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

doi:10.1016/j.ijcha.2024.101374

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

Int J Cardiol Heart Vasc. 2024 Mar 8:51:101374. doi: 10.1016/j.ijcha.2024.101374. eCollection 2024 Apr.

Authors

Samer Fawaz^{1

2}, Federico Marin^{3

4}, Sarosh A Khan^{1

2}, Rupert F G Simpson^{1

2}, Rafail A Kotronias^{3

4}, Jason Chai^{5

4}, Oxford Acute Myocardial Infarction OxAMI Study Investigators^{3

4}, Firas Al-Janabi¹, Rohan Jagathesan¹, Klio Konstantinou¹, Shah R Mohdnazri¹, Gerald J Clesham^{1

2}, Kare H Tang¹, Christopher M Cook^{1

2}, Keith M Channon^{3

4}, Adrian P Banning^{3

4}, John R Davies^{1

2}, Grigoris V Karamasis⁵, Giovanni L De Maria^{3

4}, Thomas R Keeble^{1

2}

Affiliations

¹ Essex Cardiothoracic Centre, Mid and South Essex NHS Hospitals Trust, Basildon, SS16 5NL, United Kingdom.
² Department of Circulatory Health Research, Anglia Ruskin University, Chelmsford, CM1 1SQ, United Kingdom.
³ Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, U.K.
⁴ NIHR Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, U.K.
⁵ Attikon University Hospital, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece.

Abstract

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 (R_µ) (rho = 0.30p = 0.001). The median coronary flow reserve (CFR) from continuous thermodilution (CFR_cont) and bolus thermodilution (CFR_bolus) 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 CFR_cont and CFR_bolus (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.

Keywords: Bolus; Continuous; Coronary; Microvascular; Thermodilution.