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

[Nuclear medicine examination in heart failure patients]

BACKGROUND

Recently, cardiac resynchronization therapy, by using biventricular pacemakers, has become implemented in the treatment of patients with severe heart failure. However, using the classical inclusion criteria, 30 % of patients treated with resynchronization do not improve symptoms or activity level. Phase analysis of radionuclide ventriculography gives information about pattern of ventricular contraction and may detect dyssynchrony. The method may therefore be used to select patients with dyssynctrony to resynchronization therapy. In this study we have investigated the amount of dyssynchrony, by using phase analysis of radionuclide ventriculography, in men and women as a function of left ventricular ejection fraction.

MATERIAL AND METHODS

The study is based on 1 266 radionuclide ventriculographies performed at Section of Nuclear Medicine, University Hospital North-Norway, during 1998 - 2006. The relationship between left ventricular ejection fraction and number of patients with ventricular dyssynchrony was investigated. 90 patients with no known heart problems were considered as reference values for synchrony data.

RESULTS

The phase analysis showed that 35 % of the women and 34 % of the men with left ventricular ejection fraction below 35 % had both inter- and intra-ventricular dyssynchrony.

INTERPRETATION

Today's criteria for including patients to resynchonizing therapy are not good enough. Phase analysis of radionuclide ventriculography of patients with left ventricular ejection fraction below 35 % shows that one third of the patients have both inter- and intra- ventricular dyssynchrony. These patients might be responders to resynchronization therapy.

Left ventricular systolic dyssynchrony is a predictor of cardiac remodeling after myocardial infarction

OBJECTIVES

We sought to determine whether early assessment of left ventricular (LV) dyssynchrony by tissue Doppler imaging may predict progressive ventricular enlargement and cardiac dysfunction after acute myocardial infarction (MI).

METHODS

Forty-seven patients (mean age 59.9 +/- 11.6 years) with normal QRS duration underwent tissue Doppler imaging and contrast-enhanced cardiac magnetic resonance imaging (Ce-MRI) at days 2 to 6, 3 months, and at 1 year after the index MI. Systolic dyssynchrony index (Ts-SD) was calculated from 12 LV segments, and infarct size (IS) by Ce-MRI.

RESULTS

The remodeling group (n = 16) (defined as an increase in end-systolic volume > or =10% between 1 year and baseline) had greater initial IS (27.2 +/- 9.6 vs 13.7 +/- 4.1%, P < .001) and Ts-SD (50.9 +/- 12.8 vs 33.6 +/- 7.7 milliseconds, P < .001) than nonremodeling group (n = 31). At 1 year, the remodeling group had progressive increase in Ts-SD and decrease in LV ejection fraction (57.3 +/- 18.5 and 36.0 +/- 7.6%, respectively; both P < .05 vs baseline). Both Ts-SD (odds ratio 1.19 [1.07-1.32], P = .001) and IS (odds ratio 1.65 [1.19-2.29], P = .003) were shown to be independent predictors of progressive LV remodeling. A cutoff value of Ts-SD > or =45 milliseconds predicted LV remodeling at 1 year (sensitivity 90.5%, specificity 90.9%, Area-under-curve 0.907) (P = .0005).

CONCLUSIONS

Left ventricular systolic dyssynchrony is a newly identified predictor of chronic LV remodeling after acute MI, which is independent and incremental to conventional assessment and IS as measured by Ce-MRI.

[Is resynchronization therapy necessary when optimizing right ventricular stimulation?]

Cardiac resynchronization therapy (CRT) using biventricular stimulation is hampered by coronary venous imponderabilities, complex implantation procedures, technical malfunctions and complications as well as disappointing responder rates. Despite its pathophysiological soundness and some initial success, the use of AV sequential pacing for the treatment of heart failure has been abandoned because right ventricular (RV) apical stimulation may be detrimental for cardiac mechanics, may worsen heart failure and may increase mortality. Attempts at avoiding desynchronizing effects and improving hemodynamics by pacing from alternative RV sites have been numerous but not convincing. Whether patients with left ventricular dysfunction or overt heart failure may benefit from pacing the RV outflow tract or septum, from dual site RV or His bundle stimulation instead of left ventricular based resynchronization is the topic of this review.

New Echocardiographic Techniques for Evaluating Left Ventricular Myocardial Function

Ultrasound imaging of the heart continues to play an important role in diagnosis and management of patients with cardiovascular diseases. Recent advances in ultrasound technology and introduction of newer imaging modalities have enabled improved assessment of left ventricular myocardial function. Tissue Doppler imaging and 2-dimensional speckle tracking allow more objective quantification of myocardial function in the form of tissue velocities, displacement, strain, and strain rate. Similarly, contrast-enhanced echocardiography and 3-dimensional echocardiography have provided a unique insight into left ventricular form and function that was not possible by unenhanced 2-dimensional echocardiography. In this review, the authors discuss the clinical application of these new imaging techniques in the assessment of left ventricular myocardial function.

