|Year : 2015 | Volume
| Issue : 3 | Page : 72-75
The Role of Routine ECG Testing in Preoperative Evaluation Prior to Non Cardiac Surgery
Sushma Trikha, Neelima Singh
Department of Medicine, Gajara Raja Medical College, Gwalior, Madhya Pradesh, India
|Date of Web Publication||7-Sep-2015|
Dr. Neelima Singh
"Kamla Bhawan", Dal Bazar Tiraha, Lashkar, Gwalior - 474 009, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
The current study attempts to address an issue which is the need to obtain a preoperative electrocardiography (ECG) in all patients prior to non-cardiac surgery. Significance in patients without symptoms is uncertain. Aims: To study the incidence of ECG abnormalities in preoperative patients posted for elective non-cardiac surgery. 2. To study the co-relation of risk factors with ECG abnormalities. Materials and Methods: All hospitalized clinically stable patients advised ECG for preanesthetic assessment prior to elective non-cardiac surgery were included as subjects. Co-relation of risk factors with ECG abnormalities were studied. Statistical analysis used: Statistical Package for the Social Sciences (SPSS) software (chi-square test) Results: One hundred and twenty-eight males and 65 females were enrolled for study. Preoperative ECG was normal in 116 (60.10%) and abnormal in 77 (39.90%) patients. Abnormal ECG was more common in those with hypertension, diabetes, cardiovascular disease, and smoking. No adverse postoperative event was observed in any of the patient. Conclusions: ECG being a simple non-invasive tool should be considered for all patients undergoing elective procedures and should be mandatory for those with risk factors.
Keywords: Electrocardiogram, non-cardiac surgery, preoperative
|How to cite this article:|
Trikha S, Singh N. The Role of Routine ECG Testing in Preoperative Evaluation Prior to Non Cardiac Surgery. Heart India 2015;3:72-5
| Introduction|| |
The goal of preoperative medical assessment is to reduce the patient's surgical and anesthetic perioperative morbidity or mortality, and to return them to desirable functioning as early as possible.
This study was planned to assess the utility of routine electrocardiography (ECG) in clinically stable preoperative patients with and without risk factors for coronary heart disease.
Perioperative risk is multifactorial and depends on the medical condition of the patient, the invasiveness of the surgical procedure and the type of anesthetic administered. 
Cardiovascular complications are a major cause of perioperative morbidity and mortality in patients undergoing non-cardiac surgery. Age, increased physical status score, and male gender were associated with a greater incidence of abnormal preoperative ECGs. 
Finally, a cardiological assessment is indicated if the ECG is abnormal. Routine electrocardiography has the potential to detect diseases those can have impact on perioperative care in selected patients. The availability of an ECG may be useful in determining if it is appropriate to proceed. 
Patients with coronary artery disease undergoing major non-cardiac surgery, guidelines concerning preoperative evaluation, stress testing, coronary angiography, and revascularization is justified. 
Based on the American College of Cardiology and American Heart Association guidelines, patients without risk factors are considered to be at low risk and do not require additional evaluations for coronary artery disease. Patients with 1 or 2 cardiac risk factors represent an intermediate-risk group for perioperative cardiac complications. Patients with 3 or more risk factors are at high risk for cardiac complications and the use of non-invasive testing may help further refine cardiac risk based on the presence and absence of test-induced myocardial ischemia. 
Non-invasive testing offers only limited assistance in estimating risk for these patients. 
Aims and objectives
To study the incidence of ECG abnormalities in preoperative patients posted for elective non-cardiac surgery.
To study the co-relation of risk factors with ECG abnormalities.
To assess the utility of routine ECG in clinically stable preoperative patients.
| Materials and Methods|| |
This study was conducted in JA Group of Hospitals, G.R. Medical College, Gwalior from May 2011-October 2011. Ethical clearance was given by the ethical society of G.R. Medical College, Gwalior. All hospitalized clinically stable patients advised ECG for preanesthetic assessment prior to elective non-cardiac surgery were included as subjects. Pregnant females, hemodynamically unstable patients and those undergoing emergency surgeries were excluded from the study.
