Nigerian Journal of Cardiology

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 15  |  Issue : 2  |  Page : 83--88

Audit of 24 h ambulatory electrocardiography (Holter) of 281 Nigerian patients in Benin city metropolis


Veronica Adaku Josephs, W Sadoh, J Ikhidero 
 Department of Medicine, U.B.T.H, Benin City, Nigeria

Correspondence Address:
Dr. Veronica Adaku Josephs
P.O. Box 10756, Ugbowo, Benin City, Benin 30012, Edo State
Nigeria

Abstract

Background: Recent advances in cardiovascular management have been the result of the implementation of technological advances in the form of facilities in patient care. Continuous ambulatory electrocardiography (ECG) is used for the diagnosis of symptomatic and asymptomatic arrhythmias of the cardiac patient which are not immediately apparent to the clinician, but otherwise amenable to treatment. Objective: The aim of this study is to examine the relevance of 24-h ambulatory ECG in the management of arrhythmias in the Nigerian patient. The study was carried out from Winsephs' family clinic, a private cardiology clinic in Benin City. Methods: A retrospective study of 281 adult patients referred for 24 h ambulatory ECG (Holter) between January 2006 and June 2015. Results: The indications for Holter-ECG were as follows: unexplained recurrent palpitations (174) (61.9%); effort intolerance (67) (23.8%); probable ischemic heart disease (53) (18.9%); chest pain (53) (18.9%); and an assessment of arrhythmia in congestive cardiac failure (48) (17.1%). Others were syncopal attacks (23) (8.9%) and extreme weakness (15) (5.3%). The most common rhythm abnormalities and the number of individuals affected were as follows: premature atrial contractions (PAC) (188) (66.1%), sinus tachycardia (ST) (165) (58.7%), ventricular extrasystoles (148) (52.7%), paroxysmal supraventricular tachycardia (127) (45.2%), ventricular tachycardia (55) (19.6%), bradycardia (57) (20.3%), and pause (51) (18.2%). Other significant rhythm abnormalities were atrial fibrillation (17) (6.1%) and atrial flutter (10) (3.6%). Myocardial ischemia indicated by ST depressive episodes was observed in (32) (11.4%) patients, and the majority of those affected were >55 years of age. There were five normal reports. Conclusion: Holter-ECG is becoming an indispensable tool in diagnosis, management, and follow up of the cardiac patient.



How to cite this article:
Josephs VA, Sadoh W, Ikhidero J. Audit of 24 h ambulatory electrocardiography (Holter) of 281 Nigerian patients in Benin city metropolis.Nig J Cardiol 2018;15:83-88


How to cite this URL:
Josephs VA, Sadoh W, Ikhidero J. Audit of 24 h ambulatory electrocardiography (Holter) of 281 Nigerian patients in Benin city metropolis. Nig J Cardiol [serial online] 2018 [cited 2019 Oct 24 ];15:83-88
Available from: http://www.nigjcardiol.org/text.asp?2018/15/2/83/262001


Full Text



 Introduction



Recent advances in cardiovascular management have been the result of the implementation of technological advances in the form of facilities for patient care. One such area of advancement is the use of continuous ambulatory electrocardiography (ECG) for the diagnosis of symptomatic and asymptomatic arrhythmias or conduction abnormalities of the cardiac patient [1],[2] (benign or malignant) which are not immediately apparent to the clinician but otherwise amenable to treatment. The MT-101/MT-200 Holter and evaluation software is designed to record continuous electrocardiogram for the diagnosis of arrhythmias, and for patients after resuscitation, or patients suffering from diseases such as hypertrophic cardiomyopathy, high blood pressure, or long QT syndrome.[1],[3] Prolonged ECG recording in patients engaged in normal daily activities is very invaluable in the documenting and quantization of the frequency and complexity of an arrhythmia, correlating it with patient's symptoms and evaluating the effectiveness of antiarrhythmic therapy on spontaneous arrhythmia.[4]

