Ankle-Brachial Index Estimating Cardiac Complications After Non-Cardiac Surgery

Introduction: Patients undergoing noncardiac surgery are at increased risk of cardiovascular complications. The development of methods that can accurately predict the occurrence of these events is of critical importance and large studies have been published with this purpose. Based on these studies, several algorithms have been proposed to predict of cardiovascular events postoperatively. However, quantification of this risk is often difficult to measure, especially in those patients with subclinical disease, not always detected in routine evaluation. The ankle brachial index (ABI) has proved a valuable tool in the quantification of cardiovascular risk, and perhaps the most promising when compared with other methods. It is easy, cheap, fast and feasible in office care, with a great acceptance between patients and small intra and inter observer variability. Despite strong evidence of the utility of ABI as a tool in assessing cardiovascular risk, there are no data about the use of ABI in other patients referred for non vascular surgery, which constitutes the majority of operations performed worldwide.

Objectives: To evaluate the use of ABI as a predictor of cardiovascular events in patients undergoing non-cardiac and non-vascular surgery and its applicability as a tool in the reclassification of patient risk groups established by guidelines for perioperative evaluation.

Methods: 300 moderate to high risk patients referred for non-vascular and non-cardiac will be included. Data about risk factors, signs and symptoms, physical examination and treatment used will be collected before surgery. The ABI will be measured and the patient will be monitored for 30 days to the detection of cardiovascular events: death from any cardiovascular causes, unstable angina, nonfatal myocardial infarction, isolated elevation of troponin, decompensated heart failure, cardiogenic shock, stop nonfatal heart failure, pulmonary edema, stroke and lower limb ischemia. Postoperative electrocardiogram, total creatine kinase, MB fraction and troponin I will be measured daily until 3º day and whenever clinically indicated.