This cross-sectional study examines Medicare claims data for patients undergoing noncardiac surgery to gauge the association between previous non–ST-segment elevation myocardial infarction and the risk of postoperative major adverse cardiovascular and cerebrovascular events.
Key Points
Question
What is the association between a non–ST-segment elevation myocardial infarction (NSTEMI) before noncardiac surgery and the risk of postoperative major adverse cardiovascular and cerebrovascular events (MACCE)?
Findings
This cross-sectional study found that patients who had an NSTEMI within 30 days of elective surgery had 2-fold to 3-fold higher odds of MACCE and mortality compared with patients without a previous NSTEMI. The odds of MACCE and mortality leveled between 30 and 90 days and then increased after 180 days in those who underwent coronary revascularization but did not level off in those who did not undergo revascularization.
Meaning
Delaying surgery 90 to 180 days after an NSTEMI in patients who have had revascularization may be reasonable.
Abstract
Importance
Delaying elective noncardiac surgery after a recent acute myocardial infarction is associated with better outcomes, but current American Heart Association recommendations are based on data that are more than 20 years old.
Objective
To examine the association between the time since a non–ST-segment elevation myocardial infarction (NSTEMI) and the risk of postoperative major adverse cardiovascular and cerebrovascular events (MACCE).
Design, Setting, and Participants
This cross-sectional study examined Medicare claims data between 2015 and 2020 for patients 67 years or older who had major noncardiac surgery. Data were analyzed from September 21, 2023, to February 1, 2024.
Exposure
Time elapsed between a prior NSTEMI and surgery.
Main Outcomes and Measures
MACCE (30-day mortality, in-hospital myocardial infarction, heart failure, or stroke) and all-cause 30-day mortality. Multivariable logistic regression was used to estimate the association between outcomes and time since a prior NSTEMI.
Results
The sample included 5 227 473 surgeries. The mean (SD) age was 75.7 (6.6) years; 2 981 239 (57.0%) were female, and 2 246 234 (43%) were male. There were 42 278 patients (0.81%) with a previous NSTEMI. Compared with patients without a prior NSTEMI, patients with an NSTEMI within 30 days of elective surgery had higher odds of MACCE, regardless of whether they had undergone coronary revascularization (adjusted odds ratio [aOR], 2.15; 95% CI, 1.09-4.23; P = .03) or not (aOR, 2.04; 95% CI, 1.31-3.16; P = .001). The odds of postoperative MACCE leveled off after 30 days in patients who had undergone any coronary revascularization procedure (and after 90 days in patients with drug-eluting stents) and then increased after 180 days (any revascularization at 181-365 days: aOR, 1.46; 95% CI, 1.25-1.71; P < .001; patients with drug-eluting stents at 181-365 days: aOR, 1.73; 95% CI, 1.42-2.12; P < .001). The odds of MACCE did not level off for patients who did not have revascularization. Findings for all-cause 30-day mortality were similar to those for MACCE, except that the odds of mortality in patients with previous NSTEMI who had revascularization leveled off after 60 days in elective surgeries and 90 days for nonelective surgeries (elective 30-day: aOR, 2.88; 95% CI, 1.30-6.36; P = .009; elective 61- to 90-day: aOR, 1.03; 95% CI, 0.57-1.86; P = .92; nonelective 30-day: aOR, 1.91; 95% CI, 1.52-2.40; P < .001; nonelective 91- to 120-day: aOR, 1.00; 95% CI, 0.73-1.37; P = .99).
Conclusions and Relevance
This study found that among older patients undergoing noncardiac surgery who had revascularization, the odds of postoperative MACCE and mortality leveled off between 30 and 90 days and then increased after 180 days. The odds did not level off for patients who did not have revascularization. Delaying elective noncardiac surgery to occur between 90 and 180 days after an NSTEMI may be reasonable for patients who have had revascularization.
Introduction
More than 1 million hospitalizations for major noncardiac surgery occur in the United States each year. Despite advances in surgical technique and perioperative care, major adverse cardiovascular and cerebrovascular events occur in 3% of these surgeries, and 1.9% of patients die within 30 days of surgery. Because most of these surgeries are elective, it is critical to continue seeking ways to lower the risk of complications.