There is a paucity of information on arrhythmias in the Nigerian patient. The most extensive study so far done in this regard is that done by Omotosho et al. (1997); although, it was only about hypertensives.[5] The study showed that cardiac arrhythmias are common in Nigerians with hypertensive heart disease but emphasized the rarity of dangerous arrhythmias. The causes of sudden death and its relationship to the circadian rhythm and changes in heart rate remains a puzzle to cardiovascular physicians.[4],[6] The possible explanation for the persistence of symptoms despite adequate medications is that the underlying problem is yet to be addressed. Only a long-term ECG recording can detect dangerous arrhythmias outside the routine ECG and hospital setting.[7]

The study is an audit of 24 h ambulatory ECG done on cardiac patients with persistent symptoms such as palpitations, syncope or near syncope, effort intolerance or congestive cardiac failure (CCF), dizziness despite medications, or probable ischemic heart disease (IHD) and hence, to examine the relevance of 24-h ambulatory in the management of arrhythmias or conduction abnormalities in the Nigerian patient.

 Methods



This retrospective study is an audit of the Holter reports of 281 adult patients referred for Holter-ECG (165 men and 116 women) between January 2006 and June 2015 at the Winsephs family clinic a private cardiology clinic in Benin City, which helps to serve patients from Benin City metropolis and its environs. The indication for Holter-ECG included as follows: Severe unexplained recurrent palpitations; effort intolerance; probable IHD; and in assessment of arrhythmia in CCF, unexplained recurrent syncopal attacks, dizziness or severe weakness, recurrent unexplained chest pain suggesting angina pectoris, and as post-myocardial infarction follow-up in keeping with the practice guidelines for ambulatory ECG monitoring.[8] Each of these patients was either being managed by cardiovascular physicians or had been on antihypertensive drugs at least in the past 2 years and had routine ECG done for them as part of previous management.

The information obtained from patients for Holter monitoring included: Date of birth, age, sex, Body Mass Index (BMI) as weight in kilograms/height in meters.[2] Documentations were made for the blood pressure, previous ECG, current medications, indications for Holter ECG, Chest X-ray and where possible previous echocardiography report. Patients were instructed to bath on the morning of the procedure and to stay off showers and baths until after recording since the recording unit is not waterproof.[1] The proper handling of the unit was first explained to the patient who was also asked to keep off electronic devices such as generators, microwave oven, electric shaver, or handsets to reduce interference with the recording. Recordings were made by the SCHILLER MICROVIT MT-101 Holter unit over a 24 h period. The typical electrodeposition is that of a 4-lead 2-channel recording. A stress loop is formed in every cable which is also secured with adhesive strips (according to the Schiller MT-101/MT-200 user guide). The built-in Holter display, enables the ECG signal quality to be checked before starting and the recording commenced directly from the device. To ensure good data evaluation, the ECG amplitudes are examined in the sitting, standing, and lying positions of the patient. The patient was allowed to go home after the Holter was applied and to continue on his/her daily routines.

At the end of the recording, the patient returned to the clinic to have the electrodes removed, and the data is transferred from the Holter recorder to a computer (PC). He or she was also instructed to record and time experienced symptoms and to note them in a diary which was returned to the clinic too at the end of the recording. Illiterate patients were assisted by literate relations to complete the diary.

The transferred data were later displayed and analyzed in a logical and understandable way for diagnosis. The in-built Holter analysis was closely examined to exclude artifacts and to correlate findings with patient diary to be able to give relevant information to patient and relations. Significant ST-segment depression was taken as ≥2 mm ST-segment depression from the isoelectric line.[1],[3]

The results were later printed out and the information analyzed by standard statistical methods using XP 16. The student's t-test was used to compare the differences in the ages, BMI, and maximum heart rate between the sexes and values of P < 0.05 were considered as statistically significant.[9]

For this study, the following are the definitions of different kinds of arrhythmias mentioned in this study:[10],[11],[12]

Sinus tachycardia (ST) issinus rhythm with a rate >100 beats/min in an average adult.

Sinus bradycardia (SB) is a sinus rhythm with a resting heart rate of 60 beats/min or less.

Junctional rhythm (JR) is a cardiac rhythm arising from the atrioventricular junction and usually occurs as an automatic tachycardia or as an escape mechanism.

Premature atrial contraction (PAC) is a PAC or an isolated atrial beat occurring just before a normal sinus beat.

Atrial fibrillation (AFB) is a rapid heart rate caused by chaotic electrical impulses in the atria. These signals result in rapid, uncoordinated, weak contractions of the atria.

