Intra-left ventricular electromechanical asynchrony

Longitudinal function and ventricular dyssynchrony are restored in children with pulmonary stenosis after percutaneous balloon pulmonary valvuloplasty

The aim of this study was to evaluate the impact of balloon pulmonary valvuloplasty on longitudinal ventricular dysfunction and cardiac dyssynchrony in children with congenital moderately severe pulmonary stenosis (PS). Forty-eight children with congenital moderately severe valvular pulmonary stenosis and 36 age-matched normal children were included. Successful percutaneous balloon pulmonary valvuloplasty was performed for children with PS. Longitudinal Cardiac function and myocardial synchrony was assessed by echocardiography with tissue Doppler imaging (TDI). Mitral annular plane excursion (MAPSE), tricuspid annular plane excursion (TAPSE), left ventricular systolic wave (LVs), right ventricular systolic wave (RVs) and myocardial synchrony was assessed by echocardiography with TDI. TAPSE, RVs, TAPSE/MAPSE ratio and RVs/LVs ratio were significantly lower in children with PS compared to control subjects: (P < 0.001, P < 0.001, P < 0.001 and P < 0.001). All these parameters were significantly improved after balloon valvuloplasty in children with PS. Intra& inter-ventricular dyssynchrony were significantly increased in PS patients than in control group, (P < 0.03, <0.001 and 0.02 respectively). All these variables were significantly reduced after pulmonary valvuloplasty. In children with valvular PS, balloon valvuloplasty restored longitudinal function and cardiac Synchrony. This gives good insights for the importance of early intervention in children with PS to prevent the progression for cardiac deformation.

Left and right ventricular dyssynchrony and strains from cardiovascular magnetic resonance feature tracking do not predict deterioration of ventricular function in patients with repaired tetralogy of Fallot

BACKGROUND

Patients with repaired tetralogy of Fallot (rTOF) suffer from progressive ventricular dysfunction decades after their surgical repair. We hypothesized that measures of ventricular strain and dyssynchrony would predict deterioration of ventricular function in patients with rTOF.

METHODS

A database search identified all patients at a single institution with rTOF who underwent cardiovascular magnetic resonance (CMR) at least twice, >6 months apart, without intervening surgical or catheter procedures. Seven primary predictors were derived from the first CMR using a custom feature tracking algorithm: left (LV), right (RV) and inter-ventricular dyssynchrony, LV and RV peak global circumferential strains, and LV and RV peak global longitudinal strains. Three outcomes were defined, whose changes were assessed over time: RV end-diastolic volume, and RV and LV ejection fraction. Multivariate linear mixed models were fit to investigate relationships of outcomes to predictors and ten potential baseline confounders.

RESULTS

One hundred fifty-three patients with rTOF (23 ± 14 years, 50 % male) were included. The mean follow-up duration between the first and last CMR was 2.9 ± 1.3 years. After adjustment for confounders, none of the 7 primary predictors were significantly associated with change over time in the 3 outcome variables. Only 1-17 % of the variability in the change over time in the outcome variables was explained by the baseline predictors and potential confounders.

CONCLUSIONS

In patients with repaired tetralogy of Fallot, ventricular dyssynchrony and global strain derived from cine CMR were not significantly related to changes in ventricular size and function over time. The ability to predict deterioration in ventricular function in patients with rTOF using current methods is limited.

Surgical Aspects of Cardiac Resynchronisation Therapy

Despite significant advances in the pharmacological treatment of heart failure, rates of mortality and morbidity from the condition remain a concern. The introduction of cardiac resynchronisation therapy (CRT) has been a welcome addition to the treatment strategy of patients who display ventricular dyssynchrony. Several control studies have shown significant benefits from this intervention in particular improved mortality and reduction in symptom burden. In this short review, we focus on several concepts of CRT and discuss the implications of surgical implantation of the left ventricular (LV) lead as compared to the standard transvenous approach.

Echocardiographic Predictors of Immediate Postoperative Outcomes in Patients With Severe Left Ventricular Systolic Dysfunction Undergoing On-Pump Coronary Artery Bypass Grafting

OBJECTIVES

The postoperative course following on-pump coronary artery bypass grafting (CABG) in patients with severe left ventricular (LV) systolic dysfunction is often unpredictable. Therefore, the aim of this study was to identify predictors of poor postoperative outcome in this subset of patients.

DESIGN

Prospective observational study SETTING: Single university hospital PARTICIPANTS: Forty patients with severe LV systolic dysfunction undergoing isolated on-pump CABG INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Comprehensive transesophageal echocardiographic examination was performed to obtain the indices of systolic and diastolic LV function after induction of anesthesia. A poor postoperative outcome was defined as patient death or vasoactive inotropic score≥20 for at least 6 hours and/or requiring intra-aortic balloon counterpulsation and/or mechanical ventilation for≥24 hours. Poor postoperative outcome was observed in 40% (16/40) of patients. Patients with poor postoperative outcomes had a significantly higher systolic dyssynchrony index, septal-lateral delay with a significantly lower global longitudinal strain and isovolumic acceleration, end-diastolic volume, end-systolic volume, and lateral and medial mitral annulus systolic velocity. In a binary logistic regression model, global longitudinal strain (odds ratio, 1.5, confidence interval [CI] 95%, 1.19-1.88, p = 0.001), septal-lateral delay (odds ratio, 1.02, 95% CI, 1.01-1.03; p = 0.001) and systolic dyssychrony index (odds ratio, 1.3, 95% CI, 1.13-1.48; p = 0.000) were found to be predictors of poor postoperative outcome.