Since the publication of the Goldman multifactorial index of cardiac risk in 1977, preoperative clinical evaluation has focused on reducing the risk of cardiac complications and death in patients undergoing noncardiac surgery. One key component is how long to delay elective surgery after a myocardial infarction (MI). Older studies showed reinfarction rates as high as 36% when patients underwent surgery within 3 months of a previous MI, while a more recent study using data from California between 1999 and 2004 reports a much lower reinfarction rate of 8.4% but mortality rates as high as 33% in patients with reinfarction. Largely based on these latter findings, the 2014 American College of Cardiology/American Heart Association (ACC/AHA) perioperative guidelines suggest waiting at least 60 days after an MI before noncardiac surgery in the absence of a percutaneous coronary intervention. However, there are no recent studies examining or confirming these risks, and older data may not reflect changes in case mix or advances in cardiology practice that could alter these patterns.
There is thus a need for evidence based on contemporary data that may help guide patient and physician decision-making on how long to delay elective noncardiac surgery after a recent MI. We examined the association between postoperative major adverse cardiovascular and cerebrovascular events (MACCE: all-cause 30-day mortality, acute myocardial infarction, acute ischemic stroke, and congestive heart failure) and the time elapsed since a prior non–ST-segment elevation MI (NSTEMI) in older patients undergoing elective and nonelective major noncardiac surgery using Medicare data. We examined elective and nonelective surgery separately because selection bias is less likely in the nonelective cohort since emergency surgery cannot be delayed. We also compared outcomes in patients with previous NSTEMI who underwent coronary revascularization vs those who did not because revascularization may either increase or decrease the risk of cardiac complications depending on the timing of surgery after coronary revascularization, especially in the setting of percutaneous coronary intervention.
Methods
The University of Rochester approved this study and determined that informed consent was not required because it was exempt research consisting of secondary research on preexisting data. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines were used to guide the reporting of this study.
Data Source
This secondary analysis of claims data was conducted using data in the 100% Medicare Provider Analysis and Review File and the Master Beneficiary Summary File between 2015 and 2020. These databases include information on patient demographics, including age and sex, race, and ethnicity. The database includes the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10), diagnosis and procedure codes; present-on-admission codes (which differentiate between preexisting conditions and complications that occur during the hospitalization); source and date of admission; urgency of admission; dual enrollment status; discharge destination; date of death; and hospital identifiers. These data were merged with data from the Centers for Medicare & Medicaid Services Impact files, which contain information on hospital characteristics (geographic region, rurality, number of beds, mean daily census, disproportionate share hospital percentage, and resident-to-bed ratio).
Study Population
We limited the sample to patients hospitalized for major noncardiac surgery between November 1, 2017, and November 30, 2020, using a 2-year lookback period for prior MIs and a 30-day follow-up period for 30-day mortality. We identified 6 960 259 hospitalizations in patients who underwent major noncardiac surgery and had no prior MI, or experienced an NSTEMI within the 2-year lookback period, and whose most recent MI was an NSTEMI (eFigure and eTable 1 in Supplement 1). These surgeries were identified using the 2021 Centers for Disease Control and Prevention National Healthcare Safety Network (CDC NHSN) ICD-10 operative procedure code mappings. We excluded patients younger than 67 years to have a uniform 2-year lookback period (1 537 327) and patients with a prior NSTEMI who had revascularization more than 90 days after their NSTEMI (1946). Other cases excluded from the analysis are shown in the flow diagram in the eFigure in Supplement 1. The final analytic sample consisted of 5 227 473 surgeries, of which 3 620 675 were elective and 1 606 798 were nonelective (urgent or emergent); 42 278 were patients with a prior NSTEMI.
Key Variables
The primary outcome was MACCE. The secondary outcome was 30-day mortality. The key independent (exposure) variable was the time between the index surgical admission and the most recent hospital admission for an NSTEMI within 24 months of the index surgical admission. For patients with more than 1 prior NSTEMI, the time since the most recent NSTEMI was used. We specified the time interval between NSTEMI and the index surgery as a categorical variable (no prior MI [NSTEMI or STEMI] within 730 days; prior NSTEMI ≤30, 31-60, 61-90, 91-120, 121-180, 181-365, and 365-730 days). Patients with a prior NSTEMI were further classified as either having or not having undergone revascularization within 90 days of an NSTEMI. Patients with a prior NSTEMI who had revascularization outside of this 90-day window were excluded, as previously described. We specified time as a categorical variable because (1) we assumed that the association between the outcome and elapsed time would be nonlinear and (2) increments of 30 days would make it possible to translate the research findings into clinical recommendations.