Comparison of left ventricular dyssynchrony by two-dimensional speckle tracking versus tissue Doppler imaging in patients with non-ST-elevation myocardial infarction and preserved left ventricular systolic function

Assessment of left ventricular (LV) dyssynchrony after myocardial infarction has prognostic value. There were no reference ranges for 2-dimensional (2D) speckle tracking synchrony, and it was unclear whether color tissue Doppler imaging and 2D speckle tracking synchrony indexes were comparable. One hundred twenty-two healthy volunteers and 40 patients with non-ST-elevation myocardial infarction (NSTEMI) had LV systolic and diastolic synchrony, defined as the SD of time to peak systolic (2D-SDTs) and early diastolic (2D-SDTe) velocities in the 12 basal and mid segments using 2D speckle tracking, respectively. Mean 2D-SDTs and 2D-SDTe were 29.4 +/- 16.1 and 14.2 +/- 6.1 ms in healthy subjects, respectively. Gender and mean 2D systolic velocity independently predicted 2D-SDTs, and mean 2D early diastolic velocity independently predicted 2D-SDTe. Bland-Altman analysis showed suboptimal agreement between 2D speckle tracking and tissue Doppler imaging dyssynchrony indexes. 2D speckle tracking showed lower coefficients of variation for time to peak systolic and early diastolic velocities than tissue Doppler imaging. There were no significant differences in coefficients of variation for 2D speckle tracking systolic and diastolic synchrony for high versus low frame rates. Patients with NSTEMI had significantly lower ejection fraction, but higher LV mass and wall stress than healthy subjects. Only 2D-SDTs was significantly higher in patients with NSTEMI compared with healthy subjects (37.1 +/- 22.5 vs 29.4 +/- 16.1 ms; p = 0.02). In conclusion, 2D-SDTs was gender specific and influenced by global systolic function, and 2D-SDTe was influenced by global diastolic function. 2D speckle tracking and tissue Doppler imaging dyssynchrony indexes were not comparable. 2D speckle tracking may be a more sensitive discriminator of LV systolic dyssynchrony than tissue Doppler imaging.

Difference in prevalence and pattern of mechanical dyssynchrony in left bundle branch block occurring in right ventricular apical pacing versus systolic heart failure

BACKGROUND

This study compared the prevalence and pattern of mechanical dyssynchrony in patients with normal heart and right ventricular apical (RVA) pacing versus patients with systolic heart failure (SHF) and spontaneous left bundle branch block (LBBB).

METHODS

A total of 112 patients having LBBB pattern on surface electrocardiogram were included (57 with ejection fraction>50% received RVA pacing; 55 had SHF with ejection fraction<35%). Using tissue Doppler imaging, systolic and diastolic dyssynchrony was defined by the standard deviation of the time to peak systolic and peak early diastolic velocity, respectively.

RESULTS

Despite comparable QRS duration and LBBB pattern, the prevalence of electromechanical dyssynchrony was significantly lower in the patients with RVA pacing (systolic: 54% vs 73%, chi2=4.058, P=.044; diastolic: 32% vs 61%, chi2=9.738, P=.002). The presence of coexisting systolic and diastolic dyssynchrony, isolated systolic dyssynchrony, isolated diastolic dyssynchrony, and no dyssynchrony also showed a different distribution between the 2 groups (RVA pacing: 14%, 40%, 18%, and 28%; SHF: 51%, 22%, 11%, and 16%; chi2=17.498, P=.001). Furthermore, the SHF group had a higher prevalence of medial wall (ie, septal, anteroseptal, and inferior) delay (56% vs 30%), whereas RVA pacing resulted in more free wall (ie, lateral, posterior and anterior) delay (44% vs 70%) (chi2=8.050, P=.005).

CONCLUSIONS

The prevalence of mechanical dyssynchrony is lower in patients with normal ejection fraction and RVA pacing when compared with patients with SHF and spontaneous LBBB. The pattern of delay in contraction also appears to be different between the 2 groups.

Standard values for real-time transthoracic three-dimensional echocardiographic dyssynchrony indexes in a normal population

BACKGROUND

There is a paucity of information describing the real-time 3-dimensional echocardiography (RT3DE) and dyssynchrony indexes (DIs) of a normal population. We evaluate the RT3DE DIs in a population with normal electrocardiograms and 2- and 3-dimensional echocardiographic analyses. This information is relevant for cardiac resynchronization therapy.

METHODS

We evaluated 131 healthy volunteers (73 were male, aged 46 +/- 14 years) who were referred for routine echocardiography; who presented normal cardiac structure on electrocardiography, 2-dimensional echocardiography, and RT3DE; and who had no history of cardiac diseases. We analyzed 3-dimensional left ventricular ejection fraction, left ventricle end-diastolic volume, left ventricle end-systolic volume, and left ventricular systolic DI% (6-, 12-, and 16-segment models). RT3DE data were analyzed by quantifying the statistical distribution (mean, median, standard deviation [SD], relative SD, coefficient of skewness, coefficient of kurtosis, Kolmogorov-Smirnov test, D'Agostino-Pearson test, percentiles, and 95% confidence interval).