CONCLUSION

Global longitudinal strain, systolic dyssynchrony index, and septal-lateral delay were reliable and accurate predictors of adverse outcomes in patients with severe LV systolic dysfunction undergoing on-pump CABG.

Myocardial Regional Interstitial Fibrosis is Associated With Left Intra-Ventricular Dyssynchrony in Patients With Heart Failure: A Cardiovascular Magnetic Resonance Study

Left ventricular (LV) dyssynchrony is associated with poor prognosis in patients with heart failure (HF). The mechanisms leading to LV dyssynchrony are not fully elucidated. This study evaluates whether myocardium regional variation in interstitial fibrosis is associated with LV dyssynchrony. Forty-two patients with systolic heart failure (SHF), 76 patients with heart failure with preserved ejection fraction (HFpEF) and 20 patients without HF received cardiovascular magnetic resonance imaging (MRI) study. LV was divided into 18 segments by short-axis view. In each segment, regional extracellular volume fraction (ECV) and the time taken to reach minimum regional volume (Tmv) were derived. Intra-LV dyssynchrony were represented by maximum difference (Dysyn_max) and standard deviation (Dysyn_sd) of all Tmv. The results showed that among the covariates, only age (1.87, 95% CI: 0.61-3.13, p = 0.004) and ECV (3.77, 95% CI: 2.72-4.81, p < 0.001) were positively associated with Tmv. The results remained robust in certain subgroups. In conclusion, we demonstrated that LV myocardium regional variation in interstitial fibrosis is closely related to LV intra-ventricular dyssynchrony irrespective of the LV global function. These data might help explain the pathophysiology of LV dyssynchrony and it's underlying mechanisms leading to poor prognosis.

Effects of an Isolated Complete Right Bundle Branch Block on Mechanical Ventricular Function

OBJECTIVES

The purpose of this study was to investigate the effects of an isolated complete right bundle branch block on mechanical ventricular function.

METHODS

Two groups of participants were enrolled in this study: a block group, consisting of 98 patients with isolated complete right bundle branch blocks without structural heart disease, and a control group, consisting of 92 healthy adults. The diameter, end-diastolic area, end-systolic area, and right ventricular (RV) fractional area change were obtained to evaluate morphologic and systolic function by 2-dimensional sonographic technology. Systolic and diastolic velocities and time interval parameters were measured to assess mechanical ventricular performance using pulsed wave tissue Doppler imaging.

RESULTS

Although there was no significant difference in the RV fractional area change between the patients with blocks and controls, the diameter, end-diastolic area, and end-systolic area of the RV were significantly larger in the patients with blocks (P < .05). In the patients with blocks, the peak velocities during systole and early diastole and the ratio of the peak velocities during early and late diastole decreased. The block group had a prolonged pre-ejection period, electromechanical delay time, and isovolumic relaxation time, a decreased ejection time, and an increased pre-ejection period/ejection time ratio, and the myocardial performance index (Tei index) at the basal RV lateral wall was significantly increased. There were no significant differences in any echocardiographic parameters at different sites of the left ventricle.

CONCLUSIONS

In patients with isolated complete right bundle branch blocks, systolic and diastolic functions are impaired in the RV, and follow-up is needed.

Cellular and Molecular Aspects of Dyssynchrony and Resynchronization

Dyssynchronous contraction of the ventricle significantly worsens morbidity and mortality in patients with heart failure (HF). Approximately one-third of patients with HF have cardiac dyssynchrony and are candidates for cardiac resynchronization therapy (CRT). The initial understanding of dyssynchrony and CRT was in terms of global mechanics and hemodynamics, but lack of clinical benefit in a sizable subgroup of recipients who appear otherwise appropriate has challenged this paradigm. This article reviews current understanding of these cellular and subcellular mechanisms, arguing that these aspects are key to improving CRT use, as well as translating its benefits to a wider HF population.

Radionuclide Assessment of Left Ventricular Dyssynchrony

Phase analysis of gated myocardial perfusion single-photon emission computed tomography is a widely available and reproducible measure of left ventricular (LV) dyssynchrony, which also provides comprehensive assessment of LV function, global and regional scar burden, and patterns of LV mechanical activation. Preliminary studies indicate potential use in predicting cardiac resynchronization therapy response and elucidation of mechanisms. Because advances in technology may expand capabilities for precise LV lead placement in the future, identification of specific patterns of dyssynchrony may have a critical role in guiding cardiac resynchronization therapy.

Cardiac systolic regional function and synchrony in endurance trained and untrained females

Background

Most studies on cardiac function in athletes describe overall heart function in predominately male participants. We aimed to compare segmental, regional and overall myocardial function and synchrony in female endurance athletes (ATH) and in age-matched sedentary females (CON).

Methods

In 46 ATH and 48 CON, echocardiography was used to measure peak longitudinal systolic strain and myocardial velocities in 12 left ventricular (LV) and 2 right ventricular (RV) segments. Regional and overall systolic function were calculated together with four indices of dyssynchrony.

Results

There were no differences in regional or overall LV systolic function between groups, or in any of the four dyssynchrony indices. Peak systolic velocity (s′) was higher in the RV of ATH than in CON (9.7±1.5 vs 8.7±1.5 cm/s, p=0.004), but not after indexing by cardiac length (p=0.331). Strain was similar in ATH and CON in 8 of 12 LV myocardial segments. In septum and anteroseptum, basal and mid-ventricular s′ was 6–7% and 17–19% higher in ATH than in CON (p<0.05), respectively, while s′ was 12% higher in CON in the basal LV lateral wall (p=0.013). After indexing by cardiac length, s′ was only higher in ATH in the mid-ventricular septum (p=0.041).