This was a prospective study where a total of 193 patients advised preoperative ECG for elective non-cardiac surgery were enrolled as subjects. A detailed history and clinical examination was done in order to find out the risk factors.
Clinical examination was done as per pretyped proforma, followed by recording of 12 lead ECG in all the patients in addition to routine biochemistry and skiagram.
ECG results showing atrial fibrillation, left or right bundle branch block, left ventricular hypertrophy, premature ventricular complexes, pacemaker rhythm, or Q-wave or ST-segment changes, and QT prolongation and rhythm abnormalites were classified as abnormal. The patients were followed up during hospitalization and were evaluated for the presence of perioperative cardiovascular events (PCE). Analysis was done using Statistical Package for the Social Sciences (SPSS) software. Values <0.05 were considered statistically significant.
| Results|| |
This was a prospective study conducted over a period of 6 months from May 2011 to October 2011. One hundred and twenty-eight males and 65 females were enrolled for study [Figure 1].
Eleven (5.69%) cases were from general surgery, 27 (13.98%) orthopedics, 120 (62.17%) neurosurgery, 16 (8.29%) ophthalmology, 12 (6.21%) ear nose throat (ENT), and 7 (3.6%) from gynecology department [Table 1].
Youngest patient was 10 years old and the oldest patient was 85 years of age. Mean age was 41.15 years [Table 2].
Nine (4.66%) patients had history of cardiovascular disease, 27 (13.99%) had hypertension, 13 (6.735%) had diabetes, and 39 (20.20%) were smokers [Figure 2].
|Figure 2: Image showing distribution of risk factors among the study group|
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Preoperative ECG was normal in 116 (60.10%) and abnormal in 77 (39.90%) patients.
Sinus tachycardia was the most frequent rhythm abnormality observed in 17 (8.81%) cases. Other rhythm abnormalities were sinus bradycardia 14 (7.25%), ventricular premature complexes 3 (1.55%). Conduction defects included first degree heart block in 5 (2.59%), left bundle branch block in 1 (0.52%), complete right bundle branch block in 8(4.14%), incomplete right bundle branch block in 1 (0.52%), and left anterior hemiblock in 11 (5.69%) cases. Left atrial enlargement in 2 (1.036), biatrial enlargement in 1 (0.52%), left ventricular hypertrophy was present in 6 (3.11%). Inferolateral ischemia in 3 (1.55%), anterior wall ischemia 3 (1,55%), ECG changes suggestive of old myocardial infarction was present in 5 (2.59%), poor progression of R wave in 3 (1.55%), low voltage complex in 1 (0.52%), and prolonged QT in 1 (0.52%).
Hypertensive patients had higher incidence of abnormal preoperative ECG 26/31 (83.88%) compared to normotensives 51/162 (31.48%). This co-relation was highly significant (P value = 0.0012).
Diabetics had higher incidence of abnormal ECG 11/13 (84.61%) versus non-diabetics 64/180 (35.55%) (P value = 0.041)
Patients with known cardiovascular disease had higher incidence of abnormal ECG 8/9 (88.89%) than those without cardiovascular disease 69/184 (37.5%) (P value = 0.002).
Moreover, 22/39 (56.41%) smokers versus 55/154 ( 35.71%) non-smokers had abnormal ECG (P value = 0.018).
No adverse postoperative event was observed in any of the patient.
| Discussion|| |
Advanced age places a patient at increased risk for surgical morbidity and mortality. ECG abnormality increased with every decade after 40 [Table 3].
The reason for an age-related increase in surgical complications appear to correlate with an increased likelihood of underlying disease states in older persons. 
