Improvement of Left Ventricular Function After Cardiac Resynchronization Therapy Is Predicted by Tissue Doppler Imaging Echocardiography

Multimodality Imaging for Selecting Candidates for CRT: Do We Have a Single Alley to Increase Responders?

Cardiac resynchronization therapy has evolved in recent years to provide a reduction of morbidity and mortality for many patients with heart failure. Its application and optimization is an evolving field and its use requires a multidisciplinary approach for patient and device selection, technical preprocedural planning, and optimization. While echocardiography has always been considered the first line for the evaluation of patients, additional imaging techniques have gained increasing evidence in recent years. Today different details about heart anatomy, function, dissynchrony can be investigated by magnetic resonance, cardiac computed tomography, nuclear imaging, and more, with the aim of obtaining clues to reach a maximal response from the electrical therapy. The purpose of this review is to provide a practical analysis of the single and combined use of different imaging techniques in the preoperative and perioperative phases of cardiac resynchronization therapy, underlining their main advantages, limitations, and information provided.

Electromyogram Power Spectrum and Cardiac Function Changes After Combined Aerobic Interval Training and Inspiratory Muscle Training in Chronic Heart Failure Patients

Exercise intolerance and dyspnea are the major symptoms of patients with chronic heart failure (CHF) and are associated with a poor quality of life. In addition to impaired central hemodynamics, symptoms may be attributed to changes in peripheral skeletal muscles. This study aimed to evaluate the effects of aerobic interval training (AIT) combined with inspiratory muscle training (IMT) on cardiac and skeletal muscle function and on functional capacity and dyspnea in patients with CHF and inspiratory muscle weakness.Left ventricle ejection fraction was improved significantly after AIT and AIT & IMT with a high percentage of amelioration (17%, P < 0.042) in the combined group compared to the control group. Therefore, we showed a significant improvement in maximal voluntary isometric force, isometric endurance time, root mean square, and frequency median in both strength and endurance manipulations in the aerobic and combined group; however, the improvement was superior in the combined group compared to the control group. Significant amelioration was proved in functional capacity and dyspnea after all types of training but was performed at 18% higher in 6 minutes' walk test and 43% lower in dyspnea for the combined group compared to the control group.Combining AIT to IMT had optimized exercise training benefits in reversing the cardiac remodeling process and improving skeletal muscle function, functional capacity, and dyspnea in patients with CHF.

Considering Diastolic Dyssynchrony as a Predictor of Favorable Response in LV-Only Fusion Pacing Cardiac Resynchronization Therapy

Background: CRT improves systolic and diastolic function, increasing cardiac output. Aim of the study: to assess the outcome of LV diastolic dyssynchrony in a population of fusion pacing CRT. Methods: Diastolic dyssynchrony was measured by offline speckle-tracking-derived TDI timing assessment of the simultaneity of E″ and A″ basal septal and lateral walls. New parameters introduced: E″ and, respectively, A″ time (E″T/A″T) as the time difference between E″ (respectively, A″) peak septal and lateral wall. Patients were divided into super-responders (SR), responders (R), and non-responders (NR). Results: Baseline characteristics: 62 pts (62 ± 11 y.o.) with idiopathic DCM, EF 27 ± 5.2%; 29% type III diastolic dysfunction (DD), 63% type II, 8% type I. Average follow-up 45 ± 19 months: LVEF 37 ± 7.9%, 34%SR, 61%R, 5%NR. The E″T decreased from 90 ± 20 ms to 25 ± 10 ms in SR with significant LV reverse remodeling (LV end-diastolic volume 193.7 ± 81 vs. 243.2 ± 82 mL at baseline, p < 0.0028) and lower LV filling pressures (E/E' 13.2 ± 4.6 vs. 11.4 ± 4.5, p = 0.0295). DD profile improved in 65% of R with a reduction in E/E' ratio (21 ± 9 vs. 14 ± 4 ms, p < 0.0001). Significant cut-off value calculated by ROC curve for LV diastolic dyssynchrony is E″T > 80 ms and A″T > 30 msec. Conclusions: The study identifies the cut-off values of diastolic dyssynchrony parameters as predictors of favorable outcomes in responders and super-responder patients with fusion CRT pacing. These findings may have important implications in patient selection and follow-up.

The Long-Term Change of Arrhythmias after Transcatheter Closure of Perimembranous Ventricular Septal Defects

OBJECTIVES

To observe and analyze the long-term change of different types of arrhythmias after transcatheter closure of perimembranous ventricular septal defect (pmVSD).

METHODS

We retrospectively collected the data of patients who underwent pmVSD closure in our institution from March 2002 to December 2010.

RESULTS

One hundred thirty-nine patients met the inclusion criteria, of which 265 (25.5%) had early arrhythmia. They were classified into two categories: conduction abnormality (191/1039; 18.4%) and origin abnormality (94/1039; 9.0%), including 20 patients with both types of arrhythmias. The median follow-up time was 84.5 months, and 103 patients (103/191; 53.9%) with early conduction block got permanent arrhythmias, while only three patients (3/94; 3.2%) with early anomalous origin arrhythmias still had an abnormal electrocardiogram. Serious arrhythmias (28/1039; 2.7%), including II° atrioventricular block (AVB), III° AVB, and complete left bundle branch block (CLBBB), can appear immediately in the early postoperative period (21 patients) or in the late outset (seven patients) after several months or even years (6 months to 8.3 years). Twenty patients (20/21; 95.2%) with serious arrhythmia in the early postoperative period improved after early treatment, but six patients relapsed or worsened during follow-up. At the endpoint, severe arrhythmia persisted in 13 patients, of which four patients got permanent pacemaker implanted, and one patient with recurrent CLBBB died from heart failure.

CONCLUSIONS

The probability of delayed CAVB or bundle branch block after VSD closure is low but often occurs several years after surgery. Therefore, long-term ECG follow-up should last for several years or even decades. Serious arrhythmias that appear early after transcatheter pmVSD closure may impose a risk of recurrence although they have been cured already. Close attention should be paid to the changes of cardiac function in patients with CLBBB after VSD closure, and the severity of such arrhythmia should be taken seriously and reexamined.

Left ventricular systolic dyssynchrony index and endothelial dysfunction parameters as subclinical predictors of cardiovascular involvement in patients with beta-thalassemia major

OBJECTIVE

Cardiovascular iron load is the leading cause of morbidity and mortality in beta-thalassemia major (β-TM). However, many patients remain asymptomatic until the late stage. In this cross-sectional study, we investigated the role of three-dimensional (3D) echocardiography and endothelial dysfunction parameters in asymptomatic β-TM patients, and the relationship between these parameters and cardiac magnetic resonance imaging (MRI) T2* value.

