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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 17  |  Issue : 1  |  Page : 61-66

Prevalence of arrhythmias on 24-h ambulatory Holter electrocardiogram monitoring in LASUTH: A report on 414 patients


Department of Medicine, Division of Cardiology, LASUCOM/LASUTH, Lagos State, Nigeria

Date of Submission08-Oct-2019
Date of Decision22-Nov-2019
Date of Acceptance27-Nov-2019
Date of Web Publication30-Jun-2020

Correspondence Address:
Dr. Philip A Adebola
Department of Medicine, Division of Cardiology, LASUCOM/LASUTH, Lagos State
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njc.njc_26_19

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  Abstract 


Background: The 24-h ambulatory holter electrocardiogram (ECG) monitor is particularly able to document bradyarrhythmic or tachyarrhythmic episodes which might be missed on normal 12-lead resting ECG recordings. It is, therefore, particularly useful in evaluating patients with symptomatic or asymptomatic paroxysmal tachy/bradyarrhythmias and is also useful in monitoring patients on antiarrhythmic therapy. The present study was aimed at presenting our findings on the prevalence of arrhythmias on the 24-h Holter ECG of a relatively large cohort of patients referred to our cardiac facility, over the last few years.
Methods: This was a retrospective audit of prevalence of cardiac arrhythmias among 414 patients consisting of 184 males and 230 females who were referred for 24-h Holter ambulatory ECG monitoring in LASUTH, Ikeja, Nigeria, between January 2014 and June 2019. Their age ranged from 13 to 95 years with a mean age of 50.42 ± 16.29.
Results: The most common single indications for Holter monitoring in these patients were unexplained palpitation and presyncope/syncope. Ventricular extrasystole was the most common arrhythmias found on Holter ECG. Only 14 out of the 414 patients had Holter ECG evidence of nonsustained ventricular tachycardia (VT). There was no significant difference in the prevalence of cardiac arrhythmias in males compared to their female counterparts. However, elderly patients of 65 years and above had significantly higher prevalence of cardiac arrhythmias when compared to their younger counterparts (χ2 = 54.46, P < 0.01).
Conclusion: The study suggests that palpitation is the most common reason for referral of patients for 24-h ambulatory Holter ECG test. It also showed that ventricular extrasystoles are the most common arrhythmias on the 24-h Holter ECG. In addition, it reinforces the fact that nonsustained VT is uncommon among the Nigerian patients and that elderly patients were more likely to have cardiac arrhythmias compared to their younger counterparts.

Keywords: 24-h ambulatory Holter electrocardiogram monitoring, cardiac arrhythmias, electrocardiogram


How to cite this article:
Adebola PA, Daniel FA, Ajibare AO, Reima AE. Prevalence of arrhythmias on 24-h ambulatory Holter electrocardiogram monitoring in LASUTH: A report on 414 patients. Nig J Cardiol 2020;17:61-6

How to cite this URL:
Adebola PA, Daniel FA, Ajibare AO, Reima AE. Prevalence of arrhythmias on 24-h ambulatory Holter electrocardiogram monitoring in LASUTH: A report on 414 patients. Nig J Cardiol [serial online] 2020 [cited 2020 Aug 12];17:61-6. Available from: http://www.nigjcardiol.org/text.asp?2020/17/1/61/288648




  Introduction Top


The 24-h ambulatory holter electrocardiogram (ECG) monitor is a device that has being in use over the last 2–3 decades for monitoring and evaluating the cardiac rhythm of patients throughout a whole day or longer. It is particularly able to document bradyarrhythmic or tachyarrhythmic episodes which might be missed on normal 12-lead resting ECG recordings. It is, therefore, particularly useful in evaluating patients with symptomatic or asymptomatic paroxysmal tachy/bradyarrhythmias and in monitoring patients on antiarrhythmic therapy.[1],[2] Although the common practice is to record the ambulatory ECG over 24 h, there are newer models that can actually record the ambulatory ECG for up to 48 or 72 h.[3],[4] This enhances the possibility of detecting an infrequent paroxysmal arrhythmia that could be missed on the 24-h Holter ECG recordings. Previous studies had documented the presence of arrhythmias among healthy Caucasians.[3],[4],[5],[6],[7]

Despite the widespread availability of this procedure abroad, its use in Nigeria is still limited to some teaching hospitals and few private health-care facilities. This partly explained the paucity of literature on its use in the Nigerian patients so far. The high cost of Holter ECG test is also probably a factor in its limited use in the majorly indigent Nigerian patients. Katibi et al.[8] and Adebola et al.[9] had published their preliminary findings in a relatively modest number of patients who underwent 24-h Holter ECG monitoring, more than a decade ago. Furthermore, Lasisi et al. published their studies on a modest number of 60 healthy Nigerians and chronic heart failure patients, respectively.[10],[11] Since then, there have been few attempts at revisiting this interesting subject from different perspectives. The present study was aimed at presenting our findings on the prevalence of arrhythmias on the 24-h Holter ECG of a relatively large cohort of patients, referred to our cardiac facility over the last few years.


