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CLINICAL RESEARCH: OBESITY AND HEART DISEASE

The Relationship Between Obesity and Atherosclerotic Progression and Prognosis Among Patients With Coronary Artery Bypass Grafts

The Effect of Aggressive Statin Therapy

Christina C. Wee, MD, MPH^_*,_*, Saket Girotra, MD, SM, Amy R. Weinstein, MD, MPH^_*, Murray A. Mittleman, MD, DrPH^, and Kenneth J. Mukamal, MD, MPH^_*

^_* Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts.

Manuscript received December 3, 2007; revised manuscript received May 1, 2008, accepted May 20, 2008.

^_* Reprint requests and correspondence: Dr. Christina C. Wee, Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, CO-222, Boston, Massachusetts 02215. (Email: cwee{at}bidmc.harvard.edu).

Objectives: This study examines whether obesity accelerates atherogenic progression or adverse outcomes after coronary artery bypass graft (CABG) surgery.

Background: Obesity is a major risk factor for developing coronary heart disease. Whether obesity accelerates disease progression after CABG is unclear.

Methods: We examined how body mass index (BMI) related to atherosclerotic graft progression and a clinical composite outcome of death, nonfatal myocardial infarction, stroke, CABG surgery, or angioplasty among 1,314 participants in the Post CABG trial. Participants who had undergone CABG surgery were randomly assigned in a 2 x 2 factorial design to warfarin versus placebo and aggressive low-density lipoprotein cholesterol (LDL-C) lowering with lovastatin 40 to 80 mg/day (to achieve LDL-C of 60 to 85 mg/dl) versus moderate LDL-C lowering with lovastatin 2.5 to 5 mg/day (to achieve LDL-C of 130 to 140 mg/dl). Angiographic progression was assessed by coronary angiography at 4 to 5 years.

Results: Higher BMI was associated with a higher likelihood of angiographic progression (p trend = 0.003) after adjustment for demographic factors, treatment assignment, smoking status, and years since CABG surgery, but not with clinical events (p trend = 0.81). In stratified analyses, higher BMI was associated with angiographic progression in the low-dose lovastatin group (p trend <0.001) but not in the high-dose group (p = 0.03 for test for interaction of BMI and statin treatment). In the high-dose lovastatin group, higher BMI appeared to be protective against clinical events (p trend = 0.06, test of interaction: 0.02).

Conclusions: Higher BMI is strongly associated with atherogenic progression after CABG surgery. Aggressive statin therapy may be protective against obesity-related acceleration of coronary heart disease.

Key Words: obesity • cardiac surgery • lipid lowering • atherosclerosis

Abbreviations and Acronyms   BMI = body mass index   CABG = coronary artery bypass graft   CHD = coronary heart disease   LDL-C = low-density lipoprotein cholesterol