Electrical, mechanical activation of left ventricle strongly correlated

A close relationship exists between the timing of left ventricular (LV) electrical activation and peak contraction in dyssynchronous heart failure patients, according to a new study.

Researchers analyzed 28 consecutive cardiac resynchronization therapy (CRT) patients at Maastricht University Medical Center (MUMC) in the Netherlands using a combination of coronary venous electroanatomic mapping and speckle tracking echocardiography. They published their findings in JACC: Electrophysiology.

“The demonstration of a close correlation between timing of electrical activation and peak contraction suggests that current LV lead targeting strategies, which are based on either direct intracardiac measurements of electrical activation or speckle tracking strain echocardiography, will most likely target the same myocardial region, and as such, can be regarded as corresponding,” wrote Masih Mafi-Rad, MD, of MUMC’s Department of Cardiology, and colleagues. “In this respect, the present study could be regarded as a validation of the speckle tracking approach.”

Only 23 of the 28 patients enrolled in the study were eligible for analysis. The mean age of the analysis group (15 men, eight women) was 69, and all patients were in a New York Heart Association functional class of II or III. Mean LV ejection fraction was 28 percent.

The regions of latest electrical activation and latest peak contraction corresponded in 19 of 23 patients and were adjacent in the remaining four patients. And while the researchers noted a positive correlation between electrical activation and peak contraction times, the magnitude of the relationship varied greatly among individual patients.

One limitation of the study, Mafi-Rad et al. wrote, was its small sample size. The sample group may not have been representative of the typical CRT population, which limits extrapolation of the data to larger populations.

“Several studies indicated that pacing in a region of late electrical or mechanical activation improves CRT response, but it is not known whether combining electrical and mechanical information may further improve LV lead targeting,” the researchers wrote. “Whether such a LV lead placement strategy actually increases the likelihood of a favorable CRT response needs prospective evaluation in larger, and preferably, randomized studies.”