Conclusions

We found differences between trained and untrained females in segmental systolic myocardial function, but not in global measures of systolic function, including cardiac synchrony. These findings give new insights into cardiac adaptation to endurance training and could also be of use for sports cardiologists evaluating female athletes.

Relationship between epicardial fat tissue and left ventricular synchronicity: An observational study

Objective:

Left ventricular (LV) systolic synchrony is defined as simultaneous activation of corresponding cardiac segments. Impaired synchrony has some adverse cardiovascular effects, such as LV dysfunction and impaired prognosis. Epicardial fat tissue (EFT) is visceral fat around the heart. Increased EFT thickness is associated with some disorders, such as LV dysfunction and hypertrophy, which play a role in the impairment of LV synchrony. However, the relationship between EFT and LV systolic synchrony has never been assessed. Thus, we aimed to evaluate the possible relationship between EFT and LV synchrony in this study.

Methods:

The study population consisted of 55 consecutive patients (mean age 46.4±13.4 years, 32 female) without bundle branch block (BBB). EFT and LV systolic synchrony were evaluated by transthoracic echocardiography using 2D and tissue Doppler imaging. Maximal difference (Ts-6) and standard deviation (Ts-SD-6) of time to peak systolic (Ts) myocardial tissue velocity obtained from 6 LV basal segments were used to assess LV synchrony. Multiple regression analysis was used to detect the independently related factors to LV synchrony.

Results:

The mean values of EFT thickness, Ts-6, and Ts-SD-6 were found to be 2.7±1.6 mm (ranging from 1-7 mm), 20.1±14.2 msec, and 7.7±5.6, respectively. EFT thickness also was independently associated with Ts-6 (β =0.332, p=0.01) and Ts-SD-6 (β =0.286, p=0.04).

Conclusion:

EFT thickness is associated with LV systolic synchrony in patients without BBB.

Changes in left ventricular synchrony and systolic function in dilated cardiomyopathy patients with fragmented QRS complexes

AIMS

Fragmented QRS (f-QRS) complexes are associated with adverse cardiovascular events in patients with coronary heart disease; however, the effects on patients with dilated cardiomyopathy (DCM) remain elusive. This study is to investigate the changes of left ventricular (LV) synchrony and systolic function in DCM patients with f-QRS complexes.

METHODS AND RESULTS

Twenty DCM patients with f-QRS complexes and 29 DCM patients without f-QRS (n-QRS) complexes were enrolled. The LV segmental longitudinal, radial and circumferential time to peak strain and general longitudinal systolic strain, radial strain, circumferential strain were measured, respectively, by speckle tracking imaging. The LV segmental standard deviations and maximal differences were also calculated. The LV dyssynchrony was defined as the time in peak anteroseptal wall to posterior wall strain >130 ms or longitudinal strain delay index >25%. The mean QRS durations in f-QRS and n-QRS groups were not different (P = ns). The incidence of LV dyssynchrony was 15/20 (75%) vs. 5/29 (17%) in two groups (P < 0.01). Two patients died of sudden death in f-QRS group during 2 years follow-up; however, no death in n-QRS group (P < 0.05). Patients in f-QRS group showed worsening LV dyssynchrony in f-QRS group after 2 years follow-up (P < 0.05). Overall, LV function was comparable at baseline (P = ns), but had significantly worsened only in the f-QRS group (P < 0.05).

CONCLUSION

The f-QRS complex is significantly associated with LV dyssynchrony in DCM patients and can be used as a reliable index to evaluate ventricular synchrony and predict the prognosis in DCM patients with narrow QRS complexes.

Biventricular Pacemakers in Patients With Heart Failure

Patients with heart failure may benefit from implantation of a biventricular pacemaker. This article discusses the indications for biventricular pacemaker implantation and the assessment of patients with biventricular pacemakers. Biventricular pacemakers require more assessments than do traditional single- or dual-chamber pacemakers.

Long term impact of cardiac contractility modulation on QRS duration

BACKGROUND AND PURPOSE

Cardiac contractility modulation (CCM) is an implantable device treatment for heart failure with reduced ejection fraction. CCM therapy improves patient functional status but its effect on intra-ventricular conduction remains unknown.

METHODS

70 patients treated with CCM between 12/2002 and 5/2013 had 12-vector-ECG recordings made at baseline and final follow-up visits. QRS complex duration was measured at each time point.

RESULTS

Mean follow-up was 2.8 years. Mean QRS duration was unchanged from baseline (112.0 ms) to last follow up (112.9 ms, p=n.s.). These results are strikingly different from comparative published data of several studies with heart failure patients without CCM, consistently indicating an increase in QRS duration (6.0-23.4 ms) over a similar time period.

CONCLUSIONS

CCM prevents chronic ventricular depolarization delay that occurs in heart failure and that is associated with poorer outcomes. This supports the safety of long-term CCM therapy and suggests a possible long-term benefit in maintaining QRS duration.

Right ventricular dyssynchrony in idiopathic pulmonary arterial hypertension: determinants and impact on pump function

BACKGROUND

Right ventricular (RV) dyssynchrony has been described in pulmonary arterial hypertension (PAH), but no evidence is available on its morphologic determinants and its effect on systolic function. The aim of this study was to evaluate the morphologic determinants of RV dyssynchrony by echocardiographic and cardiac magnetic resonance imaging and its effect on systolic function.

