Resting Coronary Flow Varies With Normal Cardiac Catheter Laboratory Stimuli

Cardiovasc Revasc Med. 2019 Aug;20(8):669-673. doi: 10.1016/j.carrev.2018.10.010. Epub 2018 Oct 15.

Abstract

Background: 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.

Methods: 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).

Conclusion: 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.

Keywords: Coronary artery disease; Fractional flow reserve; Instantaneous wave-free ratio.

MeSH terms

  • Adenosine / administration & dosage
  • Aged
  • Blood Flow Velocity
  • Cardiac Catheterization*
  • Coronary Artery Disease / diagnosis*
  • Coronary Artery Disease / physiopathology
  • Coronary Stenosis / diagnosis*
  • Coronary Stenosis / physiopathology
  • Coronary Vessels / physiopathology*
  • Female
  • Fractional Flow Reserve, Myocardial*
  • Humans
  • Hyperemia / physiopathology
  • Male
  • Microcirculation
  • Middle Aged
  • Predictive Value of Tests
  • Reproducibility of Results
  • Rest
  • Severity of Illness Index
  • Stress, Psychological / physiopathology
  • Vascular Resistance
  • Vasodilator Agents / administration & dosage

Substances

  • Vasodilator Agents
  • Adenosine