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

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

BACKGROUND

Previous studies have reported the presence of subtle abnormalities in the right ventricular outflow tract (RVOT) in patients with apparently normal hearts and ventricular arrhythmias (VAs) from the RVOT, including the presence of low voltage areas (LVAs). This LVAs seem to be associated with the presence of ST-segment elevation in V1 or V2 leads at the level of the 2nd intercostal space (ICS).

OBJECTIVE

Our aim was to validate an electrocardiographic marker of LVAs in the RVOT in patients with idiopathic outflow tract VAs.

METHODS

A total of 120 patients were studied, 84 patients referred for ablation of idiopathic VAs with an inferior axis by the same operator, and a control group of 36 patients without VAs. Structural heart disease including arrhythmogenic right ventricular cardiomyopathy was ruled out in all patients. An electrocardiogram was performed with V1-V2 at the 2nd ICS, and ST-segment elevation ≥1 mm and T-wave inversion beyond V1 were 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 were considered LVAs, and their presence was assessed. We compared three groups, VAs from the RVOT (n = 66), VAs from the LVOT (n = 18) and Control group (n = 36). ST-elevation, T-wave inversion and left versus right side of the VAs were tested as predictors of LVAs, respective odds ratio (ORs) (95% confidence interval [CI]) and p values, were calculated with univariate logist regression. Variables with a p < .005 were included in the multivariate analysis.

RESULTS

ST-segment elevation, T-wave inversion and LVAs were present in the RVOT group, LVOT group and Control group as follows: (62%, 17%, and 6%, p < .0001), (33%, 29%, and 0%, p = .001) and (62%, 25%, and 14%, p < .0001). The ST-segment elevation, T-wave inversion and right-sided VAs were all predictors of LVAs, respective unadjusted ORs (95% CI), p values were, 32.31 (11.33-92.13), p < .0001, 4.137 (1.615-10.60), p = .003 and 8.200 (3.309-20.32), p < .0001. After adjustment, the only independent predictor of LVAs was the ST-segment elevation, with an adjusted OR (95% CI) of 20.94 (6.787-64.61), p < .0001.

CONCLUSION

LVAs were frequently present in patients with idiopathic VAs. ST-segment elevation was the only independent predictor of their presence.

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

Characterizing patient-specific atrial conduction properties is important for understanding arrhythmia drivers, for predicting potential arrhythmia pathways, and for personalising treatment approaches. One metric that characterizes the health of the myocardial substrate is atrial conduction velocity, which describes the speed and direction of propagation of the electrical wavefront through the myocardium. Atrial conduction velocity mapping algorithms are under continuous development in research laboratories and in industry. In this review article, we give a broad overview of different categories of currently published methods for calculating CV, and give insight into their different advantages and disadvantages overall. We classify techniques into local, global, and inverse methods, and discuss these techniques with respect to their faithfulness to the biophysics, incorporation of uncertainty quantification, and their ability to take account of the atrial manifold.

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

BACKGROUND

Frequently, low voltage areas (LVAs) and diastolic potentials (DPs) are present at ablation site in sinus rhythm in patients with idiopathic premature ventricular contractions (PVCs).

OBJECTIVE

Validate these findings as substrate for PVCs and evaluate the feasibility of a simplified substrate approach based on LVAs and DPs for ablation of idiopathic outflow tract PVCs, in patients with a low PVC burden during the procedure.

METHODS

Prospective single-arm clinical trial at two centers with comparison with a historical group, matched to age and gender. The study group consisted of consecutive patients referred for ablation of frequent idiopathic PVCs with inferior axis, that presented with less than 2 PVCs/min in first 5 minutes of the procedure. The ablation was based on fast mapping of the RVOT in sinus rhythm looking for LVAs and DPs, defined as isolated small amplitude potentials occurring after the T wave of the surface ECG. The area with LVAs and DPs was tagged, and a simplified activation mapping of the PVCs was done in that area. The procedure time, success rate and recurrence rate were compared with the historical group in whom ablation was performed based on activation and pace mapping only. A validation group without PVCs was also studied to assess the prevalence of LVAs and DPs in the general population.

RESULTS

The study (n=38), historical (n=38) and validation (n=38) groups did not differ in relation to age or gender. Prevalence of LVAs and DPs was significantly higher in the study group in comparison with the validation group, respectively, 71% vs 11%, p<0.0001 and 87% vs 8%, p<0.0001. Procedure time was significantly lower in the study group when comparing to the historical group, 130 (100-164) vs 183 (160-203) min, p<0.0001 and the success rate was significantly higher, 90% vs 64%, p=0.013. The recurrence rate in patients with a successful ablation was not significantly different between both groups, Log-Rank=0.125.

CONCLUSION

Prevalence of LVAs and DPs was significantly higher in the study group than in the validation group. The proposed approach proved to be feasible, faster and more efficient than the historical approach. This article is protected by copyright. All rights reserved.

Assessment of wave front activation duration and speed across the right ventricular outflow tract using electrocardiographic imaging as predictors of the origin of the premature ventricular contractions: A validation study

AIMS

Evaluate right ventricular outflow tract (RVOT) activation duration (AD) and speed, invasively and with the electrocardiographic imaging (ECGI), as predictors of the origin of the PVCs, validating the ECGI.

METHODS

18 consecutive patients, 8 males, median age 55 (35-63) years that underwent ablation of PVCs with inferior axis and had ECGI performed before ablation. Isochronal activation maps of the RVOT in PVC were obtained with the ECGI and invasively. Total RVOT AD was measured as the time between earliest and latest activated region, and propagation speed by measuring the area of the first 10 ms of activation. Cut-off values for AD, activation speed and number of 10 ms isochrones to predict the origin of the PVCs, were obtained with the ROC curve analysis. Agreement between methods was done with Pearson correlation test and Bland-Altman plot.

RESULTS

PVCs originated from the RVOT in 11 (61%) patients. The stronger predictor of PVC origin was the AD. The median AD in PVCs from RVOT was significantly longer than from outside the RVOT, both with ECGI and invasively, respectively 62 (58-73) vs 37 (33-40) ms, p < 0.0001 and 68 (60-75) vs 35 (29-41) ms, p < 0.0001. Agreement between the two methods was good (r = 0.864, p < 0.0001). The cut-off value of 43 ms for AD measured with ECGI predicted the origin of the PVCs with a sensitivity and specificity of 100%.

CONCLUSIONS

We found good agreement between ECGI and invasive map. The AD measured with ECGI was the best predictor of the origin of the PVCs.