METHODS

In 60 consecutive idiopathic PAH (IPAH) patients with narrow QRS, RV dyssynchrony was evaluated by 2D speckle-tracking echocardiography, calculating the standard deviation of the times to peak systolic strain for the four mid-basal RV segments (RV-SD4). Patients were grouped by the median value of RV-SD4 (19 milliseconds) and compared for RV remodeling and systolic function parameters, WHO class, pulmonary hemodynamics and 6-minute walk test (6MWT).

RESULTS

Despite similar pulmonary vascular resistance and mean pulmonary arterial pressure, patients with RV-SD4 at >19 milliseconds had advanced WHO class and worse 6MWT, RV hemodynamics, RV remodeling and systolic function parameters compared with patients at ≤19 milliseconds. The morphologic determinants of RV dyssynchrony resulted RV end-diastolic area, LV diastolic eccentricity index and RV mass volume ratio (r = 0.69, r(2) = 0.47, p < 0.0001). Finally, we found a significant inverse correlation between RV mid-basal segments post-systolic shortening time and cardiac index (r = -0.64, r(2) = 0.41, p = 0.001), accounting for the significant correlation between RV-SD4 and cardiac index (r = 0.57, r(2) = 0.32, p = 0.003).

CONCLUSIONS

In IPAH with narrow QRS, RV dyssynchrony is associated with RV dilation and eccentric hypertrophy pattern, suggesting a role of segmental wall stress heterogeneity as the major determinant of mechanical delay. Post-systolic shortening, as inefficient contraction, contributes to pump dysfunction.

Speckle-tracking echocardiography elucidates the effect of pacing site on left ventricular synchronization in the normal and infarcted rat myocardium

Background

Right ventricular (RV) pacing generates regional disparities in electrical activation and mechanical function (ventricular dyssynchrony). In contrast, left ventricular (LV) or biventricular (BIV) pacing can improve cardiac efficiency in the setting of ventricular dyssynchrony, constituting the rationale for cardiac resynchronization therapy (CRT). Animal models of ventricular dyssynchrony and CRT currently relay on large mammals which are expensive and not readily available to most researchers. We developed a methodology for double-site epicardial pacing in conscious rats. Here, following post-operative recovery, we compared the effects of various pacing modes on LV dyssynchrony in normal rats and in rats with ischemic cardiomyopathy.

Methods

Two bipolar electrodes were implanted in rats as follows: Group A (n = 6) right atrial (RA) and RV sites; Group B (n = 7) RV and LV sites; Group C (n = 8) as in group B in combination with left coronary artery ligation. Electrodes were exteriorized through the back. Following post-operative recovery, two-dimensional transthoracic echocardiography was performed during pacing through the different electrodes. Segmental systolic circumferential strain (Ecc) was used to evaluate LV dyssynchrony.

Results

In normal rats, RV pacing induced marked LV dyssynchrony compared to RA pacing or sinus rhythm, as measured by the standard deviation (SD) of segmental time to peak Ecc, SD of peak Ecc, and the average delay between opposing ventricular segments. LV pacing and, to a greater extend BIV pacing diminished the LV dyssynchrony compared to RV pacing. In rats with extensive MI, the effects of LV and BIV pacing were markedly attenuated, and the response of individual animals was variable.

Conclusions

Rodent cardiac pacing mimics important features seen in humans. This model may be developed as a simple new tool to study the pathophysiology of ventricular dyssynchrony and CRT.

Mechanical dyssynchrony after cardiac resynchronization therapy for severely symptomatic heart failure is associated with risk for ventricular arrhythmias

BACKGROUND

Risk factors for ventricular arrhythmias after cardiac resynchronization defibrillator therapy (CRT-D) for severely symptomatic heart failure are of clinical importance but are not clearly defined. The objective of this study was to test the hypothesis that mechanical dyssynchrony after CRT-D is a risk factor for ventricular arrhythmias.

METHODS

A total of 266 consecutive CRT-D patients with class III or IV heart failure, QRS duration ≥120 msec, and ejection fractions ≤ 35% were prospectively studied. Dyssynchrony was assessed before and 6 months after CRT-D using speckle-tracking radial strain anteroseptal-to-posterior wall delay, predefined as ≥130 msec. Ventricular arrhythmias were predefined as appropriate antitachycardia pacing or shock, and the combined end point of ventricular arrhythmias, death, transplantation, or left ventricular assist device implantation was followed over 2 years.

RESULTS

Of the initial 266 patients, 11 died, five underwent transplantation, three received left ventricular assist devices before their 6-month echocardiographic examinations, 19 (7%) had inadequate speckle-tracking at 6-month follow-up, and 27 (10%) were lost to follow-up. Accordingly, the study group consisted of 201 patients. Dyssynchrony after CRT-D was observed in 79 (39%) and was associated with a significantly higher ventricular arrhythmic event rate: 21% (P < .001) with persistent dyssynchrony and 35% (P < .001) with new dyssynchrony, compared with 8% with no dyssynchrony after CRT-D. The combined end point of ventricular arrhythmias, death, transplantation, or left ventricular assist device implantation was significantly associated with dyssynchrony after CRT-D (hazard ratio, 2.53; 95% confidence interval, 1.49-4.28; P = .001). Dyssynchrony after CRT-D was associated with ventricular arrhythmias or death in patient subgroups by cardiomyopathy type, QRS width, and morphology (P < .05 for all).

