β-blocker Therapy is Not Associated with Reductions in Angina or Cardiovascular Events After Coronary Artery Bypass Graft Surgery: Insights from the IMAGINE Trial

Medical Therapy After CABG: the Known Knowns, the Known Unknowns, and the Unknown Unknowns

PURPOSE

Medical therapies play a central role in secondary prevention after surgical revascularization. While coronary artery bypass grafting is the most definitive treatment for ischemic heart disease, progression of atherosclerotic disease in native coronary arteries and bypass grafts result in recurrent adverse ischemic events. The aim of this review is to summarize the recent evidence regarding current therapies in secondary prevention of adverse cardiovascular outcomes after CABG and review the existing recommendations as they pertain to the CABG subpopulations.

RECENT FINDINGS

There are many pharmacologic interventions recommended for secondary prevention in patients after coronary artery bypass grafting. Most of these recommendations are based on secondary outcomes from trials which include but did not focus on surgical patients as a cohort. Even those designed with CABG in mind lack the technical and demographic scope to provide universal recommendations for all CABG patients.

CONCLUSION

Recommendations for medical therapy after surgical revascularization are chiefly based on large-scale randomized controlled trials and meta-analyses. Much of what is known about medical management after surgical revascularization results from trials comparing surgical to non-surgical approaches and important characteristics of the operative patients are omitted. These omissions create a group of patients who are relatively heterogenous making solid recommendations elusive. While advances in pharmacologic therapies are clearly adding to the armamentarium of options for secondary prevention, knowing what patients benefit most from each therapeutic option remains challenging and a personalized approach is still required.

Nomograms Based on Non-High-Density Lipoprotein to Predict Outcomes in Patients with Prior Coronary Artery Bypass Grafting with Acute Coronary Syndrome: A Single-Center Retrospective Study

Introduction

Non-high-density-lipoprotein cholesterol (non-HDL-C) is a secondary therapeutic target in cardiovascular diseases and is used for residual risk assessment in patients with coronary artery syndrome (ACS). This study was designed to determine the association between non-HDL-C in patients with prior coronary artery bypass graft (CABG) with ACS and clinical outcomes.

Methods

We retrospectively analyzed 468 patients with prior CABG with ACS and categorized them into two groups based on the median non-HDL-C level. The primary endpoints were major adverse cardiovascular events (MACEs), including cardiovascular death and recurrent myocardial infarction. Kaplan-Meier curves, Cox proportional-hazard regressions, and restricted cubic splines were used to determine the association between non-HDL-C and MACEs. The discrimination and reclassification of the nomogram based on non-HDL-C were assessed using time-dependent receiver operating characteristic (ROC) curves and net reclassification improvement (NRI).

Results

During the average follow-up time of 744.5 days, non-HDL-C was independently associated with the occurrence of MACEs (hazard ratio [HR] = 5.01, 95% confidence interval [CI] = 1.65-15.24; p = 0.005) after adjusting for other lipid parameters. The spline curves indicated a linear relationship between non-HDL-C and MACEs (p-nonlinear: 0.863). The time-dependent areas under the ROC curves of prior-CABG-ACS nomograms containing non-HDL regarding MACEs in two consecutive years were 91.7 (95% CI: 85.5-97.9) and 91.5 (95% CI: 87.3-95.7), respectively. The NRI analysis indicated that the prior-CABG-ACS model improved the reclassification ability for 1- and 2-year MACEs (22.4% and 7%, p < 0.05, respectively).

Discussion

Non-HDL is independently associated with the risk of MACEs in patients with prior CABG with ACS. The prior-CABG-ACS nomogram based on non-HDL-C and five convenient variables generates valid and stable predictions of MACE occurrence.

Beta blockers and long-term outcome after coronary artery bypass grafting: a nationwide observational study

Aims

Beta blockers are associated with improved outcomes for selected patients with cardiovascular disease. We assessed long-term utilization of beta blockers after coronary artery bypass grafting (CABG) and its association with outcome.