RESULTS

Left ventricular ejection fraction ranged from 50% to 80% (66.1% +/- 7.1%); left ventricle end-diastolic volume ranged from 39.8 to 145 mL (79.1 +/- 24.9 mL); left ventricle end-systolic volume ranged from 12.9 to 66 mL (27 +/- 12.1 mL); 6-segment DI% ranged from 0.20% to 3.80% (1.21% +/- 0.66%), median: 1.06, relative SD: 0.5482, coefficient of skewness: 1.2620 (P < .0001), coefficient of Kurtosis: 1.9956 (P = .0039); percentile 2.5%: 0.2900, percentile 97.5%: 2.8300; 12-segment DI% ranged from 0.22% to 4.01% (1.29% +/- 0.71%), median: 1.14, relative SD: 0.95, coefficient of skewness: 1.1089 (P < .0001), coefficient of Kurtosis: 1.6372 (P = .0100), percentile 2.5%: 0.2850, percentile 97.5%: 3.0700; and 16-segment DI% ranged from 0.29% to 4.88% (1.59 +/- 0.99), median: 1.39, relative SD: 0.56, coefficient of skewness: 1.0792 (P < .0001), coefficient of Kurtosis: 0.9248 (P = .07), percentile 2.5%: 0.3750, percentile 97.5%: 3.750.

CONCLUSION

This study allows for the quantification of RT3DE DIs in normal subjects, providing a comparison for patients with heart failure who may be candidates for cardiac resynchronization therapy.

Cardiac incoordination induced by left bundle branch block: its relation with left ventricular systolic function in patients with and without cardiomyopathy

Background

Although left bundle branch block (LBBB) alters the electrical activation of the heart, it is unknown how it might change the process of myocardial coordination (MC) and how it may affect the left ventricular (LV) systolic function. The present study assessed the effects of LBBB on MC in patients with LBBB with and without dilated (DCMP) or ischemic cardiomyopathy (ICMP).

Methods

Tissue Doppler echocardiography (TDE) was performed in 86 individuals: 21 with isolated LBBB, 26 patients with DCMP + LBBB, 19 patients with ICMP + LBBB and in 20 healthy individuals (Controls). MC was assessed analyzing the myocardial velocity profiles obtained from six basal segments of the LV using TDE. The LV systolic function was assessed by standard two-dimensional echocardiography and by TDE.

Results

Severe alterations in MC were observed in subjects with LBBB as compared with controls (P < 0.01 for all comparisons); these derangements were even worse in patients with DCMP and ICMP (P < 0.001 for comparisons with Controls and P < 0.01 for comparison with individuals with isolated LBBB). Some parameters of MC differed significantly between DCMP and ICMP (P < 0.01). A good or very good correlation coefficient was found between variables of MC and variables of LV systolic function.

Conclusion

LBBB induces severe derangement in the process of MC that are more pronounced in patients with cardiomyopathies and that significantly correlates with the LV systolic function. The assessment of MC may help in the evaluation of the etiology of dilated cardiomyopathy.

A single session of haemodialysis improves left ventricular synchronicity in patients with end-stage renal disease: a pilot tissue synchronization imaging study

BACKGROUND

Mechanical left ventricular (LV) dyssynchrony impairs cardiac function in patients with heart failure and LV hypertrophy (LVH) and may be a factor contributing to the high incidence of cardiac deaths in patients with end-stage renal disease (ESRD). Objectives. To evaluate the possible presence of LV dyssynchrony in ESRD patients, and acute effect of haemodialysis (HD) on LV synchronicity using a tailored echocardiographic modality, tissue synchronization imaging (TSI).

METHODS

In 13 clinically stable ESRD patients (7 men; 65 +/- 10 years) with LVH, echocardiography data were acquired before and after a single HD session for subsequent off-line TSI analysis enabling the retrieval of regional intraventricular systolic delay data. Six basal and six midventricular LV segments were evaluated. Dyssynchrony was defined as a regional difference in time to peak systolic velocity >105 ms.

RESULTS

Before HD, all patients had at least one dyssynchronous LV segment. The percentage of delayed segments correlated positively to LV end-diastolic diameter (r = 0.68, P < 0.05). HD induced a substantial decrease in the percentage of delayed segments from 36 +/- 25% to 19 +/- 14% (P < 0.01), reduced average maximal mechanical systolic LV delay from 300 +/- 89 to 225 +/- 116 ms (P < 0.05) and completely normalized LV synchronicity in three patients (23%).

CONCLUSIONS

LV dyssynchrony appears to be present frequently in ESRD patients with LVH. The severity of LV dyssynchrony correlates with LV end-diastolic diameter and decreases after a single session of HD suggesting a mechanistic relevance of volume overload and possibly other toxins accumulating in HD patients.

