A simple verbal warning preceding adenosine infusion significantly increased average peak flow velocity by 10.2% and decreased microvascular resistance in patients with stable angina.
Observational (n=72)
No
Does a verbal warning prior to adenosine infusion alter resting coronary flow and microvascular resistance in patients undergoing elective angiography?
Normal catheter laboratory stimuli, such as verbal warnings, significantly alter resting coronary flow and microvascular resistance, though changes in resting pressure-derived indices (iFR, Pd/Pa) were not statistically significant.
Absolute Event Rate: 19.63% vs 17.82%
p-value: p=<0.001
Growing evidence supports physiology-guided revascularization , with Fractional Flow Reserve (FFR) the most commonly used invasive measure of coronary blood flow impairment at the time of diagnostic angiography . Recently, there has been growing interest in stenosis severity indices measured at rest, such as Instantaneous Wave Free Ratio (iFR) and the ratio of distal coronary to aortic pressure at rest (resting Pd/Pa). Their reliability may, theoretically, be more susceptible to changes in microvascular tone and coronary flow. This study aimed to assess variability of resting coronary flow with normal catheter laboratory stimuli. Simultaneous intracoronary pressure (Pd) and Doppler Average Peak Flow Velocity (APV) recordings were made at rest and following the verbal warning preceding an intravenous adenosine infusion. Results: 72 patients undergoing elective angiography were recruited (mean age 62 years, 52.7% male) with a wide range of coronary artery disease severity (FFR 0.86 ± 0.09). Average peak flow velocity varied significantly between measurements at rest and just prior to commencement of adenosine, with a mean variation of 10.2% (17.82 ± 9.41 cm/s vs. 19.63 ± 10.44 cm/s, p < 0.001) with an accompanying significant drop in microvascular resistance (6.27 ± 2.73 mm Hg·cm −1 ·s −1 vs. 5.8 ± 2.92 mm Hg·cm −1 ·s −1 , p < 0.001). These changes occurred without significant change in systemic hemodynamic measures. Whilst there was a trend for an associated change in the resting indices, Pd/Pa and iFR, this was statistically and clinically not significant (0.92 ± 0.08 vs. 0.92 ± 0.08, p = 0.110; and 0.90 ± 0.11 vs. 0.89 ± 0.12, p = 0.073). Resting coronary flow and microvascular resistance vary significantly with normal catheter laboratory stimuli, such as simple warnings. The clinical impact of these observed changes on indices of stenosis severity, particularly those measured at rest, needs further assessment within larger cohorts. • In recent years, there has been growing role for indices measured at rest, such as iFR. • These indices may theoretically be more susceptible to resting variation in microvascular tone. • We show resting coronary flow varies significantly with normal catheter laboratory stimuli • Resting flow variability is accompanied by significant change in microvascular resistance • Associated changes in resting indices were statistically and clinically insignificant.
Modi et al. (Mon,) conducted a observational in Stable angina (n=72). Verbal warning preceding intravenous adenosine infusion vs. Baseline (rest) was evaluated on Average Peak Flow Velocity (APV) in cm/s (p=<0.001). A simple verbal warning preceding adenosine infusion significantly increased average peak flow velocity by 10.2% and decreased microvascular resistance in patients with stable angina.