METHODS

A total of 51 asymptomatic β-TM patients receiving regular blood transfusions were divided into two groups based on cardiac MRI-T2* values (MRI-T2*<20 ms and ≥20 ms), which MRI-T2*<20 ms determines myocardial iron load and evaluated by two-dimensional (2D) and 3D-echocardiography including endothelial dysfunction parameters. The relationships between ferritin levels, 2D and 3D-echocardiography measurements, endothelial dysfunction parameters, and cardiac MRI-T2* values were investigated.

RESULTS

All left ventricle ejection fraction (LVEF) obtained by 2D-echocardiography were normal (≥50%). LVEF-3D (53.25 ± 2.33 vs. 58.81 + 1.02), SDI12 (6.53 ± 0.56 vs. 2.85 + 0.48), and SDI16 (7.65 ± 0.75 vs. 3.26 + 0.49) were significantly different and negatively correlated between groups with MRI-T2*<20 ms and ≥20 ms, respectively. Flow-mediated dilatation (FMD) (6.08% ± 0.34% vs. 14.46% ± 1.12), aortic strain (7.79% ± 2.19% vs. 12.76% ± 4.19), ferritin levels were significantly different and negatively correlated between groups with MRI-T2*<20 ms and ≥20 ms, respectively. Higher ferritin, SDI12/16 were significant independent predictors of MR-T2* < 20 ms. SDI16 > 5.5, SDI12 > 4.3 predicted MRI-T2*<20ms with a sensitivity of 92%, specificity of 81% (AUC 0.85, P < .001), and sensitivity of 92%, specificity of 78% (AUC 0.83, P < .001), respectively.

CONCLUSION

SDI12/16 calculated by 3D-echocardiography may be a promising predictors of cardiovascular iron load and, decreased LVEF-3D, FMD, and aortic strain might be good indicators of subclinical cardiovascular involvement of β-TM.

In Vivo Comparison of Multiline Transmission and Diverging Wave Imaging for High-Frame-Rate Speckle-Tracking Echocardiography

High-frame-rate (HFR) speckle-tracking echocardiography (STE) assesses myocardial function by quantifying motion and deformation at high temporal resolution. Among the proposed HFR techniques, multiline transmission (MLT) and diverging wave (DW) imaging have been used in this context both being characterized by specific advantages and disadvantages. Therefore, in this article, we directly contrast both approaches in an in vivo setting while operating at the same frame rate (FR). First, images were recorded at baseline (resting condition) from healthy volunteers and patients. Next, additional acquisitions during stress echocardiography were performed on volunteers. Each scan was contoured and processed by a previously proposed 2-D HFR STE algorithm based on cross correlation. Then, strain curves and their end-systolic (ES) values were extracted for all myocardial segments for further statistical analysis. The baseline acquisitions did not reveal differences in estimated strain between the acquisition modes ( ); myocardial segments ( ); or an interaction between imaging mode and depth ( ). Similarly, during stress testing, no difference ( p = 0.7 ) was observed for the two scan sequences, stress levels or an interaction sequence-stress level ( p = 0.94 ). Overall, our findings show that MLT and DW compoundings give comparable HFR STE strain values and that the choice for using one method or the other may thus rather be based on other factors, for example, system requirements or computational cost.

Cardiac Resynchronization Therapy in Patients with Heart Failure: What is New?

Cardiac resynchronization therapy (CRT) is an established treatment of patients with medically refractory, mild-to-severe systolic heart failure (HF), impaired left ventricular function, and wide QRS complex. The pathologic activation sequence observed in patients with abnormal QRS duration and morphology results in a dyssynchronous ventricular activation and contraction leading to cardiac remodeling, worsening systolic and diastolic function, and progressive HF. In this article, the authors aim to explore the current CRT literature, focusing their attentions on the promising innovation in this field.

2D/3D Echocardiographic features of patients with reverse remodeling after cardiac resynchronization therapy

PURPOSE

To describe clinical and echocardiographic characteristics associated with reverse left ventricular (LV) remodeling after 6 months of cardiac resynchronization therapy (CRT) in patients with nonischemic dilated cardiomyopathy.

METHODS

Twenty-four consecutive patients underwent 2D and 3D echocardiography before and after 6 months of CRT implant. Several echocardiographic parameters including global longitudinal strain (GLS) and 3D mechanical dyssynchrony (MD) index were calculated. CRT response was defined as a decrease in LV end-systolic volume (LVESV) of at least 10% at follow-up. Patients were divided in two groups according to CRT response.

RESULTS

Cardiac resynchronization therapy responder (CRTR+) rate was 50%. Nonresponder (CRTR-) patients showed a less significant improvement in NYHA class at follow-up. At baseline, CRTR- presented with higher LV end-diastolic volume (LVEDV) (P = 0.031), LVESV (P = 0.024), lower left ventricular ejection fraction (LVEF) (P = 0.002) and less negative GLS (P = 0.03), and with higher diastolic dysfunction, more impaired right ventricle (RV), and higher pulmonary artery systolic pressure (PASP) (P = 0.002). No significant differences in echocardiographic parameters of MD were found. Univariate determinants of CRTR+ were LVEF (OR = 1.59, CI 95% = 1.13-2.22, P = 0.007) and TAPSE (OR 1.21, CI 95% = 1.024-1.429, P = 0.025). A ROC curve analysis showed a cutoff value of LVEF of 22.15% significantly related to CRTR+ (SE 80%, SP 50%).

CONCLUSIONS

Our findings suggest that end-stage HF patients, presenting before CRT with LVEF <22.15%, may not benefit from the procedure after 6 months. Mechanical dyssyncronicity did not provide additional information to improve candidate selection.

