Prolonged Right Ventricular Outflow Tract Endocardial Activation Duration and Presence of Deceleration Zones in Patients With Idiopathic Premature Ventricular Contractions. Association With Low Voltage Areas

Abstract

Background and AimsThe wavefront propagation velocity in the myocardium with fibrosis is characterized by the presence of deceleration zones and late activated zones, that are absent in the normal myocardium. Our aim was to study the right ventricular outflow tract (RVOT) endocardial activation duration in sinus rhythm, and assess the presence of deceleration zones, in patients with premature ventricular contractions (PVCs) and in controls.MethodsWe studied 29 patients with idiopathic PVCs from the outflow tract, subjected to catheter ablation that had an activation and voltage map of the RVOT in sinus rhythm. A control group of 15 patients without PVCs that underwent ablation of supraventricular arrhythmias was also studied. RVOT endocardial activation duration and number of 10 ms isochrones across the RVOT were assessed. Propagation speed was calculated at the zone with the higher number of isochrones per cm radius. Deceleration zones were defined as zones with >3 isochrones within 1 cm radius. Low voltage areas were defined as areas with local electrogram with amplitude <1.5 mV.ResultsThe two groups did not differ in relation to age, gender or number of points in the map. RVOT endocardial activation duration and number of 10 ms isochrones were higher in the PVC group; 56 (41–66) ms vs. 39 (35–41) ms, p = 0.001 and 5 (4–8) vs. 4 (4–5), p = 0.001. Presence of deceleration zones and low voltage areas were more frequent in the PVC group; 20 (69%) vs. 0 (0%), p < 0.0001 and 21 (72%) vs. 0 (0%), p < 0.0001. The wavefront propagation speed was significantly lower in patients with PVCs than in the control group, 0.35 (0.27–0.40) vs. 0.63 (0.56–0.66) m/s, p < 0.0001. Patients with low voltage areas had longer activation duration 60 (52–67) vs. 36 (32–40) ms, p < 0.0001, more deceleration zones, 20 (95%) vs. 0 (0%), p < 0.0001, and lower wavefront propagation speed, 0.30 (0.26–0.36) vs. 0.54 (0.36–0.66) m/s, p = 0.002, than patients without low voltage areas.ConclusionRight ventricular outflow tract endocardial activation duration was longer, propagation speed was lower and deceleration zones were more frequent in patients with PVCs than in controls and were associated with the presence of low voltage areas.

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

“…To overcome those limitations, we did a second study that included a larger sample with VAs from the right and left outflow tracts all with normal CMR, and a control group without VAs that had an ECG obtained at the 2nd ICS and a voltage map of the RVOT in sinus rhythm. 7 In this second study, ST-segment elevation was absent in the control group and present in 65% of patients with RVOT arrhythmias, but also in three out of five (60%) patients with VAs originating in the LVOT. This finding was surprising assuming that this was a marker of low voltage across the RVOT, thus unexpected in patients with arrhythmias with an origin outside the RVOT.…”

“…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

“…The DPs were mostly recorded at LVAs, which also displayed abnormal electrophysiological properties, namely a slower propagation speed both in sinus rhythm 32 and in PVC. 33 Using electrocardiographic imaging, we were able to demonstrate the presence of a dispersion of the activation-recovery interval, a known surrogate of the action potential duration across the RVOT in patients with PVCs.…”

Atrial conduction velocity mapping: clinical tools, algorithms and approaches for understanding the arrhythmogenic substrate

“…Isochronal methods use the distances between isochronal contours to calculate CV, effectively fitting distances between wavefronts to activation times in order to calculate CV. These results are often averaged across pairs of points on the wavefront to increase robustness, and are mostly applied to LAT maps obtained with clinical mapping system [ 3 , 48 , 68 – 76 ]. However, these methods could be applied for any global LAT interpolation technique, and it would even be possible for use them for probabilistic models by applying them to posterior samples of LAT maps.…”