title: Low coronary microcirculatory resistance associated with profound hypotension during intravenous adenosine infusion: implications for the functional assessment of coronary stenoses.
abstract: BACKGROUND
  Intravenous adenosine infusion produces coronary and systemic vasodilatation, generally leading to systemic hypotension. However, adenosine-induced hypotension during stable hyperemia is heterogeneous, and its relevance to coronary stenoses assessment with fractional flow reserve (FFR) remains largely unknown.
  
  
  RESULTS
  FFR, coronary flow reserve, and index of microcirculatory resistance were measured in 93 stenosed arteries (79 patients). Clinical and intracoronary measurements were analyzed among tertiles of the percentage degree of adenosine-induced hypotension, defined as follows: %ΔP(a)=-[100-(hyperemic aortic pressure×100/baseline aortic pressure)]. Overall, %ΔP(a) was -13.6±12.0%. Body mass index was associated with %ΔP(a) (r=0.258; P=0.025) and obesity, an independent predictor of profound adenosine-induced hypotension (tertile 3 of %ΔP(a); odds ratio, 3.95 [95% confidence interval, 1.48-10.54]; P=0.006). %ΔP(a) was associated with index of microcirculatory resistance (ρ=0.311; P=0.002), coronary flow reserve (r=-0.246; P=0.017), and marginally with FFR (r=0.203; P=0.051). However, index of microcirculatory resistance (β=0.003; P<0.001) and not %ΔP(a) (β=-0.001; P=0.564) was a predictor of FFR. Compared with tertiles 1 and 2 of %ΔP(a) (n=62 [66.6%]), stenoses assessed during profound adenosine-induced hypotension (n=31 [33.3%]) had lower index of microcirculatory resistance (12.4 [8.6-22.7] versus 20 [15.8-35.5]; P=0.001) and FFR values (0.77±0.13 versus 0.83±0.12; P=0.021), as well as a nonsignificant increase in coronary flow reserve (2.5±1.1 versus 2.2±0.87; P=0.170).
  
  
  CONCLUSIONS
  The modification of systemic blood pressure during intravenous adenosine infusion is related to hyperemic microcirculatory resistance in the heart. Profound adenosine-induced hypotension is associated with obesity, lower coronary microcirculatory resistance, and lower FFR values.
authors.affiliation: From the Cardiovascular Institute, Hospital Clínico San Carlos and Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain (M.E.-P., B.I., A.Q., A.F.-O., J.E.); Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain (N.G., P.J.-Q., F.A., I.J.N.-G., C.B., C.M.); International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London and Imperial College Healthcare NHS Trust, London, United Kingdom (R.P., S.S., S.N., J.T., J.D.); and Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea (B.K.K.).
authors.forename: Mauro
authors.initials: M
authors.lastname: Echavarría-Pinto
authors.forename: Nieves
authors.initials: N
authors.lastname: Gonzalo
authors.forename: Borja
authors.initials: B
authors.lastname: Ibañez
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.forename: Pilar
authors.initials: P
authors.lastname: Jimenez-Quevedo
authors.forename: Sayan
authors.initials: S
authors.lastname: Sen
authors.forename: Sukkinder
authors.initials: S
authors.lastname: Nijjer
authors.forename: Jason
authors.initials: J
authors.lastname: Tarkin
authors.forename: Fernando
authors.initials: F
authors.lastname: Alfonso
authors.forename: Ivan J
authors.initials: IJ
authors.lastname: Núñez-Gil
authors.forename: Camino
authors.initials: C
authors.lastname: Bañuelos
authors.forename: Alicia
authors.initials: A
authors.lastname: Quirós
authors.forename: Antonio
authors.initials: A
authors.lastname: Fernández-Ortiz
authors.forename: Carlos
authors.initials: C
authors.lastname: Macaya
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: Justin
authors.initials: J
authors.lastname: Davies
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
mesh_terms: D000241:Adenosine / Q000008:administration & dosage* / Q000009:adverse effects; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D015992:Body Mass Index; D023921:Coronary Stenosis / Q000150:complications / Q000175:diagnosis*; D053805:Fractional Flow Reserve, Myocardial / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000175:diagnosis* / Q000209:etiology; D007262:Infusions, Intravenous; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008875:Middle Aged; D012307:Risk Factors; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine
keywords: adenosine; coronary disease; physiology