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Mr Eduardo Alegria-Barrero
Dr. Eduardo Alegria-Ezquerra
Low-risk operations in low-risk patients may be performed after a good clinical history taking and examination only. A 12-lead ECG however should be obtained before emergency operations and intermediate or high-risk surgery. Obviously, a 12-lead ECG is also necessary for cardiac patients who need any surgery at all (except for very minor procedures). A normal ECG is a marker of low cardiac risk and may usually open the way for any noncardiac operation with no need for any other prior heart imaging procedure. A perioperative cardiac evaluation - preferebly carried out by a cardiologist - is mandatory in high-risk patients and in patients with an abnormal ECG.
Clinical evaluation prior to surgery in many countries is left to anesthesiologists. However, cardiologists are frequently involved in preoperative evaluation as well, because cardiac complications have the highest clinical and prognostic relevance for most interventions. Cardiovascular complications occur for example in 1-5% of all vascular surgical procedures (1). A classic and virtually mandatory component of preoperative evaluation is the 12-lead electrocardiogram (ECG).
The aim of this brief review is to present the current role, indications, and interpretation of preoperative ECG and the subsequent management of patients depending on its results.
The purpose of preoperative clinical evaluation is to detect the clinical circumstances which can lead to worsened outcomes. A) For patients undergoing cardiac surgery, there are more than 20 published risk scores, which include dozens of demographic and clinical variables; the most commonly used are the EuroSCORE, the Cleveland Clinic and the CABDEAL models (2). B) For noncardiac surgery, both in cardiac and noncardiac patients, many risk models have been used as well; no single index has shown clear superiority for predicting cardiac complications (3). Current risk stratification guidelines are based on the presence or absence of a number of factors classified into three groups in descending order of risk: active cardiac conditions, intermediate risk predictors and minor risk predictors (4).
Rest ECG is considered an inherent part of routine preoperative evaluation in many clinical practice guidelines, but American guidelines include abnormal ECG in the minor risk predictors category, that is, not independently associated with an increased perioperative risk (4). This statement applies only to cardiac patients though, as will be developed below. In noncardiac patients, guidelines also state that an abnormal ECG should prompt a cardiologist consultation (4).
It has been shown that the mere classification of ECGs into normal or abnormal improves the prognostic capabilities of clinical evaluation alone in noncardiac patients (5), as assessed taking into account both patient (see before) (4) and surgery (Table 1) risks. For preoperative purposes, an "abnormal" ECG is defined as (see Table 2): left ventricular hypertrophy; pathological q waves or ST-segment shift; and some abnormal rhythms (atrial fibrillation/flutter, pacemaker rhythm, ventricular ectopics) (5). Rest sinus tachycardia (of course not related to the disease requiring surgery) should probably be added to this list, as some studies have shown a close relationship with cardiac events (6). Nevertheless, more than half of preoperative ECGs are abnormal and rarely does this finding lead to modifying the therapeutic approach or correlates with outcomes in low-risk patients (7). On the other hand, the prognostic information obtained from the preoperative ECG is relevant in coronary patients (8).
Apart from socio-economic reasons, some authors have questioned that routine ECG would add prognostic value to a thorough clinical examination in patients undergoing noncardiac operations - as cardiac surgery, on its own, requires a complete cardiovascular evaluation, which obviously includes an ECG. (9).
Figure 1 shows the proposed algorithm for the evaluation of all patients undergoing noncardiac surgery (4,9). Without entering into the debate about which specialists should be in charge of the initial evaluation of surgical candidates, the algorithm considers that ECGs should be ordered for patients: (i) undergoing emergency operations; (ii) at high risk due to comorbidities (heart failure, coronary disease, cerebrovascular disease, diabetes, renal insufficiency, uncontrolled hypertension); and (iii) for high or intermediate-risk procedures (low-risk being those performed under local or locoregional anaesthesia, dental procedures, endoscopic surgery, and breast, endocrinologic, gynecologic, and plastic and reconstructive surgery). Finally, a thorough cardiological evaluation (history and physical examination, ecocardiogram and possibly a stress test for ischemia) if rest ECG is abnormal. Table 1: Cardiac risk of noncardiac surgical procedures (modified from ref. 4)
Table 2 : Criteria for abnormal preoperative ECG (in noncardiac patients) (modified from ref. 5)
The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology
1. Gregoratos G. Current guideline-based preoperative evaluation provides the best management of patients undergoing noncardiac surgery. Circulation 2008;117:3134-44. 2. Kurki TS, Järvinen O, Kataja MJ, Laurikka J, Tarkka M. Performance of three preoperative risk indices; CABDEAL, EuroSCORE and Cleveland models in a prospective coronary bypass database. Eur J Cardiothorac Surg 2002;21:406-10. 3. Gilbert K, Larocque BT, Patrick LT. Prospective evaluation of cardiac risk indices for patients undergoing noncardiac surgery. Ann Intern Med 2000;133:356-9. 4. Fleisher LA, Beckman JA, Brown KA, Calkins H, Chaikof E, Fleischmann KE, et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery) Developed in Collaboration With the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery. J Am Coll Cardiol. 2007;50:1707-32. 5. Noordzij PG, Boersma E, Bax JJ, Feringa HHH, Schreiner F, Schouten O, et al. Prognostic value of routine preoperative electrocardiography in patients undergoing noncardiac surgery. Am J Cardiol 2006;97:1103-6. 6. Biccard BM. Heart rate and outcome in patients with cardiovascular disease undergoing major noncardiac surgery. Anaesth Intensive Care 2008;36:489-501. 7. Ajimura FY, Maia AS, Hachiya A, Watanabe AS, Nunes MP, Martins MA, et al. Preoperative laboratory evaluation of patients aged over 40 years undergoing elective non-cardiac surgery. Sao Paulo Med J 2005 123:50-3. 8. Jeger RV, Probst C, Arsenic R, Lippuner T, Pfisterer ME, Seeberger MD, et al. Long-term prognostic value of the preoperative 12-lead electrocardiogram before major noncardiac surgery in coronary artery disease. Am Heart J 2006;151:508-13. 9. Schouten O, Bax JJ, Poldermans D. Assessment of cardiac risk before non-cardiac general surgery. Heart 2006;92:1866-72.
Cardiology Department. University Clinic of Navarra. Spain.
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