Isoprenaline versus nitroglycerine in head-up tilt test

Area of Science:

• Cardiology
• Clinical Trials
• Diagnostic Testing

Background:

• The Head-Up Tilt Table (HUTT) test is a crucial diagnostic tool for evaluating syncope.
• Isoprenaline and isosorbide dinitrate are pharmacologic agents used to enhance HUTT test sensitivity.
• These agents possess distinct mechanisms of action.

Purpose of the Study:

• To compare the diagnostic efficacy of isoprenaline versus isosorbide dinitrate in HUTT testing for syncope.
• To evaluate differences in response types and time to positive results between the two agents.

Main Methods:

• A comparative study involving 90 subjects under 35 years old referred for HUTT.
• Subjects underwent passive HUTT, HUTT with isosorbide dinitrate, and HUTT with isoprenaline.
• Analysis focused on HUTT-positive rates, response types, and time to positive response.

Main Results:

• Isosorbide dinitrate yielded a significantly higher rate of HUTT-positive results compared to isoprenaline (absolute risk difference of 26%, P=0.03).
• No significant differences were observed in the frequency of response types (Type 1, 2, 3) across passive, isosorbide dinitrate, and isoprenaline testing (P=0.71).
• While passive HUTT showed the longest time to positive response, the time to positive response between isosorbide dinitrate and isoprenaline was not statistically significant (P=0.074).

Conclusions:

• Isosorbide dinitrate is more effective than isoprenaline in increasing HUTT test sensitivity for syncope evaluation.
• The types of autonomic responses elicited do not differ significantly between passive HUTT, isosorbide dinitrate, and isoprenaline.
• Both isosorbide dinitrate and isoprenaline demonstrate comparable times to achieve a positive HUTT response.