Abstract
BackgroundPatients with non-ischemic heart failure etiology and left bundle branch block (LBBB) show better response to cardiac resynchronization therapy (CRT). While these patients have the most pronounced left ventricular (LV) dyssynchrony, LV dyssynchrony assessment often fails to predict outcome. We hypothesized that patients with favorable outcome from CRT can be identified by a characteristic strain distribution pattern.MethodsFrom 313 patients who underwent CRT between 2003 and 2006, we identified 10 patients who were CRT non-responders (no LV end-systolic volume [LVESV] reduction) with non-ischemic cardiomyopathy and LBBB and compared with randomly selected CRT responders (n = 10; LVESV reduction ≥15 %). Longitudinal strain (εlong) data were obtained by speckle tracking echocardiography before and after (9 ± 5 months) CRT implantation and standardized segmental εlong-time curves were obtained by averaging individual patients.ResultsIn responders, ejection fraction (EF) increased from 25 ± 9 to 40 ± 11 % (p = 0.002), while in non-responders, EF was unchanged (20 ± 8 to 21 ± 5 %, p = 0.57). Global εlong was significantly lower in non-responders at pre CRT (p = 0.02) and only improved in responders (p = 0.04) after CRT. Pre CRT septal εlong -time curves in both groups showed early septal contraction with mid-systolic decrease, while lateral εlong showed early stretch followed by vigorous mid to late contraction. Restoration of contraction synchrony was observed in both groups, though non-responder remained low amplitude of εlong.ConclusionsCRT non-responders with LBBB and non-ischemic etiology showed a similar improvement of εlong pattern with responders after CRT implantation, while amplitude of εlong remained unchanged. Lower εlong in the non-responders may account for their poor response to CRT.
Highlights
Patients with non-ischemic heart failure etiology and left bundle branch block (LBBB) show better response to cardiac resynchronization therapy (CRT)
For this purpose we analyzed the contraction pattern of CRT patients with clinical and procedural characteristics known to be associated with pronounced reverse remodeling response: nonischemic heart failure etiology, LBBB pattern on electrocardiogram (ECG), QRS duration on ECG >140 ms, and left ventricular (LV) electrode located over the mid/base lateral or posterolateral wall [1, 3, 6, 7]
From those who had a complete baseline echocardiographic study performed within 3 months before device implantation on a Vivid 7 system (GE Healthcare, Horten, Norway) and with echocardiographic follow-up (>3 months), we identified 10 patients who were CRT non-responders with the following clinical characteristics: non-ischemic cardiomyopathy, LBBB, and LV lead placed over the base/mid posterior or lateral LV wall
Summary
Patients with non-ischemic heart failure etiology and left bundle branch block (LBBB) show better response to cardiac resynchronization therapy (CRT) While these patients have the most pronounced left ventricular (LV) dyssynchrony, LV dyssynchrony assessment often fails to predict outcome. While several clinical parameters have been well established as predictors of CRT response [1, 3, 6], failure of CRT occurs even if all of clinical parameters predict otherwise It is unclear if this is due to a specific contraction pattern of these patients, or some other factors. We identified a group of patients who, despite these favorable preprocedural characteristics, did not show reverse remodeling, and compared it to a group with good CRT response using segmental strain analysis
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