Cardiac Resynchronisation Therapy and Cellular Bioenergetics: Effects Beyond Chamber Mechanics

Cardiac resynchronisation therapy is a cornerstone in the treatment of advanced dyssynchronous heart failure. However, despite its widespread clinical application, precise mechanisms through which it exerts its beneficial effects remain elusive. Several studies have pointed to a metabolic component suggesting that, both in concert with alterations in chamber mechanics and independently of them, resynchronisation reverses detrimental changes to cellular metabolism, increasing energy efficiency and metabolic reserve. These actions could partially account for the existence of responders that improve functionally but not echocardiographically. This article will attempt to summarise key components of cardiomyocyte metabolism in health and heart failure, with a focus on the dyssynchronous variant. Both chamber mechanics-related and -unrelated pathways of resynchronisation effects on bioenergetics – stemming from the ultramicroscopic level – and a possible common underlying mechanism relating mechanosensing to metabolism through the cytoskeleton will be presented. Improved insights regarding the cellular and molecular effects of resynchronisation on bioenergetics will promote our understanding of non-response, optimal device programming and lead to better patient care.

Surface electrogram-guided left ventricular lead placement improves response to cardiac resynchronization therapy

OBJECTIVE

Failure to select the optimal left ventricular (LV) segment for lead implantation is one of the most important causes of unresponsiveness to the cardiac resynchronization therapy (CRT). In our study, we aimed to investigate the echocardiographic and clinical benefits of LV lead implantation guided by an intraoperative 12-lead surface electrocardiogram (ECG) in patients with multiple target veins.

METHODS

We included 80 [42 (62.5%) male] heart failure patients who successfully underwent CRT defibrillator (CRT-D) implantation. Patients were divided into two groups. In group 1, LV lead was positioned at the site with the shortest biventricular-paced (BiV-paced) QRS duration (QRSd), as intraprocedurally measured using surface ECG. In group 2 (control), we included patients who underwent the standard unguided CRT. ECG, echocardiogram, and functional status were evaluated before and 6 months after CRT implantation in all patients.

RESULTS

In group 1, BiV-paced QRSd measurements were successfully performed in 112 of 120 coronary sinus branches during CRT and an LV lead was successfully placed at the optimal site in all patients. Compared with group 2, group 1 had a significantly higher rate (85% vs. 50%, p=0.02) of response (>15% reduction in LV end-systolic volume) to CRT as well as a shorter QRSd (p<0.001) and a greater QRS shortening (ΔQRS) associated with CRT compared with baseline (p<0.001). The mean New York Heart Association functional class was significantly improved in both groups, and no significant differences were found in clinical response to CRT (85% vs. 70%, p=0.181).

CONCLUSION

Surface ECG can be used to guide LV lead placement in patients with multiple target veins for improving response to CRT. Thus, it is a safe, feasible, and economic approach for CRT-D implantation.

Comparison of three-dimensional echocardiography and speckle tracking echocardiography in quantification and mapping of intraventricular mechanical dyssynchrony

Objectives

The aim of the study is to compare two advanced methods of evaluation of left ventricular mechanical dyssynchrony (LVMD), the speckle tracking echocardiography (STE) and the three-dimensional echocardiography (3DE).

Methods

One hundred thirty-six subjects, with or without LV dysfunction and with or without bundle branch block (BBB), were included in this study, designed to investigate agreement between magnitude and spatial pattern of LVMD as assessed by 3DE and STE. The frequency and severity of LVMD and localization of most asynchronous segments were compared.

Results

Both 3DE and STE revealed progressive rise in frequency and magnitude of LVMD with increasing disease severity. Dyssynchrony was dependent on left ventricle ejection fraction rather than the QRS duration. The frequency and magnitude of dyssynchrony were maximum in patients having LV dysfunction with left BBB. Compared with STE, 3DE diagnosed LVMD more frequently in patients having LV dysfunction with narrow QRS (17.6% vs 60.3%, respectively; P < 0.001). When the two methods were compared for localization of most asynchronous segments, the results matched only in about 50% cases.

Conclusions

Both 3DE and STE provided consistent results with progressive rise in magnitude of LVMD, correlating with disease severity. 3DE diagnosed more patients as having LVMD in those having LV dysfunction with narrow QRS. The most delayed segment assessed by two methods matched only in about half the cases. Correlation with clinical CRT responsiveness is needed to conclude which method is more accurate in dyssynchrony mapping for targeted lead placement.

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Prognostic value of real-time three-dimensional echocardiography compared to two-dimensional echocardiography in patients with systolic heart failure

Heart failure (HF) is associated with morbidity and mortality. Real-time three-dimensional echocardiography (RT3DE) may offer additional prognostic data in patients with HF. The study aimed to evaluate the prognostic value of real-time three-dimensional echocardiography (RT3DE). This is a prospective study that included 89 patients with HF and left ventricular ejection fraction (LVEF) < 0.50 who were followed for 48 months. Left atrium and ventricular volumes and functions were evaluated by RT3DE. TDI and two-dimensional echocardiography parameters were also obtained. The endpoint was a composite of death, heart transplantation and hospitalization for acute decompensated HF. The mean age was 55 ± 11 years, and the LVEF was 0.32 ± 0.10. The composite endpoint occurred in 49 patients (18 deaths, 30 hospitalizations, one heart transplant). Patients with outcomes had greater left atrial volume (40 ± 16 vs. 32 ± 12 mL/m²; p < 0.01) and right ventricle diameter (41 ± 9 vs. 37 ± 8 mm, p = 0.01), worse total emptying fraction of the left atrium (36 ± 13% vs. 41 ± 11%; p = 0.03), LVEF (0.30 ± 0.09 vs. 0.34 ± 0.11; p = 0.02), right ventricle fractional area change (34.8 ± 12.1% vs. 39.2 ± 11.3%; p = 0.04), and greater E/e' ratio (19 ± 9 vs. 16 ± 8; p = 0.04) and systolic pulmonary artery pressure (SPAP) (50 ± 15 vs. 36 ± 11 mmHg; p < 0.01). In multivariate analysis, LVEF (OR 4.6; CI 95% 1.2-17.6; p < 0.01) and SPAP (OR 12.5; CI 95% 1.8-86.9; p < 0.01) were independent predictors of patient outcomes. LVEF and the SPAP were independent predictors of outcomes in patients with HF.

