Impact of contractile reserve on acute response to cardiac resynchronization therapy

Abstract

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.

Risk of heart failure relapse in subsequent pregnancy among peripartum cardiomyopathy mothers

“…We believe that exercise stress echocardiography (no use of dobutamine) is a potential tool that adds useful additional information since it provides some evidence of how the heart might respond to the stress of pregnancy, labor, and delivery [8][9][10]. The sample size of the present cohort that underwent exercise stress echocardiography was still too small to demonstrate statistically significant differences at the P ≤0.05 level; however, the trend is clear, with no relapses in 9 women with post-PPCM pregnancies when there was adequate contractile reserve.…”

“…No normal values have been established for recovered PPCM and nonischemic cardiomyopathy patients. However, a relative gain of 15% is used as an estimate of adequate contractile reserve [8][9][10].…”

Evaluation of baseline contractile reserve vs dyssynchrony as a predictor of functional improvement and long term outcome after resynchronization pacing therapy: A radionuclide stress study

“…The relatively inhomogeneous patient population with advanced heart failure, including 28 (53%) with ischemic cardiomyopathy, reflected the current patient referral for CRT. [12][13][14][15] Although comparable to that of prior studies, the sample size was relatively small. This could have limited the power of statistical analysis.…”

“…10 It has been recognized that the effect of CRT is likely modulated by multiple factors including baseline left ventricular function and extent of ventricular dyssynchrony, correct lead positioning and pacing, but also the extent of myocardial fibrosis and tissue viability as estimated by measurement of myocardial contractile reserve (mCR). [11][12][13][14][15] Several cardiac imaging modalities have been proposed to evaluate ventricular function and dyssynchrony of contraction including M-Mode, bi-dimensional, and tissue Doppler imaging of trans-thoracic echocardiography [16][17][18] and nuclear imaging techniques with phase analysis of either ecg-gated equilibrium radionuclide angiography (ERNA) [19][20][21][22] or SPECT myocardial perfusion imaging. 23 Among several methods to unmask viable and recruitable myocardium in the failing heart, low-dose dobutamine (LDD) stress testing in association with either cardiac echocardiographic or radionuclide imaging has gained recognition as an important and accurate modality to predict functional improvement after interventions.…”

Stress echocardiography for selecting potential responders to cardiac resynchronisation therapy

“…During exercise, an increase in LVEF by ≥6.7% and/or an increase in local strain by ≥2% were found to be predictive for response to CRT. Improvement in LVEF at peak exercise before multisite pacing correlated with improvement in forward LV stroke volume early after CRT 39. More recently, we have demonstrated that a 6.5% exercise-induced increase in LVEF yielded a sensitivity of 90% and a specificity of 85% to predict late response to CRT 40.…”