Outcomes of coronary artery bypass grafting in patients with heart failure with a midrange ejection fraction.

BACKGROUND: Coronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%). METHODS: We analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively. RESULTS: In 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]). CONCLUSIONS: Heart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization.

The importance of randomization in clinical research.

Studies evaluating average treatment effects (ATE) of an intervention could broadly be classified into those with observational and randomized designs. Observational studies are limited by confounding, in addition to selection and information bias, making the evaluation of ATE hypothesis generating and not hypothesis testing. Randomization attempts to reduce the systemic error introduced by observational studies by ensuring equal distribution of prognostic factors between the treatment and control groups, thereby confirming that any difference in outcomes observed between the two groups is attributable to the treatment. While randomized controlled trials (RCT) remain the gold standard in estimating ATE of therapeutic interventions, they do have inherent limitations due to uncertain external validity. Observational studies can have a complementary role in enhancing RCTs' ability to inform routine clinical practice. In this review, we focus on the limitations of observational studies, the need for randomization, interpretation, and the limitations of RCTs.

Revascularization in ischaemic heart failure with preserved ejection fraction: a nationwide cohort study.

AIMS: Despite the common occurrence of coronary artery disease (CAD) and heart failure (HF) with preserved ejection fraction (HFpEF), there is limited evidence to guide revascularization. METHODS AND RESULTS: We investigated the long-term outcomes of coronary artery bypass grafting (CABG) in patients with HF and significant CAD across the spectrum of ejection fraction, using a large national cohort of patients from the Veteran Affairs (VA) Medical Centers in the US. Patients with HF were stratified into groups, HFpEF, HF with mid-range ejection fraction (HFmrEF), and HF with reduced ejection fraction (HFrEF) and compared to patients with no preoperative HF. We analysed 10 396 patients. Despite an increased hazard in the first year following revascularization, the long-term survival (median follow-up 6.6 years; interquartile range 3.7-10.1) of HFpEF post-CABG was similar to controls (hazard ratio 0.85, 95% confidence interval 0.68-1.06), but survival progressively declined with HFmrEF and HFrEF. Similar trends were seen with recurrent HF hospitalization with lower risk with baseline HFpEF (43.9 ± 6.9/100 patient-years) compared to HFmrEF (65.9 ± 3.8/100 patient-years) and HFrEF (93.4 ± 4.8/100 patient-years). Although HFpEF patients had lower mortality and HF hospitalization post-CABG compared to patients with a lower ejection fraction, they experienced the highest rates of future myocardial infarction. CONCLUSION: Although HFpEF patients with CAD have greater short-term risk post-CABG, their long-term survival is comparable to controls. However, they are at increased risk for HF hospitalizations and myocardial infarction. These data support the safety of CABG in HFpEF patients and suggest continuum of mortality risk for ischaemic HF when stratified by baseline ejection fraction before revascularization.

Pre-operative glycaemic control and long-term survival in diabetic patients after coronary artery bypass grafting.

OBJECTIVES: We analysed the Veteran Affairs data to evaluate the association of pre-operative glycated haemoglobin (HbA1c) and long-term outcome after isolated coronary artery bypass grafting (CABG). METHODS: Veterans with diabetes mellitus and isolated CABG (2006-2018) were divided into 4 groups (I: HbA1c <6.5%, II: HbA1c 6.5-8, III 8-10% and IV: HbA1c >10%). The relationship of pre-operative HbA1c and long-term survival was evaluated with a multivariable Cox proportional hazards model and reported as hazard ratios (HR). The cumulative incidence of secondary end-points [myocardial infarction (MI) and repeat revascularization (percutaneous intervention)] for each group was modelled as competing events with cause-specific Cox proportional hazards models. RESULTS: Overall, 16 190 patients (mean age 64.9 years, male 98%; insulin dependent 53%) with diabetes mellitus underwent isolated CABG. We observed 19.4%, 45.4%, 27% and 8.2% patients in groups I, II, III and IV, respectively. Patients with HbA1c >10% were the youngest (mean age 60.9 years) and had high rates of Insulin dependence (78%). In patients with HbA1c >10%, improvement in levels was observed in 76%. The median follow-up observed was 5.8 (3.2-8.8) years. Compared to the study mean HbA1c (7.3%), mortality rate increased with HbA1c levels >8%, and especially with pre-operative HbA1c levels >9%. Compared to patients with HbA1c <8%, HbA1c 8-10% and >10% were associated with increased MI (HR 1.24 and HR 1.39, respectively) and need for reintervention (HR 1.20 and HR 1.24, respectively). CONCLUSIONS: In patients undergoing CABG, pre-operative HbA1c >8% is associated with the increased risk of mortality and adverse cardiac events.

Advanced Data Analytics for Improved Decision-Making at a Veterans Affairs Medical Center.

EXECUTIVE SUMMARY: This article reports on a data-driven methodology for decision-making at a Veterans Affairs medical center (VAMC) to improve patient outcomes, specifically the 30-day standardized mortality ratio (SMR30). The quarterly strategic analytics for improvement and learning (SAIL) reports are used to visualize the data, study trends, provide actionable recommendations, and identify potential consequences.A case study using more than 4 years of data demonstrates the power of the methodology. After reviewing data and studying trends at other VAMCs, a decision is made to reduce the SMR30 value by 1%. In running correlation algorithms, in-hospital complications (IHC) are shown to be most closely correlated with SMR30. Modeling the results from 17 quarters' worth of data shows that a desired 1% change in SMR30 would require a targeted 18.6% decrease in IHC. This change, if accomplished, would yield good consequences on methicillin-resistant Staphylococcus aureus mitigation but potentially unintended consequences with catheter-associated urinary tract infections and patient safety indicators that would need to be monitored. This knowledge could enable healthcare leaders to make informed decisions of both potentially positive and unintended consequences that can be monitored and minimized. This study lays the groundwork for a healthy discussion among leaders, staff, and clinicians on the path forward, resources required, and-most importantly-a dashboard that reflects the progress each week rather than a quarterly SAIL report.