Statistical Analysis
We used a multivariable logistic regression model to estimate the association between the time elapsed from a prior NSTEMI and MACCE in patients undergoing elective noncardiac surgery. We adjusted for patient demographics (age, sex), dual enrollment in Medicare and Medicaid (as a proxy for socioeconomic status); enrollment in Medicare Advantage; source of admission (community, hospital transfer, skilled nursing faculty or nursing home); time since prior coronary revascularization for patients without a prior NSTEMI specified separately for coronary artery bypass graft surgery, bare metal stent, drug-eluting stent (DES), and angioplasty (specified as categorical variables: none or ≤30, 31-60, 61-90, 91-120, 121-180, 181-365, and 366-730 days); frailty; COVID-19 on admission; Elixhauser comorbidities; open vs percutaneous surgical approach; surgical procedure; and year of admission. Elixhauser comorbidities were coded as separate indicator variables using Agency for Healthcare Research and Quality software. The present-on-admission codes, which differentiate diagnoses that were present on admission from complications that occur during the hospital admission, were used to identify outcomes and comorbidities. Surgery procedure categories were specified as separate indicator variables using the 2021 CDC NHSN ICD-10 operative procedure code mappings. We separately specified the components of the Hospital Frailty Score that were not included in the Elixhauser comorbidity algorithm (eTable 1 in Supplement 1). We re-estimated this model for all-cause 30-day mortality.
We performed several additional analyses. First, we repeated these analyses in patients undergoing nonelective surgery since selection bias is less likely to occur in nonelective surgeries. We then limited the subset of patients with a prior NSTEMI who had revascularization to those who had received a DES because current AHA guidelines recommend delaying elective surgery for 6 months after a DES.
We conducted sensitivity analyses where we also adjusted for hospital characteristics (total number of beds, average daily census, disproportionate share percentage, resident to bed ratio, rurality, and geographic region). All statistical analyses were performed using Stata/MP version 18.0 (StataCorp). We used cluster robust variance estimators to account for the clustering of observations within hospitals. We estimated adjusted outcomes using average marginal effects. The threshold for statistical significance was a 2-sided P < .05. Data were analyzed from September 21, 2023, to February 1, 2024.
Results
Patient Population
The sample included 5 227 473 surgeries. The mean (SD) age was 75.7 (6.6) years; 2 981 239 (57.0%) were female, and 2 246 234 (43%) were male. Among these surgeries, 42 278 (0.81%) were in patients with a previous NSTEMI within 730 days of surgery (Table). Patients with NSTEMI were slightly older than those without such a history (77.2 years vs 75.7 years), more likely to be men (55.2% vs 42.9%), and more likely to be dually enrolled in Medicare and Medicaid (18.0% vs 12.0%). Patients with NSTEMI were more likely to have a history of cerebrovascular disease (7.4% vs 3.6%), heart failure (33.4% vs 8.7%), moderate and severe kidney failure (moderate: 21.5% vs 11.1%; severe: 4.9% vs 1.5%), and valvular heart disease (12.1% vs 6.3%). Hospital characteristics are shown in eTable 2 in Supplement 1.
Table. Patient Characteristics.
| Characteristic | No. (%) | ||
