Cardiac risk assessment with the Revised Cardiac Risk Index index before elective non-cardiac surgery: A retrospective audit from an Australian tertiary hospital

Postoperative Myocardial Infarction after Non-Cardiac Surgery: An Update

Every year, not less than 300 million non-cardiac surgery interventions are performed in the world. Perioperative mortality after non-cardiac surgery is estimated at 2% in patients over 45 years of age. Cardiovascular events account for half of these deaths, and most are due to perioperative myocardial infarction (MINS). The diagnosis of postoperative myocardial infarction, before the introduction of cardiac biomarkers, was based on symptoms and electrocardiographic changes and its incidence was largely underestimated. The incidence of MINS when a standard troponin assay is used ranges between 8 and 19% but increases to 20-30% with high-sensitivity troponin assays. Higher troponin values suggesting myocardial injury, both with or without a definite diagnosis of myocardial infarction, are associated with an increase in 30-day and 1-year mortality. Diagnostic and therapeutic strategies are reported.

Myocardial perfusion imaging failed to improve patient risk classification compared to the revised cardiac risk index for early cardiac complications after major non-cardiac surgery

BACKGROUND AND OBJECTIVE

Cardiac evaluation is desirable before major non-cardiac surgery with myocardial perfusion imaging (MPI) frequently utilised for risk assessment. However, the prognostic utility of MPI above a simple clinical risk calculator, the Revised Cardiac Risk Index (RCRI), is unknown.

METHODS AND RESULTS

We conducted a retrospective cohort study of at-risk patients who underwent MPI before major non-cardiac surgery in a tertiary hospital, incorporating 635 surgical procedures in 629 patients from 2013 to 2019. Major adverse cardiac events (MACE) within 30 days of surgery, including any myocardial infarction, acute pulmonary oedema, ventricular arrhythmia or cardiac death, occurred in 47 (7.4%) cases. We analysed predictive value of MPI for MACE using multivariable logistic regression and categorical net reclassification index. MPI-identified medium or large-sized reversible perfusion defects (p=0.02, odds ratio 2.9 (95% confidence interval 1.1-7.1) and RCRI score two or more (p=0.03, odds ratio 2.3 (95% confidence interval 1.1-4.8) were significantly associated with MACE after adjusting for age, coronary revascularisation, surgical priority, need for general anaesthesia, left ventricular ejection fraction (LVEF) and fixed perfusion defects. MPI risk factors (LVEF, reversible perfusion and fixed perfusion defects) did not improve risk classification above baseline risk factors (age, RCRI and surgical priority).

CONCLUSION

MPI risk factors are weak predictors for early cardiac complications after major non-cardiac surgery and failed to improve patient risk classification beyond essential assessment using age, RCRI and surgical priority. Clinicians should consider alternative risk assessment strategies because of MPI's poor prognostic utility and its associated time and financial costs. This article is protected by copyright. All rights reserved.