Heart failure-related elevation of carbohydrate antigen 125 identified by pre-operative cardiopulmonary exercise testing.

Heart failure is a major peri-operative risk factor associated with significant postoperative morbidity and mortality. Traditional biomarkers used in heart failure management include natriuretic peptides. Carbohydrate antigen 125 biomarker is well known to be elevated in ovarian cancer but can also be elevated in heart failure, particularly right-sided heart failure and heart failure with preserved ejection fraction. We report the management of a 71-year-old woman with a presumed diagnosis of ovarian cancer based on imaging and an elevated carbohydrate antigen 125, who underwent cardiopulmonary exercise testing as part of the pre-operative assessment. Exercise testing, despite being sub-maximal, identified significant but asymptomatic heart failure. Surgery was deferred and cardiology-led optimisation resulted in normalisation of her carbohydrate antigen biomarker, refuting her ovarian cancer diagnosis and avoidance of a major intra-abdominal surgery. This case highlights the role of biomarkers, such as carbohydrate antigen 125, in heart failure treatment and the use of exercise testing in heart failure diagnosis and management. Cardiopulmonary exercise testing facilitated the identification of hidden comorbidities leading to better pre-operative risk stratification, optimisation and collaborative decision making.