The Effects of General Versus Spinal Anesthesia on Postoperative Myocardial Injury

Overview

In this prospective, randomized, single-blind study, we aim to compare the effects of general anesthesia and spinal anesthesia on postoperative myocardial injury in elderly patients undergoing hip surgery. Cardiovascular events are a leading cause of mortality and morbidity following non-cardiac surgery, with myocardial injury after non-cardiac surgery (MINS) being a significant concern. MINS, characterized by asymptomatic elevation of troponin levels without accompanying ECG findings, is closely associated with postoperative mortality. With the increasing prevalence of comorbidities in the elderly population and the rising frequency of non-cardiac surgeries in this demographic, understanding the effects of different anesthesia types on postoperative myocardial injury is crucial.

Cardiovascular events constitute the leading cause of mortality and morbidity following non-cardiac surgery. Myocardial Injury after Non-cardiac Surgery (MINS) is a condition diagnosed postoperatively characterized by asymptomatic troponin elevation alone. Distinguishing it from myocardial infarction, it lacks symptoms and concurrent Electrocardiography (ECG) findings, yet it correlates closely with postoperative mortality. Detection can be facilitated through troponin monitoring from preoperative period to up to 72 hours postoperatively. The Vascular Events in Noncardiac Surgery Patient Cohort Assessment (VISION) study, designed to evaluate major vascular events in patients undergoing non-cardiac surgery, reported a global prevalence of MINS at 8% with over a threefold increase in 30-day mortality. The diagnostic threshold for MINS as determined by the VISION study is a non-Hs troponin T level of ≥0.03 ng/mL. With the increasing elderly population burdened with comorbidities globally, the frequency of non-cardiac surgeries in elderly patients has risen. Despite advancements in surgical and anesthetic fields, the incidence of MINS and associated mortality continue to escalate. Risk factors associated with MINS highlight age over 75 and the presence of comorbidities. Orthopedic surgeries are most commonly performed in elderly patients, with perioperative acute myocardial infarction (MI) incidence shown to increase by 31-fold in knee surgeries and 25-fold in hip surgeries. Postoperative pain and opioid use in this patient group significantly contribute to overlooked myocardial ischemia. In a sub-study of the VISION trial examining cardiovascular outcomes of orthopedic surgery, the incidence of MINS was reported at 11.9%, with 30-day mortality rates of 1% in MINS-absent patients and 9.8% in MINS-present patients, markedly higher than non-orthopedic surgeries. Several studies have identified perioperative and postoperative hypotension as the primary risk factor for MINS, emphasizing the importance of anesthesia management in preventing perioperative hypotension. However, no study has specifically focused on the relationship between chosen anesthesia technique and the development of hypotension and MINS. George R. and colleagues conducted a prospective observational cohort study in India analyzing the incidence and risk factors of MINS, finding a higher incidence in patients receiving peripheral nerve blocks compared to general anesthesia and spinal anesthesia, particularly in patients with high cardiac comorbidities. Nonetheless, no significant relationship was observed between the chosen anesthesia technique and the development of MINS in the orthopedic surgery subgroup of the VISION study. In this prospective, randomized, single-blind study, we aim to compare the effects of general anesthesia and spinal anesthesia on postoperative myocardial injury in elderly patients undergoing hip surgery.