Electrocardiographic Patterns during Left Ventricular Epicardial Pacing

BACKGROUND: There is a paucity of data concerning the use of QRS morphology patterns for identifying pacing sites during left ventricle (LV)-only epicardial pacing in patients with a biventricular device. The objective of this study was to identify QRS patterns during LV-only pacing, and to establish their relationship with LV lead position. In addition, to validate the diagnostic performance of such electrocardiogram (ECG) patterns for predicting posterolateral versus anterior and apical versus nonapical LV pacing site. METHODS: The study retrospectively analyzed data from 376 cardiac resynchronization therapy device patients. Data analyzed included ECGs registered during LV-only VVI pacing, fluoroscopic projections, and lateral chest roentgenograms that documented postimplantation LV lead position. Phase one of the study involved categorization of the ECG patterns of the first 66 study cases. Phase two of the study examined the association between ECG pattern and different LV lead positions. RESULTS: As the LV epicardial pacing site became more anteroapical, the LV-only paced QRS complexes in the precordial leads became more negative. Three ECG patterns were identified (posterolateral, intermediate, and anteroapical), and their distribution was found to be associated with LV lead position (P < 0.001). The posterolateral ECG pattern was mostly observed in cases where the LV lead was in the posterolateral area (diagnostic accuracy of 89.1% for predicting a nonapical LV lead position). The anteroapical ECG pattern was associated with LV leads in anteroapical segments (specificity of 98.5%, accuracy of 89.1% for predicting an anteroapical pacing site). CONCLUSIONS: Posterolateral and anteroapical ECG patterns are highly predictive of LV lead position.