Abstract 12281: Two Years of LDL Lowering Does Not Improve Calf Muscle Physiology or Functional Capacity in Peripheral Arterial Disease
Background: Prior research suggests statins improve walking performance in patients with peripheral arterial disease (PAD). We hypothesized that LDL reduction over 2 years would improve calf muscle perfusion, cellular metabolism, and exercise performance in PAD as measured by magnetic resonance (MRI) imaging and spectroscopy (MRS).
Methods: 68 patients with mild-to-moderate symptomatic PAD (mean age 65±11 years, ABI 0.69±0.14) were studied annually for 2 years after beginning simvastatin 40mg (S, n=20) or simvastatin 40mg/ezetimibe 10mg (S+E, n=18) if statin-naive or ezetimibe 10mg (E, n=30) if on a statin. Patients with interval study leg revascularization were excluded (n=17). Calf muscle phosphocreatine recovery time (PCr) was measured by 31P MRS immediately after symptom-limited exercise on a 1.5T scanner. Calf muscle perfusion was measured using first-pass contrast-enhanced MRI with 0.1 mM/kg gadolinium at peak exercise (excluding 6 with renal dysfunction). Slope of time intensity curve in the muscle divided by arterial input defined perfusion index. A gadolinium-enhanced MRA was graded. Six minute walk and treadmill with peak V02 were performed. Repeated measures model compared changes over time.
Results: LDL lowering from baseline to year 2 was greater in S+E (116±10 to 56±7 mg/dl) than in S (129±10 to 90±8 mg/dl, p<0.01). The LDL in E also decreased at year 2 (102±5 to 79±6 mg/dl, p<0.01). Despite this, there was no difference in perfusion, metabolism or exercise parameters between groups. Thus, data was examined together (see table). Log transformed treadmill exercise time was unchanged over time. Only rest ABI improved over time (Table).
Conclusion: Lipid lowering therapy was effective at lowering total and LDL cholesterol in PAD. Despite this, neither tissue perfusion, metabolism, nor exercise parameters changed over two years, although rest ABI did improve. Thus, LDL lowering does not improve calf muscle physiology or functional capacity in PAD.
- Peripheral arterial disease
- Magnetic resonance imaging
- Magnetic resonance spectroscopy
- Cholesterol-lowering drugs
- © 2010 by American Heart Association, Inc.