Noncontact mapping of left ventricle during CRT implant

Not all candidates for cardiac resynchronization therapy (CRT) are responders at follow-up. Echocardiographic parameters of dyssynchrony do not predict the response. Analysis of electrical properties of left ventricle (LV) by noncontact mapping (NCM) could be useful to better identify candidates for CRT.

We studied nine consecutive patients undergoing CRT. An NCM was positioned in the LV via atrial transeptal puncture. LV activation was recorded during sinus rhythm (SR), pacing from RV, from different LV epicardial locations, and in biventricular (BIV) pacing. The corresponding invasive pressure was determined. Heparin, administered during NCM, was reversed and CRT implant was completed. An offline analysis of the data was performed in order to measure transeptal and total LV activation time, to evaluate the site of earliest and latest LV activation, and the pattern of activation. No complications occurred. Mean time of total NCM procedures was 24 + or - 7 minutes. During SR, RV, LV, and BIV pacing, respectively, a "U"-shaped LV activation pattern was found in three, seven, four, and and two patients; mean LV activation time was 58.1 + or - 7.0, 81.7 + or - 15.8, 71.1 + or - 12.4, and 65.6 + or - 7.7 ms; and mean systolic LV peak pressure was 114 + or - 21, 97 + or - 18, 103 + or - 17 and 110 + or - 15 mmHg, respectively. LV activation was influenced by a slow conduction area at the pacing site and by the duration of transeptal time.

An NCM during CRT is safe and feasible. It provides an additional information on electrical activation in SR and in various modality of pacing. Further studies with larger populations are needed in order to correlate electrical to clinical outcomes.