The goal of this observational study is to learn whether metabolic inflexibility, which means reduced ability of the body to switch between using fats and sugars for energy, is associated with myocardial injury after non-cardiac surgery (MINS) in adults undergoing major elective abdominal cancer surgery.
The main question it aims to answer is:
Does pre-operative metabolic inflexibility predict myocardial injury after non-cardiac surgery (MINS) within the first 72 hours after surgery?
Participants will continue with their usual surgical care and pre-planned CPET (which can measure metabolic flexibility). As part of the study, participants will:
* Have additional blood samples taken before and after surgery * Have an echocardiogram and, where possible, muscle ultrasound * Wear a wrist-worn activity monitor before surgery * Have routine clinical and surgical information collected from their medical records * Receive a follow-up phone call around 90 days after surgery
Adults aged 18 or over
Scheduled for major elective abdominal cancer surgery with planned overnight admission
Scheduled for pre-operative CPET
Able to provide written informed consent
Less than 18 years old
Emergency surgery
Unable or unwilling to undergo CPET
Pregnancy