Left ventricular dysfunction after cardiac resynchronization therapy in congenital heart disease patients with a failing systemic right ventricle

BACKGROUND

Cardiac resynchronization therapy is rapidly emerging as an effective strategy for managing ventricular dysfunction and heart failure associated with congenital heart disease. Indications for therapy, optimal lead placement, and late outcomes are however lacking.

METHODS

We present three patients, one with Mustard procedure and two with congenitally corrected transposition of great arteries, who developed subpulmonic ventricular dysfunction 3-6 months after biventricular pacing +/- implantable cardioverter defibrillator implantation, despite initial favorable result of resynchronization therapy. Possible factors for adverse outcome are relatively high pacing rate, unfavorable alteration of torsional contraction, and increased atrioventricular valve regurgitation due to suboptimal placement of larger diameter defibrillation leads.

RESULTS

Careful evaluation of patients, particularly indications for therapy, need to be rigorous; assessment of hemodynamic response at the time of implant and appropriate programming may improve the effectiveness of cardiac resynchronization therapy (CRT) in this patient population.

CONCLUSION

Our case series emphasizes the need for a registry in the absence of randomized controlled trials, in order to identify patients who benefit most from CRT, and, importantly, recognize subgroups that respond poorly.

Relationship between QRS duration and prognosis in non-ST-segment elevation acute coronary syndrome

BACKGROUND

Previous studies have shown that prolonged QRS duration increases the risk of death in patients with heart failure and after an ST-segment elevation acute myocardial infarction. Very little data exist about the prognostic implications of QRS duration in the non-ST-segment elevation acute coronary syndrome (NST-ACS): unstable angina and non-ST elevation acute myocardial infarction (non-STEMI).

METHODS

This is a prospective and observational study in which we included 502 patients (age 71+/-10 years, 68% males, 29% diabetes) consecutively admitted for NST-ACS. QRS duration was manually measured from the 12-lead electrocardiogram. Our aim is to assess the relation between the QRS duration on admission (QRSd) and the risk of cardiovascular death (CvD) in the long-term.

RESULTS

Mean QRSd was: 93+/-19 ms. After a median follow-up of 450 days, the cumulative incidence of CvD was: 17.8%. QRSd correlated with the incidence of CvD during the follow-up period: c=0.72 (p<0.001). The best cut-off point was 90 ms (sensitivity, specificity and negative predictive value of QRSd>or=90 ms for CvD: 82, 68 and 93%). According to the Kaplan-Meier analysis, QRSd>or=90 ms was associated with an increase in the risk of CvD: 26.6% versus 7.2% (log rank: 28.6; p<0.001). Cumulative incidence of CvD was higher in QRSd>or=90 ms in patients with unstable angina: 15.5% versus 4% (p=0.02), and in those with non-STEMI: 30.5% versus 8.9% (p<0.001). After adjusting for other significant variables (Cox-regression analysis), QRSd>or=90 ms persisted as an independent predictor for overall CvD (Hazard Ratio: 2.62; 95% Confidence Interval: 1.44-4.74; p<0.001).

CONCLUSION

In NST-ACS, the QRSd, even in the normal range, has prognostic implications. QRSd>or=90 ms is independently associated with an increased risk of CvD in the long-term.

The associations between tricuspid annular plane systolic excursion (TAPSE), ventricular dyssynchrony, and ventricular interaction in heart failure patients

AIMS

Ventricular interactions may be mediated by loading conditions and biventricular timing and coordination. We sought to understand the relationships between right (RV) and left ventricular (LV) function and dyssynchrony, examine the RV correlates of LV dyssynchrony, and determine whether improved loading conditions affect inter-ventricular interaction.

METHODS AND RESULTS

In 25 heart failure patients [15 with left ventricular ejection fraction (LVEF) < 40%; 10 with LVEF >/= 50%], Doppler echocardiography and invasive bi-ventricular pressure-volume haemodynamics were obtained at baseline and 30 min after infusion of the recombinant B-type natriuretic peptide vasodilator nesiritide. RV and LV intra-ventricular dyssynchrony was measured invasively using a pressure-conductance catheter. Patients with reduced LVEF had greater LV dyssynchrony (31 +/- 3 vs. 24 +/- 7%; P = 0.003) compared to those with preserved LVEF. Tricuspid annular plane systolic excursion (TAPSE) had the highest correlation with LV dyssynchrony (r = -0.52; P = 0.0002) compared to other RV echocardiographic parameters. The association between TAPSE and LV dyssynchrony was independent of RVEF and LVEF (P = 0.008). There were no acute changes in the correlations between LV dyssynchrony and TAPSE after nesiritide.

CONCLUSION

TAPSE and LV dyssynchrony are strongly associated, independent of RV and LV ejection fraction. Of the RV echocardiographic parameters, TAPSE has the highest predictive value of LV dyssynchrony, and remained significant after vasodilator unloading.

