title: Effects of exercise rehabilitation on cardiac electrical instability assessed by T-wave alternans during ambulatory electrocardiogram monitoring in coronary artery disease patients without and with diabetes mellitus.
abstract: Effects of exercise rehabilitation on electrocardiographic markers of risk for sudden cardiac death have not been adequately studied. We examined effects of controlled exercise training on T-wave alternans (TWA) in 24-hour ambulatory electrocardiogram recordings in patients with stable coronary artery disease (CAD) without and with type 2 diabetes mellitus (DM). Consecutive patients with angiographically confirmed CAD were recruited to join the ARTEMIS (Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection) study. Exercise (n = 65) and control groups (n = 65) were matched on age, sex, DM, and previous myocardial infarction. Ambulatory electrocardiograms were recorded before and after a 2-year training period. TWA was assessed using time domain-modified moving average method by an investigator blinded to patients' clinical status. Average TWA values decreased in the rehabilitation group but not in control patients (rehabilitation [mean ± SEM]: 52.8 ± 1.7 μV vs 48.7 ± 1.5 μV, p <0.001; control: 53.7 ± 1.7 μV vs 54.3 ± 1.6 μV, p = 0.746). Changes in TWA differed between the groups (rehabilitation: -4.1 ± 1.2 μV vs controls: +0.6 ± 1.1 μV, p = 0.005). In CAD + DM patients, 50% (n = 9) of the 18 positive TWA cases were converted with exercise versus 10% (n = 2 of 20) of controls (p = 0.020). In CAD patients, 30% (n = 8 of 27) of positive TWA cases were converted with exercise versus 4% (n = 1 of 28) of controls (p = 0.012). In conclusion, this is the first report of the effectiveness of exercise rehabilitation to reduce TWA, a marker of sudden cardiac death risk, in patients with stable CAD.
authors.affiliation: Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland; Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Kenttä
authors.affiliation: Department of Exercise and Medical Physiology, Verve, Oulu, Finland; Department of Applied Sciences, London South Bank University, London, United Kingdom.
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston Massachusetts.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Nearing
authors.affiliation: Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland; Department of Exercise and Medical Physiology, Verve, Oulu, Finland.
authors.forename: Jaana J
authors.initials: JJ
authors.lastname: Karjalainen
authors.affiliation: Department of Exercise and Medical Physiology, Verve, Oulu, Finland.
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
authors.affiliation: Department of Exercise and Medical Physiology, Verve, Oulu, Finland.
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.affiliation: Medical Research Center Oulu, University of Oulu and University Hospital of Oulu, Oulu, Finland.
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Department of Medicine, Harvard Medical School, Boston Massachusetts. Electronic address: rverrier@bidmc.harvard.edu.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Verrier
mesh_terms: D003324:Coronary Artery Disease / Q000150:complications / Q000503:physiopathology / Q000534:rehabilitation*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000503:physiopathology; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D015444:Exercise / Q000502:physiology; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function; D016896:Treatment Outcome