Echocardiography and Dyssynchrony

Exercise stress echocardiography is superior to rest echocardiography in predicting left ventricular reverse remodelling and functional improvement after cardiac resynchronization therapy
Rocchi G, Bertini M, Biffi M et al.

Comment: In this study on 64 patients scheduled for CRT, (bicycle) exercise intraventricular dyssynchrony assessed by exercise TDI ECHO was a strong independent predictor of CRT response (defined as reverse remodelling and increase of exercise capacity). The authors suggest that this dynamic aspect of dyssynchrony could be used to select candidates for CRT, thus reducing ineffective implantations of biventricular pacemakers.

Reference: Eur Heart J 2009;30:89-97

Tissue Doppler imaging in the estimation of intracardiac filling pressure in decompensated patients with advanced systolic heart failure.

Mullens W, Borowski A, Curtin R et al.

Comment:

In this provocative study, the value of tissue Doppler derived E/Ea ratio was evaluated for the prediction of intracardiac filling pressures in 106 patients with advanced decompensated heart failure (EF30% and NYHA class III-IV).  Simultaneous echocardiographic and invasive hemodynamic evaluation on admission and after 48 hours of intensive medical therapy was performed in all patients.  Contrary to prior reports, sensitivity and specificity for mitral E/Ea ratio > 15 to identify a PCWP > 18 mmHg were only 66% and 50% respectively. Also, no direct association between changes in PCWP and changes in mitral E/Ea ratio was observed.  In the subgroup of patients treated with CRT, similar results were noted.  The authors conclude that E/Ea may not be as reliable to predict intracardiac filling pressures in decompensated patients with advanced systolic heart failure.

Reference: Circulation 2009;110:000-000

Echocardiographic parameters of mechanical synchrony in healthy individuals.

Conca C, Faletra F, Miyazaki et al.

Comment:

This study provides normal values and agreement among echocardiographic measures of mechanical synchrony in 160 consecutive healthy subjects.  Normal values are provided for 5 Tissue Doppler imaging parameters, real-time 3-dimensional echocardiographic measures, and speckle-tracking measures of mechanical synchrony.

Reference: Am J Cardiol 2009;103:136-142

Validation of an echocardiographic multiparametric strategy to increase responders patients after cardiac resynchronization: a multicentre study

Lafitte S, Reant P, Zaroui A et al

Comment:

This study provides for the first time a multiparametric echocardiographic strategy for prediction of reponse in CRT candidates.  The study, carried out in 200 patients, emphasises on published conventional and TDI parameters. The multiparametric approach by focusing on criteria combination decreased the mean rate of false-positive results to 14%, 5% 2% and 1% from one to four parameters respectively.

Reference: Eur Heart J 2009

Cardiac mechanics revisited: the relationship of cardiac architecture to ventricular

Buckberg G, Hoffman J, Mahajan A, Saleh S, Coghlan C

Comment:

Buckberg et al provide an in depth review on cardiac architecture and its relation to ventricular function.  Especially the description of excitation/contraction events during the preejection sequence may have clinical utility to understand cardiac resynchronization therapy.  It is suggested that biventricular pacing initiates a dynamic transmural septal contraction and thereby offsets the septum bulge during dyssynchrony by placing the septum in a midline position.  This architectural alteration changes the geometric position of the posterior papillary muscle to limit its tethering of the mitral leaflets by the bulging septum and thus improves leaflet coaptation to reduce mitral regurgitation, but without restoring the twisting motion of the septum.

Reference: Circulation 2008;118:2571-2587

Echocardiography for cardiac resynchronization therapy: recommendations for performance and reporting: a report from the American Society of Echocardiography Dyssynchrony Writing Group endorsed by the Heart Rhythm Society.

Gorcsan J 3rd, Abraham T, Agler DA et al

Comment:

This consensus report evaluates the contemporary applications of echocardiography for CRT including relative strengths and technical limitations of several techniques and proposes guidelines regarding current and possible future clinical applications.  A simplified post-CRT screening for atrioventricular optimization using Doppler mitral inflow velocities is also proposed.

Reference: JASE  2008;21:191-213

Mechanism of improvement in mitral regurgitation after cardiac resynchronization therapy.

Ypenburg C, Lancellotti P, Tops LF et al

Comment:

The authors studied radial strain assessed by speckle tracking in 68 CRT patients at baseline and followed the patients for 6 months.  The site of latest activation in early responders was mostly inferior of posterior (adjacent to the posterior papillary muscle), whereas the lateral wall was the latest activated segment in late responders.  These results suggest that dyssynchrony involving the posterior papillary muscle may lead to an immediate reduction in MR, whereas LV dyssynchrony in the lateral wall results in late reponse to CRT.

Reference: EHJ 2008;29:757-65. Cardiac-resynchronization therapy in heart failure with narrow QRS complexes.

Beshai JF, Grimm RA, Nagueh SF et al

Comment:

In this randomized controlled trial, CRT did not improve peak oxygen consumption in patients with moderate-to-severe heart failure, providing evidence that patients with heart failure and narrow QRS intervals may not benefit from CRT.  Importantly, all patients that entered the trial had to have evidence of left ventricular mechanical dyssynchrony evaluated with echocardiography (TDI in the large majority of patients).

Reference: NEJM 2007;357:2461-2471 Optimal use of echocardiography in cardiac resynchronisation therapy.

Bleeker GB, Yu CM, Nihoyannopoulos P, et al

Comment:

As in reference 2, this paper reviews the current evidence regarding the use of echocardiography in CRT.  It gives however a more European focused point of view.

Reference:

Heart 2007;93:1339-50. Diastolic filling pattern and left ventricular diameter predict response and prognosis after cardiac resynchronization therapy

Gradaus R, Stuckenborg V, Löher A et al

Comment:

This study evaluated 122 consecutive heart failure patients with an indication for CRT and presence of LV dyssynchrony assessed by echocardiography including Tissue Doppler imaging. The authors looked for clinical and echocardiographic predictors of reponse.  Overall nearly 30% of patients had no benefit from CRT.  On multivariate analyses, patients with and increased LV end systolic diameter and concomitant diastolic dysfunction (restrictive filling pattern) had a significantly worse outcome.

Reference:

Heart 2007, Nov 5

Relation of optimal lead positioning as defined by three-dimensional echocardiography to long-term benefit of cardiac resynchronization

Becker M, Hoffman R, Schmitz F et al

Comment:

In this study 58 congestive heart failure patients were studied with 3D echocardiography at baseline and 12 months after CRT implantation.  Using volume/time curves the segments with the latest minimum of systolic volume were determined preoperatively and during follow-up.  Correspondence of the segment with the latest preoperative LV contraction with the segment with the greatest effect based on CRT resulted in a significantly greater benefit of ejection fraction and peak oxygen consumption and a greater improvement in LV remodelling.

Reference: Am J C 2007;100:1671-6