Impact of contractile reserve on acute response to cardiac resynchronization therapy

Background: Cardiac resynchronization therapy (CRT) provides benefit for congestive heart failure, but still 30% of patients failed to respond to such therapy. This lack of response may be due to the presence of significant amount of scar or fibrotic tissue at myocardial level. This study sought to investigate the potential impact of myocardial contractile reserve as assessed during exercise echocardiography on acute response following CRT implantation. Methods: Fifty-one consecutive patients with heart failure (LV ejection fraction 27% ± 5%, 67% ischemic cardiomyopathy) underwent exercise Doppler echocardiography before CRT implantation to assess global contractile reserve (improvement in LV ejection fraction) and local contractile reserve in the region of the LV pacing lead (assessed by radial strain using speckle tracking analysis). Responders were defined by an increase in stroke volume ≥15% after CRT. Results: Compared with nonresponders, responders (25 patients) showed a greater exercise-induced increase in LV ejection fraction, a higher degree of mitral regurgitation and a significant extent of LV dyssynchrony. The presence of contractile reserve was directly related to the acute increase in stroke volume (r = 0.48, p<0.001). Baseline myocardial deformation as well as contractile reserve in the LV pacing lead region was greater in responders during exercise than in nonresponders (p<0.0001). Conclusions: Heart failure patients referred to CRT have less chance of improving under therapy if they have no significant mitral regurgitation, no LV dyssynchrony and no contractile myocardial recruitment at exercise

Myocardial contractile reserve during exercise predicts left ventricular reserve remodelling after cardiac resynchromization therapy

International audienceAIMS: Lack of response to cardiac resynchronization therapy (CRT) may be due to the presence of significant amount of scar or fibrotic tissue at myocardial level. This study sought to investigate the potential impact of myocardial contractile reserve as assessed during exercise echocardiography on left ventricular (LV) reverse remodelling (decrease in LV end-systolic volume > or =15% after 6 months of CRT). METHODS AND RESULTS: Fifty-one consecutive patients with heart failure underwent exercise Doppler echocardiography before CRT implantation to assess global contractile reserve and local contractile reserve (assessed by two-dimensional speckle tracking) in the region of the LV pacing lead. Responders (30 patients) showed a greater exercise-induced increase in left ventricular ejection fraction (LVEF) compared with non-responders (P < 0.001). Contractile reserve was directly related to the improvement in LVEF and to LV reverse remodelling after 6 months of CRT (P < 0.001). A 6.5% exercise-induced increase in LVEF yielded a sensitivity of 90% and a specificity of 85.7% to predict the response after 6 months of CRT. Baseline myocardial deformation as well as contractile reserve in the LV pacing lead region was greater in responders than in non-responders (P < 0.0001). CONCLUSION: Myocardial contractile reserve (global and regional) is a strong predictive factor of LV reverse remodelling after CRT

Whaling as Science

In an open letter published last year in the New York Times, 21 distinguished scientists (including three Nobel laureates) criticized Japan\u27s program of scientific research whaling, noting its poor design and unjustified reliance upon lethal sampling. In a recent Forum article in BioScience, Aron, Burke, and Freeman (2002) castigate the letter\u27s signers and accuse them of meddling in political issues without sufficient knowledge of the science involved in those issues