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

Concordance Between Mechanical and Electrical Dyssynchrony in Heart Failure Patients: A Function of the Underlying Cardiomyopathy?

BACKGROUND

Cardiac resynchronization therapy (CRT) improves heart failure (HF) symptoms through a reduction of cardiac mechanical dyssynchrony. Mechanical dyssynchrony is currently estimated by electrical dyssynchrony (QRS duration). It is known that electrical and mechanical dyssynchrony are not well correlated in HF patients. However, there is limited information about whether this relationship might be influenced by the underlying cardiomyopathy.

METHODS

Doppler echocardiography was performed in 88 patients presenting with heart failure due to ischemic (n = 42) or nonischemic (n = 46) heart disease, left ventricular ejection fraction <40%, New York Heart Association class II-IV, regardless of their QRS duration. Interventricular dyssynchrony was assessed by the time interval between preaortic and prepulmonary ejection times. Intraventricular dyssynchrony was ascertained by (1) the delay between the earliest and the latest peak negative longitudinal strain recorded in the basal and mid-segments of the lateral and septal walls (TMinMax) and (2) the standard deviation of time-to-peak in the same segments (SDdys).

RESULTS

The correlation coefficient between QRS duration and mechanical interventricular dyssynchrony was r = 0.47 (P < 0.001) in patients with nonischemic disease and nonsignificant in patients with ischemic disease. Similarly, the correlation coefficient between QRS duration and mechanical intraventricular dyssynchrony was significant in patients with nonischemic disease (r = 0.37, P = 0.01 for TMinMax; r = 0.42, P = 0.003 for SDdys) and nonsignificant in patients with ischemic disease.

CONCLUSION

The concordance between electrical dyssynchrony assessed by QRS duration and mechanical dyssynchrony assessed by myocardial strain is dependent upon the underlying cardiomyopathy. This observation may improve our understanding of the various responses observed in CRT patients.

Tissue Doppler Imaging of Mitral Annular Motion Is an Effective Surrogate of Left Ventricular Dyssynchrony and Predicts Response to Cardiac Resynchronization Therapy

OBJECTIVE

Tissue Doppler imaging of basal myocardial segments has been used to predict response to cardiac resynchronization therapy (CRT). However, in patients with poor imaging windows mechanical dyssynchrony may be difficult to assess because of poor tissue characterization. We tested the hypothesis that tissue Doppler evaluation of the mitral annulus can accurately identify the presence of left ventricular dyssynchrony and predict the response to CRT.

METHODS

Tissue Doppler imaging of 6 mitral annular sites and 6 basal myocardial segments was performed in 21 patients with heart failure, before and at 3 months after CRT device implantation. Time to peak systolic velocity (T(s)) was determined for each site and intraventricular dyssynchrony was defined as the maximal difference in T(s) between measurement sites.

RESULTS

Excellent correlation was observed between mitral annular and basal segment measurements of T(s) (r = 0.90, P < .001 at baseline and r = 0.93, P < .001 at follow-up) and maximal difference in T(s) between measurement sites (r = 0.90, P < .001 at baseline and r = 0.90, P = .003 at follow-up). Receiver operator characteristic analysis for the mitral annulus measurements demonstrated that an optimal cut-off value of T(s) = 179 milliseconds differentiated responders from nonresponders with a sensitivity of 86% and specificity of 82%; similarly, a cut-off value of maximal difference in T(s) between measurement sites = 105 milliseconds for intraventricular dyssynchrony differentiated responders from nonresponders with a sensitivity of 86% and specificity of 73%.

CONCLUSION

Tissue Doppler assessment of mitral annular motion can accurately identify left ventricular dyssynchrony and predict positive response to CRT.

Combined longitudinal and radial dyssynchrony predicts ventricular response after resynchronization therapy

OBJECTIVES

The purpose of this study was to test the hypothesis that a combined echocardiographic assessment of longitudinal dyssynchrony by tissue Doppler imaging (TDI) and radial dyssynchrony by speckle-tracking strain may predict left ventricular (LV) functional response to cardiac resynchronization therapy (CRT).

BACKGROUND

Mechanical LV dyssynchrony is associated with response to CRT; however, complex patterns may exist.

METHODS

We studied 190 heart failure patients (ejection fraction [EF] 23 +/- 6%, QRS duration 168 +/- 27 ms) before and after CRT. Longitudinal dyssynchrony was assessed by color TDI for time to peak velocity (2 sites in all and 12 sites in a subgroup of 67). Radial dyssynchrony was assessed by speckle-tracking radial strain. The LV response was defined as > or =15% increase in EF.

RESULTS

One hundred seventy-six patients (93%) had technically sufficient baseline and follow-up data available. Overall, 34% were EF nonresponders at 6 +/- 3 months after CRT. When both longitudinal dyssynchrony by 2-site TDI (> or =60 ms) and radial dyssynchrony (> or =130 ms) were positive, 95% of patients had an EF response; when both were negative, 21% had an EF response (p < 0.001 vs. both positive). The EF response rate was lowest (10%) when dyssynchrony was negative using 12-site TDI and radial strain (p < 0.001 vs. both positive). When either longitudinal or radial dyssynchrony was positive (but not both), 59% had an EF response. Combined longitudinal and radial dyssynchrony predicted EF response with 88% sensitivity and 80% specificity, which was significantly better than either technique alone (p < 0.0001).

CONCLUSIONS

Combined patterns of longitudinal and radial dyssynchrony can be predictive of LV functional response after CRT.

Biventricular Upgrading in Patients with Conventional Pacing System and Congestive Heart Failure:Results and Response Predictors

BACKGROUND

There are few studies on cardiac resynchronization therapy (CRT) in heart failure (HF) patients with preexisting right ventricular (RV) pacing. The purpose of this study was to determine the efficacy of CRT upgrading in RV-paced patients and the predictivity of electromechanical dyssynchrony parameters (EDP) evaluated by standard echocardiography (ECHO) and tissue Doppler imaging (TDI).

METHODS

Thirty-eight consecutive patients with HF [New York Heart Association (NYHA) class III or IV, LVEF < 35%], prior continuous RV pacing, and absence of atrial fibrillation were enrolled in the presence of a paced QRS > or = 150 ms and evaluated by ECHO and TDI. A responder was defined as a patient with a favorable change in NYHA class and neither HF hospitalization nor death, plus an absolute increase of LVEF > or = 10 units.

RESULTS

At six-months follow-up, the whole study population had significant improvement in symptoms, systolic function, and QRS duration (P < 0.001); 32 (84%) patients had a favorable clinical outcome, 25 (66%) were considered responders according to the previous definition. Postimplant QRS was similarly reduced in both responders and nonresponders, whereas EDP had a significant improvement only in responders (P < 0.05). Using EDP, 23 (79%) patients were responders compared with 2 (22%) patients without mechanical dyssynchrony (P = 0.002).

CONCLUSIONS

In HF patients with previous RV pacing, CRT is effective to improve clinical, functional outcome, and LV performance and to reduce electromechanical dyssynchrony in a large proportion of patients. Dyssynchrony evaluated by standard and TDI ECHO can be useful for CRT selection of paced patients.

Assessment of left ventricular dyssynchrony with real-time 3-dimensional echocardiography: comparison with Doppler tissue imaging

We studied the usefulness and reproducibility of real-time 3-dimensional (3D) echocardiography (RT3DE) for evaluating left ventricular (LV) dyssynchrony, and compared its results with Doppler tissue image (DTI) indices. Full-volume RT3DE data sets and 2-dimensional DTI from apical window were obtained in 122 participants. Using fast 3D border detection software, time to minimum systolic volume (Tmsv) was semiautomatically calculated in each region from a 17-segment model. Several dyssynchrony indices were then calculated: Tmsv-16SD, the SD of Tmsv in 16 of 17 segments, excluding the apical cap; Tmsv-12SD, the SD of Tmsv of 6 basal and 6 middle segments; and Tmsv-6SD, the SD of Tmsv of 6 basal segments. These dyssynchrony indices of RT3DE were then compared with two dyssynchrony indices measured by DTI: time to peak systolic velocity (TTPV)-12SD, the SD of time to peak systolic velocity of 12 LV segments; and time to cross over point of temporal axis (TTCO)-12SD, the SD of time to crossover point of temporal axis. RT3DE data was quantitatively analyzed in 117 of 122 patients. Tmsv-16SD (35 +/- 34 milliseconds) was significantly longer compared with Tmsv-12SD (27 +/- 30 milliseconds, P < .001) or Tmsv-6SD (23 +/- 28 milliseconds, P < .001). Tmsv-16SD increased significantly with the severity of LV systolic dysfunction. Fair correlation was noted among TTPV-12SD, TTCO-12SD, and Tmsv-16SD (r = 0.71, r = 0.73) and between Tmsv-16SD and LV ejection fraction (r = 0.80). Concordance rate between TTPV-12SD and Tmsv-16SD for detecting LV dyssynchrony was 79%. The corresponding value between TTCO-12SD and Tmsv-16SD was 80%. In conclusion, Tmsv-16SD correlated well with DTI-derived LV dyssynchrony indices. In addition to LV remodeling, fast border detection RT3DE provides useful parameters for evaluating LV dyssynchrony.