Quantification of regional left ventricular dyssynchrony by magnetic resonance imaging

Cardiac resynchronization therapy is an established treatment in patients with symptomatic heart failure and intraventricular conduction delay. Electrical dyssynchrony is typically adopted to represent myocardial activation dyssynchrony, which should be compensated by cardiac resynchronization therapy. One third of the patients, however, does not respond to the therapy. Therefore, imaging modalities aimed at the mechanical dyssynchrony estimation have been recently proposed to improve patient selection criteria. This paper presents a novel fully automated method for regional mechanical left ventricular dyssynchrony quantification in short-axis magnetic resonance imaging. The endocardial movement is described by time-displacement curves with respect to an automatically determined reference point. Different methods are proposed for time-displacement curve analysis aimed at the regional contraction timing estimation. These methods were evaluated in two groups of subjects with (nine patients) and without (six patients) left bundle branch block. The contraction timing standard deviation showed a significant increase for left bundle branch block patients with all the methods. A novel method based on phase spectrum analysis may be however preferred due to a better specificity (99.7%) and sensitivity (99.0%). In conclusion, this method provides a valuable prognostic indicator for heart failure patients with dyssynchronous ventricular contraction and it opens new possibilities for regional timing analysis.

Totally epicardial cardiac resynchronization therapy system implantation in patients with heart failure undergoing CABG

BACKGROUND

Systolic dyssynchrony is present in a considerable number of patients with heart failure (HF) undergoing coronary artery bypass grafting (CABG). Surgical revascularization offers an optimal setting for totally epicardial cardiac resynchronization therapy (CRT) system implantation.

AIM

To assess the efficacy of totally epicardial CRT implantation during CABG, in patients with HF.

METHODS

Twenty three patients with HF and dyssynchrony underwent totally epicardial CRT system implantation during CABG. This randomised, single-blind, cross-over study compared clinical and echocardiographic parameters during two periods: 3 months of active CRT (CRT+) and 3 months of inactive CRT (CRT-) pacing.

RESULTS

Twenty two patients underwent randomisation and completed both study periods. In the CRT+ group more patients improved by two NYHA classes (p=0.028), had a longer 6-minute walk test distance (p=0.047) and better quality of life (p=0.003) compared with the CRT- group. Echocardiography revealed an improved LV ejection fraction (p<0.001), smaller LV end-systolic volume (p=0.04), reduced mitral regurgitation (p=0.026) and improved LV synchrony in the CRT+ group compared with the CRT- group.

CONCLUSION

CRT delivered by a totally epicardial system implanted during CABG is associated with additional improvement of clinical and echocardiographic parameters in patients with HF and systolic dyssynchrony.

Effectiveness of cardiac resynchronisation therapy in patients with echocardiographic evidence of mechanical dyssynchrony

OBJECTIVE

Cardiac resynchronisation therapy has proven to be effective in refractory heart failure (HF) patients with QRS >120-130 ms. Therefore, the aim of our study was to verify the long-term effectiveness of cardiac resynchronisation therapy in HF patients with echocardiographic evidence of mechanical asynchrony regardless of QRS duration.

METHODS

One hundred and six patients with New York Heart Association class II-IV HF and echocardiographic documentation of interventricular and intraventricular asynchrony underwent biventricular stimulation. A clinical and functional evaluation was performed at baseline, 1, 3, 6 months, and every 6 months thereafter.

RESULTS

After a median follow-up of 16 months, a significant improvement was noted in ejection fraction, left ventricular diameters, mitral regurgitation jet area, interventricular and intraventricular echocardiographic indexes of asynchrony, and the 6-min walking distance (P < 0.001 for all). Death rates for all causes and for cardiac causes were 18.2 (95% confidence interval 12.8-25.9) and 13.5 (95% confidence interval 9.0-20.3) per 100 person-years, respectively. Patients in New York Heart Association class IV had an almost three-fold increase in risk of dying as compared to class II-III (hazard ratio 2.97, 95% confidence interval 1.30-6.79).

CONCLUSIONS

Interventricular and intraventricular asynchrony at echocardiography may be useful in identifying HF patients suitable for cardiac resynchronisation therapy, with results comparable to those obtained with QRS duration selection criteria.

Effect of bundle branch block on cardiac output: a whole heart simulation study

The heart is an electrically controlled fluid pump which operates by mechanical contraction. Whole heart modelling is a computationally daunting task which must incorporate several subsystems: mechanical, electrical, and fluidic. Numerous feedback mechanisms on many levels, and operating at different scales, exist to finely control behaviour. Understanding these interactions is necessary to understand heart operation, as well as pathologies and therapies. A review of the components in such a model is given. The authors then present a framework for their electro-mechano-fluidic whole heart model based on cable methods. The model incorporates atria and ventricles, and has functioning valves with papillary muscles. The effect of altered propagation due to left and right bundle branch block on cardiac output is examined using the cable-based model. Results are compared to clinically observed phenomena. Good agreement was obtained, but tighter coupling of mechanical and electrical events is needed to fully account for behaviour. Cable-based models offer an alternative to continuum models.

