High prevalence of left ventricular systolic and diastolic asynchrony in patients with congestive heart failure and normal QRS duration

Myocardial systolic synchrony measured by Doppler tissue imaging as a role of predictor of left ventricular ejection fraction improvement in severe congestive heart failure

BACKGROUND

The recovery of left ventricular ejection fraction (LVEF) appears to be prognostic of survival in congestive heart failure (CHF). The aim of our study was to evaluate which parameters appear to predict LVEF improvement in CHF.

METHODS

In all, 85 patients (age 64 +/- 12 years) with CHF and LVEF <35% were enrolled. Doppler tissue imaging was performed on 5 basal and 5 midsegments to assess the time from R wave to peak systolic velocity (Ts). The standard deviation (SD) of Ts was an indicator of systolics synchrony. After at least 3 months of intensive medical therapy with beta-blocker and angiotensin-converting enzyme inhibitors, follow-up echocardiography was performed. By the change in LVEF, we divided patients into group I (<5%, n = 47) and group II (>/=5%, n = 38).

RESULTS

Baseline clinical and echocardiographic parameters were similar in both groups. There was negative correlation between SD of Ts and change of LVEF ( r = -0.43, P < .001). The multivariate analysis shows that SD of Ts and dose of beta-blocker were independent predictors of LVEF improvement.

CONCLUSION

Myocardial systolic synchrony measured by Doppler tissue imaging is a predictor for LVEF improvement in severe CHF independently from QRS duration, cause of CHF, baseline LVEF, and chamber dimension.

QRS dispersion: an electrocardiographic index of systolic left ventricular dysfunction in patients with left bundle branch block

The presence of complete left bundle branch block (LBBB) in patients with congestive heart failure has been proposed to be a factor that negatively affects left ventricular (LV) systolic function. The aim of this study was to evaluate the relative predictive value of QRS dispersion (QRSD) and QRS duration (QRSd) in relation to systolic performance of the left ventricle. The ejection fraction of 130 consecutive patients with LBBB was evaluated by standard echocardiographic methods, whereas QRSd and QRSD were measured. It was demonstrated that QRSD in patients with complete LBBB is strongly related to LV contractility. We, therefore, suggest that this simple electrocardiographic index may serve as a useful screening test for detection of patients with LV systolic dysfunction.

Tissue Doppler echocardiography and biventricular pacing in heart failure: patient selection, procedural guidance, follow-up, quantification of success

Asynchronous myocardial contraction in heart failure is associated with poor prognosis. Resynchronization can be achieved by biventricular pacing (BVP), which leads to clinical improvement and reverse remodeling. However, there is a substantial subset of patients with wide QRS complexes in the electrocardiogram that does not improve despite BVP. QRS width does not predict benefit of BVP and only correlates weakly with echocardiographically determined myocardial asynchrony. Determination of asynchrony by Tissue Doppler echocardiography seems to be the best predictor for improvement after BVP, although no consensus on the optimal method to assess asynchrony has been achieved yet. Our own preliminary results show the usefulness of Tissue Doppler Imaging and Tissue Synchronization Imaging to document acute and sustained improvement after BVP. To date, all studies evaluating Tissue Doppler in BVP were performed retrospectively and no prospective studies with patient selection for BVP according to echocardiographic criteria of asynchrony were published yet. We believe that these new echocardiographic tools will help to prospectively select patients for BVP, help to guide implantation and to optimize device programming.

Comparison of Efficacy of Reverse Remodeling and Clinical Improvement for Relatively Narrow and Wide QRS Complexes After Cardiac Resynchronization Therapy for Heart Failure

INTRODUCTION

Cardiac resynchronization therapy (CRT) has been shown to reverse left ventricular (LV) remodeling and improve symptoms in heart failure patients with wide QRS complexes; however, its role in patients with mildly prolonged QRS complexes is unclear. This study investigated if CRT benefited patients with mildly prolonged QRS complexes >120 to 150 ms and explored if the severity of systolic asynchrony determined such a response.

