Background: Optimal left ventricular (LV) lead position is thought to be a major predictor of response in patients undergoing cardiac resynchronization therapy (CRT). While the post-implant posterior-anterior (PA) and lateral chest X-ray (CXR) is commonly used to determine the position of the LV lead, the accuracy to which the CXR can correctly localize the LV lead is unknown.
Methods: We collected data on 47 consecutive patients (mean age 64 years, 60% men and LV ejection fraction 23%, 49% ischemic cardiomyopathy) that underwent CRT between 2004 and 2007, who had both a post-implant CXR as well as a contrast-enhanced multi-detector computed tomography (MDCT) of the chest for any reason. The positions of the LV lead on CXR and MDCT were interpreted in a blinded fashion, independent of each other. The accuracy of the CXR in localizing various LV lead positions, with MDCT as the gold standard, was recorded.
Results: On CXR, the LV lead tip position was as follows: basal (4%), mid-ventricular (66%), and apical (30%) and anterior (2%), lateral (34%), and posterior (64%). On MDCT, the LV tip position was: basal (28%), mid-ventricular (60%), and apical (13%) and anterior (13%), lateral (19%), and posterior (68%). Compared to the MDCT gold standard, the percentage of LV lead positions the CXR correctly classified correctly were: 100% basal, 39% mid-ventricular, and 29% apical and 0% anterior, 12% lateral, and 77% posterior. Taking both PA and lateral views into consideration, the LV lead position was misclassified by CXR in 62% cases.
Conclusion: Using MDCT as a gold standard, the routine post-implant CXR performs very modestly in terms of accurate LV lead positioning.