1. – р<0.05 between baseline
Tyumen
Cardiology
Research Center
Tyumen, Melnikaite 111
Mechanical dyssynchrony and super-response to cardiac resynchronisation therapy in patients with congestive heart failure
Kuznetsov V.A., Soldatova A.M., Krinochkin D.V., Melnikov N.N., Enina T.N.
Background
Results
Some patients with congestive heart failure (CHF) treated with cardiac resynchronisation therapy (CRT) have greater improvement of cardiac remodeling after CRT and they are identified as super-responders. It remains unclear if echocardiographic cardiac dyssynchrony parameters could accurately predict super-response (SR) to CRT. % ml SR
non-SR
– р<0.05 between baseline
and postimplant level *
p<0.05
LVESV
LVEF
At baseline there were no difference in clinical characteristics, atrial fibrillation and left ventricular ejection fraction (LVEF) among the groups. Both groups demonstrated significant improvement in NYHA functional class, reduction of LVEF and LVESV (fig.1). Echocardiographic parameters of mechanical dyssynchrony were significantly higher in super-responders (tab.1). *
Aim
To evaluate potential echocardiographic predictors related to SR after CRT.
Materials and methods
Fig.1. Dynamics of LVEF and LVESV after 6 months of CRT
59 CRT patients (mean age 52.9±9.0 years, 88% men) with CHF (54% ischemic and 46% non-ischemic etiology) and II-III NYHA functional class were enrolled. After 6 months patients were divided into super-responders (reduction in left ventricular end systolic volume (LVESV) >30%, n=20) and non-super-responders (reduction of LVESV <30%, n=39). To assess mechanical dyssynchrony we evaluated interventricular mechanical delay, duration of left ventricular pre-ejection period (LVPEP) by Doppler ultrasound velocity measurements of blood flow, the maximum delay between peak systolic velocities of the septal and lateral walls of left ventricle by tissue Doppler imaging (TDI), systolic dyssynchrony index was assessed by 3D echocardiography.
Multiple logistic regression analysis showed that LVPEP was an independent predictor for CRT SR (95% confidence interval [CI] 1.007–1.055; p=0.011). In ROC curve analysis LVPEP demonstrated sensitivity 73.7% and specificity 75% (AUC 0.753; p=0.002) in prediction of SR to CRT (fig.2).
Parameter
I group (n=20)
II group (n=39) Р
Systolic dyssynchrony index (%)
9.53.4
7.54.4
0.05
LPEP (ms)
160.531.2
131.529.5
0.002
Interventricular mechanical delay (ms)
57.428.3
39.724.2
0.024
Septal to lateral wall delay (ms)
57.841.0
35.338.5
Interventricular delay by TDI (ms)
110.266.1
71.657.9
0.038
Intraventricular delay be TDI (ms)
88.445.3
67.742.8 NS
AUC=0,753, p=0,002
Table 1. Baseline parameters of mechanical dyssynchrony
Fig.2. ROC-curve for sensitivity and specificity of LPEP in prediction of response to CRT
Discussion
CRT is an effective treatment for patients with CHF. Randomized controlled trials have demonstrated that CRT is associated with decreased heart failure symptoms, heart failure hospitalization, and all-cause mortality. However approximately one-third of patients do not benefit from this therapy. In contrast some patients show greater improvement of the cardiac function after CRT implantation and they are identified as “super-responders”. SR to CRT was first described in Still there is no single unified criteria of SR. Some authors defined SR by an improvement in LVESV although different cut-offs were selected. In our study SR was defined as a relative reduction in LVESV >30% after 6 months of CRT according to several large sample studies. Despite different response criteria in most studies patients with left bundle branch block (LBBB), non-ischaemic cardiomyopathy, absence of myocadial infarction, normal left atrium size, body-mass index<30kg/m2 have the greatest benefit from CRT. In our study groups didn’t differ in QRS duration, presence of LBBB and other parameters mentioned above. Both groups demonstrated significant improvement in NYHA functional class, decrease of LVESV, however improvement in LVEF and LVESV were significantly higher in super-responders. In the present study the QRS duration and LBBB were not found to be predictive factors of greater response to CRT. The question about utilization of mechanical dyssynchrony parameters to predict CRT response is still discussed. Some authors described TDI parameters as predictors of CRT response. PROSPECT-trial sub-analysis showed that baseline level of electrical and mechanical dyssynchrony was significantly higher in super-responders. As in our study parameters of mechanical dyssynchrony significantly differed between groups and greater mechanical dyssynchrony was associated with SR to CRT. In multivariate analysis LPEP was the only independent factor associated with CRT SR. The proportion of super-responders in different studies is reported to be in the range of 12–47 %. The lack of a universal definition of SR to CRT is one of the main reasons of such a wide range. The percentage of SR found in our study was 34%. Probable it can be explained by good patient selection with assessment of mechanical dyssynchrony parameters by 2D and 3D echocardiography. .
Conclusion
Greater cardiac mechanical dyssynchrony is associated with SR to CRT in patients with CHF. LVPEP can be used as an independent predictor of CRT SR.
The authors have nothing to disclose.