METHODS AND RESULTS

Fifty-eight patients (age 66 +/- 11 years, 66% male) who had undergone CRT were studied prospectively. Of these patients, 27 had QRS duration between 120 and 150 ms (group A), and 31 had QRS duration >150 ms (group B). Tissue Doppler echocardiography and clinical assessment were performed at baseline and 3 months after CRT. Both groups had significant reduction of LV volume and increased ejection fraction, +dP/dt, and sphericity index (all P < 0.05). These improvements were greater in group B and were explained by the higher prevalence of systolic intraventricular asynchrony. Significant reverse remodeling (reduction of LV end-systolic volume >15%) was evident in 46% of group A patients and 68% of group B patients. Improvement in clinical endpoints was observed in both groups (all P < 0.01), although the changes in metabolic equivalent and New York Heart Association functional class were greater in group B. In both groups, systolic asynchrony index (TS-SD) was the most important predictor of reverse remodeling (r =-0.78, P < 0.001) and was the only independent predictor in the multivariate model (beta=-1.80, confidence interval =-2.18 to -1.42, P < 0.001); QRS duration was not. A predefined TS-SD value >32.6 ms had a sensitivity of 94% and specificity of 83% to predict reverse remodeling. Improvement of intraventricular asynchrony after CRT was evident only in responders (P = 0.01).

CONCLUSION

Improvement of LV remodeling and clinical status is evident after CRT in heart failure patients with QRS duration >120 to 150 ms. These responders are closely predicted by the severity of prepacing intraventricular asynchrony but not QRS duration.

Tissue Doppler imaging as a guide to resynchronization therapy in patients with congestive heart failure

PURPOSE OF REVIEW

Cardiac resynchronization therapy is a nonpharmacological treatment option in patients with heart failure and left bundle branch block but response rates are still disappointing.

RECENT FINDINGS

Extent of mechanical left ventricular asynchrony as detected by tissue Doppler imaging has emerged as an independent predictor of outcome to CRT. In addition, long-term therapy delivery may be further improved through optimized lead positioning and pacemaker programming.

SUMMARY

Tissue Doppler imaging should be included in the evaluation of potential CRT candidates but standardized evaluation criteria have not yet been provided.

Comparison of left ventricular function by tissue Doppler imaging in patients with diabetes mellitus without systemic hypertension versus diabetes mellitus with systemic hypertension

Because diabetes mellitus substantially increases the risk of development of heart failure, we sought to establish early alterations in left ventricular systolic and diastolic function in patients with diabetes mellitus with and without coexisting systemic hypertension. We studied 134 subjects using echocardiography comprising standard 2-dimensional and conventional Doppler as well as tissue Doppler imaging. Our study demonstrated the early appearance of both left ventricular systolic and diastolic dysfunction in diabetic patients at rest and the contributory effects of diabetes to myocardial impairment produced by hypertension, as well as the high usefulness of tissue Doppler imaging in detection and quantitation of myocardial dysfunction in diabetics. This method was superior to other echocardiographic techniques and plasma brain natriuretic peptide evaluation.

Color Doppler tissue velocity imaging can disclose systolic left ventricular asynchrony independent of the QRS morphology in patients with severe heart failure

A QRS width greater than 120 ms is assumed to be a marker of inter- and intraventricular asynchrony in severe heart failure (HF) patients. Color Doppler tissue velocity imaging (c-TVI) with a time resolution of 10 ms was used to study regional left ventricular (LV) longitudinal systolic contraction pattern in HF patients with left and right bundle branch block (LBBB and RBBB) and in patients with normal QRS width. We studied 12 women and 23 men with severe HF, with a mean age of 66 +/- 11 years in New York Heart Association functional Class 2.9 +/- 0.6. Twenty patients had LBBB and 10 of those were accepted for cardiac resynchronization therapy by biventricular pacing (CRT). Ten patients had normal QRS width, and five had RBBB. In the echocardiographic apical four chamber view, regional peak LV tissue velocities and regional LV time differences of peak tissue velocities were compared at basal and mid-LV segments. There were no significant differences in regional mean peak tissue velocities among the patient groups. In patients with LBBB accepted for CRT, the LV lateral free-wall movement at basal LV was 29 ms delayed during main systole, almost significantly different from LBBB patients not accepted for CRT (P = 0.075). Even in HF patients with normal QRS width or RBBB, significant asynchronous longitudinal LV contraction was observed.

CONCLUSIONS

For the detection of regional longitudinal LV contraction asynchrony in patients with severe HF, supplementary methods to the surface ECG, such as c-TVI, are strongly recommended.

