Abstract 18514: The Degree of Microvascular Constriction During Mental Stress Predicts the Development of Mental Stress-Induced Myocardial Ischemia

Abstract

Introduction: Mental stress-induced myocardial ischemia (MSI) has been linked to a higher rate of fatal and non-fatal cardiac events in patients with CAD, independent of traditional cardiovascular risk models. Coronary vascular constriction with mental stress is a potential mechanism of MSI that may be reflected as constriction in the peripheral circulation. Moreover, peripheral arterial constriction may itself contribute to MSI by increasing afterload. Hypothesis: We hypothesized that a more pronounced microvascular constrictor response to mental stress will be predictive of development of MSI. Methods: Patients with stable CAD (n=116) underwent a standardized mental stress test using a public speaking task. Myocardial perfusion imaging with 99m-Tc-sestamibi was used for rest and stress images. MSI was defined as a summed difference score of ≥4, based on the difference between summed stress and rest perfusion scores. 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 lowest pulse wave amplitude during the speaking task to the final three minutes of pulse wave amplitude during baseline rest. Univariate and multivariate logistic regression models were used to assess the association between PAT response and MSI. Models were adjusted for established CAD risk factors, and medications. Results: Patients with MSI (n=16, 14%) had a significantly lower PAT ratio than those without MSI (0.49 ±0.26 vs. 0.72± 0.34, p=0.01). Furthermore, the PAT response during mental stress was an independent predictor of the development of MSI, even after adjusting for aforementioned covariates (p=0.01). The peak rate-pressure product and diastolic BP during speech were similar in those with or without MSI (13580±4873 vs. 12947±2914, p=0.5; and 101±14 vs. 99±12, p=0.6, respectively). Systolic BP, diastolic BP, and heart rate changes from rest to speech were similar in those with and without MSI. Conclusion: The degree of peripheral microvascular constriction in response to mental stress predicts the risk of developing MSI in patients with stable CAD. Whether the PAT response during mental stress portends a worse long term prognosis needs to be investigated.