Positron Emission Tomography in the Routine Management of Coronary Artery Disease

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Over the past 10 years, large randomized trials have demonstrated that lipid-lowering improves perfusion and reduces risk of coronary events such as MI, death, hospitalization, balloon angioplasty, and bypass surgery in patients with established CAD.

Figure 4 illustrates progression and regression of CAD in single views of dipyridamole stress images obtained at baseline and two or more years follow-up from two different patients. Worsening is characteristic of patients without adequate risk factor treatment. Improvement in these perfusion patterns is typical of vigorous risk factor management associated with marked reduction in cardiovascular events. Changes objectively quantified by PET are greater with greater statistical significance than changes by quantitative coronary arteriography.

Figure 5 shows clinical outcomes at five-year follow-up in PET studies and at 10-year follow-up of the Familial Atherosclerosis Treatment Study (FATS) using multi-drug treatment comparable with outcomes of the HDL (high density lipoprotein) Atherosclerosis Treatment Study (HATS) of combined statin and niacin. In the authorÔÇÖs PET study,'maximal treatmentÔÇÖ indicates food with <10% of calories as fat, regular exercise and lipid active drugs dosed to target goals of LDL <2.3mmol/L (90 mg/dl), HDL >1.2mmol/L (45mg/dl), and triglycerides <1.1mmol/L (100mg/dl).'Moderate treatmentÔÇÖ indicates an American Heart Association (AHA) diet and lipid-lowering drugs not dosed to goals or on strict low fat diet (<10% of calories) without lipid drugs. 'Poor treatmentÔÇÖ indicates no diet or lipid drugs, or smoking. Over five years of follow-up, coronary events occurred in 6.6%, 20.3%, and 30.6% of patients on maximal, moderate and poor treatment, respectively (p=0.001). The HATS trial had comparable results, both better than statin monotherapy trials.

Combined intense lifestyle change plus lipid-active drugs and severity/change of perfusion abnormalities independently predicted cardiac events. By stepwise multivariate logistic regression analysis, independent predictors of the combined end-point (MI, death, percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG)) were:

  • severity of myocardial perfusion abnormalities on dipyridamole PET scans;
  • change in myocardial perfusion abnormalities between the baseline and follow-up PET scans;
  • combined intense lifestyle changes plus lipid-active drugs;
  • lipid-active medications;
  • regular exercise;
  • LDL and triglyceride levels; and
  • diabetes and coronary heart disease in a mother, father, or sibling.

 

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