[Evaluation of ventricular asynchronism by Doppler tissue imaging in patients with idiopathic dilated cardiomyopathy]

OBJECTIVES

To study ventricular asynchronism with tissue Doppler imaging in patients with primitive dilated cardiomyopathy and narrow QRS.

PATIENTS AND METHODS

We compared a group of patients with DCM and QRS < 120 ms (gr 1, n=25, 52+/-14 yrs, LVEF: 25+/-9%) with a group of normal patients (gr 2, n=16, 36+/-20 yrs). We measured the delays between the beginning of QRS and the beginnings of aortic (QA), mitral (QM), tricuspid (QT) and pulmonary (QP) flows, and of systolic (QSm) and protodiastolic (QEm) wall motion waves recorded with TDI in the basal portion of interventricular septum (IVS) and LV and RV free walls. We then calculated the differences QA-QP, QM-QT, the interparietal differences for QSm and QEm, and the maximal interparietal systolic (QSm max) and diastolic (QEm max) delays.

RESULTS

QA, QP, QM and QT were significantly lengthened in group 1 patients but there were no difference between both groups for QA-QP and QM-QT. There was a trend toward a lengthening of QSm and QEm in group 1 patients. Interparietal differences of QSm and QEm were similar in both groups; however, QSm max and QEm max were significantly longer in group 1 patients than in group 2.

CONCLUSION

Doppler study of patients with DCM and narrow QRS shows a lengthening of all electromechanical delays and suggests some degree of ventricular asynchronism by showing a significant increase in maximal interparietal systolic and diastolic delays.

Echocardiographic evaluation of cardiac resynchronization therapy: ready for routine clinical use?

Cardiac resynchronization therapy (CRT) has been proposed as an alternative treatment in patients with severe, drug-refractory heart failure. The clinical results are promising, and improvement in symptoms, exercise capacity, and systolic left ventricular (LV) function have been demonstrated after CRT, accompanied by a reduction in hospitalization and a superior survival as compared with optimized medical therapy alone. However, 20% to 30% of patients do not respond to CRT. Currently, patients are selected mainly on electrocardiogram criteria (wide QRS complex, left bundle branch block configuration). In view of the 20% to 30% of nonresponders, additional selection criteria are needed. Echocardiography (and, in particular, tissue Doppler imaging) may allow further identification of potential responders to CRT, based on assessment of inter- and intraventricular dyssynchrony. In addition, echocardiography may allow optimal LV lead positioning and follow-up after CRT. In the current review, the different echocardiographic approaches to predict response to CRT are discussed. In addition, the use of echocardiography to guide LV lead positioning and follow-up after CRT are addressed.

Tissue Doppler imaging is superior to strain rate imaging and postsystolic shortening on the prediction of reverse remodeling in both ischemic and nonischemic heart failure after cardiac resynchronization therapy

BACKGROUND

A number of noninvasive techniques have been used to predict the effectiveness of cardiac resynchronization therapy (CRT) in heart failure patients, in particular left ventricular (LV) reverse remodeling. This study compared the relative predictive values of tissue Doppler imaging (TDI) and strain-rate imaging (SRI) parameters for LV reverse remodeling in patients who received CRT and examined for potential differences in ischemic (n=22) and nonischemic (n=32) heart failure.

METHODS AND RESULTS

TDI and SRI were performed at baseline and 3-month follow-up. Eighteen parameters of intraventricular and interventricular asynchrony based on the time to peak myocardial contraction (Ts) and time to peak strain rate (Tsr) were compared, along with postsystolic shortening (PSS). Reverse remodeling with reduction of LV end-diastolic and end-systolic volumes and gain in ejection fraction (all P<0.001) was observed in the whole study population. The standard deviation of Ts of 12 LV segments (Ts-SD) is the most powerful predictor of reverse remodeling in both the ischemic (r=-0.65, P<0.001) and nonischemic (r=-0.79, P<0.001) groups. The PSS of 12 LV segments was a good predictor only for the nonischemic (r=-0.64, P<0.001) but not the ischemic (r=0.32, P=NS) group. However, parameters of SRI and interventricular asynchrony failed to predict reverse remodeling. By multiple regression analysis, independent parameters included Ts-SD in both groups (P<0.005) and PSS of 12 LV segments in the nonischemic group (P=0.03). The area of the receiver operating characteristic curve was largest for Ts-SD (0.94; CI=0.88 to 1.00).