CONCLUSIONS

Persistent or new radial dyssynchrony after CRT-D in severely symptomatic patients with heart failure with widened QRS complexes and reduced ejection fractions was associated with an increased rate of ventricular arrhythmias or death and appears to be a marker for a less favorable prognosis.

Left ventricular systolic function and systolic asynchrony in patients with septic shock and normal left ventricular ejection fraction

Few studies were performed to investigate the association between tissue Doppler imaging parameters about left ventricular (LV) systolic function and LV systolic asynchrony and prognosis in patients with septic shock and normal LV ejection fraction (LVEF). This prospective study was performed from January 2010 to April 2012 in a medical intensive care unit. Fifty-one patients with septic shock and LVEF greater than or equal to 50% were analyzed. The clinical variables and transthoracic echocardiography data were obtained on admission. The mean value of the peak myocardial systolic velocity (Sm-mean) was measured in the four LV basal segments. Tissue Doppler imaging-based parameter (Ts-SD) was used to evaluate LV intraventricular asynchrony. The 28-day all-cause mortality was 43.1%. The nonsurvivors exhibited higher baseline heart rate and Sm-mean and lower mean arterial blood pressure and Ts-SD. A cutoff value of Sm-mean greater than or equal to 6.2 cm/s in identifying 28-day mortality was determined by the receiver operating characteristic curve analysis. The patients with Sm-mean greater than or equal to 6.2 cm/s or Ts-SD less than 33 ms had higher 28-day mortality. In the Cox multivariate analysis, Sm-mean, Ts-SD, and mean arterial blood pressure emerged as independent predictors for 28-day mortality. We concluded that LV systolic dysfunction and systolic asynchrony assessed by tissue Doppler imaging were associated with improved 28-day all-cause mortality in patients with septic shock and normal LVEF.

Gated SPECT myocardial perfusion imaging, intraventricular synchronism, and cardiac events in heart failure

PURPOSE

The purpose of this study was to evaluate the ability of rest gated SPECT myocardial perfusion imaging (MPI) and intraventricular synchronism, to identify heart failure (HF) patients most likely to experience cardiac events.

METHODS

We studied 165 patients with left ventricular ejection fraction of less than 40%, who were divided in 2 groups according to the diagnosis of coronary artery disease (group 1: 136 patients) or not (group 2: 29 patients). All underwent a rest gated SPECT MPI.

RESULTS

In 160 patients, the MPI was abnormal. Mean summed rest score was 17 ± 6 (group 1) versus 10 ± 6 (group 2), P < 0.0001. Mean volumes showed a marked ventricular dilation, slightly higher among nonischemic. The mean value of the phase-derived SD was 70 ± 19 (group 1) versus 59 ± 21 degrees (group 2), P = 0.016. The histogram bandwidth showed no significant differences. Forty-four (39%) of 114 patients showed some kind of event during the follow-up. The more frequent events were HF progression (13%) and acute coronary syndrome (11%). The highest odds ratios for prediction of events were 1.91 (phase SD), 1.66 (etiology), and 1.55 (summed rest score), although the association was not significant.

CONCLUSIONS

A rest gated SPECT is a valid approach to identify HF patients most likely to experience cardiac events.

Role of echocardiography in the contemporary management of chronic heart failure

Echocardiography is an excellent noninvasive tool for the assessment of ventricular size and both systolic and diastolic function, and it is routinely used in patients with heart failure. This review will discuss the role of echocardiography in heart failure diagnosis, prognostic assessment and in the management of heart failure patients.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Assessment of left ventricular dyssynchrony and cardiac function in patients with different pacing modes using real-time three-dimensional echocardiography: Comparison with tissue Doppler imaging

The aim of this study was to evaluate the left ventricular mechanical dyssynchrony (LVMD) and left ventricular dysfunction of patients in AAI, DDD and VVI pacing modes using real-time three-dimensional echocardiography (RT3DE) and tissue Doppler imaging (TDI). The results from the RT3DE and TDI were subsequently compared. Twenty patients with sick sinus syndrome (SSS) who had undergone the implantation of a dual-chamber pacemaker were enrolled in this study and the pacemakers were programmed to AAI, DDD and VVI modes, sequentially. The RT3DE and TDI parameters were obtained following pacing for 24 h in each mode. With RT3DE, we measured the systolic dyssynchrony indices, including Tmsv₁₆-SD%, Tmsv₁₂-SD%, Tmsv₆-SD%, Tmsv₁₆-Dif%, Tmsv₁₂-Dif% and Tmsv₆-Dif%, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV) and left ventricular ejection fraction (LVEF), respectively. With TDI, we measured the standard deviation and the maximal difference in time from the QRS onset to the peak systolic velocity for 12 left ventricular myocardial segments, i.e. Ts-SD and Ts-Dif, respectively. The results showed that the Tmsv₁₆-SD% and Ts-SD in the AAI mode were significantly lower than those in the DDD and VVI modes (P<0.05); however, there were no significant differences between the DDD and VVI modes (P>0.05). The LVEF in the AAI, DDD and VVI modes was 63.1±8.9, 58.6±11.2 and 57.9±7.6%, respectively (P>0.05). There were negative correlations between the LVEF and Tmsv₁₆-SD% (r, −0.651; P<0.001) and Ts-SD (r, −0.649; P<0.0001). A moderate correlation (r, 0.698; P<0.0001) was observed between Tmsv₁₆-SD% and Ts-SD. The concordance rate between Tmsv₁₆-SD% and Ts-SD for detecting LVMD was 76%. This study showed that DDD and VVI pacing modes induced significant LVMD and a reduction in LVEF, unlike the AAI pacing mode. RT3DE and TDI were capable of objectively evaluating LVMD; however, each method had certain faults. At present, there is a lack of a uniform standard for assessing LVMD; therefore, the use of a variety of techniques and indices is necessary in order to comprehensively evaluate LVMD in patients with different cardiac pacing modes.