|---|---|---|---|
| Total (n = 5 227 473) | No NSTEMI (n = 5 185 195) | Prior NSTEMI (n = 42 278) | |
| Time to prior NSTEMI, d | |||
| ≤30 | 1985 (0.04) | NA | 1985 (4.7) |
| 31-60 | 2220 (0.04) | NA | 2220 (5.3) |
| 61-90 | 2142 (0.04) | NA | 2142 (5.1) |
| 91-120 | 2038 (0.04) | NA | 2038 (4.8) |
| 121-180 | 3788 (0.07) | NA | 3788 (9) |
| 181-365 | 11 336 (0.22) | NA | 11 336 (26.8) |
| 365-730 | 18 769 (0.36) | NA | 18 769 (44.4) |
| Age, mean (SD), y | 75.7 (6.6) | 75.7 (6.6) | 77.2 (7) |
| Sex | |||
| Male | 2 246 234 (43) | 2 222 886 (42.9) | 23 348 (55.2) |
| Female | 2 981 239 (57) | 2 962 309 (57.1) | 18 930 (44.8) |
| Race and ethnicitya | |||
| American Indian | 20 451 (0.4) | 20 224 (0.4) | 237 (0.6) |
| Asian/Pacific Islander | 95 073 (1.8) | 94 458 (1.8) | 615 (1.5) |
| Black | 355 326 (6.8) | 352 397 (6.8) | 2929 (6.9) |
| Hispanic | 308 104 (5.9) | 305 393 (6.4) | 2711 (6.4) |
| Non-Hispanic White | 4 336 508 (83) | 4 301 409 (83) | 35 099 (83) |
| Other | 33 394 (0.6) | 33 097 (0.6) | 297 (0.7) |
| Unknown | 78 617 (1.5) | 78 227 (1.5) | 390 (0.9) |
| Admission source | |||
| Community | 4 973 568 (95.1) | 4 935 140 (95.2) | 38 428 (90.9) |
| Hospital | 190 276 (3.6) | 187 352 (3.6) | 2924 (6.9) |
| SNF/nursing home | 36 465 (0.7) | 35 915 (0.7) | 550 (1.3) |
| Other | 27 164 (0.5) | 26 788 (0.5) | 376 (0.9) |
| Dual-eligible | 629 360 (12) | 621 755 (12) | 7605 (18) |
| Medicare Advantage | 1 769 788 (33.9) | 1 755 370 (33.9) | 14 418 (34.1) |
| Prior procedures | |||
| CABG | 32 764 (0.6) | 25 381 (0.5) | 7383 (17.5) |
| Drug-eluting stent | 40 346 (0.8) | 24 803 (0.5) | 15 543 (36.8) |
| Bare metal stent | 4329 (0.1) | 2843 (0.1) | 1486 (3.5) |
| Angioplasty | 5875 (0.1) | 3756 (0.1) | 2119 (5) |
| Frailty | |||
| Wheelchair use | 17 558 (0.3) | 17 363 (0.3) | 195 (0.5) |
| Supplemental oxygen | 78 552 (1.5) | 77 368 (1.5) | 1184 (2.8) |
| Dependent on caregiver | 16 301 (0.3) | 16 132 (0.3) | 169 (0.4) |
| History of falls | 8837 (0.2) | 8728 (0.2) | 109 (0.3) |
| Fecal incontinence | 12 450 (0.2) | 12 364 (0.2) | 86 (0.2) |
| Elixhauser comorbidities | |||
| AIDS | 5252 (0.1) | 5184 (0.1) | 68 (0.2) |
| Alcohol misuse | 75 260 (1.4) | 74 649 (1.4) | 611 (1.5) |
| Anemia due to nutritional deficiencies | 533 249 (10.2) | 525 895 (10.1) | 7354 (17.4) |
| Autoimmune conditions | 231 233 (4.4) | 229 377 (4.4) | 1856 (4.4) |
| Anemia due to chronic blood loss | 33 736 (0.7) | 33 217 (0.6) | 519 (1.2) |
| Lymphoma | 31 488 (0.6) | 31 197 (0.6) | 291 (0.7) |
| Leukemia | 26 353 (0.5) | 26 078 (0.5) | 275 (0.7) |
| Metatstatic cancer | 179 418 (3.4) | 178 030 (3.4) | 1388 (3.3) |
| Solid tumor without metastasis, in situ | 2095 (0.04) | 2076 (0.04) | 19 (0.04) |
| Solid tumor without metastasis | 137 870 (2.6) | 136 484 (2.6) | 1386 (3.3) |
| Cerebrovascular disease | 189 544 (3.6) | 186 409 (3.6) | 3135 (7.4) |
| Heart failure | 462 776 (8.9) | 448 675 (8.7) | 14 101 (33.4) |
| Coagulopathy | 161 847 (3.1) | 159 711 (3.1) | 2136 (5.1) |
| Dementia | 280 502 (5.4) | 277 246 (5.4) | 3256 (7.7) |
| Diabetes without chronic complications | 616 259 (11.8) | 605 463 (11.7) | 10 796 (25.5) |
| Drug misuse | 32 193 (0.6) | 31 874 (0.6) | 319 (0.8) |
| Hypertension, complicated | 966 273 (18.5) | 947 576 (18.3) | 18 697 (44.2) |
| Hypertension, uncomplicated | 2 921 300 (55.9) | 2 903 171 (56) | 18 129 (42.9) |
| Liver disease, mild | 141 024 (2.7) | 139 863 (2.7) | 1161 (2.8) |
| Liver disease and failure, moderate to severe | 16 891 (0.3) | 16 718 (0.3) | 173 (0.4) |