  Methods Top


This is a retrospective audit of 414 patients consisting of 184 males and 230 females who were referred for 24-h Holter ambulatory ECG monitoring in LASUTH between January 2014 and June 2019. Their age ranged from 13 to 95 years with a mean age of 50.42 ± 16.29. A SCHILLER MICROVIT MT-101 Holter unit was strapped to each patient's waist after necessary ECG lead placement based on bipolar V1–V5 lead recoding systems.[12],[13] The patients were told to go home and continue normal routine daily activities and to come back at about the same time the following day. They were advised to keep a record of the time they experienced significant symptoms such as palpitations, dizzy spells, chest pain, or syncope.

The 24-h Holter recording was subsequently transferred to a SCHILLER computer-based system for the analysis of the reports. The reports were reviewed by the cardiologists (authors). The Holter reports were evaluated for indications for the test and the presence of cardiac arrhythmias.

For the study, patients were classified into those with (1) normal cardiac rhythm and (2) abnormal cardiac rhythm or arrhythmias. The following were the specific arrhythmias evaluated on the Holter ECG analysis based on standard ECG diagnostic criteria.- 1. Extra-systoles which were either Atrial or Ventricular Premature Contractions (infrequent and unifocal = lown class 1, frequent and or polymorphic = Lown class ≥2), 2. Supra-ventricular tachyarrhythmias such as paroxysmal supraventricular tachycardia (PSVT), Atrial Fibrillation (AFIB). Patients with Wolff-Parkinson-White (WPW) syndrome which are also known to have predisposition to supra-ventricular tachyarrhythmias, were also documented. 3. Ventricular tachyarrythmias such as Non-sustained Ventricular Tachycardia (≥3 or more consecutive ventricular extr-systoles). 4. Bradyarrhythmias (severe) defined in the study as Holter ECG evidence of Heart Rate <40 beats per minute 14, high grade second degree AV block (Mobitz type 2) or third degree AV blocks.

The prevalence of these arrhythmias was compared with the noted indications for the Holter test and also the clinically relevant age group distribution of the patients based on (1) young individuals who were <45-years-old; (2) middle-aged individuals who were within the age range of 45–64-years–old; and (3) elderly patients who were 65-years-old and above. The prevalence of these abnormalities was expressed in terms of absolute numbers and percentages. The data were subjected to appropriate Chi-square statistical analyses, where applicable.


  Results Top


A total of 414 patients including 184 (44.4%) males and 230 (55.6%) females within the age range of 13–95 years were evaluated. 159 (38.4%) patients were young individuals of <45 years, 145 (35.0%) were middle-aged individuals between 45 and 64 years, and 110 (26.6%) were elderly patients of 65 years and above [Figure 1]a and [Figure 1]b. Palpitation was the most common single indication for Holter monitoring. Sixty-five patients were referred following the complaints of dizzy spells (presyncope) and/or syncopal attacks. A large proportion of the patients had multiple reasons or indications for referral for Holter ECG test, such as unexplained arrhythmias on resting ECG, prepacemaker implantation, heart failure, chest pains, and other poorly defined symptoms or indications. The indications for Holter ECG were not stated in eight patients [Figure 2].
Figure 1: (a and b) Distribution of patients according to gender and age groups, respectively

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Figure 2: Distribution of patients according to indications for the Holter electrocardiogram test

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Distribution of cardiac rhythms based on gender and clinical age groups

Normal sinus rhythm

One hundred and thirteen patients including 43 males and 70 females had a normal sinus rhythm. Seventy-four patients with a normal sinus rhythm were young individuals of <45 years, whereas 31 middle-aged individuals within the age range of 45 and 64 years had a normal sinus rhythm. Only eight elderly patients had a normal sinus rhythm on Holter ECG. There was a significant difference in the prevalence of cardiac arrhythmias among the different age groups [Table 1].
Table 1: Prevalence of abnormal cardiac rhythm according to gender and age groups

