ISSN- 0301-1216
Indian J. Prev. Soc. Med. Vol. 54, No.1, 2023
Electrocardiogram abnormalities detected during a routine medical examination of healthy members of the armed forces: An observational study
Munish Sharma
1, Sanjeev Sengupta
2, Kiran Maribashetti
3, Jnanaprakash B Karanth
4ABSTRACT
Background and objective: Only few studies addressed ECG findings in healthy members of the Indian armed forces or the general population of India. The study was conducted to assess the prevalence of abnormal electrocardiogram (ECG) detected during a routine medical examination of healthy members of the Indian armed forces. Method: The ECG of all the healthy members performed during a routine medical examination was initially reported by physicians at various armed forces service hospitals in the Eastern Command (EC) and later perused by the cardiologist at Command Hospital Eastern Command (CHEC).
Individuals with abnormal ECG underwent relevant cardiac evaluation at CHEC to determine the underlying pathology. Results: A total of 1,045 members of the Indian armed forces were included in the study and were categorised as follows: 244 in Group-1 (aged < 25years), 478 in Group-2 (aged between 25 to 40 years) and 323 in Group-3 (aged > 40years). Abnormal ECG was found in 108 (10.3%) individuals. Left axis deviation was the most common abnormality detected in 18 (1.2%) individuals, followed by incomplete RBBB and T wave inversion which were each found in 15 subjects (1.43% of all individuals and 13.9% of the subjects with abnormal ECG). The prevalence of ECG abnormalities detected in our study was similar to that reported in previous studies. Only five (0.47%) of the 108 individuals with abnormal ECG were found to have underlying cardiovascular disease. Conclusion: Morphological ECG abnormalities were common in the subjects but did not vary significantly from the general population, and only a minority had underlying pathology. While most of the abnormalities may only represent normal variations and their occurrence in healthy individuals during routine health check-ups should not be alarming. Evaluation of structural heart disease should be done for ECG abnormalities with prognostic significance that has been well-characterised.
Keywords: Electrocardiogram, prevalence, abnormal ECG, armed forces
Introduction
In the present day scenario we are observing increased incidence of hypertension, coronary artery disease (CAD) and stroke in young1. Screening populations who are at risk for cardiovascular disease in order to reduce morbidity and mortality is recommended. However, a debate has emerged as to whether the condition responsible for such disease could be effectively detected before its onset in healthy army personnel, which would enable the introduction of appropriate remedial measures. Indeed, systematic cardiovascular screening, beyond preventive health evaluation in recreational athletes and the general adolescent and young adult population, has not been recommended or adequately pursued previously.
____________________________
1. Department of Medicine & Cardiology, Cardiologist, Command Hospital (Eastern Command), Kolkata, Email: [email protected]
2. Senior Advisor, Department of Medicine & Cardiology, Military Hospital Secundrabad, Email: [email protected]
3. Department of Medicine, Command Hospital, Chandimandir, Email: [email protected]
4. Consultant, General Medicine, Shripad Hegde Kadave Institute of Medical Sciences, Sirsi- 581402, Email: [email protected]
Corresponding Author: Maj (Dr.) Jnanaprakash Karanth, Consultant General Medicine Shripad Hegde Kadave Institute of Medical Sciences, Sirsi; 9869720798/9538070300
Submission 15.02.2023 Revision 08.03.2023 Accepted 25.03.2023 Printing 30.03.2023
Such evaluation has been typically reserved for patients with symptoms suspected to be of cardiovascular origin.
Hence, this study was conducted to evaluate electrocardiogram (ECG) abnormalities in asymptomatic individuals and the prevalence of cardiac diseases in individuals reporting with such abnormal ECG during a routine medical examination.