CONCLUSIONS

Ts-SD is the most powerful predictor of LV reverse remodeling and was consistently useful for ischemic and nonischemic heart failure. However, PSS is useful only for nonischemic pathogenesis, whereas the role of SRI parameters was not supported by the present study.

Clinical trials update and cumulative meta-analyses from the American College of Cardiology: WATCH, SCD-HeFT, DINAMIT, CASINO, INSPIRE, STRATUS-US, RIO-Lipids and cardiac resynchronisation therapy in heart failure

This article continues a series of reports on recent research developments in the field of heart failure. Key presentations made at the American College of Cardiology meeting, held in New Orleans, Louisiana, USA in March 2004 are reported. These new data have been added to existing data in cumulative meta-analyses. The WATCH study randomised 1587 patients with heart failure and left ventricular systolic dysfunction to warfarin, aspirin or clopidogrel. The study showed no difference between the effects of these agents on mortality or myocardial infarction, but hospitalisations for heart failure were higher on aspirin (22.2%) compared to warfarin (16.1%). The SCD-HeFT study showed that ICD therapy reduced all-cause mortality at 5 years by 23% in patients with predominantly NYHA class II heart failure and left ventricular systolic dysfunction, but amiodarone was ineffective. The DINAMIT study showed that ICD therapy was not beneficial in patients with left ventricular dysfunction after a recent MI, even in those with risk factors for arrhythmic death. In CASINO, levosimendan improved survival compared with dobutamine or placebo in patients with decompensated heart failure. INSPIRE showed that SPECT imaging can be used to assess risk early after acute MI safely and accurately. Rimonabant was shown to be safe and effective in treating the combined cardiovascular risk factors of smoking and obesity. An overview of new developments in cardiac resynchronisation therapy (CRT) in heart failure is also reported.

Selective Site Pacing:. The Right Ventricular Approach

Animal data and recent findings in humans have questioned the appropriateness of pacing the heart from the right ventricular apex. Numerous, mostly small sized, studies have evaluated alternative sites within the right ventricle. There is now sufficient evidence that right ventricular apical pacing in patients with left ventricular dysfunction with or without heart failure is detrimental. Pacing from the right side of the heart as an attempt at nonpharmacological therapy for heart failure, turns out to be obsolete. In antibradycardia pacing with the need for continuous ventricular support, the interest in preserving left ventricular function drives the ongoing search for the most favorable pacing site within the right ventricle. Results, so far, are conflicting which may be attributed to the inhomogeneity of patient groups, the small cohorts studied, the differing protocols used, and the lack of accepted definitions of right ventricular lead positions. Larger studies are needed to evaluate intraoperative criteria for optimal lead placement and the potential benefit of nonapical right ventricular pacing.

Electrical and Mechanical Components of Dyssynchrony in Heart Failure Patients With Normal QRS Duration and Left Bundle-Branch Block

Background— Resynchronization pacing is an effective symptomatic treatment for heart failure patients with prolongation of the QRS duration (QRSd). Dyssynchronous contraction of the left ventricle is also observed with normal QRSd. We set out to determine how electrical activation of the left ventricular (LV) free wall differed between patients with left bundle-branch block (LBBB) and normal QRSd and if synchrony improved during pacing in patients with normal QRSd.

Methods and Results— Twenty-two patients were implanted with resynchronization pacemakers, 13 with LBBB (mean QRS, 171 ms) and 9 with normal QRSd <120 ms (mean, 100 ms). LV lead electrograms and surface ECGs in sinus rhythm (unpaced) were recorded. Conventional and tissue Doppler echocardiography were performed without pacing, with LV and biventricular pacing at optimal atrioventricular delay. Lead electrograms from the LV free wall were later in the LBBB patients in absolute terms (155 ms [SD 23] versus 65.5 ms [SD 25]; P =0.05) and also relative to the surface QRS (90.5% [SD 8] versus 65.5% [SD 24]). Improved synchrony of the left and right ventricles (interventricular synchrony) and of the LV myocardial segments (intraventricular synchrony) was observed for patients with LBBB and normal QRSd. Baseline LV synchrony correlated with timing of LV free-wall electrical activation. Improved intraventricular synchrony during pacing also correlated with LV free-wall electrical activation time.