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Extrasystoles

Of 414 patients, 246 (59.4%) had ventricular, atrial, or both types of extrasystoles. Two hundred and eleven individuals had ventricular extrasystoles, whereas 100 individuals had atrial extrasystoles. These were, by far, the most common arrhythmias on the Holter ECG reports. Majority of the extrasystoles were infrequent and unifocal extrasystoles of Lown Class 1. However, 95 (22.9%) of the 414 patients had complex and frequent ventricular extrasystole of Lown Class ≥2. Of these, 35 were in the elderly group, 43 in the middle age group, and only 17 were in the young age group. In all, 69 (43.4%) of the 159 young individuals had extrasystoles, 97 (66.9%) of the 145 middle-aged had extrasystoles, and 80 (72.7%) of the 110 elderly patients had extrasystoles [Table 2].
Table 2: Prevalence of cardiac arrhythmias among the age groups

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Ventricular tachyarrhythmias

Fourteen (3.4%) patients had Holter ECG evidence of nonsustained VT. Only two of the young patients had nonsustained VT. They were referred with a preliminary diagnosis of hypertrophic cardiomyopathy. The other patients with nonsustained VT were among the middle and elderly age groups.

Supraventricular tachyarrhythmias

Sixteen (3.8%) individuals had supraventricular tachyarrhythmias, including eight with atrial fibrillation, five with paroxysmal supra-VT, and three with features suggestive of WPW syndrome with PSVT. Seven of the eight patients with atrial fibrillation belong to the elderly age group, whereas six of the eight patients with PSVT or WPW belong to the younger age groups.

Bradyarrhythmias (severe)

Twenty-five (6.0%) patients had Holter ECG evidence of severe bradyarrhythmias (heart rate [HR] <40 bpm) and/or high-grade second-degree/third-degree AV blocks. These include 14 with third-degree AV block, 8 with high-grade second-degree AV block (Mobitz type 2 second-degree AV block), and 3 with severe bradyarrhythmias and suspected sick sinus syndrome. Majority of the patients with bradyarrhythmias belong to the elderly age group. Only one of the young individuals had a third-degree AV block [Figure 3].
Figure 3: Prevalence of different arrhythmias among the age groups

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Distribution of cardiac rhythm based on indication for Holter electrocardiogram test

(1) Palpitations: This is the most common reason for referral for Holter ECG test. Of 167 patients referred for Holter, 56 had a normal cardiac rhythm and 111 had an abnormal cardiac rhythm. Out of these, 99 patients had extrasystole, 4 had nonsustained VT, 4 had bradyarrhythmias, 2 had paroxysmal supra-VT with WPW syndrome, and 1 had paroxysmal atrial fibrillation [Table 3]. (2) Dizzy spells (presyncope/syncope): Of the 65 patients referred for this indication, 15 had a normal cardiac rhythm and 50 had an abnormal cardiac rhythm. Out of these, 38 patients had extrasystole, 7 had severe bradyarrhythmias with high-grade AV block, 3 had PSVT, and 2 had nonsustained VT. (3) Others/multiple indications: Of the 174 patients with multiple or nonspecific indications for referral, 42 had a normal cardiac rhythm and 131 had an abnormal cardiac rhythm. 104 patients had extrasystole, 13 had severe bradyarrhythmias, 8 had nonsustained VT, and 6 had atrial fibrillation.
Table 3: Prevalence of abnormal cardiac rhythm according to presenting symptoms

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  Discussion Top


A total of 414 patients including 184 males and 230 females between the ages of 13 and 95 years, who underwent standard 24-h ambulatory Holter ECG between 2014 and 2019, were evaluated. To the best of our knowledge, this is the largest retrospective study on ambulatory Holter ECG in Nigeria so far. Different clinically relevant age groups, i.e., the young of <45 years of age, the middle aged of 45–64 years, and the elderly of 65 years and above, were adequately represented in the study. In recent years, Adebayo et al.[14],[15] had reported Holter ECG studies in 310 patients. As in previous studies, the most common reason for Holter monitoring in the present study was unexplained palpitation.[8],[9],[14] One hundred and sixty-seven patients were referred for the Holter study based on complains of palpitation. This is similar to the findings of Adebola et al.,[9] in which more than half of the patients complained of palpitation. This is also similar to the findings of Adebayo et al.[15] in which 71 (23%) of 310 patients and Joseph et al.[16] in which 174 of 281 patients with palpitations were referred for Holter ECG study. Palpitation is a very subjective symptom and is entirely dependent on the patient description. The symptom of palpitation can be due to non-cardiac causes such as anxiety, anaemia, thyrotoxicosis, febrile illness, or cardiac causes such as tachyarrhythmias arising from acute pericarditis, myocarditis, cardiomyopathies, hypertensive heart disease, congenital heart disease or primary cardiac arrhythmic problems such as paroxysmal tachyarrhythmias and WPW syndromes. In the present study, 56 of the 167 patients with complaints of palpitation did not have Holter ECG evidence of arrhythmias. In the present study, 56 of the 167 patients with complaints of palpitation did not have Holter ECG evidence of arrhythmias.