Prediction of Both Electrical and Mechanical Reverse Remodeling on Acute Electrocardiogram Changes After Cardiac Resynchronization Therapy

BACKGROUND

The development of both electrical reverse remodeling and mechanical reverse remodeling (ERR+MRR) after cardiac resynchronization therapy (CRT) implantation could reduce the incidence of lethal arrhythmia, hence the prediction of ERR+MRR is clinically important.Methods and Results:Eighty-three patients (54 male; 67±12 years old) with CRT >6 months were enrolled. ERR was defined as baseline intrinsic QRS duration (iQRSd) shortening ≥10 ms in lead II on ECG after CRT, and MRR as improvement in LVEF ≥25% on echocardiography after CRT. Acute ECG changes were measured by comparing the pre-implant and immediate post-implant ECG. Ventricular arrhythmia episodes, including ventricular tachycardia and ventricular fibrillation, detected by the implanted device were recorded. Patients were classified as ERR only (n=12), MRR only (n=23), ERR+MRR (n=26), or non-responder (ERR- & MRR-, n=22). On multivariate regression analysis, difference between baseline intrinsic QRS and paced QRS duration (∆QRSd) >35 ms was a significant predictor of ERR+MRR (sensitivity, 68%; specificity, 64%; AUC, 0.7; P=0.003), and paced QTc >443 ms was a negative predictor of ERR+MRR (sensitivity, 78%; specificity, 60%; AUC, 0.7; P=0.002). On Cox proportional hazard modeling, ERR+MRR may reduce risk of ventricular arrhythma around 70% compared with non-responder (HR, 0.29; 95% CI: 0.13-0.65).

CONCLUSIONS

Acute ECG changes after CRT were useful predictors of ERR+MRR. ERR+MRR was also a protective factor for ventricular arrhythmia.

Gauging the response to cardiac resynchronization therapy: The important interplay between predictor variables and definition of a favorable outcome

AIMS

Selection of patients who are viable candidates for cardiac resynchronization therapy (CRT), prediction of the response to CRT as well as an optimal definition of a favorable response, all require further exploration. The purpose of this study was to evaluate the interplay between the prediction of the response to CRT and the definition of a favorable outcome.

METHODS

Seventy patients who received CRT were included. All patients met current guideline criteria for CRT. Forty-three echocardiographic parameters were evaluated before CRT and at 1, 3, 6, and 12 months. M-mode, 2D echocardiography, and Doppler imaging were used to quantify left ventricular (LV) systolic and diastolic function, mitral regurgitation, right ventricular systolic function, pulmonary artery pressure, and myocardial mechanical dyssynchrony. The following definitions of a favorable CRT response were used: left ventricular ejection fraction (LVEF) improvement more >5% acutely following CRT, LVEF improvement >20% at 12-month follow-up, and a LV end-systolic volume (LVESV) decrease >15% at 12-month follow-up.

RESULTS

For the LVEF improvement >5%, the best predictor was isovolumetric relaxation time (IVRT; P=.035). For improvement of LVEF >20%, the best predictors were left ventricular stroke index (LVSI; P=.044) and left ventricular fractional shortening (LVFS; P=.031). For the drop in left ventricular systolic volume (LVESV >15%), the best predictor was septal-to-lateral wall delay (ΔT) (P=.043, RR=1.023, 95% CI for RR=1.001-1.045).

CONCLUSION

The definition of a favorable CRT response influenced the optimal predictor variable(s). Standardization of defining a favorable response to CRT is needed to guide clinical decision making processes.

Impact of QT interval prolongation following antiarrhythmic drug therapy on left ventricular function

AIM

We assessed whether antiarrhythmic drug-induced QT interval prolongation affects left ventricular function.

METHODS

Study population included 54 patients with symptomatic recent onset atrial fibrillation spontaneously cardioverted to sinus rhythm. Electrocardiographic and echocardiographic studies were done before initiating and after achieving drug's steady state.

RESULTS

Significantly prolonged corrected QT interval (QTc) was noticed following only sotalol and amiodarone. The corrected precontraction time increased after sotalol (p = 0.005) and amiodarone (p = 0.017), not propafenone (p = 0.139). Analysis results between ΔEF and ΔQTc, ΔEF and ΔQTc(p), ΔE/e' and ΔQTc, ΔE/e' and ΔQTc(p) for amiodarone group were (p = 0.66, p = 0.20, p = 0.66, p = 0.33), for sotalol (p = 0.36, p = 0.51, p = 0.44, p = 0.33) and for propafenone (p = 0.38, p = 0.12, p = 0.89, p = 0.61), respectively.

CONCLUSION

QT interval prolongation following antiarrhythmic therapy does not affect significantly left ventricular function.

Multipoint Pacing versus conventional ICD in Patients with a Narrow QRS complex (MPP Narrow QRS trial): study protocol for a pilot randomized controlled trial

BACKGROUND

Despite an intensive search for predictors of the response to cardiac resynchronization therapy (CRT), the QRS duration remains the simplest and most robust predictor of a positive response. QRS duration of ≥ 130 ms is considered to be a prerequisite for CRT; however, some studies have shown that CRT may also be effective in heart failure (HF) patients with a narrow QRS (<130 ms). Since CRT can now be performed by pacing the left ventricle from multiple vectors via a single quadripolar lead, it is possible that multipoint pacing (MPP) might be effective in HF patients with a narrow QRS. This article reports the design of the MPP Narrow QRS trial, a prospective, randomized, multicenter, controlled feasibility study to investigate the efficacy of MPP using two LV pacing vectors in patients with a narrow QRS complex (100-130 ms).

METHODS

Fifty patients with a standard ICD indication will be enrolled and randomized (1:1) to either an MPP group or a Standard ICD group. All patients will undergo a low-dose dobutamine stress echo test and only those with contractile reserve will be included in the study and randomized. The primary endpoint will be the percentage of patients in each group that have reverse remodeling at 12 months, defined as a reduction in left ventricular end-systolic volume (LVESV) of >15% from the baseline.

DISCUSSION

This feasibility study will determine whether MPP improves reverse remodeling, as compared with standard ICD, in HF patients who have a narrow QRS complex (100-130 ms).

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02402816 . Registered on 25 March 2015.

Left Atrial Volume Determinants in Patients with Non-Ischemic Dilated Cardiomyopathy

BACKGROUND

Left atrial volume (LAV) is a predictor of prognosis in patients with heart failure.

OBJECTIVE

We aimed to evaluate the determinants of LAV in patients with dilated cardiomyopathy (DCM).

METHODS

Ninety patients with DCM and left ventricular (LV) ejection fraction ≤ 0.50 were included. LAV was measured with real-time three-dimensional echocardiography (eco3D). The variables evaluated were heart rate, systolic blood pressure, LV end-diastolic volume and end-systolic volume and ejection fraction (eco3D), mitral inflow E wave, tissue Doppler e' wave, E/e' ratio, intraventricular dyssynchrony, 3D dyssynchrony index and mitral regurgitation vena contracta. Pearson's coefficient was used to identify the correlation of the LAV with the assessed variables. A multiple linear regression model was developed that included LAV as the dependent variable and the variables correlated with it as the predictive variables.

