POMI Increases Mortality Risk Despite Current Strategies

Peter Henke, MD

A University of Michigan-led study has found an association between high rates of mortality with postoperative myocardial infarction are vascular surgery despite the implementation of evidence-based therapies.

A retrospective look at more than 25,000 patients highlighted the finding that despite high rates of discharge with evidence based therapies, the burden of postoperative myocardial infarction was substantial and contributed to a higher mortality rate in the following year.

To further describe the association of postoperative myocardial infarction with outcomes after major vascular surgery, investigators conducted a retrospective cohort study of 26,231 patients from the Blue Cross Blue Shield of Michigan Cardiovascular Collaborative database. Included in the study were patients who underwent open abdominal aortic aneurysm repair, endovascular aneurysm repair, peripheral arterial bypass, carotid endarterectomy, and carotid artery stenting.

From the aforementioned databases, investigators obtained information including patient demographics, comorbid conditions, and preoperative medications. Additionally, univariate analysis and logistic regression were used to identify factors associated with postoperative myocardial infarction. For the purpose of the study, postoperative myocardial infarction was defined as myocardial infarction diagnosed with ECG changes and biomarker changes occurring within 30 days of the operation.

Of the patients included in the study, 410 (1.6%) were diagnosed with a postoperative myocardial infarction. Results of the analyses revealed a greater portion of patients with postoperative myocardial infarction were dead at 1-year compared to patients with postoperative myocardial infarction (37.42% versus 5.05%; χ2=589.3; P<0.001).

Patients who experienced a postoperative myocardial infarction were typically older than those who did not (71.33 (9.2) versus 69.35 (9.89) years; T=4.026; P<0.001). Investigators did not find any other significant differences in categories between race or sex.

Analyses also revealed patients who experienced postoperative myocardial infarction were more likely to have hypertension (95.6% versus 89.2%; χ2=16.8; P<0.001), hyperlipidemia (92.2% versus 88.8%; χ2=4.45; P=0.04), type 2 diabetes mellitus (49.5% versus 34.0%; χ2=42.57; P<0.001), congestive heart failure (29.0% versus 14.9%; χ2=61.52; P<0.001), cardiac valvular disease (12.7% versus 6.5%; χ2=23.71; P<0.001), coronary artery disease (70.2% vs 50.7%; χ2=60.91; P<0.001), and kidney disease (5.6% vs 1.7%; χ2=34.91; P<0.001).

In regard to procedure, open abdominal aortic aneurysm and peripheral bypass were associated with the high risk of postoperative myocardial infarction. Following postoperative myocardial infarction, patients were discharged and received evidence-based therapy, including treatment with β-blockade (82.7%) and antiplatelet therapy (95.7%).

In an email with MD Magazine®, investigator Peter Henke, MD, Professor of Vascular Surgery and Professor of Surgery at the University of Michigan Medicine, detailed his takeaways from the results of the study.

“The main point from this study is that while postoperative MI is now uncommon amongst highest risk patients, it is very deadly long term, despite our best medical therapies (Aspirin, statins, bp control),” Henke wrote. “There is a major need for research and therapies to better treat MI's after they occur in the peri-operative setting. Things we can do now include reducing non therapeutic transfusions, as this was independently associated with postoperative myocardial infarction.”

This study, titled “Association of High Mortality With Postoperative Myocardial Infarction After Major Vascular Surgery Despite Use of Evidence-Based Therapies,” was published online in JAMA Surgery.