Systolic Function and Intraventricular Mechanical Dyssynchrony Assessed by Advanced Speckle Tracking Imaging with N-terminal Prohormone of Brain Natriuretic Peptide for Outcome Prediction in Chronic Heart Failure Patients

OBJECTIVES

The aim of this study was to assess longitudinal systolic function and mechanical synchrony parameters derived from advanced speckle tracking echocardiography (STE) and to determine their correlation with N-terminal prohormone of brain natriuretic peptide (NT-proBNP). Their influence on heart failure (HF) outcomes at a one-year follow-up, not clarified in previous studies, was also examined.

METHODS

Advanced STE was performed from August 2009 to January 2012 in 103 chronic HF patients at the University Kebangsaan Malaysia Medical Center to assess their longitudinal systolic function and synchrony parameters; NT-proBNP blood measurement was taken at the same time.

RESULTS

Longitudinal cardiac velocity; strain; strain rate; displacement; intraventricular mechanical dyssynchrony based on the standard deviation (SD) of time to peak systolic strain rate (Tsr-SD); displacement, and antero-septal to posterior (AS-P) delay were associated with cardiac events. In multivariate analysis, NT-proBNP and AS-P delay were identified as independent predictors for cardiac events. Significant correlations were found between NT-proBNP and longitudinal velocity; displacement; strain; strain rate, and ejection fraction. Log NT-proBNP levels correlated moderately with the SD of time to peak displacement and to peak strain, and there was a small correlation with maximal differences and SD of time to peak velocity. A multiple linear analysis revealed that NT-proBNP levels significantly correlated to age, ejection fraction and velocity.

CONCLUSION

Advanced STE is a promising technique which accelerates the clinical application of the quantification of myocardial function and synchrony. STE parameters and NT-proBNP have the ability to identify patients at higher risk of death and hospitalisation.

Electromechanical dyssynchrony and resynchronization of the failing heart

Patients with heart failure and decreased function frequently develop discoordinate contraction because of electric activation delay. Often termed dyssynchrony, this further decreases systolic function and chamber efficiency and worsens morbidity and mortality. In the mid- 1990s, a pacemaker-based treatment termed cardiac resynchronization therapy (CRT) was developed to restore mechanical synchrony by electrically activating both right and left sides of the heart. It is a major therapeutic advance for the new millennium. Acute chamber effects of CRT include increased cardiac output and mechanical efficiency and reduced mitral regurgitation, whereas reduction in chamber volumes ensues more chronically. Patient candidates for CRT have a prolonged QRS duration and discoordinate wall motion, although other factors may also be important because ≈30% of such selected subjects do not respond to the treatment. In contrast to existing pharmacological inotropes, CRT both acutely and chronically increases cardiac systolic function and work, yet it also reduces long-term mortality. Recent studies reveal unique molecular and cellular changes from CRT that may also contribute to this success. Heart failure with dyssynchrony displays decreased myocyte and myofilament function, calcium handling, β-adrenergic responsiveness, mitochondrial ATP synthase activity, cell survival signaling, and other changes. CRT reverses many of these abnormalities often by triggering entirely new pathways. In this review, we discuss chamber, circulatory, and basic myocardial effects of dyssynchrony and CRT in the failing heart, and we highlight new research aiming to better target and implement CRT, as well as leverage its molecular effects.

Left bundle-branch block: the relationship between electrocardiogram electrical activation and echocardiography mechanical contraction

BACKGROUND

The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently been independently published for both ECG and echocardiography. The relationship between the 2 modalities and the relation to cardiac resynchronization therapy (CRT) response was investigated.

METHODS

Sixty-six patients with LBBB by conventional criteria had a standard 12-lead ECG and 2-dimensional strain echocardiography performed before CRT implantation. Criteria for LBBB by echocardiography included early termination of contraction in one wall and prestretch and late contraction in opposing wall(s). New strict criteria by ECG included QRS duration ≥140 ms (men) or 130 ms (women), QS or rS in leads V1 and V2, and mid-QRS notching or slurring in ≥2 of leads V1, V2, V5, V6, I, and aVL. Response was defined as >15% decrease in left ventricular end-systolic volume after 6 months.

RESULTS

In 64 of 66 patients, ECG analysis was possible. Echo and ECG readings for LBBB presence were concordant in 54 (84%) of 64. Thirty-seven (82%) of 45 patients with LBBB by strict ECG criteria responded to CRT, whereas only 4 (21%) of the 19 patients without LBBB responded (sensitivity 90% and specificity 65%). Thirty-six (95%) of 38 patients with concordance for the presence of LBBB responded to CRT. In patients with concordance for the absence of LBBB, 15 (94%) of 16 did not respond.

CONCLUSION

For the first time, a close relation has been demonstrated between electrical activation by ECG and mechanical contraction by echocardiography. These findings may help identify CRT candidates.

