The Relationship Between Mental Stress-Induced Microvolt T-Wave Alternans (MTWA) and Inflammation in Post-Myocardial Infarction (MI) Patients Público

Abstract

Background: Psychological stress can provoke both fatal ventricular tachyarrhythmias (VTAs) and acute inflammatory response in post-MI patients. Microvolt T-wave alternans (MTWA) is a predictor for future VTAs and an important clinical tool for sudden cardiac death (SCD) risk stratification in these venerable patients. The relationship between mental stress-induced MTWA and inflammatory response has not been investigated to date. We aim to examine the association between inflammatory responses to acute mental stress and mental stress-induced TWA in post-MI patients in this study. Methods and Results: TWA induced by experimental psychological stress was assessed from digitized ambulatory ECGs by modified moving average analysis in 95 young and middle-aged post-MI subjects. The marker of inflammatory response--interleukin-6 (IL-6) was measured at 0 minutes, 60 minutes and 90 minutes after stress respectively. Subjects also underwent exercise as a control comparison. MTWA increased with both mental stress and exercise (P<0.0001). Both stresses induced significant increase in IL-6 at 90 minutes after stress (P=0.013 for mental stress; P=0.035 for exercise). The mental stress-induced TWA positively associated with increased IL-6 level at 90 minutes after stress (P=0.047). This effect was independent of cardiovascular risk factors, chronic psychological stress, heart function, mental-stress induced ischemia and medications. An opposite trend of IL-6 in response to exercise with exercise-induced TWA was found in multivariable analyses (P=0.053). Conclusion: Acute mental stress can elicit significant increases of TWA in patients who are younger than 60 years old and have survived from a recent myocardial infarction. The subjects with a higher (vs. lower) IL-6 level at 90 minutes after mental stress also have higher TWA during mental stress. In contrast, exercise-induced TWA tends to be inversely associated with IL-6 level at 90 minutes after stress. This may help to risk-stratify post-MI patients regarding mental stress-induced SCD and to understand specific mechanisms linking inflammation and mental stress-induced TWA, which differs from that with exercise.

Table of Contents

Background...................................................................................................... 2

Methods............................................................................................................5

Study Population.................................................................................................5

Study Design......................................................................................................5

Mental Stress Procedure.......................................................................................6

Exercise Stress Procedure.....................................................................................6

Measurement of TWA...........................................................................................6

Measurements of Inflammation Markers..................................................................7

Other Measurements............................................................................................8

Statistical Analysis...............................................................................................8

Results..............................................................................................................10

Study Population.................................................................................................10

Stress Induced Inflammatory Response..................................................................11

Stress Induced TWA.............................................................................................11

Relationship Between IL-6 and TWA.......................................................................12

Discussion.........................................................................................................13

References........................................................................................................18

Tables...............................................................................................................23

Figures..............................................................................................................26

Appendices........................................................................................................28

I. Patients inclusion and exclusion criteria for MIMS study.........................................28

II. Abbreviations..................................................................................................29

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Medicine and Surgery Health Sciences, Epidemiology
Palavra-chave	inflammation sudden cardiac death mental-stress post-myocardial infarction microvolt T-wave alternans
Committee Chair / Thesis Advisor	Shah, Amit Jasvant, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs Hospital or other health care provider

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