Differential Effects of Intravenous Versus Intracoronary Adenosine on Non-Culprit Lesion Assessment Following Acute...

During acute coronary syndrome (ACS), the validity of initial non-culprit fractional flow reserve (FFR) measurements remains controversial because of microvascular dysfunction and potential diminished adenosine response. Because the hyperemic effects of adenosine have been predominantly studied in stable patients, and high-dose intracoronary administration may produce stronger hyperemia than intravenous delivery, we compared non-culprit FFR between the acute and stabilized phases of ACS using both administration routes.

Patients presenting with ACS underwent repeated physiological assessment of relevant non-culprit lesions using both intracoronary adenosine boluses (≥100 μg) and intravenous adenosine (140 μg/kg/min) during index hospitalization and at 12-week follow-up.

A total of 53 patients (mean age 65.1±9.3 years, 7 [13.2%] women) were included in the current analysis. A significant interaction between the route of adenosine administration and change in FFR was found (P=0.035). Baseline FFR was lower when measured with intracoronary adenosine (mean difference: -0.02, 95% CI, -0.03 to -0.01). Over time, FFR measured with intravenous adenosine decreased (mean change: -0.02, 95% CI, -0.04 to -0.00), while intracoronary adenosine showed stable values (mean change: -0.00, 95% CI, -0.02 to 0.01). Concurrently, more patients were initially classified as having a non-flow-limiting lesion with intravenous adenosine (27 [50.9%] versus 15 [28.3%], P=0.008), which was no longer evident at follow-up (P=0.146). No significant change in microvascular function was observed.

During ACS, adequate intracoronary adenosine boluses elicit a stronger hyperemic response than intravenous adenosine administration, yielding lower initial FFR values that remain stable over time. Further research is warranted to investigate the dose-dependent hyperemic effects of intravenous adenosine during the acute phase of ACS.