[Electrotherapy of cardiac failure]

Intracardiac conduction disturbances, mostly manifested as a left bundle branch block (LBBB), are common findings in cardiac failure and associated with a poor prognosis. LBBB is a marker of disease progression and also leads to worsened cardiac hemodynamics by dyssynchronous contraction that can accelerate progression of the underlying disease. Cardiac resynchronization therapy (CRT) can reduce the negative effects of these disturbances leading to improvement in hemodynamics and long-term improvement in cardiopulmonary exercise tolerance, reduction of left ventricular volumes and functional mitral regurgitation. Prospective multicenter studies, such as the CARE-HF and COMPANION trials have demonstrated reduced mortality with CRT or combined treatment with defibrillator capability (CRT-D). Thus, CRT has been adopted in the current guidelines of cardiology societies. Nevertheless, there are a number of open issues with CRT, such as the high number of non-responders or the value of CRT in patients with atrial fibrillation, narrow QRS complex and mild cardiac failure or asymptomatic left ventricular dysfunction. In addition, the question whether every CRT patient needs a device with defibrillating capabilities is not fully resolved, at least for patients with dilative cardiomyopathy.

Prognostic value of tissue Doppler-derived ventricular asynchrony in patients with left bundle branch block but not advanced heart failure

OBJECTIVES

The aim of the present study was to evaluate the prognostic significance of tissue Doppler echocardiography (TDE)-derived ventricular asynchrony in patients with left bundle branch block (LBBB) but not advanced heart failure.

METHODS

Fifty-five patients (mean age 66 +/- 13 years; 33 male) with complete LBBB (QRS > 120 ms) hospitalized for an acute episode of decompensated heart failure and in New York Heart Association class II for at least 6 months before the study admission underwent standard Doppler echo and pulsed-wave TDE. Precontraction time (PCTm) from the beginning of Q wave of electrocardiogram to the onset of systolic myocardial velocity wave was evaluated in four different left ventricular (LV) basal myocardial segments (LV anterior, inferior, septal and lateral walls) and in one right ventricular (RV) lateral wall. Intraventricular activation delay (IntraV-del) was calculated by the difference of PCTm of each LV myocardial segment. Interventricular activation delay (InterV-del) was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall.

RESULTS

The mean value of EF was 40 +/- 9% and of InterV-del, IntraV-del was, respectively (97.4 +/- 46.7 and 57.9 +/- 35.5 ms). InterV-del was inversely related to EF (r = -0.68; P < 0001). During the follow-up (26 months, range 11-37 months) cardiac events were recorded in 23 (41%) patients: a worsening of heart failure (WHF) in 23 patients and cardiac death in ten patients. Cox proportional hazard multivariate analysis showed that age, and InterV-del [HR = 1.02 (P < 0.05) and 1.03 (P < 0005)] predicted mortality. A Receiver operating characteristic analysis showed that a cut-off value of InterV-del 100 ms (AUC = 0.86; P < 0001) predicted WHF and mortality with sensitivity and specificity of 75% and 90%; 81% and 84%, respectively.

CONCLUSIONS

TDE-derived interventricular asynchrony represents a prognostic indicator of major cardiac events at 2 years of follow-up in patients with LBBB but not advanced heart failure.

Coexistence and exercise exacerbation of intraleft ventricular contractile dyssynchrony in hypertensive patients with diastolic heart failure

BACKGROUND

Patients with heart failure (HF) and a normal left ventricular ejection fraction usually present with diastolic dysfunction (DD). Whether intraleft ventricular contractile dyssynchrony (IVCD) coexists with DD and contributes to the clinical manifestations of HF remains unclear. The study investigated the IVCD at rest and after exercise in hypertensive patients with diastolic HF (DHF).

METHODS

Echocardiography was performed in 60 hypertensive patients with narrow QRS, left ventricular ejection fraction > or = 50%, and no active ischemia. Patients were grouped as having DD (mitral E/A < 1 plus E deceleration time > 200 milliseconds, or mitral annular early diastolic velocity < 8 cm/s; n = 26), DD plus HF symptoms/signs (DHF, n = 13), or as non-DD (n = 21).

RESULTS

At rest, the IVCD index (SD of 12 left ventricular segmental electromechanical delays) was greater in the DHF and DD groups than that in the non-DD group (52.2 +/- 10.7 and 39.1 +/- 23.6 vs 23.1 +/- 19.9 milliseconds; P < .05 for both comparisons). Six-minute treadmill exercise induced exacerbation of dyssynchrony in the DHF group (67.0 +/- 12.9 vs 52.2 +/- 10.7 milliseconds; P < .001). Multivariate analysis revealed that the combination of IVCD index > or = 35 milliseconds at rest and > or = 50 milliseconds after exercise was independently associated with DHF (odds ratio = 20, 95% CI = 2-199, P = .009). Postexercise IVCD index correlated positively with plasma N-terminal pro-brain natriuretic peptide (r = 0.37, P = .004).

CONCLUSIONS

Exercise would aggravate intraventricular dyssynchrony in hypertensive patients with DHF, implicating a potential contribution of systolic dyssynchrony to clinical manifestations.

Assessment of intraventricular systolic asynchrony in patients with atrial fibrillation using triplane tissue Doppler imaging

BACKGROUND

Triplane tissue Doppler imaging (TDI) makes it possible to simultaneously obtain three apical view images and to measure the dyssynchrony index (DS) for 12 segments in patients with atrial fibrillation (AF). We evaluated the feasibility of using triplane TDI to assess intraventricular asynchrony in AF.

METHODS

In 50 patients with AF, triplane TDI was used for the analysis of myocardial velocity curves of 12 (six basal and six mid) left ventricular (LV) segments by apical two-, three-, and four-chamber views. Time to peak systolic velocity (Ts) was measured, and DS was calculated as the standard deviation (SD) of Ts over 12 segments. The DS(avg) was defined as the average of DS of eight consecutive cycles. To assess the cyclic variability of DS, the coefficient of variation of DS (CoV(DS)) was calculated as the SD of DS for eight cycles divided by DS(avg) [SD(DS)/DS(avg)]. CoV(RR), representing the variability of RR intervals, was defined as [SD(RR)/RR(avg)]. Patients with a left ventricular ejection fraction (LVEF) of 45% or more were classified as group A, and patients with an LVEF less than 45% as were classified as group B.

RESULTS

The mean LVEF was 47% +/- 12%. Group B showed larger LV volume and lower sphericity index compared with group A. Intraobserver and interobserver variability of DS(avg) were 6% and 9%, respectively. More severe dyssynchrony was observed in group B (DS(avg); 23.5 +/- 8.5 ms in group B vs. 17.7 +/- 6.1 ms in group A, P = .008). DS(avg) was not related to RR(avg) or CoV(RR). DS(avg) negatively correlated with ejection fraction (r = -0.404, P = .004) and sphericity index (r = -0.317, P = .025) and showed positive correlation with LV volume.

CONCLUSION

Analysis of asynchrony by triplane TDI was feasible in patients with AF. DS(avg) correlated with echocardiographic parameters of systolic function.

Symptomatic Relief: Left Ventricular Assist Devices Versus Resynchronization Therapy

In patients who have end-stage heart failure, medical therapy is of limited use, and heart transplantation is frequently not an option because of the shortage of donor hearts. Two new treatment options, left ventricular assist devices (LVADs) and implantable cardiac resynchronization therapy (CRT) devices, can improve survival and quality of life in patients who have heart failure. Both types of devices are easy to implant. However, LVADs carry the risk of infection and mechanical failure, and CRT is ineffective in a substantial proportion of patients who have heart failure. Therefore, methods must be devised to identify patients who have heart failure who are likely to benefit from these devices. Data suggest that early LVAD implantation, before end-stage heart failure develops, is critical to slowing or reversing disease progression. Similarly, in indicated patients who have less advanced disease, CRT may be particularly beneficial.