Left ventricular synchronicity is impaired in patients with active acromegaly

Acromegaly is associated with a variety of cardiovascular disturbances such as left ventricular hypertrophy, diastolic cardiac dysfunction, and hypertension. Left ventricular (LV) dyssynchrony means the impairment of synchronicity and is defined as the loss of the simultaneous peak contraction of corresponding cardiac segments. The objective of this study was to investigate whether acromegalic patients have left ventricular dyssynchrony. Dyssynchrony was evaluated in 30 patients with active acromegaly and 30 controls. All the patients and controls were subjected to a tissue synchronization imaging. The time to regional peak systolic tissue velocity (Ts) in LV by the six-basal-six-mid-segmental model was measured on ejection phase TSI images and four TSI parameters of systolic dyssynchrony were computed. All TSI parameters of LV dyssynchrony increased in patients with acromegaly compared to the controls: the standard deviation (SD) of the 12 LV segments Ts (43.5 ± 13.5 vs 26.2 ± 12.5, p < 0.001); the maximal difference in Ts between any 2 of the 12 LV segments (133.3 ± 38 vs 84.6 ± 37.6, p < 0.001); the SD of the 6 basal LV segments (41.1 ± 15.9 vs 25.4 ± 14.8, p = 0.001); and the maximal difference in Ts between any 2 of the 6 basal LV segments (102.6 ± 37.5 vs 65.2 ± 36.9, p = 0.001). In addition, there were significant relationships between the levels of growth hormone/insulin-like growth factor-1 and Ts-SD-12. LV synchronicity has been impaired in patients with acromegaly. Left ventricular dyssynchrony is associated with disease activity and it may contribute to the harmful cardiovascular effects of acromegaly.

Neuroendocrine and haemodynamic changes in single-lead atrial pacing and dual-chamber pacing modes

OBJECTIVES

Neuroendocrine and haemodynamic changes were compared between single-lead atrial (AAI) or dual-chamber (DDD) pacing modes in patients with sick sinus syndrome, in a crossover study.

METHODS

Inpatients scheduled for their first pacemaker implantation were screened for the following inclusion criteria: sick sinus syndrome; intact atrioventricular conduction; normal QRS interval. All study patients were implanted with a dual-chamber pacemaker, programmed for AAI or DDD pacing mode. Patients were allocated randomly to AAI followed by DDD pacing or to DDD followed by AAI pacing, each mode being applied for 72 h. Echocardiographic, electrocardiographic and neuroendocrine parameters were tested at the end of each pacing mode.

RESULTS

From 152 inpatients screened for inclusion, 28 were selected for treatment. Plasma levels of atrial natriuretic peptide (ANP), endothelin, aldosterone and angiotension II were significantly lower, and aortic flow velocity-time integral was significantly higher, in AAI mode than in DDD mode. Aortic pre-ejection interval, interventricular mechanical delay and QRS duration were significantly higher in DDD than in AAI mode.

CONCLUSIONS

In patients with sick sinus syndrome, DDD pacing mode can induce neuroendocrine system activation, and left ventricular dysfunction and dyssynchrony. These findings discourage the routine use of DDD pacing in patients with sick sinus syndrome.

Left ventricular systolic and diastolic dyssynchrony assessed by phase analysis of gated SPECT myocardial perfusion imaging: a comparison with speckle tracking echocardiography

OBJECTIVE

The objective of this study was to compare left ventricular (LV) systolic and diastolic dyssynchrony parameters measured by phase analysis on gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with those measured by speckle tracking echocardiography (STE).

MATERIALS AND METHODS

Two patient groups were enrolled from the Chang Bing Show Chwan Memorial Hospital. The systolic group consisted of patients with reduced LV ejection fraction (LVEF) of <50 % as assessed by routine echocardiography. The diastolic group consisted of patients with normal LVEF (>50 %) and diastolic dysfunction according to routine echocardiography (E/A <1, E/E' >8). LV systolic and diastolic dyssynchrony parameters were calculated using STE as the maximal peak-time delay between peak radial strains of two opposing LV walls and as the standard deviation of the time to peak radial strains in 6 mid-LV segments. All of the patients had gated SPECT MPI within 6 ± 11 days post STE. Phase analysis was performed on the resting gated SPECT MPI images to calculate systolic and diastolic phase standard deviation and phase histogram bandwidth as markers of LV systolic and diastolic dyssynchrony, respectively.

RESULTS

Fifty-two consecutive patients (40 men, mean age = 66 ± 13 years, LVEF = 34.4 ± 10.2 %) were enrolled in the systolic group, whereas 30 consecutive patients (15 men, mean age = 69 ± 11 years, LVEF = 72.3 ± 4.7 %, E/A all <1, E/E' = 11.7 ± 2.2) were enrolled in the diastolic group. LV systolic and diastolic dyssynchrony parameters measured by phase analysis of gated SPECT MPI and STE were correlated well in both systolic and diastolic groups, respectively.

CONCLUSION

Phase analysis on gated SPECT MPI showed good correlations with STE and is suitable for the assessment of LV systolic and diastolic dyssynchrony. As assessed with the phase analysis and STE techniques, the patients with severe LV systolic dysfunction had severe LV systolic dyssynchrony, but the patients with LV diastolic dysfunction were not necessarily with LV diastolic dyssynchrony, indicating that the LV diastolic dyssynchrony parameters characterized independent mechanisms of LV regional diastolic function.

