Idiopathic Premature Ventricular Contractions From the Outflow Tract Display an Underlying Substrate That Can Be Unmasked by a Type 2 Brugada Electrocardiographic Pattern at High Right Precordial Leads

Abstract

Background: Patients with premature ventricular contractions (PVCs) from the right ventricular outflow tract (RVOT) and apparently normal hearts, can have ST elevation similar to type 2 or type 3 Brugada pattern in the electrocardiographic (ECG) performed at a higher position. Cardiac magnetic resonance (CMR), has shown conflicting data regarding existence of structural abnormalities in patients with idiopathic PVCs from the RVOT. Objective: Our aim was to evaluate the prevalence of low voltage areas (LVAs) 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 ECG marker. Methods: A 56 consecutive patients, 45 with frequent PVCs (>10000/24 h) 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 level of the second intercostal space and the presence of ST-segment elevation with a Type 2 or 3 Brugada pattern (Type 2 BrP) was assessed. Bipolar voltage map of the RVOT was performed in sinus rhythm (0.5-1.5 mV color display). Areas with electrograms <1.5 mV represented the LVA. The area adjacent to the pulmonary valve usually displays voltage between 0.5 and 1.5 mV and is classified as transitionalvoltage zone. Presence of LVAs outside this transitional-voltage zone were estimated. We compared two groups with and without ST-segment elevation and tested for the association between ECG pattern and LVAs.

Validation of an electrocardiographic marker of low voltage areas in the right ventricular outflow tract in patients with idiopathic ventricular arrhythmias

“…The much higher incidence of ST-segment elevation in our patients with RVOT VAs has been previously described by our group in a smaller population 6 and confirmed in this larger population. The percentage of ST-segment elevation in patients with LVOT VAs in the current study is lesser than in the former one, 60% versus 27%.…”

“…However, there is an increasing amount of evidence suggesting the presence of a substrate within the RVOT in patients with VAs originating from the RVOT. [2][3][4][5][6] In the current study we found the presence of LVAs in 62% of cases using a quadripolar catheter and a point-by-point methodology, whereas Letsas et al 5 mapped the RVOT with multipolar catheters and found a similar result, respectively, the presence of LVAs in 18 out of 28 patients (64%) of cases. The LVAs described by all those authors could not be detected by LGE CMR in none.…”

“…However, several studies have been published, that report the presence of low voltage areas (LVAs) within the right ventricular outflow tract (RVOT) detected by invasive mapping, in patients with VAs originated from this location. [2][3][4][5][6] These LVAs are also associated with a lower conduction velocity 7 and a higher dispersion of the activation recovery interval a surrogate of the action potential. 8 The true nature of the LVAs is unknown and do not correspond to the identification of fibrosis on the CMR.…”

A simplified approach to radiofrequency catheter ablation of idiopathic ventricular outflow tract premature ventricular contractions

“…6 However, previous studies have shown the presence of low voltage areas (LVAs) in the RVOT of patients undergoing catheter ablation of frequent idiopathic PVCs. [7][8][9][10][11] As previously, reported by our group, LVAs were predicted by the presence of ST-elevation in V1 or V2 at the level of the second intercostal space (2nd ICS). 9,10 Furthermore, the presence of discrete diastolic potentials (DPs) on the bipolar intracardiac electrograms at the successful ablation site have also been described previously.…”

“…[7][8][9][10][11] As previously, reported by our group, LVAs were predicted by the presence of ST-elevation in V1 or V2 at the level of the second intercostal space (2nd ICS). 9,10 Furthermore, the presence of discrete diastolic potentials (DPs) on the bipolar intracardiac electrograms at the successful ablation site have also been described previously. [12][13][14] These are low amplitude potentials, occurring after the T wave of the ECG in sinus rhythm, that become presystolic, preceding the local bipolar ventricular electrogram during the PVCs.…”