Prognosis of Myocardial Injury After Non-Cardiac Surgery in Adults Aged Younger Than 45 Years

Improved Re-estimation of Perioperative Cardiac Risk Using the Surgical Apgar Score: A Retrospective Cohort Study

OBJECTIVE

To assess whether the Surgical Apgar Score (SAS) improves re-estimation of perioperative cardiac risk.

BACKGROUND

The SAS is a novel risk index that integrates three relevant and easily measurable intraoperative parameters (blood loss, heart rate, mean arterial pressure) to predict outcomes. The incremental prognostic value of the SAS when used in combination with standard preoperative risk indices is unclear.

METHODS

We conducted a retrospective cohort study of adults (18 years and older) who underwent elective noncardiac surgery at a quaternary care hospital in Canada (2009-2014). The primary outcome was postoperative acute myocardial injury. The SAS (range 0-10) was calculated based on intraoperative estimated blood loss, lowest mean arterial pressure, and lowest heart rate documented in electronic medical records. Incremental prognostic value of the SAS when combined with the Revised Cardiac Risk Index was assessed based on discrimination (c-statistic), reclassification (integrated discrimination improvement, net reclassification index), and clinical utility (decision curve analysis).

RESULTS

The cohort included 16,835 patients, of whom 607 (3.6%) patients had acute postoperative myocardial injury. Addition of the SAS to the Revised Cardiac Risk Index improved risk estimation based on the integrated discrimination improvement [2.0%; 95% confidence interval (CI): 1.5%-2.4%], continuous net reclassification index (54%; 95% CI: 46%-62%), and c-index, which increased from 0.68 (95% CI: 0.65-0.70) to 0.75 (95% CI: 0.73-0.77). On decision curve analysis, addition of the SAS to the Revised Cardiac Risk Index resulted in a higher net benefit at all decision thresholds.

CONCLUSIONS

When combined with a validated preoperative risk index, the SAS improved the accuracy of cardiac risk assessment for noncardiac surgery. Further research is needed to delineate how intraoperative data can better guide postoperative decision-making.

Higher Preoperative Red Blood Cell Distribution Width Increases the Risk of Myocardial Injury After Noncardiac Surgery in Advanced-Age Patients: A Retrospective Cohort Study

Background

Myocardial injury after noncardiac surgery (MINS) has been associated with worse outcomes. The aim of our study was to investigate the relationship between higher red blood cell distribution width (RDW) and postoperative 30-day MINS among advanced-age patients.

Methods

This was a retrospective observational study including advanced-age patients (≥65 years old) who underwent noncardiac surgery between January 2017 and August 2019 at the First Medical Center of the Chinese People's Liberation Army General Hospital. Patients were divided into two groups according to the cutoff value identified the lowest risk using Restricted Cubic Splines (RCS) model. The primary outcome was the incidence of MINS within 30 days after surgery. The relationship between RDW and MINS was investigated by univariable and multi-variable logistic regression analysis. Propensity score (PS) analysis, including propensity score matching (PSM) and inverse probability treatment weighting (IPTW), as well as subgroup analysis were also conducted to identify the effect of RDW.

Results

The result of the RCS analysis showed that the risk of MINS in advanced-age patients increases when the baseline RDW is >12.8%. In the univariate analysis, baseline RDW >12.8% was a risk factor for postoperative MINS [odds ratio (OR)=2.11; 95% confidence interval (CI): 1.83-2.44; p<0.001]. After adjustment for all possible components, there was also a high risk of MINS for patients with elevated RDW [Adjusted OR (aOR)=1.43; 95% CI: 1.27-1.61; p<0.001). The relationship remained after PS analysis (aOR=1.24; 95% CI: 1.04-1.47; p=0.016 in PSM; aOR=1.23; 95% CI: 1.05-1.44; p=0.012 in IPTW, respectively). Significant differences between two groups were established in the incidence rate of postoperative cardiac complications and mortality.

Conclusion

Elevated preoperative RDW is significantly associated with an increased risk of MINS within postoperative 30 days.

Myocardial injury in noncardiac surgery

Myocardial injury is defined as an elevation of cardiac troponin (cTn) levels with or without associated ischemic symptoms. Robust evidence suggests that myocardial injury increases postoperative mortality after noncardiac surgery. The diagnostic criteria for myocardial injury after noncardiac surgery (MINS) include an elevation of cTn levels within 30 d of surgery without evidence of non-ischemic etiology. The majority of cases of MINS do not present with ischemic symptoms and are caused by a mismatch in oxygen supply and demand. Predictive models for general cardiac risk stratification can be considered for MINS. Risk factors include comorbidities, anemia, glucose levels, and intraoperative blood pressure. Modifiable factors may help prevent MINS; however, further studies are needed. Recent guidelines recommend routine monitoring of cTn levels during the first 48 h post-operation in high-risk patients since MINS most often occurs in the first 3 days after surgery without symptoms. The use of cardiovascular drugs, such as aspirin, antihypertensives, and statins, has had beneficial effects in patients with MINS, and direct oral anticoagulants have been shown to reduce the mortality associated with MINS in a randomized controlled trial. Myocardial injury detected before noncardiac surgery was also found to be associated with postoperative mortality, though further studies are needed.