Risk stratification and perioperative management of frail cardiovascular surgery patients

Abstract

Due to the increasing longevity of patients, the number of elderly individuals in need of cardiovascular surgery rises. However, elderly patients often present with frailty, which is associated with postoperative complications and mortality. Detecting frailty can be challenging due to the absence of standardized measurement tools. This thesis assesses novel frailty biomarkers to improve preoperative risk assessment for high-risk elderly patients. Additionally, it explores perioperative treatment strategies and their impact on postoperative outcomes among frail elderly individuals. Part I of the thesis focuses on evaluating tools designed to refine risk stratification for elderly patients undergoing cardiovascular surgery. Chapter 2 examines the utilization of the AGE-reader, a device that measures "Advanced Glycation End products" (AGEs) in the skin through autofluorescence (Skin Autofluorescence or SAF). AGEs hold potential as biomarkers of biological age. The primary objective was to ascertain the relationship between SAF levels and frailty, postoperative complications, and a composite endpoint of one-year disability or mortality. The study encompassed 555 elderly heart surgery patients, with 22% identified as frail. SAF levels exhibited the strongest association with dependence in daily functioning and impaired cognition. An algorithm was developed to identify frail patients based on SAF levels, gender, medication use, preoperative hemoglobin, and EuroSCORE II. SAF levels were also linked to disability or death one-year post-surgery. Chapters 3 and 4 evaluate the association between muscle mass (Chapter 3) and density (Chapter 4) and postoperative mortality in vascular surgery patients. Low muscle mass was found to correlate with poor long-term survival, while low muscle density was associated with increased in-hospital, one-year, and long-term mortality, regardless of age, gender, and BMI. Chapter 5 explores the relationship between postoperative hemoglobin levels and functional recovery in elderly cardiac surgery patients, demonstrating that low Hb levels within 72 hours after surgery were significantly linked to increased mortality or disability three months post-surgery, negatively impacting mental quality of life. Part II of the thesis assesses perioperative care for frail cardiovascular patients. Chapter 6 outlines the process of preoperative frailty assessment and multidisciplinary decision-making for frail older vascular patients through case studies. Chapter 7 evaluates the impact of preoperative multidisciplinary decision-making on postoperative outcomes for frail older cardiac surgical patients, revealing a reduced risk of severe complications and shorter hospital stays. Chapter 8 investigates critical oxygen delivery (DO2) thresholds for acute kidney injury in patients aged 70 and above undergoing heart surgery with cardiopulmonary bypass (CPB). Results show that a DO2 below 270 ml/min/m² significantly raised the risk of acute kidney injury, but no association was found between frailty and this outcome. Increasing DO2 above the 270 ml/min/m² threshold could mitigate kidney failure risk in older patients. Chapter 9 presents a study protocol for a randomized, placebo-controlled multicenter study examining the effects of postoperative intravenous iron treatment on disability in patients with postoperative anemia. The study will involve 310 older patients who undergo elective heart surgery, with results informing whether early treatment of postoperative anemia with intravenous iron improves disability after 90 days.