Provocation of masked left ventricular mechanical dyssynchrony by treadmill exercise in patients with systolic heart failure and narrow QRS complex

Tissue Doppler imaging-derived intra-left ventricular (LV) contractile dyssynchrony is an evolving prognostic parameter for patients with systolic heart failure (HF). However, whether and how exercise could abolish the synchronicity in HF patients with narrow QRS remains less studied. We evaluated a total of 33 HF patients with impaired LV ejection fraction (<50%), QRS duration < or =120 ms, and baseline dyssynchrony index (DI; standard deviation of electromechanical delay of 12 LV segments by tissue Doppler imaging) <33 ms. After a 6-minute treadmill exercise by modified Bruce protocol, the absolute time difference from QRS onset to peak systolic myocardial velocity of each segment was recorded immediately. With similar DI at rest and peak heart rates during exercise, 11 patients (33%) developed dyssynchrony (DI > or =33 ms) after exercise, and the others did not (44.7 +/- 8.0 vs 16.2 +/- 8.3 ms, p <0.001). Patients with dyssynchrony after exercise had greater baseline mitral early diastolic velocity/annular early diastolic velocity (E/Ea) (19 +/- 17 vs 10 +/- 5, p <0.026). Multivariate analysis revealed mitral E/Ea >10 at rest, indicating higher LV filling pressure, independently predicted the exercise-evoked dyssynchrony (odds ratio 18, 95% confidence interval 2 to 163, p <0.012). In conclusion, exercise uncovered masked LV dyssynchrony in 1/3 of systolic HF patients with narrow QRS, and exercise-provoked dyssynchrony could be predicted by mitral E/Ea >10 at rest.

Relationship Between Intraventricular Cardiac Asynchrony and Degree of Systolic Dysfunction

OBJECTIVES

Cardiac asynchrony is an area of study becoming more relevant in the evaluation and management of heart failure. Our aim was to determine the prevalence of cardiac asynchrony by Doppler echocardiography and to evaluate its relationship with the degree of left ventricular (LV) systolic dysfunction.

METHODS

A total of 316 consecutive patients with LV ejection fraction less than 40% were enrolled. We divided them into 3 groups according to the degree of LV dysfunction: 31% to 40%, 21% to 30%, and less than 20%. Intraventricular asynchrony was evaluated using two methods: (1) measurement of the septal to posterior wall-motion delay (cut-off point 130 milliseconds); and (2) measurement of the difference between time from Q wave to LV ejection end, and the time from Q wave to the end of the systolic wave of the most delayed basal segment by Doppler tissue imaging (ejection- Doppler tissue imaging time; cut-off point 50 milliseconds).

RESULTS

Mean age was 62.14 +/- 13.5 years (75.7% men). No differences were found among clinical electrical and echocardiographic variables among the groups. Furthermore, no relationship was found between the existence of intraventricular cardiac asynchrony and the degree of LV systolic dysfunction. These were similar in patients with ischemic dilated cardiomyopathy and nonischemic dilated cardiomyopathy.

CONCLUSIONS

The degree of LV systolic dysfunction and its origin are not related to the presence of cardiac asynchrony. A specific echocardiographic Doppler study must always be performed to assess the existence of cardiac asynchrony in those who are candidates to resynchronization therapy.

The Mitral Annular Middiastolic Velocity Curve: Functional Correlates and Clinical Significance in Patients with Left Ventricular Hypertrophy

BACKGROUND

Little is known regarding the tissue Doppler characteristics and clinical significance of mitral annular motion during diastasis (L' wave).

METHODS

In consecutive patients with left ventricular hypertrophy and normal ejection fraction, standard Doppler and Doppler tissue imaging were performed. Patients were followed up for heart failure (HF) hospitalization.

RESULTS

Of 177 patients, 53 (30%) had an L', detected most frequently at the lateral mitral annulus, whereas 35 (20%) had middiastolic transmitral flow (L wave), which almost invariably coexisted with the L'. The L' predicted increased left ventricular filling pressure with 74% sensitivity and 82% specificity, and increased risk of future HF (hazard ratio 3.9 [P = .030]), even after adjusting for baseline clinical differences (hazard ratio 6.5 [P = .024]). When associated with an L wave, HF risk increased further.

CONCLUSIONS

Middiastolic annular motion, detectable in almost a third of patients with left ventricular hypertrophy, may be an early marker of diastolic dysfunction and a prognostic marker for HF.

Effects of region of interest tracking on the diagnosis of left ventricular dyssynchrony from Doppler tissue images

BACKGROUND

Left ventricular dyssynchrony is often diagnosed by comparing velocity curves from Doppler tissue images of two or more myocardial regions. Velocity curves are generated by placing sample volumes or regions of interest (ROIs) within the myocardium. ROIs need to be manually relocated to maintain a midmyocardial location as the heart moves, but are frequently left in a stationary position. The error caused by use of a stationary ROI may affect the diagnosis of dyssynchrony, but this has not been quantified.

