Effects of cardiac resynchronisation therapy in patients with heart failure having a narrow QRS Complex enrolled in PROSPECT.

INTRODUCTION: Current guidelines recommend cardiac resynchronisation therapy (CRT) in patients with severe symptomatic heart failure, depressed left ventricular (LV) systolic function and a wide QRS complex (>or=120 ms). However, patients with heart failure having a narrow QRS complex might also benefit from CRT. DESIGN SETTING PATIENTS INTERVENTIONS: During the Predictors of Response to Cardiac Resynchronisation Therapy (PROSPECT) trial, 41 patients were enrolled in a 'narrow' QRS sub-study. These patients had a QRS complex <130 ms, but documented evidence of mechanical dyssynchrony by any of seven pre-defined echocardiographic measures. RESULTS: After 6 months of CRT, 26 (63.4%) patients showed improvement according to the Clinical Composite Score, 4 (9.8%) remained unchanged and 11 (26.8%) worsened. In patients with paired data, the 6-min walking distance increased from 334+/-118 m to 382+/-128 m, (p=0.003) and quality-of-life score improved from 44.2+/-19.7 to 26.8+/-20.2 (p<0.0001). Furthermore, there was a significant decrease in LV end-systolic diameter (from 59+/-9 to 55+/-12 mm, p=0.002) and in LV end-diastolic diameter (from 67+/-9 to 63+/-11 mm, p=0.007). CONCLUSION: The results suggest that CRT may have a beneficial effect in heart failure patients with a narrow QRS complex and mechanical dyssynchrony as assessed by echocardiography. The majority of patients improved on clinical symptoms, and there was an evident reduction in LV diameters. Larger studies are needed to clearly define selection criteria for CRT in patients with a narrow QRS complex.

Echocardiography and non-invasive imaging in cardiac resynchronization therapy.

The beneficial effects of cardiac resynchronization therapy (CRT) on morbidity and mortality in advanced heart failure patients have been extensively demonstrated. However, previous single- and multicenter studies demonstrated that approximately 30-40% of CRT patients do not show significant clinical improvement or LV reverse remodeling despite fulfilling current inclusion criteria. In search of novel indices that may help to improve the selection of responders to CRT, non-invasive multimodality imaging has provided further insight into the mechanisms underlying CRT response. LV dyssynchrony, extent and location of myocardial scar and LV lead position have shown to be independent determinants of CRT response. An integrated evaluation of these three pathophysiological mechanisms may provide a more accurate selection of heart failure patients who will benefit from CRT and may maximize the cost-effectiveness of this therapy. The present review article provides a critical appraisal of the role of multimodality imaging in the selection of heart failure patients who are candidates for CRT with special focus on the assessment of LV mechanical dyssynchrony, LV myocardial scar tissue extent and LV lead position.

Tissue Doppler velocity is superior to strain imaging in predicting long-term cardiovascular events after cardiac resynchronisation therapy.

OBJECTIVE: To examine the predictive value of systolic dyssynchrony measured by tissue Doppler velocity versus tissue Doppler strain imaging on long-term outcome after cardiac resynchronisation therapy (CRT). DESIGN: Cohort study. SETTING: Two university hospitals. PATIENTS: Two hundred and thirty-nine patients (65 (SD 12) years, 76% males) who underwent CRT. INTERVENTIONS: Baseline echocardiography with tissue Doppler imaging (TDI) and clinical follow-up for 37 (20) months. MAIN OUTCOME MEASURES: The time to peak systolic velocity during ejection phase (Ts) and the time to peak systolic strain (T(epsilon)) were assessed for dyssynchrony, that is the maximal delay in Ts and the maximal delay in T(epsilon) among the four left ventricular basal segments. Occurrence of cardiovascular endpoints between patients with and without dyssynchrony was compared by Kaplan-Meier curves, followed by Cox regression analysis for potential predictor(s). RESULTS: There were 78 (33%) deaths, with cardiovascular causes in 64 (27%) patients, while 136 (57%) patients were hospitalised for cardiovascular events, including decompensated heart failure in 87 (36%) patients. Patients with the maximal delay in Ts of > or =65 ms showed a lower event rate for cardiovascular mortality (19% vs 38%, logrank chi2 = 7.803, p = 0.005) and other prognostic endpoints. In Cox regression analysis, the maximal delay in Ts (hazard ratio (HR) 0.463, 95% CI 0.270 to 0.792, p = 0.005) and ischaemic aetiology (HR 2.716, 95% CI 1.505 to 4.901, p = 0.001) were independent predictors of cardiovascular mortality. In contrast, the maximal delay in T(epsilon) of > or =80 ms failed to predict any cardiovascular event. CONCLUSIONS: Echocardiographic evidence of prepacing systolic dyssynchrony measured by TDI velocity, but not TDI strain, predicted lower long-term cardiovascular events after CRT.