Conclusions— Resynchronization of systole can be achieved for patients with normal QRSd and LBBB during biventricular and LV pacing. The timing of LV free-wall electrical activation correlated with the improvement in synchrony.

Left ventricular pacing improves haemodynamic variables in patients with heart failure with a normal QRS duration

OBJECTIVES

To assess whether patients with congestive heart failure (CHF) and a normal QRS duration can benefit from left ventricular (VDD-LV) pacing.

DESIGN

Cardiac resynchronisation is reserved for patients with a broad QRS duration on the premise that systolic resynchronisation is the mechanism of benefit, yet improvement from pacing correlates poorly with QRS duration. In CHF patients with a broad QRS duration, those with a high resting pulmonary capillary wedge pressure (PCWP) > 15 mm Hg benefit. In this acute haemodynamic VDD-LV pacing study, patients with CHF with a normal QRS duration were divided into two groups--patients with a resting PCWP > 15 mm Hg and patients with a resting PCWP < 15 mm Hg--to determine whether benefit is predicted by a high resting PCWP.

PATIENTS

20 patients with CHF, New York Heart Association functional class IIb-IV, all with a normal QRS duration (< or = 120 ms).

INTERVENTIONS

Temporary pacing wires were positioned to enable VDD-LV pacing and a pulmonary artery catheter was inserted for measurement of PCWP, right atrial pressure, and cardiac output.

RESULTS

In patients with a PCWP > 15 mm Hg (n = 10), cardiac output increased from 3.9 (1.5) to 4.5 (1.65) l/min (p < 0.01), despite a fall in PCWP from 24.7 (7.1) to 21.0 (6.2) mm Hg (p < 0.001). In patients with a PCWP < 15 mm Hg there was no change in PCWP or cardiac output. Combined data showed that PCWP decreased from 17.0 (9.1) to 15.3 (7.7) mm Hg during VDD-LV pacing (p < 0.014) and cardiac output increased non-significantly from 4.7 (1.5) to 4.9 (1.5) (p = 0.125).

CONCLUSIONS

Patients with CHF with a normal QRS duration and PCWP > 15 mm Hg derive acute haemodynamic benefit from VDD-LV pacing.

Cardiac Resynchronization Therapy:. Device-Based Medicine for Heart Failure

Cardiac resynchronization therapy (CRT) or biventricular pacing is a novel adjunctive therapy for patients with advanced heart failure (HF). Many patients with severe HF have a left bundle branch block or an intraventricular conduction delay, with up to 25% of patients with a QRS > 120 ms, resulting in significant left ventricular (LV) dyssynchrony and a high mortality rate. The efficacy of CRT is based on the reduction in the conduction delay between the two ventricles and optimization of the ejection fraction, decrement in mitral regurgitation, LV remodeling, thus resulting in symptom improvement. Cardiac resynchronization therapy can be achieved both transvenously using a coronary sinus branch, or epicardially. Clinical trials have demonstrated a significant improvement in the NYHA class and the exercise capacity as well as a marked reduction in the hospitalization rate. More recently, the COMPANION trial showed a 43% reduction in a composite endpoint of all-cause mortality and hospitalization in the group receiving a CRT device in combination with an implantable cardiac defibrillator (ICD). Thus, management of patients with reduced LV function, wide QRS, and symptomatic refractory HF, despite optimal drug therapy, should include CRT as an option. The adjunct of an ICD combined with CRT should be considered if the LV ejection fraction (ischemic cardiomyopathy) is <30%. There are still significant unanswered questions regarding the nonresponder population and the role of tissue Doppler imaging techniques, the impact of CRT on total mortality and CRT in dilated cardiomyopathy or chronic atrial fibrillation. The use CRT postoperatively or at time of cardiac surgery, as well as new epicardial approaches using a thoracoscopic approach or robotically assisted surgery in patients not suitable for coronary vein leads are challenging topics to address in the years to come.

Beyond the measurement of QRS complex toward mechanical dyssynchrony: cardiac resynchronisation therapy in heart failure patients with a normal QRS duration

Mechanical systolic dyssynchrony exists in many patients with heart failure, irrespective of QRS duration, and so more patients may derive benefit from cardiac resynchronisation therapy than previously considered.

