Digital (Fingertip) Thermal Monitoring of Vascular Function: A Novel, Noninvasive, Nonimaging Test to Improve Traditional Cardiovascular Risk Assessment and Monitoring of Response to Treatments

Abstract

Digital thermal monitoring (DTM) is a noninvasive, inexpensive, easily performed, operator-independent vascular function test designed to complement the existing, risk-factor based assessment of vascular health and to monitor the vascular response to therapies. It is similar to a blood pressure device, with the addition of adhesive temperature probes on the right and left index fingertips that measure fingertip temperature fall and rebound during a brief (2–5 min), arm-cuff occlusion, and release procedure (reactive hyperemia). The higher the temperature rebound, the better the vascular reactivity. In our studies, we have found that DTM indices of vascular reactivity correlate strongly with the number of cardiovascular risk factors, measured by the Framingham Risk Score (FRS), and with the burden of asymptomatic (subclinical) coronary atherosclerosis, measured by coronary calcium score and CT angiography, as well as with myocardial perfusion defects on nuclear stress testing in symptomatic subjects. Moreover, our studies have shown that DTM provides incremental predictive value over risk factor assessment for the identification of high-risk patients with both subclinical atherosclerosis (Coronary Artery Calcium Score ≥100) and coronary artery stenosis (CT angiography showing ≥ 50% stenosis). Finally, DTM indices of vascular function have shown reproducibility comparable to blood pressure measurements. These very promising findings will require corroboration, particularly in long-term, prospective studies and clinical trials. It is important to emphasize that DTM is not intended to replace measurement of risk factors or advanced imaging tests. Rather, its purpose is to complement them by providing a powerful, noninvasive vascular function assessment of coronary health.