ECG Identification of Scar-Related Ventricular Tachycardia With a Left Bundle-Branch Block Configuration

Abstract

Background-A left bundle-branch block (LBBB)-like pattern with a dominant S-wave in V 1 is common in idiopathic ventricular arrhythmias (VA). Discrimination between idiopathic and scar-related LBBB pattern VA has important clinical implications. We hypothesized that the VA QRS morphology is influenced by the presence of ventricular scar, allowing ECG discrimination of VA arising from structurally normal versus scarred myocardium. Methods and Results-Twelve-lead ECGs of 297 LBBB pattern monomorphic VA were recorded during catheter ablation procedures. QRS morphology characteristics associated with scar-related VA were identified in retrospective analysis of 118 LBBB pattern VA (95 scar-related, 23 idiopathic) to develop a stepwise algorithm that was prospectively tested in 179 LBBB pattern VA (120 scar-related, 59 idiopathic). The diagnosis of scar was based on sinus rhythm surface ECG, cardiovascular imaging, and electroanatomic catheter mapping. A precordial transition beyond V 4 , notching of the S-wave downstroke in lead V 1 or V 2 , and a duration from the onset of QRS to the S-nadir in V 1 Ͼ90 ms were independent predictors for scar-related VA. The proposed algorithm classified a VA as scar-related if any of these criteria was met. If none of the criteria was present, a VA was classified as idiopathic. In prospective validation, the algorithm was highly sensitive (96%) and specific (83%) for the identification of scar-related LBBB pattern VA. Conclusions-The QRS morphology of VA is different between scar-related and idiopathic VA. A simple ECG algorithm is sensitive for identifying scar-related LBBB VA, which could be helpful in guiding further evaluation of these patients. (Circ Arrhythm Electrophysiol. 2011;4:486-493.)

Prevalence and Prognostic Value of Concealed Structural Abnormalities in Patients With Apparently Idiopathic Ventricular Arrhythmias of Left Versus Right Ventricular Origin

“…VAs with RBBB morphology and superior QRS axis are indeed consistent with an inferior LV wall exit, which have been rarely observed in idiopathic VAs. 26 Interestingly, this matches with the observation that LV segments having LGE were frequently located in the inferior and inferolateral wall, suggesting the possible relationship of reentry circuits to the detected scar.…”

“…VAs with RBBB morphology and superior QRS axis are indeed consistent with an inferior LV wall exit, which have been rarely observed in idiopathic VAs. 26 Interestingly, this matches with the observation that LV segments having LGE were frequently located in the inferior and inferolateral wall, suggesting the possible relationship of reentry circuits to the detected scar.Another important finding of this study is that the presence of myocardial structural abnormalities on cMRI was a predictor of follow-up arrhythmic events among patients presenting with apparently idiopathic VAs. This finding fits with observations of previous studies that cMRI is able to identify patients at risk for arrhythmic events in several overt heart diseases, including ischemic cardiomyopathy, nonischemic dilated cardiomyopathy, hypertrophic cardiomyopathy, and myocarditis.…”

New Diagnostic and Therapeutic Approaches to Treat Ventricular Tachycardias Originating at the Summit of the Left Ventricle

“…7 Other ECG features suggestive of an origin at the epicardial aspect of the LV outflow tract include R wave width >85 ms, 8 presence of q wave in lead I, 9 and, specifically, aVL/aVR amplitude ratio >1.75, indicating an origin at the upper part of the LV summit. Nevertheless, QRS morphology may be influenced by the presence and extent of myocardial scar, which can be predicted by the presence of a late precordial transition, precordial notching, and a QRS-S interval >90 ms. 10 Finally, the ECG features of the tachycardia were remarkably similar to the PVCs, suggesting a common site of origin for these arrhythmias, as does the elimination of one of them when targeting the other, making PVC ablation a more than acceptable surrogate in the case that the clinical SMVT is not inducible. 5 Although the majority of idiopathic VTs originate in hearts without structural disease, a small subset can occur in conjunction with different entities such as coronary artery disease, valvular regurgitation or LV dysfunction, or abnormal MRI findings.…”

“…Nevertheless, QRS morphology may be influenced by the presence and extent of myocardial scar, which can be predicted by the presence of a late precordial transition, precordial notching, and a QRS-S interval >90 ms. 10 Finally, the ECG features of the tachycardia were remarkably similar to the PVCs, suggesting a common site of origin for these arrhythmias, as does the elimination of one of them when targeting the other, making PVC ablation a more than acceptable surrogate in the case that the clinical SMVT is not inducible.…”

Electrocardiographic Difference between Ventricular Arrhythmias from the Right Ventricular Outflow Tract and Idiopathic Right Ventricular Arrhythmias

“…In this research, we involved more VAs arising from the free wall of RVOT, and found using the presence of notching to differentiate the two conditions was not enough. In another study conducted by Wijnmaalen et al., the total number of leads expressing QRS notching during VA did not get statistically significant between the scar and nonscar groups either.…”