Atrial flutter (AF) is similar to AFB. The heartbeats in AF are more-organized (rate >150 beats min) and more-rhythmic electrical impulses than in AFB.

Premature ventricular contraction (PVC) is an isolated ventricular beat occurring before a normal sinus beat.

Ventricular tachycardia (VT) is the occurrence of two or more PVC in succession;

Paroxysmal supraventricular tachycardia (PSVT) is an episodic faster-than-normal heart rate with an abrupt onset and termination. It can last from a few minutes to several hours.

 Results



[Table 1] shows the baseline characteristics of the 281 patients who were referred for 24-h ambulatory ECG. They included 165 males of mean age 58.54 ± 14.47 years and 116 females of mean age 49.54 ± 18.84 years. This difference in the mean age between the sexes was not statistically significant (P = 1.00). Of these, 203 (72.2%) patients were hypertensive; 26 (9.3%) had dilated cardiomyopathy; 15 (5.3%) were suspected cases of IHD; 16 (5.7%) with pericarditis, 14 had rheumatic heart disease; 7 (2.5%) with ventricular septal defect.{Table 1}

The indications for Holter-ECG in decreasing order of frequency were [Table 2]: unexplained recurrent palpitations (174) (61.9%); effort intolerance (67) (23.8%); probable IHD (53) (18.9%); chest pain (53) (18.9%); and in the assessment of arrhythmia in CCF (48) (17.1%). Others were syncopal attacks (23) (8.9%) and extreme weakness (15) (5.3%).{Table 2}

Analysis of Holter reports showed that the maximum heart rate obtained were 214 and 247 beats/min (bpm) for the males and females, respectively, with a mean heart rate of 129.19 ± 36.84 and 139.60 ± 38.62 bpm for males and females, respectively (P = 1.0), and 133.66 ± 38.51 bpm overall. These differences were not statistically significant.

[Table 3] shows the distribution of frequency of observed Holter-ECG abnormalities according to age groups. [Figure 1] is a graphical representation of the same. [Table 4] shows the contribution of various forms of observed Holter-ECG abnormalities to patients' symptoms. The commonest rhythm abnormalities and the number of individuals affected were as follows: PACs (188) (66.1%), sinus tachycardia (165) (58.7%), ventricular extrasystoles (148) (52.7%), PSVT (127) (45.2%), VT (55) (19.6%) (three of these were sustained), bradycardia (57) (20.3%), and pause (51) (18.2%). Other significant rhythm abnormalities were AFB (17) (6.1%) and AF (10) (3.6%). Myocardial ischemia indicated by ST depressive episodes was observed in (32) (11.4%) patients though observed in some young people, essentially affected both middle-aged and the elderly, but the majority of those affected were >55 years of age. It can also be seen that IHD while not really symptomatic can accompany any set of symptoms [Table 4] and most of those who had chest pain experienced sinus tachycardia. There were five normal reports. About 71.5% of arrhythmias occurred in individuals >50 years of age [Figure 2]. PSVT and ST-depressive episodes were significantly more common in the men compared with the women [Figure 2], but there was generally no significant difference in prevalence of arrhythmias between the sexes.{Table 3}{Figure 1}{Table 4}{Figure 2}

 Discussion



An arrhythmia is an abnormality or disturbance in the rate or rhythm of the heartbeat.[13] Symptoms of arrhythmia are largely variable, ranging from barely perceptible to cardiovascular collapse and death. Long-lasting symptoms may affect the cardiac function leading to dizziness, fatigue, light-headedness, fainting, near syncope, rapid heartbeat (pounding), shortness of breath, and chest pain. In extreme cases, there may be collapse and death. Such arrhythmias are considered dangerous.[14] Many heart problems are noticeable only during certain activities. These include exercise eating, sex, stress, bowel movements, and even sleeping. The problems with arrhythmias are not necessarily the diagnoses when detected by ECG or the type of treatment to give. The problems are the inconsistencies with symptoms; the uncertainty of intermittency and at times, the inability of the patient to describe his or her symptoms with the appropriate language. Most of the time symptoms remain quiescent during waiting time, consultation, and preliminary ECG examinations do not demonstrate the abnormalities, only for symptoms to reappear when the patient gets back home.

