In the 2018 ESC Guidelines for the diagnosis and management of syncope, the yield of ambulatory Holter ECG monitoring was decreased from the first-line diagnostic tool with I class of recommendation to class IIA . The reason is simple - most Holter monitors record no more than 24 hours and has limited effectiveness in the diagnosis of syncope .
Despite this, due to the low cost and wide clinical acceptance, the Holter ECG monitoring is still a fairly affordable and convenient tool that allows quick diagnosis without costly and invasive studies. This tool becomes especially effective when allows recording of more than 24 hours without causing significant inconvenience to the patient.
An 86-year-old male presented to ER with chief complaints of frequent episodes of dizziness during the last 1 year. His past medical history included permanent atrial fibrillation (within 7 years, with CHADS-VASc score = 7, HAS-BLED score = 4, and EHRA score = I-II), arterial hypertension stage 3. (more than 10 years), chronic kidney disease, COPD, prostate adenoma. His daily treatment included valsartan, amlodipine, hydrochlorothiazide, indapamide, carvedilol, and rivaroxaban.
He was walking in the park when suddenly he felt severe dizziness and lost consciousness. The patient was delivered to the emergency department by the ambulance team.
At the admission to the hospital, a 12-lead ECG was performed, showing atrial fibrillation with a slightly decreased heart rate. Echocardiography was also performed: left atrium 5.1x8.4 cm, LVEF 49%, LV EDD 4.8 cm, LV EDV 111 ml., LV PWT 1.2 cm, moderate mitral regurgitation, moderate tricuspid regurgitation. The laboratory results showed no abnormalities.
The patient was also examined by a neurologist, but no acute neurological pathology was found. Taking into account the stroke in past medical history, the patient was hospitalized in the neurological department for the diagnostic workup. On the next day, the patient had an episode of bradycardia with a heart rate of up to 40 bpm, which was accompanied by a severe deterioration in the patient's condition. After this, the Holter ECG monitoring was performed, which revealed the monomorphic ventricular tachycardia.
Heart rate: 70 bpm
Figure 1. Monomorphic ventricular tachycardia.
Considering the monomorphic ventricular tachycardia on the ECG, the arrhythmogenic nature of the previous syncopal episodes was suspected. It was decided to perform a 24-hour Holter ECG study. The monitoring didn't reveal any rhythm disturbances that could potentially lead to syncope, but on the next day after monitoring, an episode of syncope repeated.
Since the frequency of syncopal episodes was more than 1 per week and the patient had concomitant permanent atrial fibrillation, it was decided to repeat the ECG monitoring (according to the Guidelines , class IIA recommendation), but this time using the Mawi Cardio patch that allows monitoring for 5 days. As a result, ECG monitoring revealed a transient complete proximal AV block with a substituting junctional rhythm with a heart rate of 42 bpm and narrow QRS complexes, as well as an episode of distal AV block with a heart rate of 38 bpm and wide QRS complexes. All episodes of bradycardia were accompanied by a deterioration in the patient's status with the development of a presyncope. An additional finding was asymptomatic slow non sustained ventricular tachycardia.
Heart rate: 43 bpm
Figure 2. Frederick's syndrome with proximal block and narrow QRS complexes.
Heart rate: 44 bpm
Figure 3. Frederick's syndrome with distal block and wide QRS complexes.
Analyzing all the data obtained, it became obvious that there was a progressive disease of the normal conducting system, as indicated by transient AV block with wide QRS complexes. Bradycardia was considered the most likely cause of syncope. Slow VT revealed by ECG monitoring was regarded as hemodynamically insignificant, but still required treatment with beta-blockers.
Considering permanent atrial fibrillation, episodes of symptomatic bradycardia, and the need for further beta-blocker treatment, a single-chamber pacemaker was implanted to the patient.
Thus, despite the decrease in the class of recommendations, continuous Holter ECG monitoring for 5 days using Mawi patches is an effective, patient-friendly, and low-cost tool for diagnosing rhythm disturbances in patients with suspected arrhythmogenic syncope and a frequency of symptomatic episodes up to several times per week.
- Brignole, M., Moya, A., de Lange, F. J., Deharo, J. C., Elliott, P. M., Fanciulli, A., ... & van Dijk, J. G. (2018). 2018 ESC Guidelines for the diagnosis and management of syncope. Kardiologia Polska (Polish Heart Journal), 76(8), 1119-1198.
- Bass, E. B., Curtiss, E. I., Arena, V. C., Hanusa, B. H., Cecchetti, A., Karpf, M., & Kapoor, W. N. (1990). The duration of Holter monitoring in patients with syncope: is 24 hours enough?. Archives of Internal Medicine, 150(5), 1073-1078.