Dizzy spells/syncope was the second most common reason for referral for Holter study in the present study. 15.7% of the patients in the present study were referred for Holter ECG test based on the symptoms of dizzy spells/syncope. This finding is also similar to the findings of previous studies on this subject.[9],[15] Adebola et al.[9] reported that 17.6% of their patients presented with dizzy spells/syncope, whereas Adebayo et al.[15] reported that 15% of their patients presented with a history of syncopal attacks. Unlike other reported studies among Nigerians, only 22 out of the 281 patients in the study of Joseph et al.[16] presented with a history of syncope. It must be emphasized that the history of dizzy spells, presyncope, and outright syncopal attacks can be difficult to differentiate or ascertain from the patients. This is why the authors sometimes referred to dizzy spells as presyncope. This is because patients tend to use vague terms such as lightheadedness, blackouts, or fainting to describe their experience. As in palpitation, the causes of these symptoms vary from extracardiac causes such as anemia, febrile ailment, and exhaustion to severe tachy/bradyarrhythmias. Of the 65 patients referred with dizzy spells/syncope actually, 15 did not have Holter ECG evidence of cardiac arrhythmias. As with palpitation, majority of the arrhythmias in the group of patients with syncope were due to the presence of extrasystoles.

Of the 414 patients, 113 had a normal cardiac rhythm devoid of any arrhythmias. Most (74) of the patients with a normal sinus rhythm were among young individuals of <45 years. In fact, only 8 of the 105 elderly patients above the age of 65 years had a normal cardiac rhythm. The findings from the present study showed that ventricular extrasystoles were, by far, the most common arrhythmias on Holter ECG. Most of these were benign unifocal and infrequent ventricular extrasystole. However, 95 patients had complex and frequent ventricular extrasystoles such as bigeminy, trigeminy, couplets, and others. These findings are similar to that of previous studies.[8],[9],[10],[14],[15],[16] It is also important to emphasize that even though ventricular extrasystole was common among all the age groups, it was particularly more common in the middle and elderly age groups. In fact, 35 (32%) of the 110 elderly patients had complex ventricular extrasystole of Lown Class ≥2, compared to only 17 (11%) of the 151 young individuals below the age of 45 years. This is similar to the findings of Adebayo et al.,[15] where only 19% of patients below 50 years had ventricular extrasystole compared to 31% of those above 50 years. Ventricular extrasystoles are generally assumed to be benign, especially if infrequent and monomorphic. However, frequent, polymorphic ventricular extrasystole could be precursor to the development of dangerous sustained VT and sudden deaths and such individuals could benefit from β-blocker therapy prophylactically.[10],[17]

Only 14 of the 414 patients had Holter ECG evidence of potentially dangerous, nonsustained VT. All but two of the patients with nonsustained VT were middle-aged or elderly individuals. This is similar to the previous findings of Adebola et al.,[9] where only 3 of the 85 patients had nonsustained VT. This is also similar to the findings of Adebayo et al.,[15] where only 6 of the 310 patients studied had sustained VT. However, 55 of the 281 patients in the study By Joseph et al.[16] had nonsustained VT. Nonsustained VT is the most dreaded arrhythmias on Holter ECG, because it is assumed that they could transit into sustained VT and possible sudden deaths.[18] While it is not absolutely compulsory that such patients be placed on antiarrhythmias, they should be referred for further cardiac investigations to exclude potentially fatal underlying cardiac diseases.

Of the 414 patients, 16 had significant supraventricular tachyarrhythmias. These were mostly cases of atrial fibrillation and paroxysmal supra-VT. Three patients had Holter ECG features suggestive of the WPW syndrome. The findings suggest that atrial fibrillation was more common among elderly individuals, whereas paroxysmal supra-VT was more common among the younger age groups. It is expected that elderly patients are more likely to be chronically hypertensive with the associated complication of atrial fibrillation.