Relationship Between QRS Duration and Left Ventricular Dyssynchrony in Patients with End-Stage Heart Failure

INTRODUCTION

Patients with end-stage heart failure and a wide QRS complex are considered candidates for cardiac resynchronization therapy (CRT). However, 20% to 30% of patients do not respond to CRT. Lack of left ventricular dyssynchrony may explain the nonresponse. Accordingly, we evaluated the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) in 90 consecutive patients with heart failure.

METHODS AND RESULTS

Ninety patients with severe heart failure (left ventricular ejection fraction <35%, New York Heart Association class III-IV) were prospectively evaluated. Based on QRS duration, 30 consecutive patients with a narrow QRS complex were included (QRS duration <or=120 ms), 30 patients with an intermediate QRS duration (120-150 ms), and 30 patients with a wide QRS complex (>150 ms). All patients underwent TDI to assess left ventricular dyssynchrony. Extensive left ventricular dyssynchrony was defined as an electromechanical delay on TDI between the septum and lateral wall, the so-called septal-to-lateral delay, of >60 ms. Severe dyssynchrony was observed in 27% of patients with narrow QRS complex, 60% with intermediate QRS duration, and 70% with wide QRS complex. No relation existed between QRS duration and septal-to-lateral delay.

CONCLUSION

From 30% to 40% of heart failure patients with QRS duration >120 ms do not exhibit left ventricular dyssynchrony, which may explain the nonresponse to CRT. Alternatively, 27% of patients with heart failure and a narrow QRS complex show significant left ventricular dyssynchrony and may be candidates for CRT.

Cardiac resynchronization by pacing: an electrical treatment of heart failure

Various modalities of cardiac pacing have been proposed in the past to improve hemodynamics, either directly or indirectly. Some of these are conventional ways of cardiac stimulation, others such as biventricular or left ventricular pacing, represent dedicated pacing techniques. Left ventricular and biventricular pacing are successfully applied in those patients with congestive heart failure who have conduction disturbances (i.e. left bundle branch block) as they correct the ensuing intra- and interventricular dyssynchrony. This is the reason why these pacing modalities are described as cardiac resynchronization therapy. According to the results of a series of studies, the cardiac resynchronization therapy seems to have a favourable clinical impact in terms of quality of life, morbidity and hospitalization rate. On-going and future studies should assess the impact of resynchronization therapy on overall mortality and its cost-effectiveness profile in specific subgroups of patients. Other open issues regard (i) the convenience of using biventricular pacing as a pacing-alone therapy or in combination with ventricular defibrillation capability, especially for potential candidates to heart transplantation, and (ii) the ways to identify properly the responders to resynchronization therapy.

Timing of cardiac contraction in humans mapped by high-temporal-resolution MRI tagging: early onset and late peak of shortening in lateral wall

Mechanical asynchrony is an important parameter in predicting the response to cardiac resynchronization therapy, but detailed knowledge of cardiac contraction timing in healthy persons is scarce. In this work, timing of cardiac contraction was mapped in 17 healthy subjects with high-temporal-resolution (14 ms) MRI myocardial tagging and strain analysis. Both the onset time of circumferential shortening (T(onset)) in early systole and the time of peak circumferential shortening (T(peak)) at end systole were determined. The onset of shortening width (time needed for 20-90% of the left ventricle to start shortening) was small (35 +/- 9 ms). A distinct spatial pattern for T(onset) was found, with earliest onset in the lateral wall and latest onset in the septum (P = 0.001). Compared with T(onset), T(peak) had a larger width (121 +/- 22 ms) and an opposite spatial pattern, with peak shortening occurring earlier in the septum than in the lateral wall (P < 0.001). Postsystolic shortening (T(peak) later than aortic valve closure; P < 0.05) was observed in 13 of the 30 cardiac segments, mainly in the lateral and basal segments. Shortening in these segments continued 58 +/- 14 ms after aortic valve closure, during which circumferential shortening increased from 16.9 +/- 1.2% to 20.0 +/- 1.5%. Maps of the timing of contraction in normal subjects may serve as a reference in detecting mechanical asynchrony due to intraventricular conduction defects or ischemia.

