Among the 50 million US adults undergo non-cardiac surgery each year, an estimated 1.4-3.9% of patients experience perioperative myocardial infarction with another 6-18% showing evidence of myocardial injury. These cardiac insults, known as myocardial injury after noncardiac surgery (MINS) are associated with a 2.7-3.2 fold higher odds of 30-day mortality, 2.2 fold higher odds of nonfatal myocardial infarction (MI), 1.55 fold increase in 30-day congestive heart failure events, and 5.2 times higher risk of stroke, highlighting the importance of predicting and treating their occurrence. MINS is treatable, and potentially preventable, by a combination of tailored intraoperative monitoring and appropriate post-operative care.
The current approach to preoperative risk stratification is predominately derived from patient-reported functional capacity associated with history, physical examination and select laboratory investigations. This approach results in significant healthcare worker time and cost expenditures, without improved perioperative outcomes. In contrast, a technological approach utilizing conventional cardiopulmonary exercise testing (CPET) has been shown to improve individualized identification of high-risk patients prior to surgery. Widespread cardiopulmonary exercise test adoption in the perioperative setting, however, has been limited by cost, technical requirements, and time investment despite its documented utility in cardiopulmonary risk assessment. However, brief submaximal cardiopulmonary exercise testing (smCPET) addresses the limitations of conventional CPET including low cost, low time investment, small footprint, and ease of operator efficiency. In our pilot (under review), we demonstrated the feasibility and performance of implementing smCPET within a high-volume pre-surgical evaluation clinic.
This proposal seeks to continue work in characterizing smCPET and its role in individualized preoperative risk identification. The aim of this study proposal is to validate two clinically relevant questions: 1) Are smCPET measures superior to usual care (Duke Activity Status Index) in patients undergoing moderate to high-risk noncardiac surgery and 2) to determine which smCPET measure is more sensitive to MINS as described by abnormalities in postoperative high-sensitivity troponin measurements.
Using a smCPET-guided approach, this study seeks to characterize its value in identifying high-risk patients for MINS, provide further validation of smCPET utility as a preoperative risk stratification approach, and preliminarily identify smCPET measures with highest association with MINS.
If validated, this would provide the foundation for a smCPET-guided clinical decision support system of preoperative identification and perioperative monitoring that could 1) enhance patient outcomes by providing early prediction and detection of MINS and 2) characterize a research methodology to stratify participants for further research in assessing perioperative strategies to reduce MINS. These findings will provide one of the first examples of quantitative and individualized preoperative risk identification methods for a common and deleterious perioperative outcome.
