Procedure Time and Automated Absolute Coronary Flow, Microvascular Resistance Measurements

CAD, coronary artery disease, atherosclerosis, angiogram, angiography
CAD, coronary artery disease, atherosclerosis, angiogram, angiography
Researchers sought to develop and validate a fully automated method to perform continuous intracoronary thermodilution.

Absolute coronary flow and microvascular resistance measurements can be successfully automated, according to results of a study published in Catheterization & Cardiovascular Interventions.

Patients (N=19) receiving physiological assessment of coronary circulation were recruited for this study at 2 centers in Europe. Conventional and automated resting and hyperemic Q and R measurements during resting flow (Qrest, Rrest) and hyperemic flow (Qhyp, Rhyp) were performed sequentially in the same vessel while maintaining the position of the intracoronary infusion microcatheter constant. The order to conventional or automated assessments was randomly assigned. The automated assessment was obtained by programming the automatic infusion pump to infuse saline at 10 ml/min for 2 minutes then to switch to 20 ml/min for 1.5 minutes and to switch back to 10 ml/min for 1 minute.

The mean age of the patients is 63.47±11.52 years, 84.2% of them are men, 31.6% are current smokers, 57.9% have hypertension, 47.4% have dyslipidemia, 73.7% have a class 1 Canadian Cardiovascular Society grading of angina, and left ventricular ejection fraction was 64.38%±14.25%.

Procedure time is significantly reduced from 5 minutes and 25 seconds to 4 minutes and 36 seconds (P =.013) with automation.

The automated and conventional evaluations of Qrest (median, 83.00 vs 89.49 ml/min; P =.493), Qhyp (median, 210.80 vs 209.55 ml/min; P =.680), Rrest (median, 949.1 vs 941.6 WU; P =.321), Rhyp (median, 380.3 vs 393.7 WU; P =.327), fractional flow reserve (FFR; median, 0.83 vs 0.81; P =.170), coronary flow reserve (CFR; median, 2.52 vs 2.57; P =.902), and microvascular resistance reserve (MRR; median, 3.06 vs 3.02; P =.729) do not differ significantly, respectively.

Significant correlations are observed between automated and conventional assessments for Qrest (R, 0.89; P <.001), Qhyp (R, 0.88; P <.001), Rrest (R, 0.90; P <.001), Rhyp (R, 0.92; P <.001), FFR (R, 0.89; P <.001), CFR (R, 0.88; P <.001), and MRR (R, 0.89; P <.001). The intraclass correlations of the measurements ranged from 0.84 (MRR) to 0.93 (Qhyp).

The major limitation of this study was the small sample size.

”The present data indicate that continuous thermodilution‐derived FFR, CFR, and MRR measurements can be performed with a programmed pump setting and a single wire pullback without vessel rewiring,” the study authors wrote. “The measurement is short (approximately 4.5 min) and virtually automated.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Candreva A, Gallinoro E, Peregrina EF, et al. Automation of intracoronary continuous thermodilution for absolute coronary flow and microvascular resistance measurements. Catheter Cardiovasc Interv. Published online June 20, 2022. doi:10.1002/ccd.30244