Of the 414 patients, 25 had Holter ECG evidence of severe bradyarrhythmias and high-grade AV blocks. These include 14 patients with third-degree AV block, 8 patients with Mobitz type 2 second-degree AV block, and 3 patients with possible sick sinus syndrome. Majority of these findings were in the elderly age group. Ten patients with third-degree AV blocks were elderly patients above the age of 65 years. Only one of the young patients below the age of 45 years had Holter ECG evidence of third-degree AV block. Of the 85 patients in Adebola et al.'s[9] study, 5 had Holter ECG evidence of high-grade AV Block (4 type 2 second-degree AV block and 1 third-degree AV block). Similarly, 11 patients had severe bradyarrhythmias (HR <40 bpm) in the study by Adebayo et al.[15] These patients were more likely to have high-grade AV block though that was not explicitly stated in that study. Elderly patients who are more likely to present with symptomatic bradyarrhythmias could benefit from permanent pacemaker implantation.


  Conclusion Top


The study showed that palpitation and dizzy spell/syncope are the most common indications for referral for 24-h ambulatory Holter ECG monitoring. The study also reinforces the fact that premature ventricular extrasystole is the most common arrhythmia on Holter ECG. Elderly patients are more likely to have cardiac arrhythmias such as extrasystoles, bradyarrhythmias, and atrial fibrillation, whereas younger individuals are more likely to have paroxysmal supra-VT. As in the findings of most of the previous studies, the study showed that the prevalence of potentially fatal nonsustained VT on Holter ECG is relatively low in the Nigerian patients.

Limitation of the study

Due to the retrospective nature of the study, the details of the nature of underlying cardiac and noncardiac diseases could not be ascertained from the patients. This was also due to the fact that a significant number of the patients were referred from outside facilities and did not have detailed medical records with LASUTH. This could have further shed more light on the findings. A large proportion of the patients had multiple reasons for referral for the 24-h Holter ECG procedure. This made it difficult to evaluate the effects of the individual indications on the Holter ECG findings. The study could not correlate symptoms from event recorder with the actual arrhythmias due to poor record documentation by the patients. It is hoped that future prospective study would be guided by the findings of this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Bjerregaard P. Premature beats in healthy subjects 40-79 years of age. Eur Heart J 1982;3:493-503.  Back to cited text no. 7
    
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Katibi IA, Beshir S, Mudashiru Z. Ambulatory 24-hour holer electrocardiography among Nigerians our experience of a referral cardiac center in Lagos Nigeria. Nige Med j 2006;47:25-7.  Back to cited text no. 8
    
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Adebola AP, Daniel FA, Lasisi GT. 24-Hour Holter monitoring at Lagos university teaching hospital-a report of 85 cases. Niger J Clin Med 2009;2:7-11.  Back to cited text no. 9
    
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Lasisi GT, Adebola AP, Ogah OS, Daniel FA. Prevalence and clinical correlates of ventricular arrhythmias on 24-hr ambulatory electrocardiograph monitoring. Niger J Clin Med 2010;2:42-7.  Back to cited text no. 10
    
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Lasisi GT, Adebola AP, Ogah OS, Daniel FA. Prevalence of ventricular arrhythmias and heart rate variability pattern in chronic heart failure. Niger Postgrad Med J 2012;19:157-62.  Back to cited text no. 11
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Knoebel SB, Crawford MH, Dunn MI, Fisch C, Forrester JS, Hutter AM Jr., et al. Guidelines for ambulatory electrocardiography. A report of the American College of Cardiology/American Heart Association task force on assessment of diagnostic and therapeutic cardiovascular procedures (subcommittee on ambulatory electrocardiography). Circulation 1989;79:206-15.  Back to cited text no. 13
    
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Adebayo RA, Ikwu AN, Balogun MO, Akintomide AO, Mene-Afejuku TO, Adeyeye VO, et al. Evaluation of the indications and arrhythmic patterns of 24 hour Holter electrocardiography among hypertensive and diabetic patients seen at OAUTHC, Ile-Ife Nigeria. Diabetes Metab Syndr Obes 2014;7:565-70.  Back to cited text no. 14
    
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Adebayo RA, Ikwu AN, Balogun MO, Akintomide AO, Ajayi OE, Adeyeye VO, et al. Heart rate variability and arrhythmic patterns of 24-hour Holter electrocardiography among Nigerians with cardiovascular diseases. Vasc Health Risk Manag 2015;11:353-9.  Back to cited text no. 15
    
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Josephs VA, Sadoh W, Ikhidero J. Audit of 24 hr ambulatory electrocardiography (Holter) of 281 Nigerian patients in Benin city metropolis. Niger J Cardiol 2018;15:83-8.  Back to cited text no. 16
    
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Bikkina M, Larson MG, Levy D. Prognostic implications of asymptomatic ventricular arrhythmias: The Framingham heart study. Ann Intern Med 1992;117:990-6.  Back to cited text no. 17
    
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    Figures

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