Materials and Methods
This study was conducted at Command Hospital (Eastern Command) and various peripheral hospitals of Indian armed forces to which it served as a referral tertiary care centre for two years. ECG of the asymptomatic individuals without a history of any medical co-morbidity who reported to dependent hospitals for a routine or periodic medical examination was included in the study. ECG (12 leads) was recorded at a speed of 25 mm/s with the individual lying in the supine position after 10 minutes of rest and ingestion of a caffeinated beverage. Besides, nicotine usage was prohibited for at least two hours before the ECG recording. A routine medical examination was done to assess any cardiac or respiratory system abnormality. ECGs were evaluated initially by the physicians and later sent to the cardiologist for perusal if required. Patients with a diagnosed cardiac disability and any individual with cardiac or respiratory symptoms were excluded from the study. Individuals were categorized in the following three groups based on their age: Group 1:
individuals below 25 years of age; Group 2: individuals from 25 to 40 years of age and Group 3: individuals above 40 years of age. All individuals with ECG abnormality underwent cardiac evaluation with 2D-ECHO, Holter monitoring, percutaneous coronary angiography or other tests as required on a case-by-case basis.
The ECG abnormalities were defined as follows: Heart rate variation, bradycardia was defined as a heart rate of less than 60 beats per min and tachycardia was defined as a heart rate of 100 or more beats per minute2. Mean QRS axis of three standard leads were defined as Right axis deviation (RAD) was defined as axis more than100 degrees, left axis deviation (LAD) as axis less than -30 and physiological LAD as an axis between 0 and -30 . 3 Poor R wave progression was defined as R-wave less than 2–4 mm in leads V3 or V4 and/or the presence of reversed R-wave; progression was defined as R in V4 < R in V3 or R in V3 < R in V2 or R in V2 < R in V1 or any combination of these 4. Complete right bundle branch block (cRBBB) was defined as per the criteria, QRS duration > 120 msec, a secondary R wave in V1/V2, wide slurred S wave in lead I and V5/V6, associated feature: ST segment or T wave depression in V1-V2.5 Incomplete RBBB (iRBBB) as QRS duration < 120 ms but > 110 ms. Secondary R’ wave in right precordial leads V1 or V2 (usually rsr’, rsR’ and rSR’) 5, 6. Left bundle branch block (LBBB) was defined as per the criteria ofQRS > 120 msec, broad R in I, V5/V6, absence of Q in V5/V6. 7 PR interval abnormalities were defined as Increased PR interval or first-degree atrioventricular (AV) block (more than 200 ms) and pre-excitation (PR interval < 120 ms with delta wave).3 Advanced heart block as any heart block higher than first-degree AV block. 3 Junctional rhythm as ECG with a rate of 40-60 beats per minute; QRS complexes are typically narrow (< 120 ms); No relationship between the QRS complexes and any preceding atrial activity (e.g., P-waves, flutter waves, fibrillatory waves) [8]. ST-segment changes were defined as Non- specific ST-segment change: ST deviation not fulfilling the criteria for injury/ischemia.6 ST Elevation changes or ST and T wave inversion suggestive of ischemia i.e, symmetrically and/or deeply inverted T waves in >2 contiguous leads; ST depression with T wave inversion in >2 contiguous leads.3,6 Pathological Q waves as >40 mS in duration and > 25% of the ensuing R wave in amplitude present on ECG in lead V1, V2, V3, V4, V5, and V6.3, 6 Left ventricular hypertrophy (LVH) by voltage criteria - Romhilt Estes voltage criteria8.
Atrial premature complex unifocal or multifocal as the P wave of the extra-systole is abnormal and different in configuration from the sinus P wave and is premature to the basic rhythm. QRS morphology remains unchanged3. Atrial fibrillation was defined as the complete absence of P waves, presence of rapid oscillation (‘f’ waves) in varying size, timing and shape; with irregularly irregular ventricular rhythm.3 We collected written and informed consent forms that were duly signed by all participants on enrolment in our study.
Statistical analysis: Data was collected in an Excel sheet and analysed. Categorical variables have been reported in numbers and percentages. Normally distributed continuous variables have been described in mean ± SD.
Results
A total of 1,045 subjects were included in the study at the end of 02 years. The mean age of the individuals was 36.5 years (SD 10.43). The findings of the study have been summarized in Table 1. Of these individuals, 244 (23.3%) subjects were in Group-1 with a mean age of 22.1 years (SD 2.02), 478 (49.9%) subjects were in Group-2 with a mean age of 34.1 years (SD 5.6) and 323 (30.9%) were in Group-3 with a mean age of 46.5 years (SD 3.4).
