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Exercise-induced effects on coronary atherosclerosis assessed by grayscale and radiofrequency intravascular ultrasound

Madssen, Erik
Doctoral thesis
Åpne
(Låst)
Fulltext (PDF) available (4.639Mb)
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http://hdl.handle.net/11250/2373742
Utgivelsesdato
2015
Metadata
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  • Institutt for sirkulasjon og bildediagnostikk [1386]
Sammendrag
Coronary atherosclerosis is a leading cause of morbidity and mortality worldwide. Physical

inactivity is an independent risk factor for coronary artery disease, and physically active

patients have an improved prognosis compared to sedate patients. Although the clinical

relationship between exercise and cardiovascular health is convincing, the pathophysiological

mechanisms responsible for improved outcomes in this large patient group are largely

unknown.

In a randomized controlled trial, we assessed exercise-induced effects on coronary

atherosclerosis in 36 patients with established coronary artery disease undergoing stent

implantation and optimal medical therapy. Patients exercised for 12 weeks, either following

an aerobic interval training protocol, or performing moderate continuous exercise. Coronary

atherosclerosis was assessed by grayscale and radiofrequency intravascular ultrasound,

quantifying both plaque geometry and tissue characteristics. Our main findings were that with

both exercise protocols there was a significant reduction in necrotic core (≈ 3 %) and a strong

trend towards a reduction of plaque burden (≈ 10 %) in non-stented coronary segments and in

separate atheroma lesions. There were no differences between exercise groups.

In a post-hoc analysis of data from the randomized controlled trial, we assessed clinical

factors at baseline that potentially were associated with a reduction in necrotic core and

plaque burden at follow-up. We found a strong association between the clinical presentation

of disease and necrotic core volume reduction after aerobic exercise (p=0.011). The

association was in favor of patients with stable coronary artery disease, and necrotic core

volume reduction was much more frequent in these patients (17/18) than in patients with

unstable coronary artery disease (8/18). There were no significant associations between any

clinical baseline explanatory variables and plaque burden reduction at follow-up.

In a third study conducted within a subgroup of patients included in the randomized

controlled trial, we assessed the reproducibility of intravascular ultrasound data acquisition in

stented coronary arteries. This was performed by repeating the intravascular ultrasound

pullback twice at the same time-point, thus simulating data collection in a serial imaging

study. Our main finding was that the inter-pullback reproducibility of geometrical data was

very good for non-stented segments with relative differences between pullbacks < 5 %. For

stented segments reproducibility was poorer, though acceptable, and < 10 %.

Taken together, the data presented in this thesis strengthens the scientific evidence for

beneficial exercise-induced effects on coronary atherosclerosis, not only with respect to

atherosclerotic burden, but also with respect to plaque vulnerability. Furthermore, exerciseinduced

effects on coronary atherosclerosis may be more beneficial in patients with stable

coronary artery disease compared to patients in the early phase after an acute coronary

syndrome. Finally, serial intravascular ultrasound imaging in stented coronary arteries seems

to be associated with a variability of 5–10 % attributed to the acquisition of images itself,

which may have implications for the design of future serial stent studies.
Består av
Paper 1: Madssen, Erik; Moholdt, Trine Tegdan; Videm, Vibeke; Wisløff, Ulrik; Hegbom, Knut; Wiseth, Rune. Coronary Atheroma Regression and Plaque Characteristics Assessed by Grayscale and Radiofrequency Intravascular Ultrasound After Aerobic Exercise. American Journal of Cardiology 2014 ;Volum 114. s. 1504-1511 http://dx.doi.org/10.1016/j.amjcard.2014.08.012 The article is reprinted with kind permission from Elsevier, sciencedirect.com

Paper 2: Madssen, Erik; Videm, Vibeke; Moholdt, Trine Tegdan; Wisløff, Ulrik; Hegbom, Knut; Wiseth, Rune. Predictors of beneficial coronary plaque changes after aerobic exercise. Medicine & Science in Sports & Exercise 2015 ;Volum 47.(11) s. 2251-2256 - Is not included due to copyright available at http://dx.doi.org/10.1249/MSS.0000000000000672

Paper 3: Madssen, Erik; Jakala, J; Proniewska, K; Kulaga, T; Hegbom, Knut; Wiseth, Rune. Reproducibility of grayscale and radiofrequency IVUS data acquisition in stented coronary arteries. Scandinavian Cardiovascular Journal 2014 ;Volum 48.(5) s. 284-290 - Is not included due to copyright available at http://dx.doi.org/10.3109/14017431.2014.942873
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NTNU
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Doctoral thesis at NTNU;2015:267

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