Speckle-tracking strain echocardiography for detecting cardiac dyssynchrony in a canine model of dyssynchrony and heart failure

Multiple echocardiographic criteria have been proposed to diagnose mechanical dyssynchrony in patients with heart failure without being validated against a model of cardiac dyssynchrony with heart failure. This study examines which of these methods can detect dyssynchrony in a canine model. Adult mongrel dogs underwent His-bundle ablation and right-ventricular pacing for 4 wk at either 110 bpm to induce dyssynchrony without heart failure (D group, n = 12) or 170 bpm to induce dyssynchrony with heart failure (DHF group, n = 9). To induce heart failure with narrow QRS, atria were paced at 190 bpm for 4 wk (HF group, n = 8). Tissue Doppler imaging (TDI) and two-dimensional echocardiography were performed at baseline and at end of study. Standard deviation of time to peak systolic velocity (color-coded TDI), time to peak S wave on pulse-wave TDI, time to peak radial and circumferential strain by speckle-tracking analysis ( Err and Ecc, respectively), and septal-to-posterior wall motion delay on M mode were obtained. In D group, only Err and Ecc were increased by dyssynchrony. In contrast, all the echocardiographic parameters of dyssynchrony appeared significantly augmented in the DHF group. Receiver-operator curve analysis showed good sensitivity of Err (90%) and Ecc (100%) to detected dyssynchrony without heart failure and excellent sensitivity and specificity of Err and Ecc to detect dyssynchrony with heart failure. Radial strain by speckle tracking is more accurate than TDI velocity to detect cardiac dyssynchrony in a canine model of dyssynchrony with or without heart failure.

Sudden death prophylaxis in heart failure

Sudden cardiac death (SCD) is the leading cause of mortality in heart failure (HF). Today the implantable cardioverter-defibrillator (ICD) has become a commonplace therapy around the world for patients with both ischemic and non-ischemic cardiomyopathy and an ejection fraction (EF) < or = 35%. However, EF alone does not discriminate between the modes of death from HF (sudden arrhythmic death vs. non-sudden death). Other risk statifiers, such as electrophysiologic study and microvolt T-wave alternans testing, should therefore be used in the appropriate settings to minimize the number of unnecessary device implants. In addition, left ventricular mechanical dyssynchrony has now become recognized as an additional major marker of cardiac mortality. Its assessment should entail echocardiography rather than measurement of the QRS duration. This will allow us to better integrate the ability of cardiac resynchronization therapy (CRT) in enhancing cardiac function with the ability of an ICD in preventing SCD. This review aims to: 1) give a synthesis of the published evidence regarding the value of implantable ICDs and CRT in the primary prophylaxis of SCD in HF; 2) discuss controversial clinical issues in this area; and 3) recommend practical device-based management strategies.

Intraventricular dyssynchrony predicts mortality and morbidity after cardiac resynchronization therapy: a study using cardiovascular magnetic resonance tissue synchronization imaging

OBJECTIVES

We aimed to assess a novel measure of left ventricular (LV) dyssynchrony, a cardiovascular magnetic resonance-tissue synchronization index (CMR-TSI), in patients with heart failure (HF). A further aim was to determine whether CMR-TSI predicts mortality and major cardiovascular events (MCE) after cardiac resynchronization therapy (CRT).

BACKGROUND

Cardiac dyssynchrony is a predictor of mortality in patients with HF. The unparalleled spatial resolution of CMR may render CMR-TSI a predictor of clinical benefit after CRT.

METHODS

In substudy A, CMR-TSI was assessed in 66 patients with HF (age 60.8 +/- 10.8 years, LV ejection fraction 23.9 +/- 12.1% [mean +/- SD]) and 20 age-matched control subjects. In substudy B, CMR-TSI was assessed in relation to clinical events in 77 patients with HF and with a QRS > or =120 ms undergoing CRT.

RESULTS

In analysis A, CMR-TSI was higher in patients with HF and a QRS <120 ms (79.5 +/- 31.2 ms, p = 0.0003) and in those with a QRS > or =120 ms (105.9 +/- 55.8 ms, p < 0.0001) than in control subjects (21.2 +/- 8.1 ms). In analysis B, a CMR-TSI > or =110 ms emerged as an independent predictor of the composite end points of death or unplanned hospitalization for MCE (hazard ratio [HR] 2.45; 95% confidence interval [CI] 1.51 to 4.34, p = 0.0002) or death from any cause or unplanned hospitalization for HF (HR 2.15; 95% CI 1.23 to 4.14, p = 0.0060) as well as death from any cause (HR: 2.6; 95% CI 1.29 to 6.73, p = 0.0061) and cardiovascular death (HR 3.82; 95% CI 1.63 to 16.5, p = 0.0007) over a mean follow-up of 764 days.

CONCLUSIONS

Myocardial dyssynchrony assessed by CMR-TSI is a powerful independent predictor of mortality and morbidity after CRT.

Impact of heart rate on mechanical dyssynchrony and left ventricular contractility in patients with heart failure and normal QRS duration

AIMS

The quantification of mechanical dyssynchrony has important diagnostic value and may help to determine optimal therapy in heart failure (HF). We hypothesized that mechanical dyssynchrony may be augmented at increased heart rates in patients with HF and normal QRS duration.

METHODS AND RESULTS

From online segmental conductance catheter signals, we derived indices to quantify temporal and spatial aspects of mechanical dyssynchrony during systole in 20 control subjects, 20 HF patients with normal QRS duration, and 12 HF patients with complete left bundle branch block (CLBBB). Data were collected at baseline, and then following a 40 bpm increase in heart rate induced by right atrial pacing. Mechanical dyssynchrony in HF patients with normal QRS duration or CLBBB was higher than that found in control subjects. In HF patients with normal QRS duration, mechanical dyssynchrony increased from 37.4+/-4.8% at baseline to 43.2+/-4.4% with increased heart rate (p<0.01), the resultant degree of mechanical dyssynchrony was similar to that at baseline in the HF patients with CLBBB. Increased heart rate did not affect dyssynchrony in the control patients.

CONCLUSION

Mechanical dyssynchrony was augmented as heart rate increased by right atrial pacing in patients with HF and normal QRS duration.

Myocellular and interstitial edema and circulating volume expansion as a cause of morbidity and mortality in heart failure

BACKGROUND

Total body sodium and volume overload are the hallmarks of the congested state in the heart failure patient and result in a variety of deleterious pathophysiologic outcomes including ventricular chamber dilation, passive congestion of both encapsulated and nonencapsulated vital organs and myocardial edema and ischemia.

METHODS AND RESULTS

We propose that congestion is itself a disease state irrespective of the underlying cardiac or renal dysfunction and that sodium and volume overload are directly related to poor clinical outcomes in such patients. In this model, the target of decongestion therapy should be normalization of total body sodium and volume in an expeditious manner and with a durable result.

CONCLUSIONS

Additionally, novel tools to continuously measure the effectiveness and adequacy of decongestion therapy in all compartments are required if improved clinical outcomes are to be attained.

Prevalence of Mechanical Dyssynchrony in Heart Failure Patients with Different QRS Durations

BACKGROUND

Cardiac resynchronization therapy (CRT) has emerged as an established therapy for congestive heart failure. However, up to 30% of patients fail to respond to CRT despite prolonged QRS.

OBJECTIVES

This study aimed at defining the prevalence of interventricular and intraventricular dyssynchrony in heart failure patients with different QRS durations.

METHODS

A total of 123 consecutive patients with severe heart failure (LVEF < 35% and NYHA class III-IV) were prospectively evaluated using 12-lead electrocardiogram and complete echocardiographic examination including tissue Doppler imaging.

RESULTS

According to the QRS duration, 56 patients had a QRS duration < or = 120 ms (Group 1), 33 patients had a QRS duration between 120 and 150 ms (Group 2), and 34 patients had a QRS duration > or = 150 ms (Group 3). Intraventricular dyssynchrony was present in 36% of Group 1 patients, in 58% of Group 2 patients, and in 79% of Group 3 patients (P < 0.000). Linear regression demonstrated a weak relation between QRS and intraventricular dyssynchrony. A greater proportion of patients with interventricular dyssynchrony was observed in Group 3 or Group 2 compared to patients with normal QRS duration (32% in Group 1 vs. 51.5% in Group 2 vs. 76.5% in Group 3, P < 0.000). Linear regression demonstrated a significant relation between QRS duration and interventricular mechanical delay.

