Holter Monitoring in assessing Cardiac Arrhythmias in Symptomatic Patients: A Prospective Observational Study

BACKGROUND The 24hr ECG Holter monitoring system is helpful in assessing cardiac arrhythmias in patients presenting with palpitation, dizziness, presyncope and syncope, which are not detected by standard office electrocardiogram. METHODS This was a single center prospective observational study conducted to assess the prevalence of cardiac arrhythmias among 78 patients consisting of 41 males and 37 females referred for 24 hr ECG Holter monitoring in BPKIHS, Dharan, Nepal, between October 2021 to December 2021. RESULTS The most common indication for 24 hr ECG Holter monitoring in these patients was unexplained palpitation. Ventricular ectopics were the most common arrhythmias detected, followed by supraventricular ectopics, most of which were benign. Among 18 patients with significant bradyarrhythmia, 3 had sinus bradycardia with significant pause, 3 had AF with significant pause, and 2 had high grade/complete AV block. CONCLUSIONS The study showed that most of the arrhythmias detected are benign and prevalence of potentially fatal ventricular and supraventricular tachyarrythmias are relatively low in our population. ABSTRACT


BACKGROUND
Holter monitoring is commonly employed for the diagnostic evaluation of unexplained symptoms like palpitations, lightheadedness, blackouts, drop attacks and atypical chest pain.1 It is particularly able to document bradyarrhythmic or tachyarrhythmic episodes which might be missed on normal 12-lead resting ECG recordings.2,3 Despite the widespread availability of this procedure abroad, its use in Nepal is still limited to some teaching hospitals and few private health-care facilities. Badri et al. 4 had published the prevalence of various arrhythmias in 255 patients with palpitation who underwent 24-h Holter ECG monitoring, about a decade ago. Since then, there have been few attempts at revisiting this interesting subject from different perspectives.
The aim of this study is to evaluate the prevalence of arrhythmias on the 24-h Holter ECG in patients referred to our cardiac facility at BPKIHS for evaluation of unexplained syncope, dizziness and palpitations.

METHODOLOGY
A single center prospective observational study was conducted to assess the prevalence of cardiac arrhythmias in 78 consecutive patients presenting with unexplained syncope, dizziness and palpitations using 24hr ECG holter monitoring from October 2021 to December 2021. Each patient provided an informed consent and the study was approved by institutional review committee (IRC), BPKIHS, Dharan (Ref No: 55/078/079).
Inclusion Criteria -Age greater than 18 years with a symptom of unexplained syncope, dizziness or palpitations, either as a chronic problem or a single episode.
Exclusion Criteria -Patients with any definitive evidence of myocardial ischaemia, which was detected on a resting electrocardiogram and with any definite evidence of arrhythmia, which was detected on a resting electrocardiogram. The patients with other known medical causes of the symptoms, a history of documented arrhythmias, or a history of or the current use of antiarrhythmics, were also excluded.

Nepal Mediciti Medical Journal
The sample size was estimated using following formula, A sample size of 78 patients was taken. A SEER 12 Digital Holter ECG Recorder unit was strapped to each patient after necessary ECG lead placement based on Mason-Likar 10 electrode 12 lead monitoring system.6 The patients were admitted and advised to continue normal routine daily activities. They were advised to keep a record of the time they experienced significant symptoms such as palpitations, dizzy spells, presyncope or syncope. The 24-h Holter recording was subsequently transferred to a MARS computer based ECG analysis and editing system for the analysis of the reports using CARDIODAY holter ecg software. The reports were reviewed by the cardiologists (authors).
The Holter reports were evaluated for the presence of cardiac arrhythmias. For the study, patients were classified into those with (a) normal cardiac rhythm and (b) abnormal cardiac rhythm or arrhythmias. The specific arrhythmias were evaluated on the Holter ECG analysis based on standard ECG diagnostic criteria.7 Extra-systoles include either Atrial or Ventricular Premature Contractions (infrequent and unifocal = Lown class 1, frequent and/or polymorphic = Lown class ≥2), Supra-ventricular tachyarrhythmias include 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 included. Ventricular tachyarrythmias include Sustained or Non-sustained Ventricular Tachycardia (≥3 or more consecutive ventricular extrasystoles lasting less than 30 sec) and ventricular fibrillation. Severe bradyarrhythmias were defined in the study as Holter ECG evidence of Heart Rate <40 beats per minute, high grade second degree AV block (Mobitz type 2) or third degree AV blocks. The holter data collection also included the baseline rhythm, average heart rate, minimum heart rate, maximum heart rate and documentation of symptoms during recording. The prevalence of these arrhythmias were compared with the noted indications for the Holter test and also the clinically relevant age group distribution (<45 years, 45-64 years and ≥65 years).
All the data were analyzed by using SPSS, version 16 (SPSS Inc., Chicago IL). The prevalence of these abnormalities were expressed in terms of absolute numbers and percentages. The data were subjected to appropriate Chi-square statistical analyses, where applicable.

