Effect of combination therapy with lipid-reducing drugs in patients with coronary heart disease and "normal" cholesterol levels. A randomized, placebo-controlled trial. Harvard Atherosclerosis Reversibility Project (HARP) Study Group.

BACKGROUND

Combination drug therapy has been shown to decrease cholesterol levels in hyperlipidemic patients. However, its efficacy has not been well studied in patients previously considered to be normolipidemic, many of whom are now candidates for this therapy.

OBJECTIVE

To determine the efficacy and tolerability of multidrug therapy designed to improve low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels in patients with coronary heart disease and average lipid levels.

DESIGN

Randomized, placebo-controlled, 2.5-year trial comparing patients receiving usual care with patients receiving stepped-care drug therapy.

INTERVENTION

Stepped-care therapy (pravastatin, nicotinic acid, cholestyramine, and gemfibrozil) to decrease total cholesterol levels to less than 4.1 mmol/L (160 mg/dL) and the ratio of LDL cholesterol to HDL cholesterol to less than 2.0.

SETTING

2 academic, urban, tertiary care hospitals.

PATIENTS

91 patients (80 men and 11 women) with coronary heart disease, a mean age of 60 years, total cholesterol levels less than 6.4 mmol/L (250 mg/dL) at baseline, and ratios of total cholesterol to HDL cholesterol greater than 4.0 at baseline.

MEASUREMENTS

Fasting serum lipoprotein profile, fasting apolipoprotein levels, and frequency of adverse effects. Patients were assessed every 6 weeks during drug titration and every 3 months thereafter.

RESULTS

Mean lipid levels at baseline were as follows: total cholesterol, 5.5 mmol/L (214 mg/dL); LDL cholesterol, 3.6 mmol/L (140 mg/dL); HDL cholesterol, 1.1 mmol/L (42 mg/dL); and triglycerides, 1.8 mmol/L (159 mg/dL). With pravastatin, changes in levels from baseline were -22% for total cholesterol, -32% for LDL cholesterol +8% for HDL cholesterol, and -15% for triglycerides (P < 0.001 for all comparisons). With the addition of 1.5 g of nicotinic acid, additional changes were -6% for total cholesterol (P < 0.002). -11% for LDL cholesterol, +8% for HDL cholesterol, and -10% for triglycerides (P < 0.001 for all comparisons). With 2.25 to 3 g of nicotinic acid, these changes were -7% for total cholesterol (P = 0.007), -14% for LDL cholesterol (P < 0.001), +6% for HDL cholesterol (P = 0.02), and -13% for triglycerides (P = 0.03). With cholestyramine, total cholesterol and LDL cholesterol levels were unchanged compared with the previous step; the change in HDL cholesterol level was -8% (P = 0.03); and the change in triglyceride level was +46% (P < 0.001). With gemfibrozil, total cholesterol level was unchanged; the additional change in LDL cholesterol level was +12% (P = 0.09); the change in HDL cholesterol level was +12% (P = 0.03); and the change in triglyceride level was -37% (P < 0.001). Apolipoprotein B levels decreased by 25% overall (P < 0.001); lipoprotein(a) levels did not change significantly. Adverse effects were primarily attributable to nicotinic acid or cholestyramine. In 18 of the 35 patients (50%) whose baseline LDL cholesterol levels were greater than 3.35 mmol/L (130 mg/dL), pravastatin decreased LDL cholesterol levels to 2.6 mmol/L (100 mg/dL) or less by 6 weeks; 70% of patients needed combination therapy to reach this National Cholesterol Education Program goal during the 2.5 years of the study. Adding nicotinic acid to pravastatin produced LDL cholesterol levels of 2.6 mmol/L or less in 15 more of these 35 patients, so that 94% (n = 33) of the patients receiving these two drugs reached this goal.

CONCLUSIONS

To reach current goals for LDL cholesterol levels, most normolipidemic patients with coronary heart disease in this study needed combination therapy. Pravastatin with nicotinic acid and pravastatin with gemfibrozil are well-tolerated combinations that can maintain target LDL cholesterol levels, decrease triglyceride levels, and increase HDL cholesterol levels. Adding resin to these combinations produced no further benefit.