CONCLUSIONS

Although both interventricular and intraventricular dyssynchrony increased with the increasing QRS duration, the correlation between intraventricular mechanical and electrical dyssynchrony was weak. The lack of intraventricular dyssynchrony in a fraction of patients with standard CRT indication by QRS duration may provide us insight into the nonresponders rates.

Tissue Doppler imaging a new prognosticator for cardiovascular diseases

Tissue Doppler imaging (TDI) is evolving as a useful echocardiographic tool for quantitative assessment of left ventricular (LV) systolic and diastolic function. Recent studies have explored the prognostic role of TDI-derived parameters in major cardiac diseases, such as heart failure, acute myocardial infarction, and hypertension. In these conditions, myocardial mitral annular or basal segmental (Sm) systolic and early diastolic (Ea or Em) velocities have been shown to predict mortality or cardiovascular events. In particular, those with reduced Sm or Em values of <3 cm/s have a very poor prognosis. In heart failure and after myocardial infarction, noninvasive assessment of LV diastolic pressure by transmitral to mitral annular early diastolic velocity ratio (E/Ea or E/Em) is a strong prognosticator, especially when E/Ea is > or =15. In addition, systolic intraventricular dyssynchrony measured by segmental analysis of myocardial velocities is another independent predictor of adverse clinical outcome in heart failure subjects, even when the QRS duration is normal. In heart failure patients who received cardiac resynchronization therapy, the presence of systolic dyssynchrony at baseline is associated with favorable LV remodeling, which in turn predicts a favorable long-term clinical outcome. Finally, TDI and derived deformation parameters improve prognostic assessment during dobutamine stress echocardiography. A high mean Sm value in the basal segments of patients with suspected coronary artery disease is associated with lower mortality rate or myocardial infarction and is superior to the wall motion score.

Prevalence of Dyssynchrony Derived from Echocardiographic Criteria in Heart Failure Patients with Normal or Prolonged QRS Duration

Cardiac resynchronization therapy (CRT) for heart failure is targeted at specific patients with mechanical dyssynchrony. We aimed to evaluate the prevalence of dyssynchrony in heart failure patients with either normal or prolonged QRS duration using Doppler imaging. Sixty heart failure patients with idiopathic dilated cardiomyopathy (30 with prolonged QRS duration 30 with normal QRS duration) underwent standard echocardiography and tissue Doppler imaging examinations. Difference between left and right ventricular pre-ejection intervals of more than 40 msec was considered a marker of interventricular dyssynchrony. Intraventricular dyssynchrony was defined as a delay of 60 msec between the time to peak velocities of the septum and left ventricular lateral wall. Patients who have either intra- or interventricular dyssynchrony were defined as with cardiac dyssynchrony. Dyssynchrony was observed in 7 (23.3%) heart failure patients with normal QRS duration versus 26 (86.7%) patients with prolonged QRS duration. There was significant difference between the prevalence of dyssynchrony derived from echo criteria in two groups (P<0.05). Although patients with prolonged QRS duration have a high prevalence of dyssynchrony, yet some still have good cardiac synchronicity. Moreover, dyssynchrony also exists in a small percentage of heart failure patients with normal QRS duration. To identify the potential responders for CRT, both QRS duration and cardiac synchronicity should be assessed.

Tissue Doppler predicts long-term clinical outcome after cardiac resynchronization therapy

BACKGROUND

Pulsed-wave tissue Doppler imaging (TDI) was shown to predict short-term left ventricular functional recovery after cardiac resynchronization therapy (CRT). However, few data are available regarding the baseline cardiac asynchrony and clinical outcome after CRT. Therefore, we aimed to investigate the prognostic value of pre-CRT cardiac asynchrony on clinical outcome after CRT.

METHODS

The study population consisted of 48 consecutive patients with moderate to severe heart failure and a wide QRS complex undergoing implantation of biventricular pacemaker. Cardiac asynchrony was assessed at pulsed-wave TDI from measurements of regional electromechanical coupling times in basal segments of both ventricles (Sum asynchrony). Clinical end-points were cardiac mortality and hospitalization for worsening heart failure.

RESULTS

During a follow-up period of 970+/-319 days, clinical end-point (9 deaths, 15 hospitalizations) occurred in 24 patients (clinical nonresponders). At baseline, responders showed higher asynchrony than nonresponders (153+/-57 ms vs. 103+/-58 ms, p<0.01). Sum asynchrony of >98 ms showed the highest accuracy (AUC=0.80, sensitivity 92%, specificity 67%) to identify responders. In contrast, baseline NYHA class, conventional echo-Doppler indices and QRS complex duration were similar in both groups. Eight end-point events (3 deaths) occurred in 30 patients with significant Sum asynchrony (>98 ms) as compared to 16 events (6 deaths) in 18 patients with smaller Sum asynchrony (27% vs. 89%; HR 0.14; 95% CI 0.04 to 0.46; p<0.001). Favorable clinical outcome was associated with larger left ventricular functional recovery at 2 years follow-up (p<0.001).

CONCLUSIONS

TDI-derived index of baseline intra- and interventricular asynchrony appears to predict long-term clinical outcome after CRT.

Left ventricular isovolumic flow sequence during sinus and paced rhythms: new insights from use of high-resolution Doppler and ultrasonic digital particle imaging velocimetry

OBJECTIVES

We sought to clarify the role of isovolumic intervals during a cardiac cycle by in vivo visualization of left ventricular (LV) intracavitary flow dynamics.

BACKGROUND

Asynchronous LV deformation during isovolumic contraction (IVC) and isovolumic relaxation (IVR) might represent a transient feature of myocardial wall mechanics that reverses the direction of blood flow.

METHODS

In 10 beating porcine hearts, the changes in LV intracavitary flow were recorded at baseline and after LV epicardial and right atrial pacing with high-resolution Doppler and contrast echocardiography. Two-dimensional vector flow fields were generated offline from B-mode contrast images with particle imaging velocimetry.

RESULTS

During IVC, flow from the LV apex accelerated toward the base, whereas blood from the base was redirected toward the outflow through formation of an anterior vortex. Conversely, during IVR, flow was initially directed toward the apex and then briefly reversed toward the base. Epicardial pacing from the LV base altered the stages of flow redirection during the pre-ejection period and delayed mitral valve closure (28 +/- 14 ms vs. 61 +/- 13 ms, p < 0.001) and aortic valve opening (77 +/- 18 ms vs. 111 +/- 18 ms, p = 0.004).

CONCLUSIONS

Isovolumic intervals are not periods of hemodynamic stasis but, rather, phases with dynamic changes in intracavitary flow. Experimentally induced aberrant epicardial electrical activation alters stages of flow redirection and prolongs the pre-ejection period. Normal electromechanical activation through the His-Purkinje system in mammalian hearts maintains an inherent synchrony with the sequence of intracavitary flow redirection.

Beta-Blocker Therapy Induces Ventricular Resynchronization in Dilated Cardiomyopathy With Narrow QRS Complex

OBJECTIVES

We sought to evaluate the effects of beta-blocker therapy on regional and global myocardial mechanics in addition to ventricular synchrony in patients with heart failure and normal QRS by using tissue Doppler and strain echocardiography.

BACKGROUND

It is unknown whether beta-blocker therapy can influence mechanical synchrony.

METHODS

Conventional and strain echocardiography were performed in 15 healthy age-matched volunteers and in 25 patients with idiopathic dilated cardiomyopathy (IDC). Of these, 15 IDC patients on standard heart failure therapy were studied prior to and at 1 and 6 months after initiation of carvedilol therapy and compared to the controls.

