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538428 
Journal Article 
Myocardial contractile reserve predicts improvementin left ventricular function after cardiac resynchronization therapy 
Ypenburg, C; Sieders, A; Bleeker, GB; Holman, ER; van der Wall, EE; Schalij, MJ; Bax, JJ 
2007 
Yes 
American Heart Journal
ISSN: 0002-8703
EISSN: 1097-6744 
154 
6 
1160-1165 
English 
Background Myocardial contractile reserve has been shown to provide important prognostic information in patients with heart failure. We hypothesized that myocardial contractile reserve would predict left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT). Methods Thirty-one consecutive patients with heart failure (LV ejection fraction [LVEF] 26% +/- 7%, 35% nonischemic cardiomyopathy) underwent echocardiography during low-dose dobutamine infusion before CRT implantation to assess global contractile reserve (improvement in LVEF) and local contractile reserve in the region of the LV pacing lead (assessed by radial strain using speckle tracking analysis). Responders were defined by a decrease in LV end-systolic volume >= 15% after 6 months of CRT. Results During low-dose dobutamine infusion, responders showed a greater increase in LVEF compared with nonresponders (Delta 13% +/- 8% vs 3% +/- 4%, P < .001). Furthermore, contractile reserve was directly related to improvement in LVEF after 6 months of CRT (r = 0.80, P < .001). Moreover, a cutoff value of > 7.5% increase in dobutamine-induced LVEF exhibited a sensitivity of 76% and a specificity of 86% to predict response after 6 months of CRT (area under the curve 0.87). Lastly, contractile reserve in the region in the LV pacing lead was present only in responders (a strain during low-dose dobutamine 6% +/- 5% in responders vs -1% +/- 4% in nonresponders, P = .002). Conclusions The current study demonstrates that myocardial contractile reserve (>7.5% increase in LVEF during low-dose dobutamine infusion) predicts LV reverse remodeling after CRT. 
chronic heart-failure; long-term survival; nonischemic cardiomyopathy; stress echocardiography; clinical improvement; ejection fraction; scar; tissue; viability; strain; dyssynchrony