OBJECTIVE

We hypothesized that using a stationary ROI to quantify dyssynchrony from Doppler tissue images would affect the diagnosis of dyssynchrony in patients with heart failure.

METHODS

We quantified dyssynchrony in 18 patients with heart failure using 4 published dyssynchrony parameters: septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, SD of the 12 basal and midwall times to peak, and cross-correlation delay (XCD). Each dyssynchrony parameter was measured using both tracked and stationary ROIs.

RESULTS

Use of a stationary ROI did not change the diagnosis of dyssynchrony when using XCD. However, ROI tracking changed the diagnosis of dyssynchrony in 17%, 11%, and 17% of patients when using septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, and SD of the 12 basal and midwall times to peak, respectively. XCD showed the lowest percent difference between tracked and stationary ROIs (4 +/- 9% vs 22 +/- 53%, 50 +/- 167%, and 12 +/- 30%, respectively, for septal-to-lateral delay, maximum difference in the basal 2- or 4-chamber times to peak, and SD of the 12 basal and midwall times to peak).

CONCLUSION

Manual ROI tracking is required when using conventional time-to-peak parameters to diagnose dyssynchrony. XCD diagnosis of dyssynchrony can be performed accurately with a stationary ROI.

Assessment of Longitudinal and Radial Ventricular Dyssynchrony in Ischemic and Nonischemic Chronic Systolic Heart Failure: A Two-Dimensional Echocardiographic Speckle-Tracking Strain Study

BACKGROUND

Current guidelines recommend a QRS greater than or equal to 120 milliseconds to select candidates for cardiac resynchronization therapy. However, ischemic and nonischemic cardiomyopathies are two different entities and they might be selected following different approaches. We sought, thus, after a validation the new 2-dimensional (2D) speckle-tracking strain (STS) against color Doppler tissue imaging (DTI)-strain (S) to compare the different correlation between electrical and mechanical dyssynchrony (DYS) in ischemic and nonischemic cardiomyopathies.

METHODS

We measured: (1) QRS duration; (2) mechanical interventricular DYS (the difference between preaortic and prepulmonary ejection times); (3) left intraventricular DYS (the SD of time-to-peak of longitudinal DTI-S); and (4) longitudinal and radial 2D-STS in the basal and middle segments of lateral and septal left ventricular walls in 95 patients with chronic heart failure caused by ischemic (n = 49) or nonischemic (n = 46) heart disease. Twelve healthy control subjects were also explored.

RESULTS

Mechanical interventricular DYS was correlated (DTI-S: P < .001) with QRS-duration, but not in ischemic heart disease. DTI-S and 2D-STS measurements were correlated (R = 0.6, P < .001) in the overall population. Longitudinal 2D-S DYS was correlated with QRS duration in patients with nonischemic, (P = .003) but not with ischemic heart disease, whereas radial 2D-S DYS was correlated with QRS width in both subgroups (r = 0.48, P = .003, and r = 0.43, P = .003, respectively).

CONCLUSIONS

The profile of DYS is influenced by the underlying cause of heart failure. The 2D-STS is a new tool for cardiac DYS assessment. Its ability to measure both longitudinal and radial intraventricular DYS is noteworthy.

Fusion beat in patients with heart failure treated with left ventricular pacing: may ECG morphology relate to mechanical synchrony? A pilot study

BACKGROUND

Electrical fusion between left ventricular pacing and spontaneous right ventricular activation is considered the key to resynchronisation in sinus rhythm patients treated with single-site left ventricular pacing.

AIM

Use of QRS morphology to optimize device programming in patients with heart failure (HF), sinus rhythm (SR), left bundle branch block (LBBB), treated with single-site left ventricular pacing.

METHODS AND RESULTS

We defined the "fusion band" (FB) as the range of AV intervals within which surface ECG showed an intermediate morphology between the native LBBB and the fully paced right bundle branch block patterns.Twenty-four patients were enrolled. Echo-derived parameters were collected in the FB and compared with the basal LBBB condition. Velocity time integral and ejection time did not improve significantly. Diastolic filling time, ejection fraction and myocardial performance index showed a statistically significant improvement in the FB. Interventricular delay and mitral regurgitation progressively and significantly decreased as AV delay shortened in the FB. The tissue Doppler asynchrony index (Ts-SD-12-ejection) showed a non significant decreasing trend in the FB. The indications provided by the tested parameters were mostly concordant in that part of the FB corresponding to the shortest AV intervals.

CONCLUSION

Using ECG criteria based on the FB may constitute an attractive option for a safe, simple and rapid optimization of resynchronization therapy in patients with HF, SR and LBBB.

