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

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
Parola chiave	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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