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Randomized Controlled Trial
. 2023 Jun 5;19(2):e155-e166.
doi: 10.4244/EIJ-D-22-00772.

Reproducibility of bolus versus continuous thermodilution for assessment of coronary microvascular function in patients with ANOCA

Emanuele Gallinoro  1   2 , Dario Tino Bertolone  1   3 , Estefania Fernandez-Peregrina  1 , Pasquale Paolisso  1   3 , Konstantinos Bermpeis  1 , Giuseppe Esposito  1   3 , Andrea Gomez-Lopez  1 , Alessandro Candreva  1   4   5 , Niya Mileva  1 , Marta Belmonte  1 , Takuya Mizukami  1 , Stephane Fournier  6 , Marc Vanderheyden  1 , Eric Wyffels  1 , Jozef Bartunek  1 , Jeroen Sonck  1 , Emanuele Barbato  1   3 , Carlos Collet  1 , Bernard De Bruyne  1   6
Affiliations
Randomized Controlled Trial

Reproducibility of bolus versus continuous thermodilution for assessment of coronary microvascular function in patients with ANOCA

Emanuele Gallinoro et al. EuroIntervention. .

Abstract

Background: A bolus thermodilution-derived index of microcirculatory resistance (IMR) has emerged as the standard for assessing coronary microvascular dysfunction (CMD). Continuous thermodilution has recently been introduced as a tool to quantify absolute coronary flow and microvascular resistance directly. Microvascular resistance reserve (MRR) derived from continuous thermodilution has been proposed as a novel metric of microvascular function, which is independent of epicardial stenoses and myocardial mass.

Aims: We aimed to assess the reproducibility of bolus and continuous thermodilution in assessing coronary microvascular function.

Methods: Patients with angina and non-obstructive coronary artery disease (ANOCA) at angiography were prospectively enrolled. Bolus and continuous intracoronary thermodilution measurements were obtained in duplicate in the left anterior descending artery (LAD). Patients were randomly assigned in a 1:1 ratio to undergo either bolus thermodilution first or continuous thermodilution first.

Results: A total of 102 patients were enrolled. The mean fractional flow reserve (FFR) was 0.86±0.06. Coronary flow reserve (CFR) calculated with continuous thermodilution (CFRcont) was significantly lower than bolus thermodilution-derived CFR (CFRbolus; 2.63±0.65 vs 3.29±1.17; p<0.001). CFRcont showed a higher reproducibility than CFRbolus (variability: 12.7±10.4% continuous vs 31.26±24.85% bolus; p<0.001). MRR showed a higher reproducibility than IMR (variability 12.4±10.1% continuous vs 24.2±19.3% bolus; p<0.001). No correlation was found between MRR and IMR (r=0.1, 95% confidence interval: -0.09 to 0.29; p=0.305).

Conclusions: In the assessment of coronary microvascular function, continuous thermodilution demonstrated significantly less variability on repeated measurements than bolus thermodilution.

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Conflict of interest statement

G. Esposito is supported by a research grant from the CardioPaTh PhD Program. P. Paolisso is supported by a research grant from the CardioPaTh PhD Program. D. Bertolone is supported by a research grant from the CardioPaTh PhD Program. E. Barbato declares speaker fees from Abbott Vascular, Boston Scientific, and GE Healthcare. C. Collet reports receiving research grants from Biosensor, GE Healthcare, Medis Medical Imaging, Pie Medical Imaging, CathWorks, Boston Scientific, Siemens, HeartFlow, and Abbott Vascular; and consultancy fees from HeartFlow, OpSens, Pie Medical Imaging, Abbott Vascular, and Philips. B. De Bruyne has an institutional consulting relationship with Boston Scientific, Abbott Vascular, CathWorks, Siemens, GE Healthcare, and Coroventis Research; has received institutional research grants from Abbott Vascular, Coroventis Research, CathWorks, and Boston Scientific; and holds minor equities in Philips, Siemens, GE Healthcare, Edwards Lifesciences, HeartFlow, OpSens, and Celiad. The other authors have no conflicts of interest to declare.

Figures

Central illustration
Central illustration. Study design and main results.
CFR: coronary flow reserve; FFR: fractional flow reserve; IMR: index of microvascular resistance; MRR: microvascular resistance reserve; ANOCA: angina and non-obstructive coronary artery; Pa: aortic pressure; Pd: distal coronary pressure; Q: absolute coronary blood flow; RRR: resistance reserve ratio; Rμ: absolute microvascular resistance; Tmn: mean transit time
Figure 1
Figure 1. Reproducibility of Qrest and Qhyp.
Scatter plots (A,C) and Bland-Altman plots (B,D) for repeated measurements of Qrest and Qhyp. ICC: intraclass correlation coefficient; LLA: lower limit of agreement; Qhyp: absolute hyperaemic coronary flow; Qrest: absolute coronary flow at rest; R: Pearson correlation coefficient; SD: standard deviation; ULA: upper limit of agreement
Figure 2
Figure 2. Reproducibility of CFRcont and CFRbolus.
Scatter plots and Bland-Altman plots for repeated measurements of CFRcont (A,B) and CFRbolus (C,D). CFRcont: coronary flow reserve calculated with continuous thermodilution; CFRbolus: coronary flow reserve calculated with bolus thermodilution; ICC: intraclass correlation coefficient; LLA: lower limit of agreement; R: Pearson correlation coefficient; SD: standard deviation; ULA: upper limit of agreement
Figure 3
Figure 3. Reproducibility of MRR and IMR.
Scatter plots and Bland-Altman plots for repeated measurements of MRR (A,B) and IMR (C,D). ICC: intraclass correlation coefficient; IMR: index of microvascular resistance; LLA: lower limit of agreement; MRR: microvascular resistance reserve; R: Pearson correlation coefficient; RRR: resistance reserve ratio; SD: standard deviation; ULA: upper limit of agreement
Figure 4
Figure 4. Variability of bolus thermodilution- and continuous thermodilution-derived measurements. Barplots with the variability (expressed as %) of the main indices derived by bolus and continuous thermodilution.
CFR: coronary flow reserve; FFR: fractional flow reserve; IMR: index of microvascular resistance; MRR: microvascular resistance reserve; Qhyp: absolute hyperaemic coronary flow; Qrest: absolute coronary flow at rest; RRR: resistance reserve ratio; Rμ,hyp: absolute resistance during hyperaemia; Rμ,rest: absolute resistance at rest; Tmn,hyp: mean transit time during hyperaemia; Tmn,rest: mean transit time at rest
Figure 5
Figure 5. Correlation between bolus and continuous thermodilution-derived CFR.
A scatter plot (A) and a Bland-Altman plot (B) showing the correlation and the agreement between CFRcont and CFRbolus. CFRbolus: coronary flow reserve calculated with bolus thermodilution; CFRcont: coronary flow reserve calculated with continuous thermodilution; ICC: intraclass correlation coefficient; LLA: lower limit of agreement; R: Pearson correlation coefficient; SD: standard deviation; ULA: upper limit of agreement
Figure 6
Figure 6. Correlation between MRR and IMR-RRR.
Scatter plot showing the correlation between MRR and IMR (A) or RRR (B). IMR: index of microvascular resistance; MRR: microvascular resistance reserve; R: Pearson correlation coefficient; RRR: resistance reserve ratio
See this image and copyright information in PMC

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