Idiopathic premature ventricular contractions from the outflow tract
display an underlying substrate that can be unmasked by a Brugada
electrocardiographic pattern at high right precordial leads
Abstract
Background and aims: Cardiac magnetic resonance (CMR), has shown
conflicting data regarding existence of structural abnormalities in
patients with idiopathic premature ventricular contractions (PVCs) from
the right ventricular outflow tract (RVOT). Our aim was to evaluate the
prevalence of low voltage areas (LVA) in the RVOT of patients with PVCS
from the outflow tract and in a control group. Secondly, assess for the
presence of a non-invasive electrocardiographic (ECG) marker. Methods:
56 consecutive patients, 45 with frequent PVCs (>10000/24h)
LBBB, vertical axis, negative in aVL and 11 subjects without PVCs.
Arrhythmogenic right ventricular cardiomyopathy was ruled out in all
patients. An ECG was performed with V1-V2 at the 2nd intercostal space
and the presence of a Brugada ECG pattern (BrP) was assessed. Bipolar
voltage map of the RVOT was performed in sinus rhythm (0.5 mV-1.5 mV
colour display). Areas with electrograms < 1.5 mV represented
the LVA. We tested for the association between high BrP and LVA.
Results: None of the patients in the control group had BrP or LVA. In
the PVC group, 29 patients (64%) had type 2 BrP and 28 (62%) had LVAs.
LVAs were more frequent in patients with BrP; 93% versus 4%,
p<0.0001, which was associated with LVA, OR (95% CI): 202.50
(16.92- 2423), p<0.0001. Conclusions: LVAs were frequently
present in the RVOT of patients with idiopathic PVCs. They were absent
in controls and can be unmasked by the presence of BrP in high right
precordial leads.