Long-term effectiveness of cardiac resynchronization therapy in patients with refractory heart failure and "narrow" QRS

OBJECTIVES

The aim of the study was to evaluate the effectiveness of cardiac resynchronization therapy (CRT) in patients with refractory heart failure (HF) and incomplete left bundle branch block ("narrow" QRS), together with echocardiographic evidence of interventricular and intraventricular asynchrony.

BACKGROUND

Cardiac resynchronization therapy has been proven effective in patients with HF and wide QRS by ameliorating contraction asynchrony.

METHODS

Fifty-two patients with severe HF received biventricular pacing. The patients were eligible in the presence of echocardiographic evidence of interventricular and intraventricular asynchrony, regardless of QRS duration. The patient population was divided into group 1 (n = 38), with a QRS duration >120 ms, and group 2 (n = 14), with a QRS duration < or =120 ms.

RESULTS

The baseline parameters considered in the study were similar in both groups. At follow-up, CRT determined narrowing of the QRS interval in the entire population and in group 1 (p < 0.001), whereas a small increase in QRS duration was observed in group 2 (p = NS); in all patients and within groups, we observed improvement of New York Heart Association functional class (p < 0.001 in all), left ventricular ejection fraction (p < 0.001 in all), left ventricular end-diastolic and end-systolic diameter (p < 0.05 within groups), mitral regurgitation area (p < 0.001 in all), interventricular delay (p < 0.001 in all), and deceleration time (group 1: p < 0.001, group 2: p < 0.05), with no significant difference between groups. The 6-min walking test improved in both groups (group 1: p < 0.001; group 2: p < 0.01).

CONCLUSIONS

Cardiac resynchronization therapy determined clinical and functional benefit that was similar in patients with wide or "narrow" QRS. Cardiac resynchronization therapy may be helpful in patients with echocardiographic evidence of interventricular and intraventricular asynchrony and incomplete left bundle branch block.

Tissue Doppler, strain, and strain rate echocardiography for the assessment of left and right systolic ventricular function

Tissue Doppler (TDE), strain, and strain rate echocardiography are emerging real time ultrasound techniques that provide a measure of wall motion. They offer an objective means to quantify global and regional left and right ventricular function and to improve the accuracy and reproducibility of conventional echocardiography studies. Radial and longitudinal ventricular function can be assessed by the analysis of myocardial wall velocity and displacement indices, or by the analysis of wall deformation using the rate of deformation of a myocardial segment (strain rate) and its deformation over time (strain). A quick and easy assessment of left ventricular ejection fraction is obtained by mitral annular velocity measurement during a routine study, especially in patients with poor endocardial definition or abnormal septal motion. Strain rate and strain are less affected by passive myocardial motion and tend to be uniform throughout the left ventricle in normal subjects. This paper reviews the underlying principles of TDE, strain, and strain rate echocardiography and discusses currently available quantification tools and clinical applications.

Cardiac resynchronization therapy in heart failure: recent advances and new insights

Newer non-pharmacological therapies for heart failure are being evaluated for patients of congestive heart failure (CHF). Mechanical support with left ventricular assist devices and heart transplantation are reserved for the minority of patients who have severely decompensated heart failure. Despite these therapeutic advances, it is generally accepted that current therapies do not adequately address the clinical need of patients with heart failure, and additional strategies are being developed. Cardiac resynchronization therapy (CRT) is a new modality that involves synchronization of ventricular contraction and has shown a lot of promise in managing symptomatic patients of CHF who are on optimal medical therapy and have interventricular conduction delay (IVCD). It has improved exercise tolerance and NYHA functional class in such patients in sinus rhythm and a recent meta-analysis has also shown mortality benefits in CHF. Recently benefits of CRT have also been observed in CHF patients who do not have wide QRS complexes on electrocardiogram (EKG). It has also been shown to benefit drug refractory angina in CHF. Recent studies have also focused on the combined use of CRT and implantable cardioverter defibrillator (ICD) and it has shown encouraging results. Our aim in this descriptive review is to define practice guidelines and to improve clinicians' knowledge of the available published clinical evidence, concentrating on few randomized controlled trials.

New pacing technologies for heart failure

Heart failure is a sizeable problem in elderly populations, and although pharmacological treatment has improved, outcome generally remains poor. New pacing technologies have been developed to treat heart failure, with promising results