RESULTS

Mean age was 52 ± 11 years-old, LV ejection fraction: 31.5 ± 8.0% (16-50%) and LAV: 39.2±15.7 ml/m2. The variables that correlated with the LAV were LV end-diastolic volume (r = 0.38; p < 0.01), LV end-systolic volume (r = 0.43; p < 0.001), LV ejection fraction (r = -0.36; p < 0.01), E wave (r = 0.50; p < 0.01), E/e' ratio (r = 0.51; p < 0.01) and mitral regurgitation (r = 0.53; p < 0.01). A multivariate analysis identified the E/e' ratio (p = 0.02) and mitral regurgitation (p = 0.02) as the only independent variables associated with LAV increase.

CONCLUSION

The LAV is independently determined by LV filling pressures (E/e' ratio) and mitral regurgitation in DCM.

Glycoproteins identified from heart failure and treatment models

Conduction abnormalities can lead to dyssynchronous contraction, which significantly worsens morbidity and mortality of heart failure. Cardiac resynchronization therapy (CRT) can reverse ventricular remodeling and improve cardiac function. Although the underlying molecular changes are unknown, the use of a canine model of dyssynchronous heart failure (DHF) and CRT has shown that there are global changes across the cardiac proteome. This study determines changes in serum glycoprotein concentration from DHF and CRT compared to normal. We hypothesize that CRT invokes protective or advantageous pathways that can be reflected in the circulating proteome. Two prong discovery approaches were carried out on pooled normal, DHF, and CRT samples composed of individual canine serum to determine the overall protein concentration and the N-linked glycosites of circulating glycoproteins. The level of the glycoproteins was altered in DHF and CRT compared to control sera, with 63 glycopeptides substantially increased in DHF and/or CRT. Among the 32 elevated glycosite-containing peptides in DHF, 13 glycopeptides were reverted to normal level after CRT therapy. We further verify the changes of glycopeptides using label-free LC-MS from individual canine serum. Circulating glycoproteins such as alpha-fetoprotein, alpha-2-macroglobulin, galectin-3-binding protein, and collectin-10 show association to failing heart and CRT treatment model.

Left-ventricular mechanical activation and aortic-arch orientation recovered from magneto-hydrodynamic voltages observed in 12-lead ECGs obtained inside MRIs: a feasibility study

To explore use of the Magnetohydrodynamic Voltage (VMHD), observed in intra-MRI 12-lead electrocardiograms (ECG), to indicate the timing of the onset of left-ventricular mechanical activation (LVMA) and the orientation of the aortic-arch (AAO). Blood flow through the aortic arch during systole, in the presence of the MRI magnetic field (B 0), generates VMHD. Since the magnitude and direction of VMHD are determined by the timing and directionality of blood flow relative to B 0, we hypothesized that clinically useful measures, LVMA and AAO, could be extracted from temporal and vectorial VMHD characteristics. VMHD signals were extracted from 12-lead ECG traces by comparing traces obtained inside and outside the MRI scanner. VMHD was converted into the Vectorcardiogram frame of reference. LVMA was quantified in 1 subject at 1.5T and 3 subjects at 3T, and the result compared to CINE MRI. AAO was inferred for 4 subjects at 3T and compared to anatomical imaging of the aortic arch orientation in the transverse plane. A < 10% error was observed in LVMA measurements, while a < 3° error was observed in aortic arch orientation measurements. The temporal and vectorial nature of VMHD is useful in estimating these clinically relevant parameters.

Development of a multiparametric score to predict left ventricular remodelling and prognosis after cardiac resynchronization therapy

AIMS

Optimal delivery of CRT requires appropriate patient selection and device implantation. Echocardiographic predictors of CRT response individually appear to enhance patient selection, but do not fully reflect the complex underlying myocardial dysfunction. We hypothesized that a multiparametric approach would offer greater predictive value and sought to derive a score incorporating baseline characteristics including: dyssynchrony, LV function, and LV lead position.

METHODS AND RESULTS

Data were analysed from 294 patients undergoing CRT between June 2008 and December 2012. All patients were in sinus rhythm with QRS >120 ms, NYHA class II-IV, and LVEF <35%. Detailed clinical assessment including echocardiography was completed at baseline and 6 months after CRT. Response was defined as a ≥15% reduction in LV end-systolic volume. Dyssynchrony (interventricular delay and radial strain delay), global longitudinal strain, and LV lead position were independent predictors of LV remodelling and were used to derive a predictive score which correlated with reduction in LV volume (r = - 0.5, P < 0.001) and was higher with QRS >150 ms and non-ischaemic aetiology. A cut-off score <0.6 offered the highest specificity and positive predictive value (100%) to determine non-response. A score >3.28 offered high specificity (specificity 86%, sensitivity 70%) to predict response. Survival proportion at longer term follow-up was low (21%) in the group with predictive score <0.6.

CONCLUSION

A multiparametric strategy, which defines anticipated probability of response to CRT, offers potential to predict non-responders with poor long-term survival following CRT. The value of this approach in avoiding unnecessary device implantation with potential for harm requires validation in large multicentre studies.

Model-based navigation of left and right ventricular leads to optimal targets for cardiac resynchronization therapy: a single-center feasibility study

BACKGROUND

Left ventricular (LV) and right ventricular pacing site characteristics have been shown to influence response to cardiac resynchronization therapy (CRT). This study aimed to determine the clinical feasibility of image-guided lead delivery using a 3-dimensional navigational model displaying both LV and right ventricular (RV) pacing targets. Serial echocardiographic measures of clinical response and procedural metrics were evaluated.

METHODS AND RESULTS

Thirty-one consecutive patients underwent preimplant cardiac MRI with the generation of a 3-dimensional navigational model depicting optimal segmental targets for LV and RV leads. Lead delivery was guided by the model in matched views to intraprocedural fluoroscopy. Blinded assessment of final lead tip location was performed from postprocedural cardiac computed tomography. Clinical and LV remodeling response criteria were assessed at baseline, 3 months, and 6 months using a 6-minute hall walk, quality of life questionnaire, and echocardiography. Mean age and LV ejection fraction was 66 ± 8 years and 26 ± 8%, respectively. LV leads were successfully delivered to a target or adjacent segment in 30 of 31 patients (97%), 68% being nonposterolateral. RV leads were delivered to a target or adjacent segment in 30 of 31 patients (97%), 26% being nonapical. Twenty-three patients (74%) met standard criteria for response (LV end-systolic volume reduction ≥ 15%), 18 patients (58%) for super-response (LV end-systolic volume reduction ≥ 30%). LV ejection fraction improved at 6 months (31 ± 8 versus 26 ± 8%, P=0.04).

