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By Harold L. Karpman, MD, FACC, FACP
Clinical Professor of Medicine,
UCLA School of Medicine
Dr. Karpman reports no financial relationships relevant to this field of study.
SYNOPSIS: Intensive lifestyle modifications (i.e., diet and exercise) are associated with a decrease in both coronary and carotid atherosclerotic burdens.
Jhamnani S, et al. Meta-analysis of the effects of lifestyle modifications on coronary and carotid atherosclerotic burden. Amer J Cardiol 2015; 115:267–275.
The guidelines for secondary prevention of atherosclerotic disease, published by the American Heart Association/American College of Cardiology1 and the European Society of Cardiology,2 clearly indicate that lifestyle changes, including dietary modifications and regular exercise, are both important forms of therapy for atherosclerotic cardiovascular disease; however, to date, randomized, controlled trials designed to establish the beneficial effects of these measures on atherosclerotic coronary or carotid artery disease progression have not been convincing. Because of the shortcomings, Jhamnani and colleagues3 decided to perform a meta-analysis of the literature to critically examine and quantify the effectiveness of intensive lifestyle modifications on atherosclerotic disease progression. They focused their literature analysis on coronary and carotid arteries because of the important prognostic value of these arterial systems with respect to cardiac and cerebral vascular events and overall morbidity and mortality.
The Jhamnani meta-analysis included only randomized, controlled trials evaluating the efficacy of lifestyle measures comparing diet and/or exercise intervention vs usual care.3 They included only studies that were prospective and which clearly reported the subject selection process, interventions, and follow-up and also included baseline and follow-up data on quantitative coronary angiograms and/or measurements of carotid intimal-media thickness. Trials in which subjects received medication along with diet and/or exercise were not included. When available, clinical outcomes were reported to complement the review. The results suggested that intensive lifestyle modifications were associated with a significant decrease in both coronary and carotid atherosclerotic burdens.
Published studies have demonstrated that compliance with short-term medical therapy ranges between 70-80%, whereas long-term medical therapy compliance drops to 40-50% and, finally, with respect to lifestyle changes, short- and long-term compliance is very low, at 20-30%.4 A strong correlation exists between the level of compliance and the beneficial changes that occur in angiographically documented lesion stenosis, in effect demonstrating that a modest lifestyle change can lead to a decrease in atherosclerotic progression.5 The beneficial effects of exercise and diet have been well documented to improve cardiovascular and all-cause mortality,6 often even halting or reversing atherosclerotic disease. Known cardiovascular risk markers, such as lipid profiles, inflammatory risk markers, and total body weight, also improved with diet and exercise. It is important to recognize that the coronary angiographic studies essentially included patients aged 32-75 years with coronary artery disease with a predominance of men. The carotid intima-medial thickness populations studied were very broad, with an almost equal proportion of men and women.
This meta-analysis was not without limitations, since many of the trials, especially the coronary angiographic studies, were in relatively old populations, and the number of patients in each study was relatively small since there were ethical issues in having control groups that did not receive statin therapy and/or other medications. It was difficult to control the character of the diet in each study and the character and amount of exercise that was performed by the treated and the control groups of subjects. Further, randomized, controlled trials examining the effects of intensive lifestyle measures on atherosclerotic progression in coronary and carotid arteries are needed using up-to-date techniques. For example, coronary CT angiography would obviously simplify the evaluation of the coronary arteries and, in addition, would allow careful evaluation of soft plaque in addition to the degree of stenosis of the coronary arteries.