RESULTS

There was significant mechanical dyssynchrony in IDC compared with control patients. Patients placed on carvedilol demonstrated a significant decrease in the inferoseptal to lateral wall delay in peak strain (normalized to the R-R interval) between baseline and 1 month and between baseline and 6 months. Similarly, global time to peak segmental strain (455 +/- 51 ms vs. 423 +/- 59 ms, respectively, p = 0.02, and 455 +/- 51 ms vs. 415 +/- 50 ms, respectively, p = 0.01) and the coefficient of variation of the time to peak segmental strain decreased (17 +/- 4% vs. 15 +/- 5%, respectively, p = 0.02, and 17 +/- 4% vs. 14 +/- 5%, respectively, p = 0.03), from baseline to 1 month and between baseline and 6 months, respectively. Global strain significantly increased from baseline to 1 month (-8.2 +/- 1.8 to -10.4 +/- 3.9, respectively, p = 0.01) and between baseline and 6 months (-8.2 +/- 1.8% to -12.0 +/- 3.2%, respectively, p = 0.008). Improvements in left ventricular ejection fraction and reverse remodeling were coincident with reductions in mechanical dyssynchrony.

CONCLUSIONS

The use of carvedilol improves contractile function and dyssynchrony in heart failure patients with normal QRS.

The Benefits of Biventricular Pacing in Heart Failure Patients with Narrow QRS, NYHA Class II and Right Ventricular Pacing

OBJECTIVE

To identify subgroups of heart failure patients who might benefit from biventricular pacing.

BACKGROUND

Cardiac resynchronization therapy (CRT) improves the quality of life, New York Heart Association (NYHA) functional class, and exercise capacity and decreases hospitalizations for heart failure for patients who have severe heart failure and a wide QRS. It is unclear if other populations of heart failure patients would benefit from CRT.

METHODS

One hundred forty-four consecutive heart failure patients who underwent CRT and completed 3 months of follow-up were reviewed. Demographic, echocardiographic, electrocardiographic, and clinical outcome data were analyzed to assess the relationship of functional class and QRS duration before device implantation to postimplant outcomes.

RESULTS

There were 20, 88, and 36 patients in NYHA functional class II, III, and IV, respectively. Thirty-four patients had right ventricular pacing and another 29 patients had a QRS duration < or = 150 ms. Patients who were in NYHA functional class II at baseline had significant improvement in left ventricular ejection fraction and indices of left ventricular remodeling after CRT. Similar significant findings were seen in the subgroup with right ventricular pacing at baseline after CRT. However, in the subgroup with a narrow QRS duration, there were no significant changes in the indices of left ventricular remodeling or in the NYHA functional class and there was a significant increase in the QRS duration. For the study cohort as a whole, an improvement in NYHA functional class after CRT correlated with a significant decrease in adverse clinical outcomes.

CONCLUSIONS

Heart failure patients who were in NYHA functional class II and those with right ventricular pacing appeared to benefit from CRT.

Cardiac Resynchronization Therapy and Other New Approaches for the Treatment of Heart Failure in the Elderly

Approximately 15% to 20% of patients with systolic heart failure have a QRS duration greater than 120 ms, which is most commonly seen as left bundle-branch block (LBBB). In LBBB, the left ventricle is activated through the septum from the right ventricle, resulting in a significant delay between the onset of right (RV) and left ventricular (LV) contraction. In patients with LV dysfunction, ventricular dyssynchrony caused by LBBB places the already failing left ventricle at an additional mechanical disadvantage. Ventricular dyssynchrony appears to have a deleterious impact on the natural history of heart failure, as a wide QRS complex has been associated with increased mortality in patients experiencing heart failure. On the basis of these observations, investigators hypothesized that patients with LV dysfunction and delayed ventricular conduction would benefit from pacing at sites that achieve a more favorable contraction pattern, and correct interatrial and/or interventricular conduction delays to maintain optimal atrial-ventricular (AV) synchrony. Multiple clinical trials of cardiac resynchronization therapy have demonstrated that it is safe and effective, with patients achieving significant improvement in both clinical symptoms as well as multiple measures of functional status and exercise capacity. Moreover, it has reduced measures of morbidity and mortality in several studies. Thus, cardiac resynchronization therapy should be routinely offered to eligible patients experiencing heart failure.

Effect of left ventricular endocardial activation pattern on echocardiographic and clinical response to cardiac resynchronization therapy

OBJECTIVE

To explore the left ventricular (LV) electrical activation pattern in heart failure (HF) and its implication to cardiac resynchronization therapy (CRT).

DESIGN AND SETTING

Observational study at the University Teaching Hospital.

PATIENTS

23 optimally treated patients with HF with New York Heart Association class III, QRS duration >120 ms and LV ejection fraction <35%.

INTERVENTIONS

The LV endocardial activation pattern and total activation time (Tat) was determined by non-contact mapping and the LV mechanical dys-synchrony was determined by standard deviation (Ts-SD) and maximal difference (Ts-diff) of time to peak systolic contraction (Ts) among 12 LV segments using tissue Doppler imaging before receiving CRT.

MAIN OUTCOME MEASURES

Correlation between electrical and mechanical dys-synchrony; volumetric responder to CRT at 3 months; HF hospitalisation or death by Kaplan-Meier analysis.

RESULTS

Homogenous (type I, n = 8) and presence of conduction block (type II, n = 15) patterns were identified. Significant correlation between Tat and Ts-SD/Ts-diff was noted only in type II (r = 0.73/0.56, p = 0.002/0.03). Ts-SD and Ts-diff in type II were significantly longer than type I. 12 patients in type II and 2 in type I were CRT responders (p = 0.01). After 487 (447) days, patients with type II pattern had significantly lower risk of HF hospitalisation or death than those with type I (log rank chi(2) = 5.25; p = 0.02).

CONCLUSION

Patients with type II LV endocardial activation pattern had a more favourable echocardiographic and clinical response to CRT than those with type I pattern.

Assessment of left ventricular asynchrony using volume-time curves of 16 segments by real-time 3 dimensional echocardiography: Comparison with tissue Doppler imaging

BACKGROUND

Recent technical developments with high-resolution real-time 3 dimensional echocardiography (RT3DE) facilitate the acquisition of high quality images and the analysis of segmental volume-time curves (VTCs).

AIMS

To assess left ventricular (LV) asynchrony using the VTCs of 16 segments by RT3DE, and to evaluate accuracy compared to tissue Doppler imaging (TDI).

METHODS

Twenty-three heart failure (HF) patients (LVEF: 25+/-6%, age: 60+/-13 years) and 16 normal controls underwent TDI and RT3DE. The standard deviation (SD3) of the end systolic time reaching minimal systolic volume for the 16 segments on VTCs was obtained by RT3DE. The standard deviation (SD2) of the electromechanical coupling time for the 8 segments was measured using TDI.

RESULTS

SD3 was markedly higher in HF patients than in controls (7.7+/-2.5 vs 1.5+/-1.0%, P<0.01) and increased as LVEF decreased (r=-0.85, P<0.01). SD2 was also significantly higher in HF patients (27.0+/-8.6 vs 12.6+/-5.0 ms, P<0.01) and had a good negative correlation with LVEF (r=-0.72, P<0.01). SD3 was well correlated to SD2 (r=0.66, P<0.01).

CONCLUSIONS

We suggest that analysis of VTCs in 16 segments using RT3DE may be a useful alternative to TDI for the evaluation of LV asynchrony.

Role of Diastolic Dyssynchrony in the Delayed Relaxation Pattern of Left Ventricular Filling

We investigated the extent to which diastolic dyssynchrony contributes to the delayed relaxation pattern of left ventricular filling and limitation in exercise capacity. In 100 patients with diabetes, preserved left ventricular systolic function, normal filling pressure, and no coronary disease, we measured magnitude of early diastolic tissue lengthening (tissue velocity and strain rate) and diastolic dyssynchrony (SD in QRS to peak early diastolic tissue velocity interval across 4 basal myocardial segments). From transmitral flow patients were divided into those with normal filling (50 patients) and delayed relaxation (50 patients). Myocardial lengthening was reduced and SD in interval from QRS onset to peak early diastolic tissue velocity across all segments was higher in patients with delayed relaxation compared with control patients. Myocardial lengthening was the only predictor of delayed relaxation and correlation with exercise capacity was better for lengthening indices than SD in interval from QRS onset to peak early diastolic tissue velocity across all segments. Therefore, in this group a reduced rate of myocardial lengthening plays a more important role in delayed relaxation than diastolic dyssynchrony.

Diastolic and Systolic Asynchrony in Patients With Diastolic Heart Failure

OBJECTIVES

The present study aimed to examine whether diastolic and systolic asynchrony exist in diastolic heart failure (DHF) and their prevalence and relationship to systolic heart failure (SHF) patients.