| Chronic pulmonary disease | 993 066 (19) | 981 991 (18.9) | 11 075 (26.2) |
| Neurological disorders affecting movement | 183 646 (3.5) | 182 162 (3.5) | 1484 (3.5) |
| Neurological disorders, other | 205 294 (3.9) | 202 924 (3.9) | 2370 (5.6) |
| Seizures | 91 160 (1.7) | 90 219 (1.7) | 941 (2.2) |
| Obesity | 974 677 (18.7) | 967 921 (18.7) | 6756 (16) |
| Paralysis | 171 978 (3.3) | 169 404 (3.3) | 2574 (6.1) |
| Peripheral vascular disease | 361 701 (6.9) | 355 717 (6.9) | 5984 (14.2) |
| Psychosis | 76 728 (1.5) | 76 163 (1.5) | 565 (1.3) |
| Pulmonary circulation disease | 110 191 (2.1) | 108 291 (2.1) | 1900 (4.5) |
| Kidney failure, moderate | 584 200 (11.2) | 575 127 (11.1) | 9073 (21.5) |
| Kidney failure, severe | 80 507 (1.5) | 78 442 (1.5) | 2065 (4.9) |
| Hypothyroidism | 999 143 (19.1) | 991 316 (19.1) | 7827 (18.5) |
| Other thyroid disorders | 64 363 (1.2) | 63 884 (1.2) | 479 (1.1) |
| Peptic ulcer with bleeding | 42 211 (0.8) | 41 727 (0.8) | 484 (1.1) |
| Valvular disease | 333 900 (6.4) | 328 780 (6.3) | 5120 (12.1) |
| Weight loss | 252 089 (4.8) | 248 915 (4.8) | 3174 (7.5) |
| Procedural approach | |||
| Open | 4 244 843 (81.2) | 4 212 733 (81.3) | 32 110 (76) |
| Percutaneous or laparascopic | 982 630 (18.8) | 972 462 (18.8) | 10 168 (24.1) |
| Procedure | |||
| Abdominal aortic aneurysm repair | 5515 (0.1) | 5448 (0.1) | 67 (0.2) |
| Bile duct, liver, or pancreatic surgery | 59 541 (1.1) | 59 154 (1.1) | 387 (0.9) |
| Carotid endarterectomy | 165 267 (3.2) | 161 225 (3.1) | 4042 (9.6) |
| Colon surgery | 404 207 (7.7) | 400 229 (7.7) | 3978 (9.4) |
| Craniotomy | 258 360 (4.9) | 255 319 (4.9) | 3041 (7.2) |
| Spinal fusion | 528 749 (10.1) | 525 726 (10.1) | 3023 (7.2) |
| Gastric surgery | 86 935 (1.7) | 86 188 (1.7) | 747 (1.8) |
| Hysterectomy | 52 603 (1) | 52 382 (1) | 221 (0.5) |
| Rectal surgery | 33 157 (0.6) | 32 900 (0.6) | 257 (0.6) |
| Arthoplasty of knee | 1 238 228 (23.7) | 1 233 301 (23.8) | 4927 (11.7) |
| Arthoplasty of hip | 1 158 116 (22.2) | 1 150 212 (22.2) | 7904 (18.7) |
| Laminectomy | 132 108 (2.5) | 131 175 (2.5) | 933 (2.2) |
| Neck surgery | 17 484 (0.3) | 17 331 (0.3) | 153 (0.4) |
| Kidney surgery | 82 511 (1.6) | 81 826 (1.6) | 685 (1.6) |
| Ovarian surgery | 13 585 (0.3) | 13 525 (0.3) | 60 (0.1) |
| Prostate surgery | 68 213 (1.3) | 67 967 (1.3) | 246 (0.6) |
| Peripheral vascular bypass surgery | 71 385 (1.4) | 69 477 (1.3) | 1908 (4.5) |
| Small bowel surgery | 161 593 (3.1) | 159 963 (3.1) | 1630 (3.9) |
| Spleen surgery | 7262 (0.1) | 7198 (0.1) | 64 (0.2) |
| Thoracic surgery | 218 834 (4.2) | 216 422 (4.2) | 2412 (5.7) |
| Thyroid and/or parathyroid surgery | 16 440 (0.3) | 16 330 (0.3) | 110 (0.3) |
| Exploratory laparotomy | 136 756 (2.6) | 135 263 (2.6) | 1493 (3.5) |
| Gallbladder surgery | 310 624 (5.9) | 306 634 (5.9) | 3990 (9.4) |
| Outcomes | |||
| MACCE | 226 147 (4.3) | 221 409 (4.3) | 4738 (11.2) |
| 30-d Mortality | 166 646 (3.2) | 163 414 (3.2) | 3232 (7.6) |
| Myocardial infarction | 24 469 (0.5) | 23 559 (0.5) | 910 (2.2) |
| Heart failure | 40 217 (0.8) | 39 223 (0.8) | 994 (2.4) |
| Stroke | 18 565 (0.4) | 18 240 (0.4) | 325 (0.8) |
| Nonhome discharge | 1 508 400 (28.9) | 1 491 935 (28.8) | 16 465 (38.9) |
Abbreviations: CABG, coronary artery bypass graft surgery; MACCE, major adverse cardiovascular and cerebrovascular events; NA, not applicable; NSTEMI, non–ST-segment elevation myocardial infarction; SNF, skilled nursing facility.
