Perioperative Acute MI Associated With Non-Cardiac Surgery
What are the recent national trends in perioperative acute myocardial infarction (AMI) incidence, management strategies, and outcomes?
Patients ≥45 years of age undergoing noncardiac surgery in the United States from 2005-2013 were identified from the National Inpatient Sample (NIS). Perioperative AMI was identified based on International Classification of Diseases, Ninth Revision (ICD-9) codes for ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). Invasive management of AMI was defined as in-hospital coronary angiography, percutaneous coronary intervention or coronary artery bypass grafting; patients not undergoing these procedures were assumed to have been managed conservatively. Propensity-score matching was used to compare AMI patients with similar baseline characteristics who were treated invasively versus conservatively. In an effort to exclude non-perioperative AMI, a sensitivity analysis was performed, excluding patients who were urgently or emergently hospitalized.
A total of 9,566,277 hospitalizations met the inclusion criteria. AMI occurred in 84,093 patients (0.88%); STEMI accounted for 17,854 (21.2%) and NSTEMI for 66,239 (78.8%). Over the study period, incidence of AMI per 100,000 surgeries declined from 898 in 2005 to 729 in 2013 (p for trend < 0.0001). In a model adjusted for demographics and clinical covariates, types of surgery associated with increased risk of AMI were noncardiac transplant (odds ratio [OR], 1.99), thoracic (OR, 1.63), and vascular (OR, 1.56). AMI was more common in patients undergoing urgent versus elective surgery (adjusted OR, 2.38). Although AMI was associated with increased in-hospital mortality (adjusted OR, 5.76), AMI-associated mortality declined from 20.1% in 2005 to 15.5% in 2013 (p value for trend < 0.0001). An invasive strategy was applied in 17,511 (20.8%) of AMI cases, with an increase from 20.2% in 2005 to 23.7% in 2013 (p < 0.001). In a propensity-matched cohort, invasive management was associated with lower in-hospital mortality than conservative management (8.9% vs. 18.1%, p < 0.001).
Based on this observational cohort study, perioperative AMI incidence in the United States has declined in recent years, and AMI-associated in-hospital mortality has also declined. Invasive management appears to be associated with decreased mortality.
Strengths of this study include its very large sample size, variety of surgical procedures considered, and statistical methods used to account for confounders that could potentially bias toward invasive management of AMI. Limitations are chiefly related to the use of an administrative database, including potential for coding errors and lack of chronology for any given hospital admission. Trends identified may reflect improved adherence to guidelines for perioperative management and increased early recognition and treatment of acute coronary syndromes.
This manuscript elaborates upon a previously published paper from the same group (Smilowitz NR, et al., JAMA Cardiol 2017;2:181-7) describing trends in perioperative major adverse cardiovascular and cerebrovascular events (MACCE) in the NIS. The prior study demonstrated that while the overall incidence of perioperative MACCE declined from 3.1% to 2.6% of hospitalizations (p < 0.0001 for trend) over the study period of 2004-2013, perioperative ischemic stroke increased slightly, but significantly from 0.52% to 0.77% (p < 0.0001).
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