Table- 1: Summary of ECG findings
ECG Abnormality
Age group (in years)
Total Percent of AbnormalPercent of Total
<25 25-40 >40
Total ECG 244 478 323 1045 --- 10
Normal ECG 219 447 271 937 --- 89.66
Physiological LAD 7 4 7 18 16.7 1.72
iRBBB 3 8 4 15 13.9 1.43
T inversion inferior leads 1 2 10 13 12.0 1.24
Sinus tachycardia 1 1 5 7 6.5 0.67
Sinus bradycardia 5 2 0 7 6.5 0.67
Pre-excitation 1 2 3 6 5.6 0.57
LAD 1 0 4 5 4.6 0.48
cRBBB 0 3 2 5 4.6 0.48
LVH by voltage criteria 4 1 0 5 4.6 0.48
T inversion in anterior leads/ lateral leads 0 1 3 4 3.7 0.38
Increased PR 0 0 3 3 2.8 0.29
Atrial fibrillation 0 1 2 3 2.8 0.29
APC 1 1 1 3 2.8 0.29
LBBB 0 1 2 3 2.8 0.29
Junctional rhythm 0 2 0 2 1.9 0.19
VPC 0 2 0 2 1.9 0.19
Poor R wave progression 0 0 2 2 1.9 0.19
Deep T inversion anterolateral leads 0 0 2 2 1.9 0.19
Significant Q waves anterior/inferior leads 0 0 2 2 1.9 0.19
Wrong lead placement 1 0 0 1 0.9 0.10
Advanced heart block 0 0 0 0 0.0 0
Total 25 31 52 108 10.33
APC: Atrial premature complexes; LAD: Left axis deviation; LBBB: Left bundle branch block;
LVH: Left ventricular hypertrophy; iRBBB: incomplete Right bundle branch block; cRBBB: complete RBBB; VPC: Ventricular premature complexes
Of the 1045 participants, 108 (10.3%) were found to have ECG abnormalities. In regard to the group-wise analysis, there were 52 (48.1%) ECG abnormalities in Group-3 followed by 31 (28.7%) subjects with ECG abnormalities in Group-2.
Overall, the most common ECG abnormality was physiological LAD, found in 18 (1.72%) of total subjects and 16.7% of subjects with ECG abnormalities. Out of these 18 subjects, seven were in Group-1 and Group-3 and four were in Group-2. The next common abnormalities were incomplete RBBB and T wave inversion which were found in 15
(1.43% of the total number of subjects and 13.9% of subjects with abnormal ECG) subjects. The most common abnormality in Group-1 was physiological LAD (7 out of 25), whereas incomplete RBBB (8 out of 31) and T wave inversion (15 out of 52) were the most common in Group-2 and Group-3 respectively. Sinus tachycardia was found in seven (1.24%) subjects and more in Group-3. Sinus bradycardia was found in seven (0.67%) subjects and more in Group- 3. Pre-excitation was found in six (0.57%) subjects. LVH by voltage criteria was found in five (0.48%) subjects and was more in Group-1. Pathological Q waves were seen in two subjects (0.19%) who were both in Group-3.
Detection of structural heart abnormality: Out of the 108 subjects with ECG abnormality, only five (0.47%) were found to have structural heart disease. Out of the five, two subjects in Group-3 who had deep T wave inversion in anterolateral leads were found to have hypertrophic cardiomyopathy. Two subjects in Group-3 with significant Q waves in anteroinferior leads were found to have significant coronary artery disease. One subject with RBBB in ECG in Group - 2 had structural heart abnormality in the form of the atrial septal defect.
Discussion
Only few studies addressed ECG findings in healthy members of the armed forces or the general population of India. The ECG abnormalities commonly seen in healthy young adults are sinus bradycardia, sinus tachycardia, incomplete RBBB, RAD, LAD, prolonged QRS duration, tall R wave and deep S wave in chest leads.9 Previously, Singhal et al analysed the prevalence of ECG abnormalities in healthy members of the Indian Air Force, while Hingorani P et al had reported a similar study conducted on the general population.10, 11 The comparative description of various ECG abnormalities has been summarised in Table 1.