Information is not available about what races and ethnicities were represented in the other category.
Unadjusted Outcomes
Overall, the prevalence of postoperative MACCE in patients with NSTEMI (n = 42 278) vs those without (n = 5 185 195) was 4738 (11.2%) vs 221 409 (4.3%), while the prevalence of 30-day mortality was 3232 (7.6%) vs 163 414 (3.2%), respectively (Table). The prevalence of postoperative MI was 910 (2.2%) vs 23 559 (0.5%); heart failure, 994 (2.4%) vs 39 223 (1.0%); and stroke, 325 (0.8%) vs 18 240 (0.4%), in patients with NSTEMI compared with those without NSTEMI. The unadjusted outcomes (MACCE and the components of MACCE) for patients who did or did not undergo revascularization are shown in eTable 3 in Supplement 1.
Adjusted Outcomes for Elective Surgery After a Prior NSTEMI
MACCE
Patients with NSTEMI within 30 days of elective surgery who did not have revascularization had higher odds of postoperative MACCE (adjusted odds ratio [aOR] 2.04; 95% CI, 1.31-3.16; P = .001) than patients without a previous NSTEMI (Figure 1 and eTable 4 in Supplement 1). Inspection of Figure 1 suggests that the odds of MACCE did not level off over time among the group without revascularization.
Figure 1. Association of Major Adverse Cardiac Events and Time Since Previous Non–ST-Segment Elevation Myocardial Infarction in Patients Undergoing Noncardiac Surgery.
Odds ratios (ORs) were adjusted for age, sex, dual enrollment in Medicare and Medicaid, site of origin, prior revascularization, frailty, comorbidities, surgical procedure, and year of admission. Unadjusted ORs were not adjusted for dual enrollment, prior revascularization, frailties, or comorbidities. MI indicates myocardial infarction.
Patients with NSTEMI within 30 days of elective surgery who had revascularization also had an elevated odds of postoperative MACCE (aOR, 2.15; 95% CI, 1.09-4.23; P = .03) (Figure 1 and eTable 4 in Supplement 1). However, in patients with NSTEMI who had revascularization, the odds of MACCE leveled off after 30 days. The odds of MACCE in these patients between 31 and 60 days were not significantly different than in patients without a prior NSTEMI (aOR, 1.3; 95% CI, 0.82-2.06; P = .26). The odds of MACCE were not significantly different in patients with a prior NSTEMI who underwent DES placement compared with patients without a prior NSTEMI when 30 or less, 31 to 60, 61 to 90, and 121 to 180 days elapsed between a prior NSTEMI and surgery (Figure 2). However, the confidence intervals for these odds ratios were wide, and it was not possible to rule out clinically important increases in risk. After 180 days, the odds of MACCE increased significantly in the main analysis (181-365 days: aOR, 1.46; 95% CI, 1.25-1.71; P < .001) and for those patients who underwent DES placement (181-365 days: aOR, 1.73; 95% CI, 1.42-2.12; P < .001) (Figure 1 and Figure 2).
Figure 2. Subgroup Analysis of Association of Major Adverse Cardiac Events and Time Since Previous Non–ST-Segment Elevation Myocardial Infarction (NSTEMI) in Patients Undergoing Noncardiac Surgery.
Patients with a prior NSTEMI in the revascularization group were limited to drug-eluting stents. Odds ratios (ORs) were adjusted for age, sex, dual enrollment in Medicare and Medicaid, site of origin, prior revascularization, frailty, comorbidities, surgical procedure, and year of admission. Unadjusted ORs were not adjusted for dual enrollment, prior revascularization, frailties, or comorbidities. MI indicates myocardial infarction.
Mortality
Patients with a prior NSTEMI within 30 days of elective surgery who did not have revascularization had higher odds of all-cause 30-day mortality (aOR, 2.27; 95% CI, 1.32-3.92; P = .003) than patients without a prior NSTEMI (Figure 3). Inspection of Figure 3 suggests that the odds of mortality did not level off over time. Patients with a history of NSTEMI 30 days or fewer before elective surgery who had revascularization also had an elevated odds of mortality (aOR, 2.88; 95% CI, 1.30-6.36; P = .009) (Figure 3). However, for patients who had revascularization, the odds of mortality leveled off after 60 days. Between 61 and 90 days, the adjusted odds of mortality was 1.03 (95% CI, 0.57-1.86; P = .92).
Figure 3. Association of 30-Day Mortality and Time Since Previous Non–ST-Segment Elevation Myocardial Infarction in Patients Undergoing Noncardiac Surgery.