Quantitative comparison of 2D and 3D circumferential strain using MRI tagging in normal and LBBB hearts

The response to cardiac resynchronization therapy (CRT), which is applied to patients with heart failure (HF) and left bundle-branch block (LBBB), can be predicted from the mechanical dyssynchrony measured on circumferential strain. Circumferential strain can be assessed by either 2D or 3D strain analysis. In this study was evaluated the difference between 2D and 3D circumferential strain using MR tagging with high temporal resolution (14 ms). Six healthy volunteers and five patients with LBBB were evaluated. We compared the 2D and 3D circumferential strains by computing the mechanical dyssynchrony and the cross correlation (r) between 2D and 3D strain curves, and by quantifying the differences in peak circumferential shortening, time to onset, and time to peak of shortening. The obtained maximum r(2) values were 0.97 +/- 0.03 and 0.87 +/- 0.16 for the healthy and LBBB populations, respectively, and thus showed a good similarity between 2D and 3D strain curves. No significant difference was observed between 2D and 3D in time to onset, time to peak, or peak circumferential shortening. Thus, to measure dyssynchrony, 2D strain analysis will suffice. Since 2D analysis is easier to implement than 3D analysis, this finding brings the application of MRI tagging and strain analysis closer to the clinical routine.

Cross-correlation Quantification of Dyssynchrony: A New Method for Quantifying the Synchrony of Contraction and Relaxation in the Heart

BACKGROUND

Quantification of left ventricular dyssynchrony using Doppler tissue imaging may improve selection of patients who will benefit from cardiac resynchronization therapy. Most methods used to quantify dyssynchrony use a time-to-peak analysis, which is quantitatively simplistic and requires manual identification of systole and selection of peak velocities.

METHODS

We developed and tested a new, highly automatable dyssynchrony parameter, cross-correlation delay (XCD), that does not require identification of systole or manual selection of peak systolic velocities. XCD uses all velocity data points from 3 consecutive beats (approximately 420 points). We tested XCD on 11 members of a positive control group (responders to cardiac resynchronization therapy with a >or=15% reduction in left ventricular end-systolic volume) and 12 members of a negative control group (normal 12-lead electrocardiogram and 2-dimensional echocardiogram findings). We compared XCD to septal-to-lateral delay in time-to-peak (SLD), maximum difference in the basal 2- or 4-chamber times to peak (MaxDiff), and SD of the 12 basal and midwall times-to-peak (Ts-SD).

RESULTS

XCD and Ts-SD were significantly different between the positive and negative control groups (both P <or= .0001). SLD and MaxDiff demonstrated no difference between the positive and negative control groups. XCD and Ts-SD were superior to SLD and MaxDiff in discriminating between positive and negative control groups (both P < .01 by receiver operating characteristic comparison). XCD, SLD, MaxDiff, and Ts-SD demonstrated dyssynchrony in 0%, 50%, 58%, and 50% of the negative control group, respectively. XCD was the only parameter that decreased after resynchronization in the positive control group (from 160 +/- 88-69 +/- 61 milliseconds, P = .003).

CONCLUSION

XCD is superior to existing parameters at discriminating patients with left ventricular dyssynchrony from those with normal function.

Optimal use of echocardiography in cardiac resynchronisation therapy

Echocardiography has several roles in patients with cardiac resynchronisation therapy (CRT). First, it can optimise selection of CRT candidates by demonstration of left ventricular (LV) dyssynchrony. Second, it can be used to assess immediate response to CRT, including detection of acute LV resynchronisation. Echocardiography is also useful to evaluate long-term benefit from CRT. Finally, echocardiography is important in optimisation of pacemaker settings, including AV and VV optimisation.

Assessment of left ventricular dyssynchrony in patients with heart failure and normal QRS duration

Cardiac resynchronization therapy (CRT) is an important component of heart failure therapy in patients with a left ventricular ejection fraction <35%, class III or ambulatory class IV symptoms, and a QRS duration >120 ms. The QRS duration criterion for patient selection is imperfect. About 30% of patients with an increased QRS duration are nonresponders to CRT and many with a normal QRS duration with mechanical dyssynchrony respond to CRT. The authors review the currently available echocardiographic tools for the assessment of ventricular dyssynchrony in patients with heart failure.

Measurements of mechanical asynchrony in patients with heart failure: is the puzzle completed?

Numerous randomized clinical trials demonstrated the beneficial effects of cardiac resynchronization therapy (CRT) in the treatment of moderate to severe heart failure. Despite careful patient selection, there is still a percentage of non-responders, that is as high as 30-50%. Patients are selected mainly on electrocardiogram criteria. Recent studies have observed that the severity of mechanical systolic asynchrony is a much better predictor of a response after CRT. Echocardiography allows a non-invasive evaluation atrioventricular and inter- and intraventricular synchrony; furthermore, recent advances have provided direct evidence of wall motion resynchronization in patients receiving CRT. Nevertheless, although many authors tried to search for the best echocardiographic index to identify systolic asynchrony, and consequently responders to CRT before the procedure, this issue is still a matter of debate. Our aim was to make an updated review of the more recent studies on this topic.