Abstract
BackgroundIt is important to understand the relationship between electrical and mechanical ventricular activation in CRT patients. By measuring local electrical activation at multiple locations within the coronary veins and myocardial contraction at the same locations in the left ventricle, we determined the relationship between electrical and mechanical activation at potential left ventricular pacing locations.MethodsIn this study, mechanical contraction times were computed using high temporal resolution cine cardiovascular magnetic resonance (CMR) data, while electrical activation times were derived from intra-procedural local electrograms.ResultsIn our cohort, there was a strong correlation between electrical and mechanical delay times within each patient (R2 = 0.78 ± 0.23). Additionally, the latest electrically activated location corresponded with the latest mechanically contracting location in 91% of patients.ConclusionsThis study provides initial evidence that our method of obtaining non-invasive mechanical activation patterns accurately reflects the underlying electromechanical substrate of intraventricular dyssynchrony.
Highlights
It is important to understand the relationship between electrical and mechanical ventricular activation in Cardiac resynchronization therapy (CRT) patients
The purpose of this study was to combine regional mechanical contraction timing information throughout the left ventricular (LV) derived from cardiovascular magnetic resonance (CMR) with measures of electrical activation delay derived from local electrograms acquired at several locations in the LV from within the coronary veins
This study was conducted in eleven patients enrolled for CRT based upon current guidelines (QRS Duration > 120 ms, Ejection Fraction < 35%, and NYHA Heart Failure Class III-IV despite optimal medical therapy)
Summary
It is important to understand the relationship between electrical and mechanical ventricular activation in CRT patients. Cardiac resynchronization therapy (CRT) is a treatment option for drugrefractory heart failure patients with low ejection fraction and evidence of left ventricular (LV) electrical dyssynchrony. Several groups have shown that pacing the LV in the latest contracting segment (greatest mechanical dyssynchrony) results in improved response to CRT [5,6,7,8,9]. Canine and human studies have seen varied results when pacing at the latest electrically activated region [12,13]. These contradictory findings may be a result of the complex interaction between electrical and mechanical dyssynchrony
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