Odds ratios (ORs) were adjusted for age, sex, dual enrollment in Medicare and Medicaid, site of origin, prior revascularization, frailty, comorbidities, surgical procedure, and year of admission. Unadjusted ORs were not adjusted for dual enrollment, prior revascularization, frailties, or comorbidities. MI indicates myocardial infarction.
Adjusted Outcomes for Nonelective Surgery After a Prior NSTEMI
MACCE
Patients with a prior NSTEMI within 30 days of nonelective surgery who did not have revascularization had higher odds of postoperative MACCE (aOR, 1.87; 95% CI, 1.60-2.19; P < .001) than patients without a previous NSTEMI (Figure 1 and eTable 5 in Supplement 1). Inspection of Figure 1 suggests that the odds of MACCE did not level off over time. Patients with a prior NSTEMI within 30 days of nonelective surgery who had revascularization also had higher odds of postoperative MACCE (aOR, 1.96; 95% CI, 1.59-2.43; P < .001) than patients without a prior NSTEMI (Figure 1 and eTable 5 in Supplement 1). However, inspection of Figure 1 suggests that the odds of MACCE leveled off after 30 days. The adjusted odds of MACCE between 31 and 60 days was 1.18 (95% CI, 0.94-1.46; P = .15). In those patients with a prior NSTEMI with a DES, the odds of postoperative MACCE leveled off after 90 days (Figure 2).
After 180 days, the odds of MACCE increased significantly in the main analysis (181-365 days: aOR, 1.23; 95% CI, 1.10-1.37; P < .001) and for those patients who underwent DES (181-365 days: aOR, 1.27; 95% CI, 1.10-1.47; P = .001) (Figure 1 and Figure 2).
Mortality
Patients with a prior NSTEMI within 30 days of nonelective surgery who did not have revascularization also had a higher odds of 30-day mortality (aOR, 2.18; 95% CI, 1.85-2.58; P < .001) compared with patients without a prior NSTEMI (Figure 3). Inspection of Figure 3 suggests that the odds of mortality did not level off over time. Patients with a prior NSTEMI within 30 days of nonelective surgery who had revascularization also had a higher odds of 30-day mortality (aOR, 1.91; 95% CI, 1.52-2.40; P < .001) compared with patients without a prior NSTEMI (Figure 3). Inspection of Figure 3 suggests that the odds of mortality leveled off after 90 days; the adjusted odds ratio of mortality between 91 and 120 days was 1.00 (95% CI, 0.73-1.37; P = .99).
The results of the sensitivity analyses, in which we also adjusted for hospital characteristics, were similar to the main analyses (eTables 4 and 5 in Supplement 1).
Discussion
Using national data for 5.2 million Medicare beneficiaries from 2017 to 2020, we found that patients who underwent elective noncardiac surgery within 30 days of an NSTEMI had a 2-fold higher odds of postoperative MACCE and all-cause 30-day mortality. Most importantly, we found that the overall odds of postoperative MACCE after a prior NSTEMI leveled off after 30 days in patients who had revascularization, and after 90 days in the subset of patients with DES, and then increased after 180 days. The odds of MACCE did not level off for patients who did not have revascularization. The findings were generally consistent across elective and nonelective surgeries. The results for all-cause 30-day mortality were similar to those for MACCE except that the odds of mortality in patients with NSTEMI who had revascularization leveled off after 60 days in elective surgeries and 90 days for nonelective surgeries.
Implications
The findings of this study may have important implications for clinical practice. The most recent ACC/AHA guidelines recommend that elective noncardiac surgery be delayed at least 60 days after an MI in patients who have not undergone a coronary intervention. These recommendations were based on evidence from a single study of half a million patients in California between 1999 and 2004. Our findings suggest that it may be reasonable to delay elective noncardiac surgery between 90 and 180 days after a prior NSTEMI for patients who have undergone coronary revascularization. However, for patients with a prior NSTEMI who have not had revascularization, there is no clear evidence that delaying surgery lowers the risk of adverse outcomes because the risk of MACCE and mortality remains persistently elevated in these patients.
Strengths and Limitations
This study has several important strengths. First, we separately examined the association between surgical timing and outcomes in patients with NSTEMI who did and did not have revascularization. Second, examining outcomes in patients undergoing nonelective surgery minimizes selection bias and helps confirm the results in the elective cohort. Because this was a nonrandomized study, higher-risk patients may have delayed elective surgery longer than lower-risk patients; this is unlikely to be the case for nonelective surgeries. Given current AHA recommendations, it is also possible that “elective” cases performed before 60 days have elapsed after an NSTEMI are not truly elective. The evidence that the findings for elective surgeries were consistent with nonelective surgeries supports the robustness of our main findings for patients having elective surgeries. Third, this study is population based and therefore may be broadly applicable to older patients undergoing noncardiac surgery.