BACKGROUND

Few data exist on mechanical asynchrony in DHF.

METHODS

Tissue Doppler echocardiography was performed in 373 heart failure patients (281 with SHF and 92 with DHF) and 100 normal subjects. Diastolic and systolic asynchrony was determined by measuring the standard deviation of time to peak myocardial systolic (Ts-SD) and peak early diastolic (Te-SD) velocity using a 6-basal, 6-mid-segmental model, respectively.

RESULTS

Both heart failure groups had prolonged Te-SD (DHF vs. SHF vs. controls subjects: 32.2 +/- 18.0 ms vs. 38.0 +/- 25.2 ms vs. 19.5 +/- 7.1 ms) and Ts-SD (31.8 +/- 17.0 ms vs. 36.7 +/- 15.2 ms vs. 17.6 +/- 7.9 ms) compared with the control group (all p < 0.001 vs. control subjects). Based on normal values, the DHF group had comparable diastolic (35.9% vs. 43.1%; chi-square = 1.48, p = NS), but less systolic asynchrony than the SHF group (39.1% vs. 56.9%; chi-square = 8.82, p = 0.003). Normal synchrony, isolated systolic, isolated diastolic, and combined asynchrony were observed in 39.1%, 25.0%, 21.7%, and 14.1% of DHF patients, respectively, and these were 25.6%, 31.3%, 17.4%, and 25.6%, correspondingly, in SHF (chi-square = 10.01, p = 0.019). The correlation between systolic and diastolic asynchrony, and between the myocardial velocities and corresponding mechanical asynchrony appeared weak. A wide QRS duration (>120 ms) was rare in DHF (10.9% vs. 37.7% in SHF) (chi-square = 16.69, p < 0.001).

CONCLUSIONS

Diastolic and/or systolic asynchrony was common in 61% of DHF patients despite narrow QRS complex. The presence of asynchrony was not related to myocardial systolic or diastolic function. Systolic and diastolic asynchrony were not tightly coupled, implying distinct mechanisms.

Usefulness of clinical, electrocardiographic, and echocardiographic parameters to detect cardiac asynchrony in patients with left ventricular dysfunction secondary to ischemic or nonischemic heart disease

OBJECTIVES

Specific evaluation using echocardiographic Doppler is superior to the measurement of the QRS complex to detect cardiac asynchrony. Nevertheless, no clinical, electrocardiographic, or echocardiographic parameters have been evaluated to obtain an accurate and easy-to-use marker of cardiac asynchrony in patients with depressed left ventricular (LV) ejection fraction. Our aim was to determine whether there is any marker of cardiac asynchrony in patients with LV systolic dysfunction that allows us to obviate the performance of a specific echocardiographic study before cardiac resynchronization therapy.

METHODS

In all, 316 consecutive patients with LV ejection fraction less than 40% were enrolled. Interventricular asynchrony was defined as an interventricular mechanical delay longer than 40 milliseconds. Intraventricular asynchrony was defined as 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 greater than 50 milliseconds.

RESULTS

In all, 177 (56%) had ischemic and 139 (44%) had nonischemic heart disease. The logistic regression analysis showed that only the presence of left bundle branch block was an independent predictor of interventricular asynchrony despite the cause of the underlying disease (odds ratio and 95% confidence interval 7.2 [3.9-13.4], P < .001; 5.99 [2.7-13.2], P < .001; and 8.75 [3.2-23.8], P < .001 for the total population, ischemic and nonischemic groups, respectively). Nevertheless, none of the studied parameters was found as a predictor of intraventricular asynchrony.

CONCLUSIONS

The presence of left bundle branch block is a marker of interventricular asynchrony in patients with ventricular dysfunction despite the cause of the underlying cardiac disease. Nevertheless, intraventricular cardiac asynchrony cannot be detected using conventional parameters. A specific echocardiographic evaluation before cardiac resynchronization therapy must be performed in all these patients. Our aim was to determine whether there is any marker of cardiac asynchrony in patients with left ventricular systolic dysfunction that allows us to obviate the performance of a specific echocardiographic study before cardiac resynchronization therapy. Our results showed that only the presence of left bundle branch block was an independent predictor of interventricular asynchrony despite the cause of the underlying disease but none of the studied parameters was found as a predictor of intraventricular asynchrony.

Cardiac Resynchronization Therapy in Patients With a Narrow QRS Complex

OBJECTIVES

The purpose of this study was to evaluate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with narrow QRS complex (<120 ms) and evidence of left ventricular (LV) dyssynchrony on tissue Doppler imaging (TDI).

BACKGROUND

Cardiac resynchronization therapy is beneficial in selected heart failure patients with wide QRS complex (> or =120 ms). Patients with narrow QRS complex are currently not eligible for CRT, and the potential effects of CRT are not well studied.

METHODS

Thirty-three consecutive patients with narrow QRS complex and 33 consecutive patients with wide QRS complex (control group) were prospectively included. All patients needed to have LV dyssynchrony > or =65 ms on TDI, New York Heart Association (NYHA) functional class III/IV heart failure, and LV ejection fraction < or =35%.

RESULTS

Baseline characteristics, particularly LV dyssynchrony, were comparable between patients with narrow and wide QRS complex (110 +/- 8 ms vs. 175 +/- 22 ms; p = NS). No significant relationship was observed between baseline QRS duration and LV dyssynchrony (r = 0.21; p = NS). The improvement in clinical symptoms and LV reverse remodeling was comparable between patients with narrow and wide QRS complex (mean NYHA functional class reduction 0.9 +/- 0.6 vs. 1.1 +/- 0.6 [p = NS] and mean LV end-systolic volume reduction 39 +/- 34 ml vs. 44 +/- 46 ml [p = NS]).

CONCLUSIONS

Cardiac resynchronization therapy appears to be beneficial in patients with narrow QRS complex and severe LV dyssynchrony on TDI, with similar improvement in symptoms and comparable LV reverse remodeling to patients with wide QRS complex. The current results need confirmation in larger patient cohorts.

Asynchrony of Left Ventricular Systolic Performance After the First Acute Myocardial Infarction in Patients with Narrow QRS Complexes: Doppler Tissue Imaging Study

BACKGROUND

Left ventricular (LV) electromechanical delay results in asynchronized contraction. However, it is not known if the presence of cardiac diseases without QRS prolongation may result in interventricular or intraventricular asynchrony. Doppler tissue imaging is now established for detecting regional contractile abnormalities and asynchrony in the LV.

OBJECTIVES

The aim of the study was to assess the degree of LV asynchrony after the first acute myocardial infarction (AMI) in patients with a narrow QRS complex using Doppler tissue imaging and correlate this with the site and extent of the infarction.

METHODS

Echocardiography with Doppler tissue imaging was performed within 1 week of AMI in 155 patients and compared with 50 age- and sex-matched healthy volunteers. Regional myocardial velocities were assessed at the 4 mitral annular sites, and the corresponding systolic velocity (Sm), early diastolic velocity (Em), time to peak Sm (Ts), and time to peak Em (Te) were measured. To assess LV synchronicity, SDs of Ts (Ts-SD) and Te (Te-SD) of all the 4 mitral annular sites were computed. Location and size of infarct were confirmed by echocardiographic wall-motion score index.

RESULTS

QRS complex duration was normal in all patients. Wall-motion score index was significantly higher in patients with anterior than inferior AMI (2.02 +/- 0.34 vs 1.24 +/- 0.21, P < .001). Ts-SD was significantly higher in patient than control group, and in patients with anterior than inferior AMI (38.21 +/- 2.59 vs 21.06 +/- 0.52 milliseconds and 43.18 +/- 3.77 vs 33.24 +/- 1.4 milliseconds, respectively, P < .001 for each), whereas Te-SD did not differ significantly among these groups (20.35 +/- 1.77 vs 18.17 +/- 1.14 milliseconds and 21.6 +/- 1.35 vs 19.1 +/- 1.11 milliseconds, respectively, P > .05 for each). A strong positive correlation was detected between LV systolic asynchrony (Ts-SD) and wall-motion score index (r = .77), LV mass (r = .67), LV end-systolic dimension (r = .65), and LV end-diastolic dimension (r = .5). The correlation was negative with LV ejection fraction (r = -.70) and Sm (r = -.6); the correlation was weak with Em (r = -.33) (P < .001 for all). In multivariate logistic regression analysis, infarct size was found to be the most independent predictor for systolic asynchrony (odds ratio 3.59, 95% confidence interval [1.43-9.33], P < .001).

