Minimal Microvascular Resistance: Agreement Between Continuous and Bolus Thermodilution
Thabo Mahendiran1,2, Daniëlle Keulards3, Nico H J Pijls3
1Cardiovascular Center Aalst, OLV Clinic, Aalst, Belgium.
Summary
Continuous thermodilution accurately measures microvascular resistance (Rμ,hyper), agreeing well with PET imaging. However, the index of microcirculatory resistance (IMR) did not correlate with invasive Rμ,hyper in patients with angina.
Area of Science:
- Cardiovascular research
- Medical imaging
- Hemodynamics
Background:
- Continuous thermodilution quantifies absolute microvascular resistance (Rμ,hyper), a key indicator of microvascular function.
- Increased Rμ,hyper suggests microvascular dysfunction.
- Bolus thermodilution provides the index of microcirculatory resistance (IMR) as a surrogate for Rμ,hyper.
Purpose of the Study:
- To compare invasive Rμ,hyper (continuous thermodilution) with the gold standard [15O]H2O PET Rμ,hyper.
- To assess the correlation between invasive Rμ,hyper and IMR.
Main Methods:
- Accuracy of invasive Rμ,hyper was evaluated against PET Rμ,hyper in 24 patients (46 measurements).
- Agreement between invasive Rμ,hyper and IMR was assessed in 250 patients with angina and non-obstructive coronary arteries.
Main Results:
- Invasive Rμ,hyper strongly correlated with PET Rμ,hyper (r=0.86) with good absolute agreement (ICC=0.82).
- No significant systematic or proportional bias was found between invasive Rμ,hyper and PET Rμ,hyper.
- Invasive Rμ,hyper showed no significant correlation with IMR (r=0.11).
Conclusions:
- Invasive Rμ,hyper from continuous thermodilution demonstrates excellent agreement with non-invasive PET Rμ,hyper.
- IMR lacks significant correlation with invasive Rμ,hyper in patients with angina and non-obstructive coronary arteries.
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