Methods and results

All 35 184 patients in Sweden who underwent first-time isolated CABG between 1 January 2006 and 31 December 2017 and were followed for at least 6 months were included in a nationwide observational study. Multivariable Cox regression models using time-updated data on dispensed prescriptions were used to assess associations between different types of beta blockers and outcomes. The primary outcome was major adverse cardiovascular events (MACEs), a composite of all-cause mortality, stroke, and myocardial infarction (MI). Subgroup analyses were performed in patients with and without previous MI, heart failure, and reduced left ventricular ejection fraction (LVEF). Median follow-up was 5.2 years (range 0–11). At baseline, 33 159 (94.2%) patients were dispensed beta blockers, 30 563 (92.2%) of which were cardioselective beta blockers. After 10 years, the dispensing of cardioselective beta blockers had declined to 73.7% of all patients. Ongoing treatment with cardioselective beta blockers was associated with a slight reduction in MACEs [hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.89–0.98, P = 0.0063]. The reduction was largely driven by a reduced risk of MI (HR 0.83, 95% CI 0.75–0.92, P = 0.0003), while there was no significant reduction in all-cause mortality (HR 0.99, 95% CI 0.93–1.05) and stroke (HR 0.96, 95% CI 0.87–1.05). The reduced risk for MI was consistent in all the investigated subgroups.

Conclusion

Ongoing treatment with cardioselective beta blockers after CABG is associated with a reduction in MACEs, mainly because of reduced long-term risk for MI. The association between cardioselective beta blockers and MI was consistent in patients with and patients without previous MI, heart failure, atrial fibrillation, or reduced LVEF.

Secondary Prevention Medications Post Coronary Artery Bypass Grafting Surgery-A Literature Review

Secondary prevention after coronary artery bypass graft (CABG) surgery is imperative in slowing the progression of atherosclerosis in both native and grafted vessels. Aspirin and statins remain the key medications for all patients without significant contraindications. The evidence for dual antiplatelet therapy with clopidogrel is less convincing, but there is hope for newer antiplatelet agents, such as ticagrelor. Meanwhile, β-blockers and angiotensin converting enzyme inhibitors might only offer benefits to specific sub-groups. Post-CABG patients appear to have different medication needs to the general cardiovascular patient and respond differently. In this review, we cover the drug regimens proposed by recent guidelines and the evidence behind their use. Assessing the evidence behind these recommendations, we find that there is an unmet need in some areas for robust population-specific evidence. We hope that future research will address this gap.

Association between perioperative β-blocker use and clinical outcome of non-cardiac surgery in coronary revascularized patients without severe ventricular dysfunction or heart failure

Perioperative use of β-blocker has been encouraged in patients undergoing non-cardiac surgery despite weak evidence, especially in patients without left ventricular systolic dysfunction (LVSD) or heart failure (HF). This study evaluated the effects of perioperative β-blocker on clinical outcomes after non-cardiac surgery among coronary revascularized patients without LVSD or HF. Among a total of 503 patients with a history of coronary revascularization (either by percutaneous coronary intervention or coronary arterial bypass grafts) undergoing non-cardiac surgery, those without severe LVSD defined by ejection fraction over 30% or HF were evaluated. The primary outcome was a composite of death, myocardial infarction, repeat revascularization, and stroke during 1-year follow-up. Perioperative β-blocker was used in 271 (53.9%) patients. During 1-year follow-up, we found no significant difference in primary outcome between the two groups on multivariate analysis (hazard ratio [HR], 1.01; confidence interval [CI] 95%, 0.56–1.82; P = 0.963). The same result was shown in propensity-matched population (HR, 1.25; CI 95%, 0.65–2.38; P = 0.504). In coronary revascularized patients without severe LVSD or HF, perioperative β-blocker use may not be associated with postoperative clinical outcome of non-cardiac surgery. Larger registry data is needed to support this finding.

Rationale for administering beta-blocker therapy to patients undergoing coronary artery bypass surgery: a systematic review

INTRODUCTION

Secondary preventative therapies are essential for patients undergoing coronary artery bypass graft (CABG) surgery to optimize perioperative and long-term outcomes. Beta-blockers are commonly used to treat patients with coronary artery disease and congestive heart failure (CHF), but their role for CABG patients remains unclear. The goal of this systematic review was to evaluate the rationale for administering beta-blockers to the CABG population and to assess their efficacy before and after coronary surgical revascularization.

AREAS COVERED

A systematic literature review was performed to retrieve relevant articles from the PubMed database published between 1985 and 2017.

EXPERT OPINION

Outside of the surgical field, strong evidence supports the use of beta-blockers for patients with a history of previous myocardial infarction (MI) or CHF. For the CABG population, studies have suggested that perioperative beta-blocker therapy is beneficial, with an associated reduction in mortality, particularly among those with a history of previous MI or CHF. Beta-blocker administration has also clearly been shown to lower the rate of new-onset postoperative atrial fibrillation after CABG. Among the different types of beta-blockers, perioperative carvedilol appears to be the most beneficial. In the absence of contraindications, nearly all CABG patients are candidates for perioperative beta-blocker therapy.