International Journal of Cardiology: Heart & Vasculature (Apr 2024)

Comparison of bolus versus continuous thermodilution derived indices of microvascular dysfunction in revascularized coronary syndromes

  • Samer Fawaz,
  • Federico Marin,
  • Sarosh A Khan,
  • Rupert F G Simpson,
  • Rafail A Kotronias,
  • Jason Chai,
  • Oxford Acute Myocardial Infarction (OxAMI) Study Investigators,
  • Firas Al-Janabi,
  • Rohan Jagathesan,
  • Klio Konstantinou,
  • Shah R Mohdnazri,
  • Gerald J Clesham,
  • Kare H Tang,
  • Christopher M Cook,
  • Keith M Channon,
  • Adrian P Banning,
  • John R Davies,
  • Grigoris V Karamasis,
  • Giovanni L De Maria,
  • Thomas R Keeble

Journal volume & issue
Vol. 51
p. 101374

Abstract

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Background: The assessment of coronary microvascular dysfunction (CMD) using invasive methods is a field of growing interest, however the preferred method remains debated. Bolus and continuous thermodilution are commonly used methods, but weak agreement has been observed in patients with angina with non-obstructive coronary arteries (ANOCA). This study examined their agreement in revascularized acute coronary syndromes (ACS) and chronic coronary syndromes (CCS) patients. Objective: To compare bolus thermodilution and continuous thermodilution indices of CMD in revascularized ACS and CCS patients and assess their diagnostic agreement at pre-defined cut-off points. Methods: Patients from two centers underwent paired bolus and continuous thermodilution assessments after revascularization. CMD indices were compared between the two methods and their agreements at binary cut-off points were assessed. Results: Ninety-six patients and 116 vessels were included. The mean age was 64 ± 11 years, and 20 (21 %) were female. Overall, weak correlations were observed between the Index of Microcirculatory Resistance (IMR) and continuous thermodilution microvascular resistance (Rµ) (rho = 0.30p = 0.001). The median coronary flow reserve (CFR) from continuous thermodilution (CFRcont) and bolus thermodilution (CFRbolus) were 2.19 (1.76–2.67) and 2.55 (1.50–3.58), respectively (p < 0.001). Weak correlation and agreement were observed between CFRcont and CFRbolus (rho = 0.37, p < 0.001, ICC 0.228 [0.055–0.389]). When assessed at CFR cut-off values of 2.0 and 2.5, the methods disagreed in 41 (35 %) and 45 (39 %) of cases, respectively. Conclusions: There is a significant difference and weak agreement between bolus and continuous thermodilution-derived indices, which must be considered when diagnosing CMD in ACS and CCS patients.

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