RESULTS
Overall 78 consecutive patients including 41(52.6%) males and 37(47.4%) females within the age range of 19-88 years with mean age of 56.83(±18.30) years were studied. Twenty two (28.1%) patients were young individuals of <45 years, 25 (32.1%) were middle-aged individuals between 45 and 64 years, and 31 (39.7%) were elderly patients of 65 years and above [ Figure 1(a and b)]. Sixteen (20.5%) patients were hypertensive, 18(23.1%) were diabetic, 10(12.8%) were smoker and 19(24.4%) were regular alcohol consumer. Palpitation (65.4%) was the most common indication for holter monitoring followed by dizziness (23.1%), presyncope (7.7%) and syncope (3.8%) as shown in figure 2(a and b).The mean minimum heart rate was 55 bpm, the mean maximum heart rate was 117bpm and the mean average heart was 74 bpm. Twenty nine (37.2%) cases revealed normal Holter study and arrhythmias were detected in 49 (62.8%) cases as listed in Table 1.     In the present study, dizziness, presyncope and syncope were the other indications for Holter monitoring in 18(23.1%), 6(7.7%) and 3(3.8%) patients respectively. This finding is also similar to the findings of previous studies on this subject. Adebola et al.11 reported that 17.6% of their patients presented with dizzy spells/ syncope, whereas Adebayo et al.10 reported that 15% of their patients presented with a history of syncopal attacks. As in palpitation, the causes of these symptoms vary from extracardiac causes such as anemia, febrile illness, and exhaustion to severe tachy/ bradyarrhythmias. Of the 27 patients referred with dizziness presyncope and syncope in the present study, 7 did not have Holter ECG evidence of cardiac arrhythmias.
Of the 78 patients in our study, 29 had normal cardiac rhythm devoid of any arrhythmias. Most of the patients with normal cardiac rhythm were young and middle age individuals and only 7 of the 31 elderly patients above the age of 65 years had a normal cardiac rhythm. Ventricular ectopics (35.9%) was the most common arrhythmia found on Holter ECG, followed by supraventricular ectopics (30.8%). Most of the ventricular and supraventricular ectopics were of Lown class 1. These findings are similar to that of previous studies.10,12 Even though ventricular and supraventricular ectopics were common in all age groups, they were particularly more common in elderly age groups. In fact, 13 (42%) of the 31 elderly patients had ventricular and supraventricular ectopics, as compared to 6 (27%) of the 22 young individuals. This is similar to the findings of Adebayo et al. 10, where only 19% of patients below 50 years had ventricular ectopics compared to 31% of those above 50 years. In our study, 9 (11.5%) patients had supraventricular tachyarrythmias. These were mostly atrial fibrillation, of which 3 out of 6 patients were of elderly age group. Likewise, PSVT was seen in 3 patients, 2 of them in elderly age group and one in younger age group. Inappropriate sinus tachycardia was seen in one patient of younger age group. These findings suggest that atrial fibrillation is more common in elderly population. Ventricular and supraventricular ectopics are generally assumed to be benign, especially if infrequent and monomorphic. However, frequent, polymorphic ventricular and supraventricular ectopics could be precursor to the development of dangerous sustained tachyarrythmias and sudden deaths and such individuals could benefit from β-blocker therapy.

LIMITATIONS OF THE STUDY
Due to the short duration of our study, only limited number of patients could be included for analysis. The patients were admitted in the ward for 24 hr ECG Holter monitoring which might have affected their daily routine activities and might have missed the arrhythmias related to exertion.

CONCLUSIONS
Among the patients with nonspecific symptoms like palpitation, dizziness, presyncope and syncope, 24 hr Holter monitoring has an important role in the diagnosis of cardiac arrhythmia as a cause of such symptoms, particularly in the elderly patients. The study showed that palpitation is the most common indication for 24 hr Holter monitoring and ventricular ectopics are the most common arrhythmias detected. Most of the arrhythmias detected are benign and prevalence of potentially fatal ventricular and supraventricular tachyarrythmias are relatively low in our population.