Abstract 12344: Early Peak Aortocoronary Artery Gradient During Regadenoson Mediated Coronary Fractional Flow Reserve Assessment: Are We Recognizing “Early Hyperemia”?
Background: From Dec 14th 2012 through April 30th 2013 our cath labs used IV Regadenoson (Rg) to induce hyperemia for FFR assessment due to a shortage of Adenosine. Some patients exhibited a previously undescribed pattern of coronary pressure response to Rg.
Methods: We reviewed 138 Rg FFR assessments. FFR measurement at our hospital is performed using either the Volcano S5 tower, ComboMap or SmartMap systems. The S5 tower alone stores entire FFR traces. Only FFR measurements made with this system could be reviewed. Tracings that were incomplete/poor quality or those with failure to record complete data from onset of Rg administration were excluded. All patients had prior IC nitrates. 36 FFR measuements were analyzed.
Results: Two patterns emerged. The first exhibits increasing Pd-Pa until classical hyperemia (CH) with FFR at nadir of pressures. In the second, not previously described ("early hyperemia", EH), the largest Pd-Pa (FFR) occured during the induction of hyperemia, before nadir of pressures. EH was observed in 20 (56%) cases. There was no difference in time to nadir (CH vs. EH, 51 vs 55 sec) but time to maximum Pd-Pa was 63 vs. 38 sec respectively. CH group had lower EF (48 vs 56, P = 0.0324), other baseline characteristics were similar. EH was numerically more common in diabetics (70% vs 50%, P=NS). Nadir Pd-Pa (FFR) in both groups was almost entirely due to the diastolic pressure gradient.
Conclusions: Physiological mechanisms causing EH, which may not be confined to Rg, are uncertain. Possibilities include differential vasodilatation (epicardial vs. microvascular) or pressure/wave phase effects. This unusual pattern may have important clinical implications. One patient (fig 1) had a LAD FFR of 0.74 early during the induction of hyperemia. However, at nadir of pressures the maximum Pd-Pa was 0.83. This patient was referred for CABG. A prospective, physiology study is required to elucidate the mechanisms and any clinical implications of EH FFR.
- © 2013 by American Heart Association, Inc.