12-Lead 24-Hour Holter ECG monitoring in Type 1 Brugada patients: prevalence and characterization of electrical events

Background. 12 lead-Holter monitoring is commonly used for the assessment of spontaneous type 1 Brugada pattern burden. However, it may also assess prevalence and morphology of premature ventricular contractions (PVC) in these patients, an information that in present literature is lacking. Purpose. We investigated the prevalence and morphology of ventricular arrhythmias in subjects with Brugada syndrome (BRs) phenotype during 24-hour 12 lead-Holter monitoring (12-L Holter). Methods. From January 2013 to August 2020, a total of 188 patients with type 1 BRs phenotype (spontaneous or drug induced) were screened. For the purpose of the present study 12-L Holter recordings were performed positioning the right precordial leads at the second (V1-V2) and the fourth (V3-V4) intercostal spaces. Results. Mean age was 50 years (range 20-79 years) and 88 (77%) were males. 19 subjects (16%) had a spontaneous type 1 BRs whereas 95 (83%) presented a drug induced type 1 pattern. 3 patients had implanted an ICD in secondary prevention after an aborted sudden cardiac death and 8 subjects were on idroquinidine as anti-arrhythmic profilaxis. The majority of patients were asymptomatic, while 5 (4%) had history of suspected cardiac syncope. 47 subjects (41%) had performed an electrophysiological study, positive in 7 cases (15%). Out of the total 188 patients 114 (60%) presented PVCs. Baseline characteristics did not differ within patients presenting or not PVCs. In 79 (69%) patients PVCs were monomorphic, while in the other 33 subjects (31%) more than one morphology was present. PVCs were classified according to their morphology: (i) left bundle branch block (LBBB)/inferior axis, suggesting an origin from the right ventricular outflow tract (RVOT), in 58 (51%) subjects; (ii) right bundle branch block (RBBB)/left axis, suggesting an origin close to the posterior fascicle of the left bundle branch in 46 (40%).The remaining 10 (9%) patients presented multiple morphologies. According to prevalence during 12-L Holter, PVCs were classified as follows: (i) 1-59, in 86 patients (75%); (ii) 60-749, in 21 patients (18%); (iii) 750-9000, in 6 patients (5%); (iv) >9000, in 1 patient. 2 patients, additionally to PVCs, also displayed Non-Sustained Ventricular Tachycardia from RVOT origin. Conclusions. In our population of subjects with BRs phenotype the prevalence of PCVs was similar to that of the general population. Site of origin of the prevalent PVCs is the RVOT or the area close to the posterior fascicle of the left bundle branch. Repetitive ventricular arrhythmias are extremely rare.