 19% vs 22%, respectively).
• Positive responses in some patients required isoproterenol after a negative adenosine test.
• Microneurography revealed differing sympathetic responses to adenosine and isoproterenol.

Conclusions:

• Adenosine is effective in inducing neurally mediated syncope with a diagnostic yield similar to routine tilt testing.
• Adenosine and isoproterenol may have complementary roles, suggesting a combined protocol.
• An initial adenosine tilt followed by isoproterenol if needed could improve diagnostic yield and reduce test duration.