Relative Merits of M-Mode Echocardiography and Tissue Doppler Imaging for Prediction of Response to Cardiac Resynchronization Therapy in Patients With Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy
M-mode echocardiography (using the septal-to-posterior wall motion delay [SPWMD]) and color-coded tissue Doppler imaging (TDI; using the septal-to-lateral delay in peak systolic velocity) have been proposed for assessment of left ventricular (LV) dyssynchrony and prediction of response to cardiac resynchronization therapy (CRT). In this study, a head-to-head comparison between M-mode echocardiography and color-coded TDI was performed for assessment of LV dyssynchrony and prediction of response to CRT. Consecutive (n = 98) patients with severe heart failure (New York Heart Association class III/IV), LV ejection fraction < or =35%, and QRS duration >120 ms underwent CRT. Before pacemaker implantation, LV dyssynchrony was assessed by M-mode echocardiography (SPWMD) and color-coded TDI (septal-to-lateral delay). At baseline and 6 months after implantation, clinical and echocardiographic parameters were evaluated. SPWMD measurement was not feasible in 41% of patients due to akinesia of the septal and/or posterior walls or poor acoustic windows. Conversely, the septal-to-lateral delay could be assessed in 96% of patients. At 6-month follow-up, 75 patients (77%) were classified as responders to CRT (improvement > or =1 New York Heart Association class). The sensitivity and specificity of SPWMD were lower compared with those of septal-to-lateral delay (66% vs 90%, p <0.05; 50% vs 82%, p = NS, respectively). In conclusion, LV dyssynchrony assessment was feasible in 59% of patients with M-mode echocardiography compared with 96% (p <0.05) when color-coded TDI was used. Color-coded TDI was superior to M-mode echocardiography for prediction of response to CRT.
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- "M-mode based methodology to assess intra-LV dyssynchrony was not evaluated because it was previously demonstrated that such a method is feasible in approximately 60% of the candidates to cardio-resynchronization therapy  . By PW-TDI, myocardial-systolic-wave (S) was identified with reference to the QRS as the first positive wave peaking after aortic valve opening using LV pre-ejection time for reference . "
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ABSTRACT: Reproducibility of Doppler echocardiography for assessment of inter-ventricular and intra-left ventricular (LV) dyssynchrony, and its clinical implications, have not been established.
Twenty-eight subjects (heart failure stages A-C, 61% with QRS ≥ 120 ms, ejection fraction (EF) ≤ 35%) underwent two consecutive echo-studies within 24h to evaluate test-re-test reproducibility of inter-ventricular electromechanical delay (VV delay, by traditional pulsed-Doppler), and intra-LV electromechanical delay between opposite LV walls by color-coded Doppler tissue-velocity (COLOR-DTI), and by pulsed-Doppler tissue spectrum (PW-DTI). Reproducibility of LV internal diastolic diameter (LVIDD) and of EF (by Simpson's method) assessments was evaluated contextually for reference.
Intra-study and inter-study reproducibility of inter-ventricular and intra-LV electromechanical dyssynchrony was in general good, and comparable to the reproducibility of LVIDD and EF assessments. Between-study reproducibility of PW-TDI method was fair, but showed poor agreement with COLOR-TDI method. In repeated studies, agreement of significant electromechanical delay by COLOR-TDI was comparable to the agreement of EF ≤ 35%. In the 5 patients who had simultaneously large QRS, EF ≤ 35%, and significant inter- and intra-ventricular dyssynchrony at study #1, 3 had EF 36-40% and 1 showed no significant dyssynchrony by study #2.
In serial echocardiographic studies, Doppler echocardiography showed a good test-re-test reproducibility for the identification of significant electromechanical delay. Planimetry for EF assessment was a source of variability as relevant as Doppler echocardiography, but COLOR-DTI may add meaningful and reproducible information to QRS duration for cardiac-resynchronization therapy.
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ABSTRACT: Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced heart failure (HF), depressed
left ventricular function, and wide QRS complex. A significant number of patients do not respond to CRT. Recent studies suggest
that assessment of mechanical dyssynchrony may allow identification of potential CRT responders. In addition, the presence
of scar tissue and venous anatomy may play a role in the selection of candidates. In this chapter the role of various cardiac
imaging modalities addressing these issues in the selection of potential CRT candidates is discussed extensively.
Over the past decades, chronic HF has demonstrated an exponential increase, with a poor long-term outcome.1 Despite the advances
in pharmacological therapy, including ACE inhibitors, beta-blockers, and spironolactone, mortality remains high. After the
first admission for HF, the 1-year survival is 63% and the 5-year survival is only 30%.1–6 HF patients die either from progressive
HF or sudden cardiac death.7 In addition to the high mortality, morbidity is also substantial, with frequent re-hospitalizations
for decompensated HF 3 and extensive co-morbidity.
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