Abstract 17559: Norepinephrine Levels are Associated With the Magnitude of Vasoconstriction During Mental Stress

Abstract

Background: Patients with CAD develop varying degrees of microvascular vasoconstriction in response to mental stress, leading to myocardial ischemia. Catecholamine increases during mental stress may explain this effect. We hypothesized, in a cohort of stable CAD patients, that increased epinephrine and norepinephrine levels from rest to peak mental stress predict peripheral microvascular vasoconstriction. Methods: We analyzed data from 204 patients with CAD and high quality vascular data. Subjects underwent a standardized mental stress test using a public speaking task. Peripheral arterial tonometry (PAT) was used to assess peripheral microvascular function during rest and mental stress. The PAT response was calculated as a ratio of the minimum pulse wave amplitude during the speaking task to the mean amplitude during rest. Plasma epinephrine and norepinephrine levels were obtained 15 minutes before and at peak mental stress. Linear regression modeling was used to adjust for potential confounders. Results: The mean (SD) age was 64 (8), 16% were women, and 28% were African American. Subjects in the quartile with the greatest vasoconstriction had the highest increase in norepinephrine levels (73.5 (31.4) ng/mL [mean (SEM]), while those in the quartile with the least vasoconstriction had decreased norepinephrine levels by 47.7 (32.5) ng/mL, p for trend<0.001 (Figure). There was no significant association between PAT and epinephrine. After multivariable adjustment for sociodemographics, CAD risk factors, medical history, medication use, major depression, and PTSD, the association between the PAT ratio and norepinephrine remained significant (p=0.003). Conclusion: Changes in circulating norepinephrine, but not epinephrine levels predict peripheral microvascular vasoconstriction during mental stress.