Seventy-seven (39.90%) preoperative patients had abnormal ECG. In a study by Liu LL et al., out of 513 patients aged 70 years and above undergoing non-cardiac surgery, 386 patients (75.2%) had abnormal preoperative ECG.  This difference can be attributed to the age-group involved which ranged from 10 years to 85 years. Mean age being 41.15 years [Table 2].
ECG abnormalities included sinus tachycardia which was the most common rhythm abnormality observed in 17 (8.81%), sinus bradycardia 14 (7.25%). Logically sinus tachycardia is not an abnormality requiring cardiac intervention.
ECGs based on an age cutoff alone may not be indicated, because ECG abnormalities in older people are prevalent but non-specific and less useful than the presence and severity of co-morbidities in predicting postoperative cardiac complications.
Hypertensive patients had higher incidence of abnormal preoperative ECG 26/31 (83.88%) compared to normotensives 51/162 (31.48%) P value = 0.0012.
During the postoperative period, diabetic patients are at risk of poor wound healing, increased infection rates and acute renal failure. 
Diabetics had higher incidence of abnormal preoperative ECG 11/13 (84.61%) versus non-diabetics 64/180 (35.55%) P value = 0.041.
Myocardial infarction, pulmonary edema, ventricular fibrillation, primary cardiac arrest, or complete heart block are defined as major perioperative cardiac complications.
Patients with known cardiovascular disease had higher incidence of abnormal ECG 8/9 (88.89%) than those without 69/184 (37.5%) P value = 0.002.
Smokers had higher incidence of ECG abnormality compared to non-smokers 22/39 (56.41%) smokers versus 55/154 (35.71%) non-smokers (P value = 0.018).
Previous study on 7306 anesthetized patients showed overall mortality of 1.2% and most of the deaths occurred in elderly 70 years and above.  In our study there was no adverse postoperative outcome. This difference can be attributed to lower mean age of our patients.
Some studies have questioned the utility of preoperative ECG for screening asymptomatic individuals undergoing a variety of surgical procedures but they agree to the point that clinical risk factors should form the basis of risk assessment and prediction.  More so the usefulness of its routine use in lower risk surgery is questionable. 
Though, ECG monitoring has been included in the minimum mandatory monitoring guidelines there is no absolute consensus as to who should have a preoperative ECG. 
Neither preoperative ECGs nor results of preoperative screening questionnaires were predictive of adverse cardiovascular perioperative events questioning the utility of preoperative ECGs in the ambulatory surgery setting, in younger, relatively healthy patients. 
The aim of the preoperative cardiac risk assessment is to evaluate the presence and degree of coronary artery disease along with other risk factors such as cerebrovascular disease, renal insufficiency, and diabetes mellitus that may influence the perioperative risk of these patients. 
Patients with > or =3 risk factors or active cardiac conditions should undergo stress testing. 
Performing routine screening tests in patients who are otherwise healthy is invariably of little value in detecting diseases and in changing the anesthetic management or outcome. 
Our study strengthens the argument for preoperative ECG in those with risk factors like diabetes, hypertension and cardiovascular disease, and smokers.
As abnormal preoperative ECGs are frequent we feel that a minimum test for evaluation of heart should include at least an ECG prior to any elective surgery because preoperative testing offers a platform for detection of asymptomatic significant cardiac abnormalities that may require follow-up in future.
| Limitations|| |
This study had its limitations. Firstly, the sample size was small. Secondly, older patients and those with significant co-morbidities and risk factors seems to be under represented in our study as these patients tend to opt for medical treatment rather than surgical if options are available.
| Conclusion|| |
Abnormalities on preoperative ECGs are common but are of limited value in predicting postoperative cardiac complications. ECG being a simple non-invasive and economical tool should be considered for all patients undergoing elective procedures and should be mandatory for those with risk factors.
Further studies in clinically stable patients with risk factors like diabetes and hypertension and smoking will further enlighten us regarding the utility of routine ECG in preoperative patients.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]