Yang, Dachun

AbstractBackgroundCardiac resynchronization therapy (CRT) reverses left ventricular remodeling and improves left ventricular systolic function. However, little is known about whether CRT improves ventricular conduction.ObjectiveTo determine the relationship between CRT response and QRS narrowing.MethodsThe study included consecutive patients who underwent CRT with defibrillator (CRT‐D) implantation between January 2002 and December 2012 and had subsequent generator replacement (GR). At the time of GR, super‐responder was defined as those who had left ventricular ejection fraction (LVEF) of 50% or more; patients who had an LVEF of 36–49% with an increase of more than 5% were considered responders, and the others were nonresponders. All patients were assessed 6 months after CRT‐D implantation and at the time of GR.ResultsOf 114 study patients, 58 (50.9%) were nonresponders, 29 (25.4%) responders, and 27 (23.7%) super‐responders. QRS narrowing at 6 months was significant in super‐responders (175.4 ± 21.4 to 159.7 ± 20.7 ms, P = 0.001) and responders (169.0 ± 21.3 to 157.7 ± 17.6 ms, P = 0.008). At time of GR, only super‐responders had further QRS narrowing (159.7 ± 20.7 to 146.3 ± 19.2 ms, P < 0.001). QRS duration change after 6 months was independently associated with super‐response (hazard ratio: 1.20 for every 5 ms QRS duration narrowing; 95% confidence interval, 1.06–1.38; P = 0.005), and QRS narrowing of 10 ms or more was associated with lower risk of all‐cause mortality after GR.ConclusionContinuous QRS narrowing after CRT, as an electrical marker, is associated with a super‐response to CRT. Further QRS narrowing 6 months after CRT implantation was associated with lower risk of mortality after GR.

BackgroundLeft ventricular (LV) pacing in cardiac resynchronization therapy (CRT) can be achieved via a transvenous or epicardial route. A surgically implanted epicardial LV (eLV) lead is used after a standard transvenous LV (tLV) lead implantation has failed. However, studies of clinical outcomes in patients with eLV leads and comparisons of outcome between tLV and eLV‐CRT are sparse. Therefore, the purpose of this study is to compare clinical response between tLV‐CRT and eLV‐CRT, as well as to understand the differences within the eLV‐CRT population.MethodsForty‐four patients received eLV‐CRT following unsuccessful attempts of tLV‐CRT implantation between 2002 and 2013 at the University of California, San Diego (UCSD) and Mayo Clinics. These patients were matched for age, gender, and etiology of cardiomyopathy in a 1:2 ratio with a cohort of patients who received tLV‐CRT during the same time period.ResultsDuring a mean follow‐up of 57 months, similar clinical outcomes and survival rate were noted between tLV and eLV‐CRT patients (all P > 0.05). Within the eLV‐CRT group, dilated cardiomyopathy patients had significant improvement in New York Heart Association class and ejection fraction (both P < 0.05), while ischemic cardiomyopathy patients did not (both P > 0.05). eLV‐CRT patients with nonanterior lead location had significantly improved survival (P < 0.001). There was also a trend for improved survival in those with nonapical lead location (P = 0.09).ConclusionIn this case‐matched two‐centered study, comparable improvements were noted in patients with tLV‐CRT and eLV‐CRT. Operators should target nonanterior and nonapical locations during eLV‐CRT implantation. Use of eLV‐CRT should be considered a viable alternative for CRT candidates.