CONCLUSIONS

This study demonstrates clinical feasibility of dual cardiac resynchronization therapy lead delivery to optimal targets using a 3-dimensional navigational model. High procedural success, acceptable procedural times, and a low rate of early procedural complications were observed.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01640769.

Application of CRT-D in a Marfan syndrome patient with chronic heart failure accompanied by ventricular tachycardia and ventricular fibrillation

Marfan syndrome is a systemic connective tissue disease that could affect the cardiovascular system and eventually lead to heart enlargement and heart failure with high mortality, mainly due to progressive heart failure and/or sudden cardiac death caused by malignant arrhythmia. Here we report that a patient received a cardiac resynchronization therapy-defibrillator (CRT-D) with a pre-monitor function for heart failure and experienced obvious improvements in his cardiac function. Postoperative follow-up showed that the patient had reduced morbidity and hospitalization for heart failure, and also experienced improved quality of life.

Biventricular pacing in heart failure: a review

Biventricular pacing has been an exciting recent advance in the management of drug-refractory heart failure. This new therapy has evolved as much from necessity as scientific observation, since benefits derived from pharmacotherapy currently appear to have reached their peak. Clinical trials of biventricular pacing are establishing morbidity and mortality benefits in heart failure. New challenges in the use of these pacemakers are now arising. These include the accurate diagnosis of ventricular dyssynchrony and, hence, potential responders to the refinement of implantation of the left ventricular lead to the appropriate dyssynchronous ventricular area and optimization of pacemaker programming. This review gives a general overview of the principles and the current evidence for the use of biventricular pacemakers in the treatment of heart failure. In addition, a discussion of current research and future projects is included.

Prognostic significance of left ventricular dyssynchrony by phase analysis of gated SPECT in medically treated patients with dilated cardiomyopathy

PURPOSE

The study aimed to investigate the value of clinical variables and rest gated single-photon emission computed tomography (SPECT) in predicting cardiac deaths in medically treated dilated cardiomyopathy (DCM) patients.

METHODS

This is a retrospective study. Fifty-six consecutive hospitalized DCM patients who underwent rest gated SPECT myocardial perfusion imaging were initially recruited. Patients were further excluded for receiving heart transplantation, cardiac resynchronization treatment, and noncardiac death during follow-up. The remaining 48 medically treated DCM patients were selected into the final analysis. Phase analysis of gated SPECT was conducted to identify left ventricular (LV) dyssynchrony. Cardiac death during follow-up was considered as the only endpoint. Univariate and multivariate Cox proportional hazards regression analysis were performed to identify the independent predictors of cardiac death. Kaplan-Meier cumulative survival analysis with stratification was performed, and survival curves were compared by log-rank test.

RESULTS

The mean age was 47.5 ± 15.8 years (range, 15-76 yrs) and 85.4% were men. The mean LV ejection fraction was 22.2 ± 7.7%. During the follow-up period (22.7 ± 5.1 mos), 12 (25.0%) cardiac deaths occurred. Compared to survivors, patients with cardiac death had lower body mass index (BMI, P = 0.010), higher percent of prolonged QRS duration (QRSD, P = 0.043), and severe LV dyssynchrony (P = 0.002). Multivariate Cox analysis demonstrated that severe LV dyssynchrony [hazard ratio = 9.607, 95% confidential interval (95% CI) 2.064-44.713, P = 0.004] and BMI (hazard ratio = 0.851, 95% CI 0.732-0.989, P = 0.036) were predictive of cardiac death.

CONCLUSION

Left ventricular dyssynchrony assessed by phase analysis of gated SPECT and BMI are predictive of cardiac death in medically treated DCM patients.

Influence of pacing site characteristics on response to cardiac resynchronization therapy

BACKGROUND

Transmural scar occupying left ventricular (LV) pacing regions has been associated with reduced response to cardiac resynchronization therapy (CRT). However, spatial influences of lead tip delivery relative to scar at both pacing sites remain poorly explored. This study evaluated scar distribution relative to LV and right ventricular (RV) lead tip placement through coregistration of late gadolinium enhancement MRI and cardiac computed tomographic (CT) findings. Influences on CRT response were assessed by serial echocardiography.

METHODS AND RESULTS

Sixty patients receiving CRT underwent preimplant late gadolinium enhancement MRI, postimplant cardiac CT, and serial echocardiography. Blinded segmental evaluations of mechanical delay, percentage scar burden, and lead tip location were performed. Response to CRT was defined as a reduction in LV end-systolic volume ≥15% at 6 months. The mean age and LV ejection fraction were 64±9 years and 25±7%, respectively. Mean scar volume was higher among CRT nonresponders for both the LV (23±23% versus 8±14% [P=0.01]) and RV pacing regions (40±32% versus 24±30% [P=0.04]). Significant pacing region scar was identified in 13% of LV pacing regions and 37% of RV pacing regions. Absence of scar in both regions was associated with an 81% response rate compared with 55%, 25%, and 0%, respectively, when the RV, LV, or both pacing regions contained scar. LV pacing region dyssynchrony was not predictive of response.

CONCLUSIONS

Myocardial scar occupying the LV pacing region is associated with nonresponse to CRT. Scar occupying the RV pacing region is encountered at higher frequency and seems to provide a more intermediate influence on CRT response.

Association between QRS duration and outcome with cardiac resynchronization therapy: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review and meta-analysis of randomized and observational studies to evaluate the associations between QRS duration (QRSd) at baseline or in follow-up and outcomes with cardiac resynchronization therapy (CRT).

METHODS

We searched online databases to December 2010 and included 6 randomized controlled trials (RCTs) and 38 observational studies. Outcomes included clinical/functional response, left ventricular (LV) remodeling, hospitalizations and mortality.

RESULTS

In RCTs, a benefit of CRT was evident only in patients with QRSd >150ms. In observational studies, those meeting either clinical or remodeling CRT response definitions had both wider pooled baseline QRSd and significantly more QRS narrowing with CRT than non-responders.

CONCLUSIONS

RCTs demonstrate that benefit with CRT appears restricted to those with baseline QRSd wider than 150ms. Both wider baseline QRS and more QRS narrowing are associated with CRT response in observational studies. Electrocardiographic QRSd plays an important role in CRT patient selection and follow-up.