CONCLUSION

AMI has a significant impact on regional myocardial contractility and LV systolic (but not diastolic) synchronicity early in the course even in the absence of QRS widening or bundle branch block. The degree of LV systolic asynchrony is greater with anterior than inferior AMI and mainly determined by infarct size.

Prognostic value of intraventricular dyssynchrony according to clinical stage of left ventricular impairment

Intraventricular dyssynchrony has prognostic implications in patients who have severe functional limitation and decreased ejection fraction. Patients with less advanced cardiac disease often exhibit intraventricular dyssynchrony, but there is little available information about its prognostic relevance in such patients. We investigated the prognostic effect of intraventricular dyssynchrony on outcome in 318 patients with known or suspected coronary artery disease who were classified according to the presence or absence of left ventricular dysfunction and heart failure symptoms. Mortality was considered the primary end point over a median follow-up of 56 months, and a Cox proportional hazards model was used for survival analysis. Despite a low prevalence (8%) of left bundle branch block, there was a high prevalence of intraventricular dyssynchrony even in patients without symptomatic heart failure. The magnitude of intraventricular dyssynchrony correlated poorly with QRS duration (r = 0.25), end-systolic volume index (r = 0.27), and number of scar segments (r = 0.25). There were 58 deaths during follow-up. Ventricular volume, ischemic burden, and magnitude of intraventricular dyssynchrony predicted outcome, but magnitude of intraventricular dyssynchrony was an independent predictor of survival only in patients with asymptomatic left ventricular dysfunction. In conclusion, patients with known or suspected coronary artery disease have a high prevalence of intraventricular dyssynchrony. Although ventricular volume, ischemic burden, and intraventricular dyssynchrony are potentially important prognostic markers, the relative importance of intraventricular dyssynchrony changes with the clinical setting and may be greatest in patients with preclinical disease.

Prediction of Response to Cardiac Resynchronization Therapy: The Selection of Candidates for CRT (SCART) Study

BACKGROUND

The aim of this study was to evaluate the ability of baseline clinical and echocardiographic parameters to predict a positive response to CRT.

METHODS

We analyzed 6-month data from the first 133 consecutive patients enrolled in a multicenter prospective study. These patients had symptomatic heart failure (HF) refractory to pharmacological therapy (NYHA class II-IV), left ventricular ejection fraction (LVEF) < or =35%, and prespecified electrocardiographic, echocardiographic or tissue Doppler imaging markers of left ventricular (LV) dyssynchrony.

RESULTS

After a follow-up period of 6 months, 1 patient died and 13 were hospitalized for worsening HF. There were significant (P < 0.01) clinical, functional, and echocardiographic improvements that included: New York heart Association Class, Quality-of-Life Score, QRS duration, LVEF, LV end-diastolic and end-systolic diameter (LVESD), and severity of mitral regurgitation A positive response was documented in 90/133 (68%) patients who presented an improved clinical composite score associated to an increase in LVEF > or = 5 units. A multivariate analysis identified that a smaller LVESD (OR = 0.957, 95% CI 0.920-0.996; P = 0.030) and longer interventricular mechanical delay (IVMD) (OR = 1.017, 95% CI 1.005-1.029, P = 0.007) as independent predictors of a positive response. Receiver-operating curve analysis showed that a positive response to CRT may be predicted in patients with IVMD > 44 ms (with a sensitivity of 66% and a specificity of 55%) or with LVESD < 60 mm (with a sensitivity of 66% and a specificity of 61%).

CONCLUSIONS

Our results confirm the limited value of QRS duration in the selection of patients for CRT. A less-advanced stage of disease and echocardiographic evidence of interventricular dyssynchrony demonstrated to predict response to CRT, while intraventricular dyssynchrony did not predict response.

Benefits of Cardiac Resynchronization Therapy for Heart Failure Patients With Narrow QRS Complexes and Coexisting Systolic Asynchrony by Echocardiography

OBJECTIVES

This study was designed to evaluate the role of cardiac resynchronization therapy (CRT) in heart failure (HF) patients with narrow QRS complexes (<120 ms) and echocardiographic evidence of mechanical asynchrony.

BACKGROUND

Cardiac resynchronization therapy is currently recommended to advanced HF patients with prolonged QRS duration. Echocardiographic assessment of systolic mechanical asynchrony has been proven useful to predict a favorable response after CRT.

METHODS

A total of 102 HF patients with New York Heart Association (NYHA) functional class III or IV were enrolled. Among them, 51 had wide QRS (>120 ms) and 51 had narrow QRS (<120 ms). Tissue Doppler imaging (TDI) was employed to select patients with systolic asynchrony (increased asynchrony index) in the narrow-QRS group. Clinical and echocardiographic assessments were performed at baseline and 3 months after CRT.

RESULTS

There was a significant reduction of left ventricular (LV) end-systolic volume in both narrow (122 +/- 42 cc vs. 103 +/- 47 cc, p < 0.001) and wide (148 +/- 74 cc vs. 112 +/- 64 cc, p < 0.001) QRS groups. Improvement of NYHA functional class (both p < 0.001), maximal exercise capacity (both p < 0.05), 6-min hall-walk distance (both p < 0.01), ejection fraction (both p < 0.001), and mitral regurgitation (both p < 0.005) was also observed. In both groups, the degree of baseline mechanical asynchrony determined LV reverse remodeling to a similar extent, as shown by the superimposed regression lines. Withholding CRT for 4 weeks resulted in loss of echocardiographic benefits.

CONCLUSIONS

Cardiac resynchronization therapy for HF patients with narrow QRS complexes and coexisting mechanical asynchrony by TDI results in LV reverse remodeling and improvement of clinical status. The amplitude of benefit is similar to the wide-QRS group provided that similar extent of systolic asynchrony is selected.

Cardiac Dysfunction in Heart Failure: The Cardiologist's Love Affair with Time

Translating research into clinical practice has been a challenge throughout medical history. From the present review, it should be clear that this is particularly the case for heart failure. As a consequence, public awareness of this disease has been disillusionedly low, despite its prognosis being worse than that of most cancers and many other chronic diseases. We explore how over the past 150 years since Ludwig and Marey concepts about the evaluation of cardiac performance in patients with heart failure have emerged. From this historical-physiologic perspective, we have seen how 3 increasingly reductionist approaches or schools of thought have evolved in parallel, that is, an input-output approach, a hemodynamic pump approach, and a muscular pump approach. Each one of these has provided complementary insights into the pathophysiology of heart failure and has resulted in measurements or derived indices, some of which still being in use in present-day cardiology. From the third, most reductionist muscular pump approach, we have learned that myocardial and ventricular relaxation properties as well as temporal and spatial nonuniformities have been largely overlooked in the 2 other, input-output and hemodynamic pump, approaches. A key message from the present review is that relaxation and nonuniformities can be fully understood only from within the time-space continuum of cardiac pumping. As cyclicity and rhythm are, in some way, the most basic aspects of cardiac function, considerations of time should dominate over any measurement of cardiac performance as a muscular pump. Any measurement that is blind for the arrow of cardiac time should therefore be interpreted with caution. We have seen how the escape from the time domain-as with the calculation of LV ejection fraction-fascinating though as it may be, has undoubtedly served to hinder a rational scientific debate on the recent, so-called systolic-diastolic heart failure controversy. Lacking appreciation of early relaxation abnormalities and inappropriate degrees of nonuniformities has, indeed, led to some unfortunate misunderstandings about the pathophysiologic time progression of heart failure, in particular, heart failure with compensated hemodynamic pump function (ie, with normal or preserved LV ejection fraction). We have seen that with the introduction of newer powerful diagnostic techniques, as, for example, TDI and MRI, to evaluate ventricular "muscular pump" function, this debate can now be held in a more serene physiologic context. These aspects will be elaborated further in subsequent chapter papers of this symposium. With ongoing stem and other cell-based therapies and future reductionistic insights into cardiac cellular performance, we foresee the emergence of a fourth simple-parallel school of thought viewing the heart as a network of communicating different cell types, that is, cardiomyocytes, endothelial cells, fibroblasts, neurons. In this postgenomic age with the introduction of the rapidly evolving discipline of in vivo molecular imaging techniques, we anticipate that novel measurements of cardiac performance in patients with heart failure will soon become available and complement biopsy and other already available cardiac cellular biomarkers (cardiac troponin I; creatine kinase-MB; myoglobin; BNP). Through the use of these novel biomarkers as a fourth diagnostic track in the evaluation of cardiac performance in patients with heart failure, we will soon be able to increasingly understand the behavior of the heart as a complex biologic system-in other words, how these "low-level" biologic functions and signal transduction pathways at a cellular level contribute to the above "high-level" or system-level approach of cardiac performance at the muscular, the hemodynamic, and the input-output pump system levels and, hopefully, how they could contribute to an early diagnosis of chronic heart failure, in patients.