In our study, 10.3% of the total subjects were found to have ECG abnormality. In the study conducted by Singhal A et al on the serving air force personnel of the Indian air force, the prevalence of ECG abnormalities was 3.59%, which is lower than that in our study10. In a study performed in China on the general population, Rao X et al found the prevalence of abnormal ECG ranging from 7.74% to 20.9%.12 Our study was selectively conducted on the serving armed forces personnel who were aged from 18 to 54 years old and did not include females. However, the other studies were performed on all age groups, including the elderly general population of both genders. Hence, this demographic difference in the subjects explains the variation in the findings of our study compared to the other studies.
The other common ECG abnormalities observed in our study do not appear to vary significantly from those of similar studies reported earlier. The most common ECG abnormality found in our study was LAD (physiological LAD:
1.72%, LAD: 0.48%) which was also the most common abnormality noted in the study of Singhal et al. In both studies, none of the individuals who reported to have LAD were found to have any underlying cardiac disease.10
The interpretation of ST-segment abnormalities is of vital importance due to their association with ischemic changes. In our study, nonspecific ST-segment changes were seen in 0.38% of the subjects, which is much less than that found by Pooja Hingorani et al in 2.5% of the population.11 In the study conducted by Pooja Hingorani et al, T wave inversion was seen in only 10 (0.2%) subjects.11 Rose et al, in a cohort study of European men aged between 40-59 years, reported non-specific ST-segment changes varying from 2.6-3.6% of the subjects and T wave abnormalities in 3.4-5.9%
respectively, which are much higher than those in our study.12 This may be due to variability in the interpretation of ST-segment changes. In participants of clinical trials, Dmitrienko et al found T wave abnormalities in 9.5% of the
subjects.13 Nonspecific T wave changes, in the absence of structural heart disease may occur due to electrolyte imbalance, hyperventilation, postural change, tachycardia and even stroke or intra- cranial haemorrhage.
The same percentage of ECG abnormalities was found in all age groups. Few abnormal ECGs in subjects are skewed toward a specific group. Sinus tachycardia was seen more in the older age group, while bradycardia was found more in the younger age group, which was due to the increased vagal tone in young individuals14. Similarly, the left axis deviation was seen more in the older age group. LVH by voltage criteria were seen mainly in young subjects, which was likely due to the fact that exercise induces more muscle mass. Pathological Q waves were seen in subjects of the older age group who were found to have coronary artery disease, implying more prevalence of CAD in elderly. Nonspecific T inversion was also seen more in older age group, which implied that nonspecific ECG changes with advanced age.
ECG abnormality and structural heart disease: Only five (0.47%) subjects were detected with structural heart disease; two subjects who had deep T wave inversion in anterolateral leads were found to have hypertrophic cardiomyopathy and belonged to the higher age group subjects (Group-3). Other two subjects in Group-3, who were found to have significant Q waves in antero-inferior leads, had significant coronary artery disease. The remaining one patient had complete RBBB and was found to have ASD in group-2. Thus, it appears that ECG probability of heart disease underlying an abnormal ECG increases with age, and abnormal ECG findings in young serving personnel is of little clinical significance. However, few ECG abnormities that are already well-defined, such as pathological Q waves, deep symmetrical T wave inversion, LBBB, RBBB, and atrial fibrillation, may be further assessed, evaluated and treated accordingly.
Conclusion
The morphological ECG abnormalities seen in the present study with armed forces personal did not vary significantly from the general population. Only a minority of these subjects had underlying pathology. While most of the abnormalities may only represent normal variations and their occurrence in healthy individuals during routine health check-ups should not be alarming. Evaluation of structural heart disease should be done for ECG abnormalities with prognostic significance that has been well-characterised. It is recommended that assimilation of similar data from a larger database be consolidated to get a broader picture of the exact prevalence of ECG abnormality in young and healthy subjects of Indian armed forces and for further defining benign ECG abnormities and the level of further evaluation.
Ethical and informed consent: Ethical approval was obtained from the institutional review board of the centre concerned. Informed written consent was obtained before the study started and confidentiality was maintained throughout.
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Citation: Sharma Munish, Sengupta S, Maribashetti K, Karanth JPB.
Electrocardiogram abnormalities detected during a routine medical examination of healthy members of the armed forces: An observational study. J Prev Soc Med, 2022; 54 (1): 14-19.