Prevalence of cardiac dyssynchrony and correlation with atrio-ventricular block and QRS width in dilated cardiomyopathy: an echocardiographic study

INTRODUCTION

Cardiac dyssynchrony causes disorganised cardiac contraction, delayed wall contraction and reduced pumping efficiency. We aimed to assess the prevalence of different types of dyssynchrony in patients with dilated cardiomyopathy (DCM), and to establish the correlation between atrio-ventricular block and atrio-ventricular dyssynchrony (AVD), and between impaired intra-ventricular conduction and the existence of inter-ventricular dyssynchrony (inter-VD) and intra-left ventricular dyssynchrony (intra-LVD).

METHODS

We included 40 patients in New York Heart Association stage III or IV, admitted consecutively with DCM with severe left ventricular dysfunction (left ventricular end-diastolic diameter ≥ 60 mm and/or ≥ 30 mm/m(2)) and left ventricular ejection fraction < 35%. Electrocardiographic and echocardiographic data were evaluated in all patients. Patients were divided into two groups: group 1: eight patients, with a QRS duration ≥ 120 ms, and all presented with left bundle branch block; group 2: 32 patients with a narrow QRS < 120 ms.

RESULTS

Overall, the mean age was 54.7 ± 16.8 years and patients in group 1 were older (67.2 ± 13.6 vs 51.5 ± 15.8 years, p = 0.01). The prevalence of atrio-ventricular dyssynchrony (AVD), inter-VD and intra-LVD was respectively 40, 47.5 and 70%. Two patients (5%) did not exhibit dyssynchrony. AVD was present with a similar frequency in the two groups (37.5% in group 1 vs 40.6% in group 2, p = 0.8). There was no correlation of the magnitude of AVD with the duration of the PR interval (from the beginning of the P wave to the beginning of the QRS complex) (r(2) = 0.02, p = 0.37) or the QRS width (r(2) = 0.01, p = 0.38). A greater proportion of patients with inter-VD was observed in group 1 (87.5 vs 60%, p = 0.03). There was a trend towards a more important inter-ventricular mechanical delay according to QRS width (r(2) = 0.009, p = 0.06). The proportion of intra-LVD was similar in all groups, with a high prevalence (87.5% in group 1 and 65.6% in group 2, p = 0.39).

CONCLUSION

The assessment of cardiac dyssynchrony is possible in our country. Intra-ventricular mechanical dyssynchrony had a high prevalence in patients with DCM, irrespective of the QRS width. These data emphasise the usefulness of echocardiography in the screening of patients.

Improvement of left ventricular function under cardiac resynchronization therapy goes along with a reduced incidence of ventricular arrhythmia

Objectives

The beneficial effects of cardiac resynchronization therapy (CRT) are thought to result from favorable left ventricular (LV) reverse remodeling, however CRT is only successful in about 70% of patients. Whether response to CRT is associated with a decrease in ventricular arrhythmias (VA) is still discussed controversially. Therefore, we investigated the incidence of VA in CRT responders in comparison with non-responders.

Methods

In this nonrandomized, two-center, observational study patients with moderate-to-severe heart failure, LV ejection fraction (LVEF) ≤35%, and QRS duration >120 ms undergoing CRT were included. After 6 months patients were classified as CRT responders or non-responders. Incidence of VA was compared between both groups by Kaplan-Meier analysis and Cox regression analysis. ROC analysis was performed to determine the aptitude of LVEF cut-off values to predict VA.

Results

In total 126 consecutive patients (64±11years; 67%male) were included, 74 were classified as responders and 52 as non-responders. While the mean LVEF at baseline was comparable in both groups (25±7% vs. 24±8%; P = 0.4583) only the responder group showed an improvement of LVEF (36±6% vs. 24±7; p<0.0001) under CRT. In total in 56 patients VA were observed during a mean follow-up of 28±14 months, with CRT responders experiencing fewer VA than non-responders (35% vs. 58%, p<0.0061). Secondary preventive CRT implantation was associated with a higher likelihood of VA. As determined by ROC analysis an increase of LVEF by >7% was found to be a predictor of a significantly lower incidence of VA (AUC = 0.606).

Conclusions

Improvement of left ventricular function under cardiac resynchronization therapy goes along with a reduced incidence of ventricular arrhythmia.

Use of real-time three-dimensional echocardiography to assess left ventricular systolic synchronization after dual-chamber pacing therapy

This study was designed to evaluate the left ventricular systolic synchronization in patients implanted with dual-chamber DDD mode cardiac pacemakers by real-time three-dimensional echocardiography (RT3DE). Twenty patients implanted with DDD mode cardiac pacemakers for 12 months and 20 healthy subjects underwent RT3DE. This method provided left ventricular end-diastolic volume (LEDV), left ventricular end-systolic volume (LESV), stroke volume (SV), left ventricular ejection fraction (LVEF), the mean value of the time to minimal systolic volume of the 16 left ventricular segments (Tmean), the standard deviation of Tmean (T-SD), the maximal difference of the time to minimal systolic volume of the 16 left ventricular segments (Tmax) and time-volume curves of the 16 left ventricular segments. Results showed that compared with the healthy group, LESV was significantly increased (P<0.05), SV and LVEF were significantly decreased (P<0.05) and T-SD and Tmax were significantly prolonged (P<0.05) in patients implanted with DDD mode cardiac pacemakers. The time to minimal systolic volume of the 16 left ventricular segments time-volume curves differed in patients implanted with DDD mode cardiac pacemakers. Asynchronization of the left ventricular systolic performance in patients implanted with DDD mode cardiac pacemakers was observed. The results showed that RT3DE is a quantitative method used to evaluate left ventricular systolic synchronization.

Midterm Follow-up of Robotic Biventricular Pacing Demonstrates Excellent Lead Stability and Improved Response Rates

BACKGROUND

: Robotically assisted left ventricular (LV) lead placement is an effective minimally invasive rescue procedure for cardiac resynchronization in the setting of failed coronary sinus lead insertion. The long-term response rate and durability of this technique has not been reported. The authors evaluated the midterm outcome of biventricular pacing performed with robotically placed LV leads.

METHODS

: Forty-two patients underwent implantation of LV epicardial leads using robotic assistance and the posterior approach. Half of the patients had prior cardiac surgery. All leads were placed in an optimal site along the posterolateral surface of the LV. The patients were prospectively followed up for clinical response, LV reverse remodeling, and LV lead stability over a mean period of 16.7 ± 9.5 months (range, 3-34 months). A multivariate Cox proportional hazards model was used to determine predictors of response.