Are left ventricular diastolic function and diastolic asynchrony important determinants of response to cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) has been shown to reduce symptoms and reverse left ventricular (LV) remodeling. It is not known, however, whether diastolic function will improve after CRT and diastolic asynchrony will predict LV reverse remodeling. Seventy-six patients (mean age 65 +/- 12 years, 74% men) who received CRT were studied at baseline and after 3 months. Diastolic function was assessed by transmitral Doppler and tissue Doppler imaging. LV systolic and diastolic asynchrony were assessed by the time to peak myocardial contraction (Ts) and early diastolic relaxation (Te) using the 6 basal, 6 mid-segmental model. There were 42 responders (55%) with LV reverse remodeling (defined as a reduction of LV end-systolic volume >or=15%). Parameters of systolic function were significantly improved only in the responders. For diastolic function, there were reductions of transmitral E velocity in the 2 groups, without any change in atrial velocity or the E/A ratio. Tissue Doppler imaging revealed that myocardial early diastolic velocity was unchanged in responders but was significantly worsened in nonresponders. The systolic asynchrony index (the SD of Ts of 12 LV segments) correlated significantly with LV reverse remodeling (r = -0.64, p <0.001) but not the diastolic asynchrony index (the SD of Te of 12 LV segments) (r = -0.10, p = NS). The systolic asynchrony index was the only independent predictor of reverse remodeling (beta = -0.99, 95% confidence interval -1.41 to -0.58, p <0.001). In conclusion, CRT improves systolic function and systolic asynchrony but has a neutral effect on diastolic function and diastolic asynchrony. LV reverse remodeling response is determined by the severity of prepacing systolic asynchrony but not diastolic asynchrony or the diastolic filling pattern.

Ventricular Pacing Lead Location Alters Systemic Hemodynamics and Left Ventricular Function in Patients With and Without Reduced Ejection Fraction

OBJECTIVES

We compared left ventricular (LV) systolic and diastolic function during right ventricular (RV), LV, and biventricular (BiV) pacing in patients with narrow QRS duration with and without LV dysfunction.

BACKGROUND

The optimal RV pacing lead location for patients with a standard indication for ventricular pacing remains controversial.

METHODS

Left ventricular pressure and volume data were determined via conductance catheter during electrophysiology study in 31 patients divided into groups with ejection fraction (EF) > or =40% (n = 17) or EF <40% (n = 14). QRS duration was 91 +/- 18 versus 106 +/- 25 ms, respectively (p = NS). Hemodynamic data were recorded during atrial and dual chamber pacing from the RV apex, RV free wall, RV septum, LV free wall, and BiV.

RESULTS

In patients with EF > or =40%, RV pacing at 1 or more sites, but not LV free wall or BiV pacing, significantly (p < 0.05) impaired cardiac output (CO), stroke work (SW), EF, and LV relaxation compared with atrial overdrive pacing. Right ventricular pacing also impaired hemodynamics and LV function in patients with EF <40%. However, LV and BiV pacing increased CO, SW, EF, and LV +dP/dt(MAX) in patients with LV dysfunction. Left ventricular and BiV pacing enhanced an index of global LV cycle efficiency in patients with depressed EF. The detrimental hemodynamic effects of RV pacing were attenuated by selecting the optimal RV pacing site.

CONCLUSIONS

Right ventricular pacing worsens LV function in patients with and without LV dysfunction unless the RV pacing site is optimized. Left ventricular and BiV pacing preserve LV function in patients with EF >40% and improve function in patients with EF <40% despite no clinical indication for BiV pacing.

Right ventricular pacing can induce ventricular dyssynchrony in patients with atrial fibrillation after atrioventricular node ablation

OBJECTIVES

This study was designed to assess the effects of long-term right ventricular (RV) pacing on left ventricular (LV) dyssynchrony, LV function, and heart failure symptoms.

BACKGROUND

Atrioventricular (AV) node ablation and subsequent long-term RV pacing is a well-established treatment option in patients with atrial fibrillation (AF).

METHODS

In 55 patients with drug-refractory AF, AV node ablation and implantation of a pacemaker was performed. At baseline and after a mean of 3.8 +/- 1.7 years, LV dyssynchrony (by M-mode echocardiography and tissue Doppler imaging), LV function, and volumes and functional status were assessed.

RESULTS

After long-term RV pacing, 27 patients (49%) had developed LV dyssynchrony. Concomitantly, these patients worsened in heart failure symptoms (New York Heart Association functional class increased from 1.8 +/- 0.6 to 2.2 +/- 0.7, p < 0.05), with a decrease in LV ejection fraction (from 48 +/- 7% to 43 +/- 7%, p < 0.05) and an increase in LV end-diastolic volume (from 116 +/- 39 ml to 130 +/- 52 ml, p < 0.05). Conversely, patients without LV dyssynchrony did not deteriorate in heart failure symptoms, LV function, or LV volumes.

CONCLUSIONS

Long-term RV pacing can induce LV dyssynchrony in almost 50% of patients treated with AV node ablation for chronic AF. The development of LV dyssynchrony was associated with deterioration in heart failure symptoms, systolic LV function, and LV dilatation.

A Retrospective Pilot Study

An epidemic disease - a major cause of chronic disability - congestive heart failure adversely affects the health of millions. Congestive heart failure is the most frequent cause of cardiovascular hospital admissions and shares a significant responsibility for the high cost of healthcare. Despite medical and technological advances, studies show that the treatment of heart failure is suboptimal. Physician knowledge and awareness of appropriate treatment may contribute to patient compliance and improve delivery of healthcare. The purpose of this article is to examine how patients with heart failure in a heart failure clinic are managed. Recommendations are proposed and the role of nurses and clinicians in heart failure management is discussed.

Cardiac resynchronization therapy: Role of patient selection

Cardiac resynchronization therapy (CRT) is a well-accepted and effective therapy for treating patients with a wide QRS complex, significant left ventricular systolic dysfunction, and symptoms of advanced heart failure. However, approximately 25% to 30% of patients fail to respond to this therapy. Most large studies have used electrical dyssynchrony (wide QRS) as a main entrance criterion. Emerging data suggest that mechanical dyssynchrony may be a more important factor in selecting appropriate candidates for CRT. New echocardiographic (ECHO) imaging modalities such as tissue Doppler imaging, three-dimensional ECHO, and speckle tracking ECHO are able to quantify left ventricular mechanical dyssynchrony. These techniques are currently being used to assist in the selection of patients for CRT. Recently published and ongoing studies are addressing the use of CRT in patients who do not meet the standard criteria, such as patients with atrial fibrillation, mild to moderate heart failure, narrow QRS complex, and acute myocardial infarction.

Cardiac resynchronization therapy: redefining the role of device therapy in heart failure

That cardiac dyssynchrony can contribute to a decline in cardiac efficiency has been recognized in one form or another for at least 50 years. Although revascularization and beta-blockers can improve cardiac synchrony, there was little interest in or awareness of this clinical entity until the advent of specific, highly effective therapy using atriobiventricular pacing, often described as cardiac resynchronization therapy. Over the last few years, significant advances in cardiac resynchronization therapy technology and the publication of large-scale clinical trials using cardiac resynchronization therapy devices in patients with heart failure have led to the widespread use of these devices. This review will briefly describe the complex nature of cardiac dyssynchrony, what is known about its epidemiology, the effects of cardiac resynchronization therapy, appropriate patient selection, practical aspects, such as implantation and monitoring, and some still unanswered questions.

Severe pulmonary arterial hypertension due to Angiostrongylosus vasorum in a dog

A dog was presented with a history of dyspnea, coughing, and ascites. Angiostrongylosis and severe pulmonary arterial hypertension (PAH) were found, as well as a marked discordance between the electrical and mechanical events of the heart. Pulmonary arterial hypertension related to Angiostrongylus vasorum has rarely been reported.