Prognostic value of QRS duration after transcatheter aortic valve implantation for aortic stenosis using the CoreValve

Transcatheter aortic valve implantation (TAVI) is effective in treating severe aortic stenosis in high-risk surgical patients. We evaluated the value of the QRS duration (QRSd) in predicting the mid-term morbidity and mortality after TAVI. We conducted a prospective cohort study of 91 consecutive patients who underwent TAVI using the CoreValve at our teaching hospital cardiology unit in 2008 to 2010 who survived to hospital discharge; 57% were women, and their mean age was 84 ± 7 years. The QRSd at discharge was used to classify the patients into 3 groups: QRSd ≤120 ms, n = 18 (20%); QRSd >120 ms but ≤150 ms, n = 30 (33%); and QRSd >150 ms, n = 43 (47%). We used 2 end points: (1) all-cause mortality and (2) all-cause mortality or admission for heart failure. After a median of 12 months, the normal-QRSd patients showed a trend toward, or had, significantly better overall survival and survival free of admission for heart failure compared with the intermediate-QRSd group (p = 0.084 and p = 0.002, respectively) and the long-QRSd group (p = 0.015 and p = 0.001, respectively). The factors significantly associated with all-cause mortality were the Society of Thoracic Surgeons score, aortic valve area, post-TAVI dilation, acute kidney injury, hospital days after TAVI, and QRSd at discharge. On multivariate analysis, QRSd was the strongest independent predictor of all-cause mortality (hazard ratio 1.036, 95% confidence interval 1.016 to 1.056; p <0.001) and all-cause mortality or heart failure admission (hazard ratio 1.025, 95% confidence interval 1.011 to 1.039; p <0.001). The other independent predictors were the Society of Thoracic Surgeons score, acute kidney injury, and post-TAVI hospital days. In conclusion, a longer QRSd after TAVI was associated with greater morbidity and mortality after 12 months. The QRSd at discharge independently predicted mortality and morbidity after TAVI.

Circulating microRNA changes in heart failure patients treated with cardiac resynchronization therapy: responders vs. non-responders

AIMS

MicroRNAs (miRNAs) play an important role in the pathogenesis of structural alterations of the failing heart through their ability to regulate negatively the expression levels of genes that govern the process of adaptive and maladaptive cardiac remodelling. We studied whether LV reverse remodelling after CRT was associated with changes of circulating miRNAs in patients with heart failure (HF) and dyssynchrony.

METHODS AND RESULTS

A prospective, non-randomized self-control trial was performed in 81 patients with HF eligible for CRT. At baseline, to select the HF miRNA profile, we evaluated the expression of 84 miRNAs (implicated in the pathogenesis of structural alterations of the failing heart) in three groups of patients: healthy subjects (healthy group, n = 15); patients with HF (HF group, n = 81); and patients without HF matched for age, sex, and concomitant disease with HF patients (control group, n = 60). At 12 months, the selected miRNA profile was evaluated in plasma from responder (n = 55) and non-responder HF patients (n = 26) to CRT. In the test cohort, the HF patients were characterized by lower expression of 48 miRNAs (all P < 0.04) as compared with healthy subjects. In the validation cohort, the HF patients were characterized by lower expression of 24 miRNAs (all P < 0.03) as compared with control patients. At 12 months, 55 patients (68%) were considered responders and 26 non-responders to CRT (32%). Responders showed an increase in expression of 19 miRNAs (all P < 0.03) compared with baseline expression, whereas in the non-responders we observed an increase of six miRNAs (all P < 0.05) compared with baseline expression. At follow-up, miRNAs were differentially expressed between responders and non-responders. The responders were characterized by higher expression of five miRNAs (miRNA-26b-5p, miRNA-145-5p, miRNA-92a-3p, miRNA-30e-5p, and miRNA-29a-3p; P < 0.01 for all) as compared with non-responders.

CONCLUSIONS

In responders, reverse remodelling is associated with favourable changes in miRNAs that regulate cardiac fibrosis, apoptosis, and hypertrophy.

Impacts of mitral E/e' on myocardial contractile motion and synchronicity in heart failure patients with reduced ejection fraction: An exercise-echocardiography study

BACKGROUND

The association between diastolic abnormality and postexercise contractile decompensation is uncertain in heart failure (HF) patients with reduced left ventricular ejection fraction (LVEF).

HYPOTHESIS

The higher mitral E/annular early diastolic velocity (E/e') is relevant to postexercise regional myocardial contractile maladaptation.

METHODS

Seventy HF patients with LVEF <50 % (56 males, 58 ± 15 years) were studied pre- and postexercise using tissue Doppler echocardiography. We evaluated the mean and standard deviation of systolic myocardial velocity (Sm) and electromechanical delay (Ts) of 12 left ventricular segments, and further analyzed the corresponding changes of septal and posterolateral segments.

RESULTS

The higher mitral E/e' was associated with more blunted heterogeneity of Sm and greater ventricular dyssynchrony after exercise. This is due to the posterolateral wall not being able to increase Sm with exercise to the same degree as the septum (decreased posterolateral/septal Sm ratio). Furthermore, the postexercise aggravated difference of Ts between septum and posterolateral segments leads to more dyssynchronous contraction in the higher E/e' groups. An E/e' ≥10 predicted a postexercise posterolateral/septal Sm ≤ 1 (odds ratio [OR]: 5.8, 95% confidence interval [CI]: 1.5-22.6, P = 0.011), and a difference of Ts between septum and posterolateral segments >65 ms (OR: 64, 95% CI: = 6-651, P < 0.001) in HF patients with reduced LVEF in multivariate analysis.

CONCLUSIONS

The higher mitral E/e'-related postexercise maladaptation of myocardial contractile motion and synchronicity suggests the involvement of systolic abnormality in exercise pathophysiology in HF patients with reduced LVEF.