RESULTS

: All patients had successful LV lead placement with no postoperative mortality. Statistically significant improvements in left ventricular ejection fraction, NYHA heart failure class, systolic left ventricular internal dimension index, and diastolic left ventricular internal dimension index. The 3-month clinical response rate was 81% and dropped to 71% at average maximal follow-up. Multivariate analysis of 9 variables revealed only LVEF greater than 15% and absence of pulmonary hypertension to be predictors of response. No difference in operative time, response rate, or LV lead stability was detected when primary versus reoperative cases were compared.

CONCLUSIONS

: Robotic LV lead placement is a reliable technique for optimal lead placement with durable long-term results.

Intraoperative characterization of interventricular mechanical dyssynchrony using electroanatomic mapping system--a feasibility study

BACKGROUND

Interventricular mechanical dyssynchrony (VVMD) is a strong predictor of cardiac resynchronization therapy (CRT) response. However, no simple and reliable clinical method of measuring VVMD during CRT implant is currently available. We tested the hypothesis that the EnSite™ NavX™ system (St. Jude Medical, St. Paul, MN, USA) can be used intraoperatively to determine VVMD, thereby facilitating CRT optimization.

METHODS

During CRT implant, the leads in the right atrium (RA), right ventricle (RV), and left ventricle (LV) were connected to the EnSite™ NavX™ system to record the real-time 3D motion of the lead electrodes. The distances from RA to RV lead electrodes (RA-RV) and RA to LV lead electrodes (RA-LV) were computed over ten cardiac cycles during each of RV pacing and biventricular (BiV) pacing, respectively. The degree of synchrony was computed from the distance waveforms between RA-RV and RA-LV by a cross-covariance method to characterize VVMD. Septal-to-posterior wall motion delay (SPWMD) from M-mode echocardiography (echo) was measured for reference at each pacing intervention. VVMD was present in all five patients undergoing CRT implant.

RESULTS

Four of the five patients demonstrated clear improvement in EnSite™ NavX™-derived VVMD during BiV versus RV pacing, which corresponded to the SPWMD results by echo.

CONCLUSIONS

It is feasible to characterize VVMD and resynchronization in CRT patients with the EnSite™ NavX™ system during implant, demonstrating its potential as a tool for intraoperative CRT optimization.

Imaging for planning of cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is a novel therapy for patients with refractory heart failure (HF). Large clinical trials evaluating CRT have demonstrated significant improvements in cardiac survival, decreases in recurrent HF hospitalization, and improvements in indexes of quality of life. Although numerous mechanisms are involved in CRT's therapeutic effects, correction of both interventricular and intraventricular mechanical dyssynchrony has been postulated as the key mechanism. To date, most large randomized controlled trials evaluating CRT have identified dyssynchronous patients on the basis of prolongation of the QRS complex from the baseline electrocardiogram. Concerns have been raised regarding the use of this measure for patient selection, stemming from a significant 30% to 40% nonresponse rate to CRT. Because of the cost and invasive nature of CRT, optimal patient selection for this therapy has become a priority for HF specialists and electrophysiologists. Cardiac imaging modalities have attempted to fulfill this need to improve patient selection by identifying mechanical dyssynchrony. Although early echocardiographic studies reported promising results, more recent larger scale studies have curtailed this enthusiasm, with a lack of established selection criteria for CRT in the current practice guidelines. This review summarizes the evidence to date and the potential role of imaging modalities in the selection and care of patients with HF referred for CRT.

Reduced septal glucose metabolism predicts response to cardiac resynchronization therapy

BACKGROUND

Up to 50% of patients do not respond to Cardiac Resynchronization Therapy (CRT). Recent work has focused on quantifying mechanical dyssynchrony and left ventricular scar. Septal reverse-mismatch (R-MM) (reduced FDG uptake vs perfusion) has been observed in patients with cardiomyopathy and prolonged QRS duration. We hypothesized that a greater quantity of septal R-MM would indicate a greater potential for reversibility of the cardiomyopathy, when the dyssynchrony is improved with CRT. Therefore, this study's objective was to assess whether greater septal R-MM pattern predicts response to CRT.

METHODS AND RESULTS

Forty-nine patients had pre-implant Rubidium-82 and Fluorine-18-fluorodeoxyglucose PET scanning. Total and regional left ventricular scar size and extent of R-MM were calculated. Response to CRT was defined as ≥10% improvement in left ventricular end-systolic volume or ≥5% absolute ejection fraction improvement. In the non-ischemic cardiomyopathy subset non-responders had significantly less septal R-MM than responders (13.1% compared to 27.1%, P = .012). There were correlations between the extent of septal R-MM and the increase in ejection fraction (r = 0.692, P = .0004) and reduction in left ventricular end-systolic volume (r = -0.579, P = .004). For each 5% absolute increase in extent of septal R-MM the odds ratio of being a responder was 2.17 (95% CI 1.15, 4.11, P = .017). Extent of septal R-MM displayed high sensitivity and specificity (area under curve = 0.855, P = .017) to predict response.

CONCLUSIONS

In patients with non-ischemic cardiomyopathy, greater extent of septal glucose metabolic R-MM pattern, predicted response to CRT. This parameter may be useful for identifying patients who benefit from CRT.

A practical approach to imaging dyssynchrony for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is believed to benefit patients by primarily correcting heterogeneity in regional ventricular mechanical contraction, known as dyssynchrony. Although many symptomatic heart failure patients with depressed left ventricular ejection fraction and widened electrocardiographic QRS complexes have clinical improvement from CRT, a significant subset of approximately one-third do not seem to respond. Because the degree of mechanical dyssynchrony may be widely variable, interest has remained high to attempt to improve patient selection for CRT using cardiac imaging as a means to quantify dyssynchrony. This article will review the principal echocardiographic methods of dyssynchrony analysis by tissue Doppler imaging, (opposing wall delay, 12-site standard deviation or Yu index, and longitudinal strain), routine pulsed-Doppler (interventricular mechanical delay, pre-ejection delay and filling time ratio), and speckle tracking (including radial, circumferential, and longitudinal strain). In addition, dyssynchrony analysis by cardiac magnetic resonance imaging is introduced as a potential alternative technique. The technical features, strengths and limitations, and clinical evidence for these methods are discussed, including a practical clinical approach.