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Background— Current recommendations require a QRS duration of ≥120 ms as a condition for prescribing cardiac resynchronization therapy (CRT). This study was designed to test the hypothesis that patients with heart failure (HF) of ischemic origin, current indications for defibrillator implantation, and QRS <120 ms may benefit from CRT in the presence of marked mechanical dyssynchrony. Methods and Results— Patients with intraventricular dyssynchrony on echocardiography were randomly assigned to CRT or dual-chamber defibrillator implantation (CRT defibrillator and dual-chamber implantable cardioverter-defibrillator arm, respectively). The primary end point was the HF clinical composite response, which scores patients as improved, unchanged, or worsened. The secondary end point was the cumulative survival from HF hospitalization and HF death. An additional secondary end point was the composite of HF hospitalization, HF death, and spontaneous ventricular fibrillation. Twenty-three of 56 patients with CRT defibrillator showed an improvement in their clinical composite response at 1 year, compared with 9 of 55 patients with dual-chamber implantable cardioverter-defibrillator (41% versus 16%; P =0.004). After a median follow-up of 16 months, the CRT defibrillator arm showed a nonsignificant higher survival from HF hospitalization and HF death ( P =0.077), and a significantly higher survival from the combined end point of HF hospitalization, HF death, and spontaneous ventricular fibrillation ( P =0.028). Conclusions— In this comparison of CRT defibrillator and dual-chamber implantable cardioverter-defibrillator, CRT improved clinical status in some patients with ischemic cardiomyopathy, mild-to-moderate symptoms, narrow QRS duration, and mechanical dyssynchrony on echocardiography. Clinical Trial Registration— URL: http://clinicaltrials.gov . Unique identifier: NCT01577446.

The present study suggests that more physiological pacing from the RV sept can improve EF and quality of life (QoL) in patients with permanent AF and low EF needing a PM.

AimsTo evaluate whether quantification of the extent of scarred left ventricular (LV) tissue by speckle-tracking strain echo (2DSE) can predict response to cardiac resynchronization therapy (CRT) in patients with ischaemic dilated cardiomyopathy (DCM). Methods and resultsForty-five patients (58.3 + 8.3 years; 24 males) with ischaemic DCM scheduled for CRT, and 25 controls were studied. A week before implantation all the patients underwent standard Doppler echo, 2DSE, and contrast-enhanced magnetic resonance (MR). Clinical and echocardiographic evaluation was repeated 6 months after CRT. The patients were considered as responders to CRT if LV end-systolic volume decreased by 15%. In DCM patients, LV ejection fraction was 29.2 + 5.1%. By evaluating the 765 segments with MR, subendocardial infarct was identified in 17.0% and transmural infarct in 18.3%. With 2DSE, the average global longitudinal strain (GLS) was 223.1 + 3.6% in controls and 215.1 + 5.1% in DCM (P ¼ 0.001). GLS showed a close correlation with total scar burden using MR (r ¼ 0.64, P , 0.001). At follow-up, patients were subdivided into responders (n ¼ 30; 66.7%) and non-responders (n ¼ 15; 33.3%) to CRT. GLS was significantly different in non-responders than in responders (GLS: 210.4 + 5.1 in nonresponders vs. 218.4 + 14% in responders, P , 0.001). In a multivariable analysis, GLS (P , 0.0001) and radial intraventricular dyssynchrony (P , 0.001) were powerful independent determinants of response to CRT. ConclusionGLS is strongly associated with total scar burden assessed by MR, and is an excellent independent predictor of response to CRT.--

Pulsed DMI is an effective noninvasive technique for assessing the severity of regional delay in activation of LV walls in patients with LBBB. The impairment of interventricular systolic sychronicity is strongly related to LV dilatation and to the degree of global systolic dysfunction. Therefore, patients with dilated cardiomyopathy suitable for cardiac resynchronization therapy may be better selected.

Contractile reserve was a strong predictive factor of response to CRT in the studied population.

In patients with acute chest pain, the occurrence of multiple cardiovascular risk factors adversely affected CFR in an additive manner, in absence of significant angiographic stenosis. Diabetes mellitus was a powerful coronary risk factor decreasing CFR both in patients with or without significant LAD disease.

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