An ambulatory electrocardiogram is more likely to detect abnormal heartbeats that occur during these activities. A continuous or ambulatory ECG is the most useful noninvasive method to document and analyze the quantitative frequency and complexity of arrhythmia.[6] It also correlates arrhythmias with patient's symptoms. In this study, for instance, 81% of patients who had syncopal attacks had episodes of PSVT.

The most accurate type of continuous ECG is the Holter “monitor” which generally records in tapes 2 or 3 ECG channels for 24–48 h.[7] Modern-day Holter-ECG can record for up to 72 h (1). Both the Holter recorder and the computer (PC) are provided for the exclusive use of qualified physicians or trained personnel under his direct supervision.[1] The numerical and graphical results, as well as any interpretation suggested by the device, should be examined with respect to the patient's overall clinical condition and the quality of the recorded data.

One of the advantages of Holter monitoring is that is that one can continue on ones daily activities while your cardiac activities are being recorded. Many of the patients in this study are resident in places several tens of kilometers away from Benin, and they were people from all works of life. The use of the Holter diary in which the patient records his or her complaints makes it easy for the clinician to correlate Holter abnormalities such as ST-depressive episodes, VT or PSVT, with symptoms such as chest pain or syncopal attack.[15] Thus, Holter-ECG is very useful in documenting out of hospital cardiovascular events.[16] It is more sensitive than the standard 12-lead ECG or exercises ECG in detecting extrasystoles.[16],[17] In recent times, Holter-ECG has been employed in the diagnosis of latent arrhythmias in patients with acute respiratory viral infections. Acute pericarditis usually follows acute respiratory viral infection. Holter-ECG has shown that about 78% of patients with acute respiratory viral infection had rhythm and conduction abnormalities. All the seven patients with pericarditis in this study had rhythm abnormalities in agreement with other studies on viral respiratory infections and the heart.

Continuous ambulatory ECG can also be used to evaluate the effect of antiarrhythmic drugs in such patients.

In this study, the most common form of arrhythmia in the patients was sinus tachycardia followed by supraventricular and ventricular extrasystoles. These findings are in agreement with that of Omotosho et al. (1991); although, their study was done on mainly hypertensives alone using routine ECG.[4] Furthermore, these three groups of arrhythmias were most common among individuals who were ≥40 years of age. Continuous ambulatory ECG recording not only revealed many more arrhythmias but it also unmasked VT in a significant number of patients (19.6%) also within the same age groups. Omotosho et al. described rarity of VT in their study.

The incidence of ST-depressive episodes among the patients in this study (11.3%) is noteworthy. ST-depressive episodes denote acute ischemic events.[1] Holter-ECG is very useful in the detection of silent myocardial ischemia. Recent studies have shown that >80%–90% of ischemic episodes detected by this method are asymptomatic, and so are not associated with angina.[1] The findings in this study show that ST-depressive episode appears to be the only frequent event among patients with IHD. Holter-ECG monitoring has been employed for mass screening for IHD with useful results. While it is well known that systemic hypertension is a major risk factor for IHD, the latter is still being described as very rare in this environment. Use of ambulatory ECG in the chronic hypertensives, especially in the noncompliant ones will unmask the state of IHD in these patients.

Diurnal variation in heart rate makes it difficult to observe dangerous arrhythmias in patients during routine clinic visits. A cardiovascular cause of syncope may cause the patient to develop arrhythmia coincident with syncope or presyncope.[9] It has been shown that the 1 year mortality for patients with cardiovascular syncope is 19%–30%. Long periods of severe bradycardia and wide pauses may occur during sleeping hours and may result in angina pectoris or cardiac arrest. These rhythm abnormalities are detectable by Holter monitoring. When the symptoms are very infrequent, the implantable loop recorder which is advancement in ambulatory recording can be used for more prolonged periods of recording.

 Conclusion



The uses of Holter-ECG have become very necessary for diagnosis, management, and follow-up of the cardiac patient regardless of age. As much as possible, it should be made available in every cardiology center and employed in the routine cardiovascular workup of these patients.

Limitations to the study

There were few patients who were unable to complete their Holter diaries. Although this did not affect ECG data interpretation, the Holter event of these could not be correlated with diary except where the patient introduced markers. Furthermore, Holter recordings had to be repeated when recordings were prematurely interrupted or terminated.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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