This study has several potential limitations. First, although we examined the risk of postoperative MACCE in patients as a function of the time elapsed since a prior NSTEMI and surgery, we did not examine the counterfactual: namely, the risk of MACCE in patients with a prior NSTEMI who did not undergo surgery. Thus, the findings of this study may help guide patient and physician shared decision-making concerning surgical timing (ie, how long to delay surgery) but cannot assist patients in deciding between operative and nonoperative management. It is plausible that patients with the most severe ischemic heart disease did not pursue surgery. From a practical standpoint, it is not possible to study the counterfactual (the association between outcome and time since an NSTEMI in the absence of surgery). It would be impossible to match patients with a prior MI who underwent surgery to patients who did not undergo surgery because detailed Medicare inpatient claims data are only available for patients who have been hospitalized with an acute medical problem. Comparing patients who underwent elective surgery with those hospitalized for an acute medical condition would not allow us to examine the risk of MACCE purely as a function of the time elapsed after an NSTEMI because hospital admission for a medical condition will also drive outcomes. The alternative would be to use claims data for patients who are not hospitalized. However, these data are unlikely to include diagnostic information as granular as inpatient claims data.
Second, patients with more severe ischemic heart disease may have delayed surgery longer than patients with less severe disease. The risk of unmeasured confounding is partly mitigated by comprehensive risk adjustment, in which we adjusted for heart failure and other end-organ dysfunctions that may accompany ischemic heart disease (eg, kidney, liver, and neurologic disease). Third, survivorship bias may contribute to the decline in postoperative MACCE over time because patients with more severe ischemic heart disease are more likely to die earlier. Fourth, the protective effect of revascularization may be partly due to the death of sicker patients who underwent revascularization, especially since an early invasive approach to NSTEMIs is indicated in high-risk patients.
Fifth, the findings of this study do not necessarily apply to patients younger than 67 years. Sixth, we did not include STEMIs in our analyses because of sample size considerations. We did not combine NSTEMIs and STEMIs into a single category (acute MI) because our exploratory analyses revealed that patients with a prior STEMI experienced worse outcomes than patients with prior NSTEMIs. Seventh, we could not determine the extent to which discontinuation of dual-antiplatelet therapy, which is recommended at 6 months after implantation of a percutaneous coronary intervention, contributed to postoperative MACCE. Eighth, we excluded cases with missing data. However, given the low percentage of missing data (2.3%), it is unlikely that this complete case analysis would bias our analysis. Finally, in light of this nonrandomized study’s limitations, it is impossible to make causal inferences. Therefore, the results of this study should be interpreted with caution. Nonetheless, in the absence of randomized clinical trials, we believe that this nonrandomized trial is sufficiently rigorous to provide moderate-quality level of evidence (ie, AHA/ACC level B-NR) on which to base future recommendations on surgical timing after a prior MI.
Conclusions
This study found that the odds of postoperative MACCE and mortality leveled off between 30 and 90 days after an NSTEMI and increased after 180 days in older patients with a prior NSTEMI who had revascularization. The odds of postoperative MACCE and mortality did not level off in patients with a prior NSTEMI who did not have revascularization. Delaying elective noncardiac surgery between 90 and 180 days after a prior NSTEMI in patients who have revascularization may be reasonable. Additional studies using all-payer data are required to examine the association between surgical timing and MACCE in younger patients. Further efforts to incorporate additional cardiac prognostic factors in widely used surgical risk prediction tools should be encouraged.
eFigure. Flow Diagram Describing Selection of Cases in the Analytic Cohort.
eTable 1. ICD-10-CM and ICD-10-PCS codes used to identify patient characteristics.
eTable 2. Hospital Characteristics.
eTable 3. Patient Outcomes in Patients with Prior Acute Myocardial Infarction.
eTable 4. Models for Postoperative MACCE following elective surgery.
eTable 5. Models for Postoperative MACCE following non-elective surgery.
Data sharing statement
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eFigure. Flow Diagram Describing Selection of Cases in the Analytic Cohort.
eTable 1. ICD-10-CM and ICD-10-PCS codes used to identify patient characteristics.
eTable 2. Hospital Characteristics.
eTable 3. Patient Outcomes in Patients with Prior Acute Myocardial Infarction.
eTable 4. Models for Postoperative MACCE following elective surgery.
eTable 5. Models for Postoperative MACCE following non-elective surgery.
Data sharing statement
