Cardiac Medical Therapy Post-Coronary Bypass Grafting

We read with interest the recent review by Okrainec et al. entitled, “Cardiac Medical Therapy in Patients After Undergoing Coronary Artery Bypass Graft Surgery” (1). We congratulate the investigators on a comprehensive review of this important subject. We would, however, like to make a few comments regarding the use of certain drugs following coronary artery bypass grafting (CABG). We agree entirely with the researchers that aspirin and statins should be given to all patients following surgery, with strong evidence to support this. Okrainec et al. (1) state that “current data do not support the use of beta-blockers, calcium channel blockers (CCB), and nitrates, and more evidence is needed regarding the use of angiotensin-converting enzyme inhibitors (ACEI).”

Although we agree that CCB and nitrates lack data on their use postbypass surgery, beta-blocker and ACEI use may be warranted in a wide range of patients post-CABG. In a large cohort of patients who underwent CABG after myocardial infarction (MI), beta-blockers reduced one-year mortality from 12% to 4% (2). Many patients who have undergone CABG but not had an ST-segment elevation MI are given cardio-selective beta-blockers postoperatively based on the efficacy of such drugs post-MI; however, use of such drugs in non-ST-segment elevation MI is currently unknown as definitions for MI have recently evolved from a creatine kinase-based enzyme rise to a troponin-based rise. Use of beta-blockers in patients with left ventricular (LV) impairment is also strongly supported by numerous controlled trials, and these patients should certainly receive beta-blockers post-CABG. We agree that use of beta-blockers in patients without prior MI (ST-segment or non-ST-segment elevation) or LV impairment is more debatable.

We also believe there is sufficient evidence to warrant the use of ACEI in most patients following CABG. In the Heart Outcomes Prevention Evaluation (HOPE) trial, use of the ACEI ramipril improved outcomes in patients with diabetes or known vascular disease but without LV dysfunction (3); approximately 25% of the participants had previously undergone CABG. The small study evaluating quinapril post-CABG showed no effect of the ACEI on the primary end point of change in exercise endurance or incidence of ischemia on Holter monitor (4); however, fewer patients receiving quinapril experienced ischemic events compared with placebo (3.5% vs. 15%; p = 0.02), suggesting benefit to those receiving quinapril. Current research suggests that ACEI act as vascular protective agents, and as such most patients undergoing CABG for coronary disease are likely to benefit and should be prescribed them.

We agree that aspirin and statins should be used post-CABG. However, we also believe that ACEI should also be routinely used where possible; use of beta-blockers should also be strongly recommended especially in patients with a history of MI and/or LV impairment.

• American College of Cardiology Foundation