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Index of Microcirculatory Resistance Measured during Intracoronary Adenosine-Induced Hyperemia.

ABSTRACT: Background:The index of microcirculatory resistance is an invasive measure of coronary microvascular function that has to be calculated during maximal hyperemia, classically achieved with intravenous adenosine (IV). The aim of this study was to evaluate the use of intracoronary (IC) adenosine for the calculation of IMR. Methods and Results:31 patients with stable coronary artery disease were included in the study. Coronary pressure and thermodilution measurements were obtained at rest and during maximal hyperemia using a pressure-temperature sensor-tipped coronary guidewire. Duplicate measurements were performed using first IC and then IV adenosine. Dispersion of transit times was comparable for IC and IV adenosine. IMR values based on IC vs IV adenosine showed a high level of agreement and an intraclass correlation coefficient of 0.90. Applying an upper normal limit of 25, misclassification of IMR using IC adenosine was seen in just one patient in whom IC adenosine resulted in a lower value. A simplified procedure based on a single bolus dose of saline did not change the level of agreement or the rate of misclassification. Conclusions:We found an excellent agreement between IMR values measured during hyperemia induced by IC as compared to IV adenosine. The use of IC adenosine may facilitate invasive assessment of microvascular function and is potentially time- and cost-saving with less patient discomfort as compared to IV infusion. The trail is registered with NCT03369184.

SUBMITTER: Santos-Pardo I

PROVIDER: S-EPMC7243016 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Index of Microcirculatory Resistance Measured during Intracoronary Adenosine-Induced Hyperemia.

Santos-Pardo Irene I Alström Patrik P Witt Nils N

Journal of interventional cardiology 20200512

<h4>Background</h4>The index of microcirculatory resistance is an invasive measure of coronary microvascular function that has to be calculated during maximal hyperemia, classically achieved with intravenous adenosine (IV). The aim of this study was to evaluate the use of intracoronary (IC) adenosine for the calculation of IMR.<h4>Methods and results</h4>31 patients with stable coronary artery disease were included in the study. Coronary pressure and thermodilution measurements were obtained at ...[more]

PMID: 32508541

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Project description:BackgroundThe pulmonary microcirculation is the chief regulatory site for resistance in the pulmonary circuit. Despite pulmonary microvascular dysfunction being implicated in the pathogenesis of several pulmonary vascular conditions, there are currently no techniques for the specific assessment of pulmonary microvascular integrity in humans. Peak hyperemic flow assessment using thermodilution-derived mean transit-time (T(mn)) facilitate accurate coronary microcirculatory evaluation, but remain unvalidated in the lung circulation. Using a high primate model, we aimed to explore the use of T(mn) as a surrogate of pulmonary blood flow for the purpose of measuring the novel indices Pulmonary Flow Reserve [PFR = (maximum hyperemic)/(basal flow)] and Pulmonary Index of Microcirculatory Resistance [PIMR = (maximum hyperemic distal pulmonary artery pressure)x(maximum hyperemic T(mn))]. Ultimately, we aimed to investigate the effect of progressive pulmonary microvascular obstruction on PFR and PIMR.Methods and resultsTemperature- and pressure-sensor guidewires (TPSG) were placed in segmental pulmonary arteries (SPA) of 13 baboons and intravascular temperature measured. T(mn) and hemodynamics were recorded at rest and following intra-SPA administration of the vasodilator agents adenosine (10-400 microg/kg/min) and papaverine (3-24 mg). Temperature did not vary with intra-SPA sensor position (0.010+/-0.009 v 0.010+/-0.009 degrees C; distal v proximal; p = 0.1), supporting T(mn) use in lung for the purpose of hemodynamic indices derivation. Adenosine (to 200 microg/kg/min) & papaverine (to 24 mg) induced dose-dependent flow augmentations (40+/-7% & 35+/-13% T(mn) reductions v baseline, respectively; p<0.0001). PFR and PIMR were then calculated before and after progressive administration of ceramic microspheres into the SPA. Cumulative microsphere doses progressively reduced PFR (1.41+/-0.06, 1.26+/-0.19, 1.17+/-0.07 & 1.01+/-0.03; for 0, 10(4), 10(5) & 10(6) microspheres; p = 0.009) and increased PIMR (5.7+/-0.6, 6.3+/-1.0, 6.8+/-0.6 & 7.6+/-0.6 mmHg.sec; p = 0.0048).ConclusionsThermodilution-derived mean transit time can be accurately and reproducibly measured in the pulmonary circulation using TPSG. Mean transit time-derived PFR and PIMR can be assessed using a TPSG and adenosine or papaverine as hyperemic agents. These novel indices detect progressive pulmonary microvascular obstruction and thus have with a potential role for pulmonary microcirculatory assessment in humans.

Project description:BackgroundThe coronary angiography-derived index of microcirculatory resistance (caIMR) is a novel noninvasive method to assess coronary microvascular dysfunction (CMD). However, the association between caIMR and the prognosis of patients with dilated cardiomyopathy (DCM) is unclear. We aimed to explore the role of the caIMR in evaluating the outcome of patients with DCM.MethodsWe consecutively and retrospectively enrolled patients with DCM in the Department of Cardiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China, from January 2013 to January 2018. The caIMR was calculated for eligible patients. The primary end point in this study was composite events, including rehospitalization related to heart failure (HF), device implantation, heart transplantation, or cardiac death. Patients were categorized into groups based on whether they had composite events (the events and no-events groups), and differences in the baseline and end points between these two groups were analyzed.ResultsA total of 95 eligible patients with DCM were enrolled in the study, 36 of whom had end point events. The best cutoff values of the caIMR for the left anterior descending (LAD) artery, left circumflex (LCX) artery, and right coronary artery (RCA) were >29.8 with an area under the curve (AUC) of 0.828, >25.5 with an AUC of 0.720, and >29.7 with an AUC of 0.717, respectively (all P values <0.001). Patients were then classified into the higher caIMR group and the lower caIMR group based on the cutoff value. Kaplan-Meier analyses showed that patients with a higher caIMR had increased cumulative risks of end point events regardless of the cutoff values for the LAD, LCX, and RCA (all log-rank P values <0.001). After adjustment for confounders, Cox regression analyses indicated that LAD-caIMR was an independent risk factor for end point events in patients with DCM [hazard ratio (HR) =1.11; 95% CI: 1.06-1.16].ConclusionsA higher caIMR was significantly associated with the poor prognosis of patients with DCM.

Dataset Information

Index of Microcirculatory Resistance Measured during Intracoronary Adenosine-Induced Hyperemia.

Publications

Index of Microcirculatory Resistance Measured during Intracoronary Adenosine-Induced Hyperemia.

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