Comparison of Non‐Invasive Peripheral Vascular Function to Invasive Measures of Coronary Function in Patients with Suspected Coronary Microvascular Dysfunction

Abstract

IntroductionThe purpose of this study is to compare non‐invasive vascular assessments to invasive gold standard measures of coronary flow and resistance in patients with suspected coronary microvascular dysfunction (CMD), a condition driven by systemic endothelial dysfunction. We hypothesize that non‐invasive measures will be associated with both coronary flow and resistance following pharmacological hyperemia.MethodsForty‐one patients with suspected CMD attended the Cardiovascular Integrative Physiology Clinic at Southlake Regional Health Centre. Patients underwent finger‐based arterial tonometry (RHPAT) to non‐invasively quantify microvascular endothelial function (EndoPAT). A subset of participants (n=15) also concurrently completed flow mediated dilation (FMD) of the brachial artery to assess conduit artery endothelial function. Briefly, a standard blood pressure cuff was positioned on the right arm of patients, distal to the elbow joint. Baseline recordings preceded 5 minutes of forearm ischemia, and was followed by cuff deflation, eliciting reperfusion. Within 4 months, patients underwent coronary reactivity testing using the Doppler guidewire method. Specifically, the coronary flow reserve (CFR), and the index of microvascular resistance (IMR) were calculated during pharmacologically‐induced hyperemia using adenosine, then acetylcholine, then dobutamine. Prior to each stimuli, baseline measures were obtained to ensure hemodynamics results to baseline.ResultsRHPAT was negatively correlated to the IMR during dobutamine (r=−0.39, p=0.04), but not the CFR (r=0.14, p=0.49). FMD was negatively correlated to the IMR during adenosine (r=−0.64, p=0.01), but not the CFR (r=0.29, p=0.30). RHPAT and FMD were not correlated to the IMR or CFR during acetylcholine.ConclusionThese preliminary results suggest that measures of non‐invasive peripheral vascular function can predict pharmacologically induced changes in coronary resistance, but not coronary flow.Support or Funding InformationSt. Jude MedicalThe Heart of Gold Cardiac Research FundYork UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.