Hyperlipidaemia management after primary coronary artery bypass surgery: a survey of patients and general practitioners

Impact of statins and beta-blocker therapy on mortality after coronary artery bypass graft surgery

BACKGROUND

We conducted a retrospective cohort study of patients after first-time isolated coronary artery bypass graft surgery (CABG) and assessed the impact of a discharge regimen including beta-blockers and statin therapy and their relationship to long-term all cause mortality and major adverse cardiovascular events (MACE).

METHODS

We identified patients age >18 years, undergoing first time isolated CABG from 1993 to 2005. Patients were identified using the Cardiovascular Information Registry (CVIR). We collected follow-up information at 30, 60, 90 days and yearly follow-up. The registry is approved for use in research by the institutional review broad.

RESULTS

We identified 5,205 patients who underwent single isolated CABG between January 1993 and December 2005. The mean age was 64.5±9.7 years and over 70% were male. There was a significant difference in the low density lipoproteins (LDL) concentration between those with or without statin medications (134±41.9 mg/dL) (no statin) vs. 126±44.8 mg/dL (with statin), P=0.001. A discharge regimen with statin therapy was associated with and overall reduction in 30 day, 1 year and long-term mortality. In addition, overall the triple ischemic endpoint of death, myocardial infarction (MI) and stroke was also significantly lower in the statin vs. no-statin group. In addition, statin and beta-blockers exerted synergistic effect on overall mortality outcomes short-term and in the long-term. We note that the predictors of overall death include no therapy with statin therapy and age [hazard ratios (HR) 1.1, 95% CI: 1.04-1.078, P<0.001] and presence of renal failure (HR 2.0, P=0.005). The estimated 11-year Kaplan Meier curves for mortality between the two groups starts to diverge immediately post discharge after single isolated CABG and continue to diverge through out the follow-up period.

CONCLUSIONS

A post-discharge regimen of statins independently reduces overall and 1 year mortality. These results confirm those of earlier studies within a contemporary surgical population and support the current clinical guidelines.

Lipid lowering and coronary bypass graft surgery

This article reviews the rationale for lipid lowering in patients who have coronary heart disease, and specifically for post-bypass patients. It has been well demonstrated that after coronary artery bypass graft surgery, atherosclerosis continues to progress in the native circulation and develops at an accelerated rate in saphenous vein bypass grafts. During the last decade, numerous clinical trials based on angiographic or clinical outcomes have clearly shown the beneficial effect of lipid lowering in coronary heart disease. Three trials (CLAS, post-CABG, and CARE) have demonstrated delayed progression of atherosclerosis in SVGs and/or a reduction of cardiac deaths, nonfatal MI, and the need for revascularization after lowering LDL-cholesterol. The recommended target of LDL cholesterol level of more than 100 mg/dl can be safely reached with diet and monotherapy using one of the statin drugs (HMG-CoA reductase inhibitors). Despite this widely-circulated information, there appears to be inadequate public and professional awareness of the importance of properly managing hyperlipidemia after coronary artery bypass graft surgery.

Management of dyslipidemia after coronary artery bypass grafting

The results of serial angiographic studies and intervention trials in patients after coronary artery bypass artery grafting have provided ample evidence that abnormalities of the plasma lipoprotein system are one of the most significant risk factors for a rapid atherosclerotic attrition of saphenous vein grafts. In addition to confirming the well recognized role and contribution of cholesterol-rich LDL or lipoprotein B particles to the progression of atherosclerotic lesions, intervention trials have also provided strong evidence for the atherogenic capacity of some intact and partly delipidized triglyceride-rich very low density lipoprotein and intermediate density lipoprotein (lipoprotein B complex) particles, and the protective effect of some (high density lipoprotein 3) but not all high density lipoprotein particles. Most importantly, those studies have emphasized the need for an early, aggressive treatment of dyslipoproteinemias with pharmacological agents as the most efficient therapeutic approach to delaying, if not preventing, the detrimental effect of atherosclerosis on saphenous vein grafts.